JP3204852B2 - Non-linear dielectric constant measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring a nonlinear dielectric constant of a dielectric material.

[0002]

2. Description of the Related Art In recent years, various types of surface acoustic wave devices, such as surface acoustic wave devices for mobile communication, have been operated at higher frequencies and higher powers, and the dielectric constant of piezoelectric materials used in these devices has been increasing. Is becoming a situation where the non-linear characteristics of can not be ignored. Also, devices utilizing the nonlinear characteristics of materials, such as concorva, are being developed. In recent years, research on thinning has made great progress, and research aimed at application to next-generation ultra-high-density memory has been actively conducted. As described above, as applied research on piezoelectric materials is actively conducted, the evaluation of nonlinear characteristics of dielectric constant and the state of crystallinity of dielectric materials and the polarization state of ferroelectrics are closely related to the nonlinear characteristics of dielectric constant. Observations are becoming increasingly important. Conventionally, to observe the crystallinity of a dielectric material and the state of polarization of a ferroelectric, analysis by X-ray diffraction,
It was generally used for observation of a DE curve by a Sawyer tower circuit.

[0003]

However, with the conventional X-ray diffraction method or the method using the Sawyer tower circuit, it is impossible to measure the micro distribution of the polarization of the ferroelectric or the micro distribution of the nonlinear constant of the dielectric constant. Was.

An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a non-linear dielectric constant measuring apparatus capable of observing a micro-distribution of a non-linear dielectric constant and a micro-distribution of a crystal state and a polarization of a dielectric substance.

[0005]

According to a first aspect of the present invention, there is provided a non-linear dielectric constant measuring apparatus according to the first aspect of the present invention, wherein a non-linear dielectric constant measuring device has a first surface and a second surface which oppose each other. What is claimed is: 1. A non-linear dielectric constant measuring device for measuring a dielectric constant, comprising: a first electrode formed on a first surface of the dielectric; and a tip provided to be in contact with a second surface of the dielectric. A voltage applying means connected to the first electrode and the second electrode for applying an AC signal having a predetermined frequency to a minute region of the dielectric; And an LC resonance circuit including an inductor and a capacitor in a minute region of a dielectric sandwiched between the capacitor and the second electrode, and the AC signal is applied to the minute region of the dielectric. When the frequency of the AC signal and the minute area An oscillating means for generating an oscillating signal whose oscillation frequency changes in accordance with the non-linear dielectric constant, and a signal having an amplitude corresponding to the frequency of the alternating-current signal and the non-linear dielectric constant of the minute area by frequency-demodulating the oscillating signal And demodulating means for outputting a non-linear dielectric constant in a minute region of the dielectric based on the electric signal.

According to a second aspect of the present invention, there is provided a nonlinear dielectric constant measuring apparatus,
A non-linear dielectric constant measuring device for measuring a non-linear dielectric constant in a minute region which is a part of a dielectric having a first surface and a second surface opposed to each other, wherein the device is formed on a first surface of the dielectric. A first electrode, a second electrode made of a transparent material formed on a second surface of the dielectric, and a first electrode connected to the first electrode and the second electrode. Voltage applying means for applying an AC signal having a predetermined frequency to a region, light irradiating means for irradiating a light beam to a minute region of the dielectric via the second electrode, and when the light beam is irradiated A photoelectric conversion unit that photoelectrically converts reflected light reflected from the minute region of the dielectric and outputs an electric signal, and measures a nonlinear dielectric constant of the minute region of the dielectric based on the electric signal. It is characterized by the following.

According to a third aspect of the present invention, there is provided a nonlinear dielectric constant measuring apparatus,
The nonlinear dielectric constant measuring apparatus according to claim 1 or 2,
Detecting means for synchronously detecting the electric signal based on the AC signal and outputting a DC signal corresponding to the amplitude of the electric signal; and a non-linear dielectric in a minute region of the dielectric based on the DC signal. It is characterized by measuring the rate.

According to a fourth aspect of the present invention, in the non-linear dielectric constant measuring apparatus according to the first aspect, the resonance circuit has a cylindrical shape having two opposed bottom surfaces. A conductor case having one bottom surface of the cylindrical shape short-circuited and terminated and having an opening in the other bottom surface, and connected to the center of one bottom surface of the conductor case;
And a column-shaped second electrode provided in the conductor case such that the distal end extends from the connection portion along the axial center of the conductor case to the opening. Is a reentrant cavity resonator in which the other bottom surface is in contact with the top surface of the dielectric.

According to a fifth aspect of the present invention, there is provided a nonlinear dielectric constant measuring apparatus,
5. The non-linear dielectric constant measuring apparatus according to claim 1, further comprising: moving the dielectric in a one-dimensional direction or a two-dimensional direction such that the second electrode scans on a second surface of the dielectric. A moving means for moving by means of.

According to a sixth aspect of the present invention, there is provided a nonlinear dielectric constant measuring apparatus,
The nonlinear dielectric constant measuring apparatus according to claim 2 or 3,
Further, a moving means for moving the dielectric in a one-dimensional direction or a two-dimensional direction perpendicular to the light beam irradiated by the light irradiating means is provided.

[0011]

In the nonlinear dielectric constant measuring apparatus according to the first aspect, the voltage applying means applies the AC signal having a predetermined frequency to the first electrode and the second electrode, so that the voltage is applied to the first electrode and the second electrode. The AC signal is applied to a minute area of the body. The oscillating means generates an oscillating signal whose oscillation frequency changes according to the frequency of the AC signal and the nonlinear dielectric constant of the minute region when the AC signal is applied to the minute region of the dielectric. Next, the demodulation means:
The oscillation signal is frequency-demodulated, and a signal having an amplitude corresponding to the frequency of the AC signal and the nonlinear dielectric constant of the minute region of the dielectric is output as an electric signal. Then, based on the electric signal, a nonlinear dielectric constant in an electric region of the minute region of the dielectric is measured.

According to a second aspect of the present invention, in the nonlinear dielectric constant measuring apparatus, the voltage applying means applies the AC signal to the first electrode and the second electrode, so that the dielectric material has a small size. The AC signal is applied to the region.
Thus, the light reflectance of the minute region of the dielectric changes according to the AC signal and the nonlinear dielectric constant of the minute region of the dielectric. When the light irradiating unit irradiates a light beam to the minute region of the dielectric via the second electrode made of the transparent material, the minute region of the dielectric changes in the light reflectance. A light beam having a corresponding intensity is reflected as reflected light. Next, the photoelectric conversion unit photoelectrically converts the reflected light reflected from the minute region of the dielectric to output an electric signal. Then, the nonlinear dielectric constant in the optical region of the minute region of the dielectric is measured based on the electric signal.

Further, in the nonlinear dielectric constant measuring apparatus according to claim 3, the detecting means synchronously detects the electric signal based on the AC signal and outputs a DC signal corresponding to the amplitude of the electric signal. I do. Then, the nonlinear dielectric constant of the minute region of the dielectric is measured based on the DC signal.

Preferably, the resonance circuit has a cylindrical shape having two bottom surfaces opposed to each other, and one of the bottom surfaces of the cylindrical shape is short-circuited. A conductor case terminated at the other end and having an opening at the other bottom surface, and connected to the center of one bottom surface of the conductor case, and the tip portion is formed at the opening along the axial center of the conductor case from the connection portion. A second electrode having a columnar shape provided in the conductor case so as to extend to the conductor case, and the other bottom surface of the conductor case is in contact with the upper surface of the dielectric. is there.

According to a fifth aspect of the present invention, in the nonlinear dielectric constant measuring apparatus according to the first, third, or fourth aspect, the moving means may be such that the second electrode is a second surface of the dielectric. The dielectric is moved in a one-dimensional or two-dimensional direction so as to scan above. This makes it possible to measure the distribution of the nonlinear dielectric constant in a linear or planar electrical region on the surface of the dielectric.

According to a sixth aspect of the present invention, in the nonlinear dielectric constant measuring apparatus, the moving means of the nonlinear dielectric constant measuring apparatus is perpendicular to the light beam irradiated by the light irradiating means. The above dielectric is placed in one-dimensional direction or 2
Move in the dimension direction. This makes it possible to measure the distribution of the nonlinear dielectric constant in an optical region on a straight line or a plane on the surface of the dielectric.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. <Basic Circuit> FIG. 1 is a block diagram showing a basic circuit of a nonlinear dielectric constant measuring apparatus according to the present invention.

The nonlinear dielectric constant measuring apparatus shown in FIG. 1 generates (a) an AC voltage Vp having a frequency fp,
An AC power supply 9 that generates an AC electric field Ep in the minute region 2a of the dielectric sample 2 by applying the AC voltage Vp to the electrode 4 and the electrode 4, and outputs the AC voltage Vp as a reference signal; 4 and a minute area 2a interposed between the measurement electrodes 50, a resonance circuit section 10 including a capacitor section 1 constituted by the electrodes 4 and the measurement electrodes 50. Electrode 50
An oscillator 20 for generating an oscillation signal whose oscillation frequency changes in accordance with the frequency fp and the third-order dielectric constant ε ₃ of the minute region 2a when applied to (c); An FM demodulation circuit 26 for demodulating and outputting as a demodulated signal a signal having an amplitude corresponding to the frequency fp and the third-order permittivity ε ₃ of the minute area 2a; and (d) the demodulated signal based on the reference signal. And a lock-in amplifier 27 which synchronously detects the frequency fp and outputs a DC signal having an amplitude corresponding to the tertiary dielectric constant ε ₃ of the minute region 2a. characterized by being configured to measure the next permittivity epsilon _3.

The configuration of the basic circuit shown in FIG. 1 will be described below in detail with reference to the drawings.

As shown in FIG. 1, the resonance circuit 10
Is composed of a dielectric sample 2, an electrode 4, a measurement electrode 50, a mechanism 7, and a coil 6. The dielectric sample 2 has substantially parallel upper and lower surfaces, and the dielectric sample 2
The electrode 4 is formed on the lower surface of the substrate. The measurement electrode 50 is formed of a conductor having a sharp tip 50 a, and is fixed such that the tip 50 a contacts the upper surface of the dielectric sample 2. The dielectric sample 2, the electrode 4, and the measuring electrode 50
Constitutes the capacitor section 1. The mechanism section 7 includes an insulating section 8 formed on the upper surface, mounts and holds the dielectric sample 2 on its surface, and responds to a control signal from a mechanism control section 25 to control the dielectric sample. The dielectric sample 2 is moved in the one-dimensional direction or the two-dimensional direction while maintaining the state in which the tip part 50a of the measurement electrode 50 is in contact with the upper surface of the dielectric sample 2. Further, the coil 6 has an inductance L, one end of which is connected to the measuring electrode 50 and the input end of the negative resistance circuit 5, while the other end is connected to the electrode 4.
Further, the AC power supply 9 applies the AC voltage Vp to the measurement electrode 5.
0 and the electrode 4, the measurement electrode 50
An AC electric field Ep is generated in the minute area 2a of the dielectric sample 2 located between the electrode 4 and the electrode 4, and the AC voltage Vp is output to the lock-in amplifier 27 as a reference signal. In the resonance circuit section 10 configured as described above, the measurement electrode 5
0, the electrode 4, and the minute region 2a of the dielectric sample 2 sandwiched between the electrode 50 and the tip 50a of the measurement electrode 50 forms a capacitance Cs.
As described above, since the coil 6 is connected in parallel with the capacitance Cs, the capacitance Cs and the coil 6 form an LC resonance circuit. This L
The C resonance circuit is connected to the negative resistance circuit 5 and the oscillator 20
Is configured. The oscillator 20 oscillates and generates an oscillating signal that is frequency-modulated according to a change in the capacitance Cs, and outputs the oscillated signal to the FM demodulation circuit 26 as described in detail below. The FM demodulation circuit 26 demodulates the frequency-modulated oscillation signal and outputs the demodulated signal to the lock-in amplifier 27.

As shown in FIG. 2, the lock-in amplifier 27 includes input terminals T1 and T2, an amplifier 271, a waveform shaper 272, in-phase distributors 273 and 274, a 90-degree phase shifter 275, Mixers 277a and 277b
, Low-pass filters 278a and 278b, and output terminals T3 and T4. The amplifier 271 amplifies the demodulated signal input through the input terminal T1 and outputs the signal to the in-phase distributor 273. The in-phase distributor 273 distributes the amplified demodulated signal in-phase to the mixer 277 a and the mixer 2.
77b. On the other hand, the waveform shaper 272 shapes the reference signal input via the input terminal T2 into a square wave, and outputs the square wave to the in-phase distributor 274. The in-phase distributor 274 distributes the reference signal output from the waveform shaper 272 in phase, and outputs the reference signal to the mixer 277 b and the 90-degree phase shifter 275. 9
The 0-degree phase shifter 275 shifts the phase of the reference signal by 90 degrees at the frequency of the reference signal and outputs the resultant signal to the mixer 277a. The mixer 277a multiplies and mixes the demodulated signal with a reference signal shifted by 90 degrees, converts the demodulated signal into a signal having a frequency of the sum and difference of the frequency of the demodulated signal and the frequency of the reference signal, Output to the pass filter 278a. The low-pass filter 278a allows only the DC signal of the input mixed signal to pass and outputs the output voltage V through the output terminal T3.
and outputs the a ₁ to the display control unit 28. The mixer 277b
The reference signal and the demodulated signal are multiplied and mixed, converted into a signal having a frequency of the sum and difference between the frequency of the demodulated signal and the frequency of the reference signal, and output to the low-pass filter 278b. The low-pass filter 278b allows only the DC signal of the input mixed signal to pass, and
And outputs the output voltage Va ₂ to the display control unit 28 via.
Here, the voltage Va ₁ output from the low-pass filter 278a is obtained by multiplying the demodulated signal and the reference signal in phase by mixing the demodulated signal with the demodulated signal by shifting the phase of the reference signal by 90 degrees. The absolute value of the voltage after filtering is | Va
And | is the phase difference between the demodulated signal and the reference signal. Similarly, the voltage Va ₂ output from the low-pass filter 278b is expressed by Expression 2.

[0022]

[Equation 1] Va ₁ = │Va│ · sin φ

[Equation 2] Va ₂ = │Va│ · cos φ

The display control unit 28 includes a lock-in amplifier 27
Output voltage Va ₁ and the output voltage Va ₂ Metropolitan output voltage │Va│ and the phase difference φ the following equation (3) from each input from the number 4
And the output voltage of the lock-in amplifier 27 |
Control is performed so that a measurement value designated from among Va│, Va ₁ , and Va ₂ and the position signal input from the mechanism control unit 25 is displayed on the display screen of the display 29. In response, the display 29 displays each value of each parameter according to the instruction signal of the display control unit 28.

[0024]

| Va | = √ (Va ₁ ² + Va ₂ ² )

## EQU4 ## φ = tan ⁻¹ (Va ₁ / Va ₂ )

In the nonlinear dielectric constant measuring apparatus having the basic circuit constructed as described above, the sine wave having the frequency fp is applied to the measuring electrode 50 and the electrode 4 by the AC power supply 9 in the minute area 2a of the dielectric sample 2. When the AC voltage Vp is applied, an AC electric field Ep which is a sine wave having an amplitude proportional to the amplitude of the AC voltage Vp and the same frequency as the frequency fp of the AC voltage Vp is generated in the minute area 2a.
The AC voltage Vp and the AC electric field Ep can be expressed by Expressions 6 and 7 using the angular frequency ωp expressed by Expression 5. Here, Vp ₀ is the amplitude of the AC voltage Vp, and Ep ₀ is the AC electric field E
The amplitude of p.

[0026]

Ωp = 2πfp

Vp = Vp ₀ cosωp

[Equation 7] Ep = Ep ₀ cosωp

Further, the dielectric constant εt of the small region 2a upon application of the alternating voltage Vp, as is known, the alternating electric field Ep and secondary dielectric constant epsilon ₂ and third order dielectric constant epsilon ₃ quartic Using the dielectric constant ε ₄ of the following formula, it is expressed by the following equation 8.

[0028]

８t = ε ₂ + ε ₃ Ep + (１ ／) ε ₄ Ep ²

Here, Equation 8 can be derived as follows. When the electric flux density and the electric field of the dielectric sample 2 when an electric field is applied to the dielectric sample 2 are D and E, respectively, the internal energy stored per unit volume of the dielectric sample 2;
Assuming that the electric enthalpy is U and H, respectively, and the derivatives of the electric flux density D, the electric field E, the internal energy U and the electric enthalpy H are dD, dE, dU and dH, respectively, the following equations 9 and 10 are obtained. Holds.

[0030]

## EQU9 ## dU = EdD

H = U-ED

From the above equations (9) and (10), the differential dH is expressed by the following equation (11). Therefore, the electric flux density D is represented by Expression 12.

[0032]

## EQU11 ## dH = -DdE

D = -∂H / ∂E

Next, when the electric enthalpy H is Taylor-expanded to the fourth-order term at the origin as a function of the electric field E, the electric enthalpy H is given by the following equation (13).

[0034]

H = (1/2) (∂ ² H / ∂E ² ) ₀ E ² + (1/6) (∂ ³ H /
∂E ³ ) ₀ E ³ + (1/24) (∂ ⁴ H / ∂E ⁴ ) ₀ E ⁴

Here, the zero-order term is set to 0 by setting the energy stored in the field when the electric field E = 0 to zero. In addition, the first-order term becomes zero from the fact that the electric flux density D = 0 when the electric field E = 0 and the equation (12). Further, the electric flux density D is expressed by the following Expression 14 from Expressions 12 and 13.

[0036]

D = − (∂ ² H / ∂E ² ) ₀ E- (1/2) (∂ ³ H / ∂
E ³ ) ₀ E ^2- (1/6) (∂ ⁴ H / ∂E ⁴ ) ₀ E ³ = ε ₂ E + (１) ε ₃ E ² + (１)) ₄ E ³

Here,-(∂ ² H / ∂E ² ) ₀ = ε ₂ , − (∂ ³
H / ∂E ³ ) ₀ = ε ₃ and − (∂ ⁴ H / ∂E ⁴ ) ₀ = ε ₄ .
From the above, when the electric enthalpy H is Taylor-expanded, ε ₂ corresponding to the second-order expansion coefficient is called a second-order permittivity, and ε ₃ corresponding to the third-order expansion coefficient is called the third-order dielectric constant. Ε ₄ corresponding to the fourth order expansion coefficient is called a fourth order permittivity. Further, in Equation 14, a case is considered where a minute electric field ΔE corresponding to the oscillation signal is superimposed on the AC electric field Ep. At this time, assuming that the electric flux density corresponding to the AC electric field Ep is Dp and the minute electric flux density corresponding to the minute electric field ΔE is ΔD, Equation 14 can be expressed as the following Equation 15.

[0038]

Dp + ΔD = ε ₂ (Ep + ΔE) + (1/2) ε
₃ (Ep + ΔE) ² + (1/6) ε ₄ (Ep + ΔE) ³

Here, the electric flux density Dp is expressed by the following equation (16). Since the small electric field ΔE is sufficiently smaller than the AC electric field Ep, the term including (ΔE) ² and (ΔE) ³ is 0. And ΔD of the second term in Equation 15 can be expressed as in Equation 17.

[0040]

Dp = ε ₂ Ep + (１) ε ₃ Ep ² + (1/6) ε ₄ Ep ³

ΔD = ε ₂ ΔE + ε ₃ Ep ΔE + (1/2) ε ₄ Ep ² ΔE = {ε ₂ + ε ₃ Ep + (1/2) ε ₄ Ep ² } ΔE = εtΔE

As is apparent from Equation 17, the small electric field ΔE
Equation 8 can be derived as a proportionality coefficient εt between the electric field density ΔD generated by the small electric field ΔE. In this specification, a third-order permittivity ε ₃ , a fourth-order permittivity ε ₄
And the like are referred to as non-linear dielectric constants. In this basic circuit, the responsiveness to an oscillation signal, which is an electric signal, is observed. Therefore, the nonlinear dielectric constant referred to here is a nonlinear dielectric constant in an electric region. In addition, the tertiary dielectric constant ε ₃ is inverted between positive and negative, especially when the direction of the AC electric field Ep and the direction of the polarization P are the same, and when the direction of the AC electric field Ep and the direction of the polarization P are opposite. . Also, in Equation 8, 4
The dielectric constant higher than the next dielectric constant ε ₄ is ignored,
Since the higher-order permittivity is sufficiently smaller than the second-order, third-order, and fourth-order permittivity, there is no effect of ignoring the higher-order permittivity in the following description. In the following description, the mathematical expressions are limited to one dimension in the thickness direction of the dielectric sample 2. Further, since the capacitance Cs formed by the minute region 2a sandwiched between the measurement electrode 50 and the electrode 4 is proportional to the dielectric constant εt, the thickness d of the dielectric sample 2 and the tip of the measurement electrode 50 are Using the positive constant Ce determined by the area and the dielectric sample 2 and Equation 8, the following equation 18 can be used.

[0042]

Cs = Ce (1 / d) {ε ₂ + ε ₃ Ep + (1/2) ε ₄ Ep ² }

Further, the capacitance C expressed by the equation (18)
s can be expressed as in Expression 21 by using a capacitance C ₀ expressed by Expression 19 and a capacitance change amount ΔC expressed by Expression 20. Here, the capacitance C ₀ is a capacitance formed by the minute region 2a sandwiched between the measurement electrode 50, the electrode 4, the measurement electrode 50, and the electrode 4 when the AC voltage Vp is not applied, and The amount ΔC is a capacitance change amount from the capacitance C ₀ when the AC voltage Vp is applied.

[0044]

C ₀ = Ce (1 / d) ε ₂

ＣC = Ce (1 / d) ｛ε ₃ Ep + (1/2) ε ₄ Ep ² △

## EQU21 ## Cs = C ₀ + △ C

By substituting the AC electric field Ep expressed by the equation (7) into the right side of the equation (20), and further transforming it using the formula of the trigonometric function expressed by the equation (22), ΔC can be expressed by the following equation (23). it can.

[0046]

Cos ² (ωp · t) = {1 + cos (2ωp · t)} / 2

Equation 23] △ C = Ce (1 / d ) {ε 4 Ep 0 2/4 + ε 3 Ep 0 cos
(ωp · t) + (ε 4 Ep 0 2/4) cos (2ωp · t)}

Further, Equation 23 is obtained by changing the capacitances ΔC ₂ , ΔC ₃ , which are expressed by the following Equations 24, 25 and 26.
It can be rewritten as Equation 27 using ΔC ₄ . Here, the capacitance change amount ΔC ₂ is a change amount that does not change with time in proportion to the square of the fourth-order permittivity ε ₄ and the amplitude Ep ₀ of the AC electric field Ep, and the capacitance change amount ΔC 2 ₃ is the third dielectric constant ε ₃ and the amplitude E of the AC electric field Ep.
This is a capacitance change amount having an amplitude proportional to p ₀ and having an angular frequency ωp and changing alternately. Further, the capacitance variation △ C ₄ is the fourth-order dielectric constant epsilon ₄ with alternating electric field Ep of the change in capacitance that varies alternately have a and angular frequency 2ωp an amplitude proportional to the square of the amplitude Ep ₀ Quantity.

[0048]

Equation 24] _{△ C 2 = Ce (1 /} d) (ε 4 Ep 0 2/4)

２５C ₃ = Ce (1 / d) ε ₃ Ep ₀ cos (ωp · t)

[Number 26] _{△ C 4 = Ce (1 /} d) (ε 4 Ep 0 2/4) cos (2ωp ·
t)

数 C = △ C ₂ + △ C ₃ + △ C ₄

On the other hand, the capacitor section 1 and the coil 6 constitute an LC resonance circuit as described above, and the resonance frequency f _LC of the LC resonance circuit is expressed by the following equation 28 as is known.

[0050]

F _LC = 1 / {2π√ (L · Cs)} = 1 / [2π√ {L · (C ₀ + ΔC)}]

[0051] Further, the ε ₄ Ep _{0 ^2/4} in the epsilon ₃ Ep ₀ to the number 26 in number 25, since the secondary sufficiently smaller than the dielectric constant epsilon _2, the number 19 to the number 20 from the C ₀ »ΔC is Holds. Therefore, when Expression 28 is rewritten using the approximate expression expressed by Expression 29, the relationship between the capacitance change amount ΔC and the resonance frequency change amount Δf _LC can be expressed as Expression 30.

[0052]

数 (1 + △ C / C ₀ ) = (1 + △ C / C ₀ ) ^-1/2 ≒ 1−
(1/2) (△ C / C ₀ )

数 C / C ₀ = −2 △ f _LC / f _LC

As described above, the resonance frequency f _LC of the LC resonance circuit changes by the resonance frequency change Δf _LC in proportion to the capacitance change ΔC of the capacitance Cs. The resonance circuit section 10 and the negative resistance circuit 5
Since the oscillator 20 is configured, the oscillator 20 has an oscillation frequency f _OSC that is the same frequency as the resonance frequency f _LC.
Oscillates and generates an FM demodulation circuit 26
Output to Here, the resonance frequency f _LC of the LC resonant circuit as described above, since the changes by the capacitance change amount △ proportion to C and resonance frequency variation △ f _LC of the capacitance Cs, the oscillation frequency f _OSC same Then, the capacitance Cs changes in proportion to the capacitance change amount ΔC. Further, as described above, the capacitance change amount ΔC is determined by the third-order dielectric constant ε ₃ and the amplitude Ep _{0 of the} AC electric field Ep.
Amplitude proportional to the square of the amplitude Ep ₀ of the capacitance variation △ C ₃ to have a have an amplitude and angular frequency ωp varies alternately proportional, fourth-order dielectric constant epsilon ₄ with alternating electric field Ep in since the a and having an angular frequency 2ωp including a capacitance variation △ C ₄ which changes alternately, the oscillation signal is proportional to the cubic dielectric constant epsilon ₃ and the AC electric field amplitude Ep ₀ of Ep amplitude And a signal S ₃ having an angular frequency ωp, that is, a frequency fp, and an amplitude proportional to the square of the fourth-order permittivity ε ₄ and the amplitude Ep ₀ of the AC electric field Ep, and having an angular frequency 2ω
p, that is, an oscillation signal frequency-modulated by the signal S ₄ having a frequency of 2 fp. In this case, the frequency deviation of the frequency-modulated oscillation signal, the amplitude of the signal S _3,
Is proportional to the amplitude of the signal S _4.

The FM demodulation circuit 26 performs an FM demodulation process on the oscillating signal to perform a signal S ₃ having a third-order dielectric constant ε ₃ and an amplitude proportional to the amplitude Ep ₀ of the AC electric field Ep and having the frequency fp. And the fourth-order permittivity ε ₄ and the amplitude E of the AC electric field Ep
A demodulated signal including a signal S ₄ having an amplitude proportional to the square of p ₀ and having a frequency of 2 fp is output to a terminal T 1 of the lock-in amplifier 27.

In the lock-in amplifier 27, the mixer 2
77a multiplies and mixes one demodulated signal that has been amplified and distributed in phase with a reference signal that has been waveform-shaped and phase-shifted by 90 degrees, and mixes the sum of the frequency of the demodulated signal and the frequency of the reference signal. And outputs the signal to the low-pass filter 278a.
8a is an output voltage | which is a DC component of the mixed signal.
Va│sinφ is applied to the display control unit 28 via the terminal T3.
Output to On the other hand, the mixer 277b multiplies and mixes the other demodulated signal in-phase distributed with the waveform-shaped reference signal and mixes the resulting signal with a signal having a frequency equal to the sum of the frequency of the demodulated signal and the frequency of the reference signal. And outputs it to the low-pass filter 278b.
Is the output voltage | V, which is the DC component of the mixed signal.
Only a│cosφ is output to the display control unit 28 via the terminal T4.

Here, since the signal S ₃ is a signal having the frequency fp of the reference signal, the mixer 277a and the mixer 277b respectively transmit the reference signal and the frequency f.
and outputs a DC signal which is output voltage │Va│sinφ the output voltage │Va│cosφ that occurs upon mixing by multiplying the signal S ₃ having to p. That is, the output voltage Va ₁
And the output voltage Va ₂ becomes a voltage corresponding to the phase difference φ and the third-order permittivity ε ₃ . Here, in particular, when the third-order dielectric constant ε ₃ is a real number and a positive value, as is apparent from Equation 25, the capacitance change amount ΔC ₃ and the AC electric field Ep change in phase. As is apparent from Equation 30, the capacitance change amount ΔC ₃ is equal to the resonance frequency change amount Δf _LC
And changes in the opposite phase. From the above, the third-order dielectric constant ε ₃
Is a real number and a positive value, the resonance frequency change amount Δf _LC changes in the opposite phase to the AC electric field Ep. Further, since the AC electric field Ep and the AC voltage Vp change in phase, when the third-order dielectric constant ε ₃ is a real number and a positive value, the phase difference φ between the reference signal and the signal S ₃ becomes π. Become. Similarly, when the third-order permittivity ε ₃ is a real number and a negative value, the phase difference φ between the reference signal and the signal S ₃ becomes zero. As described above, when the third-order permittivity ε ₃ is a real number, the phase difference φ between the reference signal and the signal S ₃ takes a value of 0 or π, the output voltage Va ₁ becomes 0, and the output voltage Va _Two
Only output. When the third-order permittivity ε ₃ is positive, the phase difference φ becomes π, and the output voltage Va ₂ is output as a negative value. When the third-order permittivity ε ₃ is negative,
The phase difference φ becomes 0, and the output voltage Va ₂ is output with a positive value.

Next, the display control unit 28 calculates the phase difference φ and the voltage | Va | from the input voltages Va ₁ and Va ₂ , and outputs the position signal input from the mechanism control unit 25 and the voltage V
The display 29 is controlled so that parameters designated from among a ₁ , Va ₂ , | Va | and the phase difference φ are displayed on the display screen of the display 29. In response, the display 29 displays each value of each parameter according to the instruction signal of the display control unit 28.

As described in detail above, an AC electric field Vp is applied to the measurement electrode 50 and the electrode 4 to apply the dielectric sample 2
When is the generation of small regions 2a to alternating electric field Ep, the oscillator 20 generates oscillates an oscillation signal frequency-modulated by a signal containing the signal S _3. Next FM demodulation circuit 26 FM demodulating the oscillating signal to generate a demodulated signal containing the signal S _3. Furthermore, lock-in amplifier 2
7, by synchronous detection of said demodulated signal on the basis of a reference signal having a frequency fp the demodulated signal, proportional to the amplitude of the signal S _3, i.e. the cubic dielectric constant epsilon ₃ and above the small region 2a It outputs a DC signal proportional to the amplitude of the AC voltage Vp. Therefore, by sequentially changing the position of the minute region 2a and measuring the DC signal by the mechanism unit 7 and the mechanism control unit 25, the difference in the third-order dielectric constant ε ₃ in the electrical region of each minute region 2a is obtained. Can be observed by the value of the DC signal. Further, since the nonlinear dielectric constant measuring apparatus having the basic circuit includes the lock-in amplifier 27 and can also output the value of the phase difference φ as described above, the third-order dielectric constant ε ₃ is defined as the absolute value. It can also be observed in phase form. On the other hand, the polarization of a material is given by the volume average value of the micro dipoles that compose it. When this polarization is completely oriented in one direction, the uniaxial anisotropy of the material also becomes the largest, and as a result, The third-order permittivity ε ₃ also becomes maximum. Conversely, when the micro dipole points in a random direction, the polarization becomes zero as a result, and the measurement direction has no directivity, so that the third-order dielectric constant ε ₃ also becomes zero. When the polarization is in the opposite direction, the third-order permittivity ε ₃ changes its sign. Since the above relationship exists between the polarization of the material and the third-order permittivity, the minute region 2a of the dielectric sample 2 is determined based on the measured third-order permittivity ε _3.
The state of polarization at can be observed.

In the above basic circuit, a third-order dielectric constant ε ₃ is measured by using an AC voltage Vp having a frequency fp as a reference signal, but the present invention is not limited to this.
Using a signal having a frequency of 2 fp as a reference signal, 4
It may be configured to determine the next permittivity epsilon _4. As described above, the nonlinear dielectric constant in the electric region can be measured.

Further, since the demodulated signal is synchronously detected using the lock-in amplifier 27, other unwanted noise not synchronized with the reference signal is removed, and the lock-in amplifier 27 is removed.
A signal power to noise power ratio S / N of the DC signal obtained by can be significantly improved, it is possible to further enhance the accuracy of the third-order dielectric constant epsilon ₃ measurements.

In the above basic circuit, the output of the lock-in amplifier 27 is observed. However, the present invention is not limited to this, and the demodulated signal output from the FM demodulation circuit 26 is observed and the Third-order dielectric constant ε in minute region 2a
₃ may be measured. In this case,
The modulation index in the oscillator 20 is set to a value sufficiently smaller than 1, so that the energy of the carrier and the sidebands are substantially included in the carrier, the first upper sideband, and the first lower sideband.
At this time, the amplitude of at least one of the first upper sideband and the first lower sideband is measured by a spectrum analyzer or the like, so that the output voltage Va (absolute value of the DC signal) when the lock-in amplifier 27 is used. ) Can be obtained, and the third-order permittivity ε ₃ can be measured in the same manner as described above. Also, by measuring the amplitude of at least one of the second upper sideband and the second lower sideband with a spectrum analyzer or the like, the fourth-order permittivity ε ₄
Can be measured.

<First Embodiment> FIG. 3 is a block diagram showing the structure of a nonlinear dielectric constant measuring apparatus according to a first embodiment of the present invention. The nonlinear dielectric constant measuring apparatus according to the first embodiment shown in FIG. 3 is characterized in that a resonance circuit section 10a is provided with a reentrant cavity resonator 30 instead of the LC resonance circuit shown in FIG. The nonlinear dielectric constant measuring apparatus of the first embodiment is
The configuration other than the resonance circuit section 10a is configured similarly to the above-described basic circuit. With the configuration as described above, the nonlinear dielectric constant measuring apparatus according to the first embodiment can measure the nonlinear dielectric constant in the electric region. Hereinafter, the configuration of the nonlinear dielectric constant measuring apparatus according to the first embodiment will be described with reference to the drawings.

FIG. 4 is a cross-sectional view of the reentrant cavity resonator 30 when it comes into contact with the dielectric sample 2, and FIG. 5 shows the reentrant cavity resonator 30 as seen from the direction in contact with the dielectric sample 2. It is a top view. The dielectric sample 2 is shown in FIG.
As shown in FIG. 1, similarly to the dielectric sample 2 of FIG. 1, the dielectric sample 2 has substantially parallel upper and lower surfaces, and an electrode 4 is formed on the lower surface of the dielectric sample 2. The reentrant cavity resonator 30 includes a conductor case 31, a center conductor 32, and a connector 40. The conductor case 31 includes a lower bottom surface having an annular contact surface portion 33 in contact with the surface of the dielectric sample 2 and a circular hole 34 formed through the thickness direction to mount the connector 40. And a cylindrical conductor having an upper bottom surface. The center conductor 32 is formed of a columnar conductor, and the axis of the center conductor 32 and the conductor case 3
One end is connected to the conductor case 3 so that the axes of
1 is connected to the center of the upper bottom surface, while the other end is formed so as to be conical and thin, and the leading end thereof comes into contact with the minute region 2a of the dielectric sample 2 with a predetermined contact area. A unit 35 is provided. The connector 40 includes an outer conductor 41, an insulator 42, and a center conductor 43. The center conductor 43 is insulated from the conductor case 31 and has the hole 34.
Penetrate through. The center conductor 43 is connected to the center conductor 32 via the connection conductor 44. The outer conductor 41 is electrically connected to the conductor case, and the connector 40 is fixed to the conductor case 31. With the above configuration, the capacitance Cg is formed by the ring-shaped region 2b which is a part of the dielectric sample 2 sandwiched between the contact surface portion 33 and the electrode 4, and the tip portion 3
The capacitance Cs is formed by the minute region 2a of the dielectric sample 2 sandwiched between the electrode 5 and the electrode 4. Here, the contact area of the tip portion 35 is configured to be sufficiently smaller than the contact area of the contact surface portion 33 in contact with the dielectric sample 2.

As shown in FIG. 3, the AC power supply 9 applies the AC voltage Vp to the conductor case 31 and the electrode 4 of the reentrant cavity resonator 30 so that the minute area 2 a
And the region 2b generates an AC electric field Ep, and outputs the AC voltage Vp to the lock-in amplifier 27 as a reference signal. Further, the mechanism section 7 includes an insulating section 8 formed on the upper surface thereof, the dielectric sample 2 is placed and held on the surface thereof, and in response to a control signal from the mechanism control section 25, The dielectric sample 2 is moved one-dimensionally or two-dimensionally while the tip 35 of the center conductor 32 and the contact surface 33 of the conductor case 31 are kept in contact with the upper surface of the dielectric sample 2. Move in the direction. As described above, the resonance circuit section 10a of the nonlinear dielectric constant measuring apparatus according to the first embodiment is configured. Parts other than the resonance circuit section 10a are configured in the same manner as the above-described basic circuit of FIG.

FIG. 6 shows a reentrant cavity resonator 3 including the capacitor unit 1 and the AC power supply 9 configured as described above.
It is a circuit diagram showing the equivalent circuit of 0. The equivalent circuit of FIG.
One end of the transmission line constituted by the center conductor 32 and the cylindrical side surface of the conductor case 31 which is a ground conductor is short-circuited by the short-circuit surface 36 which is the upper bottom surface of the conductor case 31, and is the other end of the transmission line. The terminal T35, which is the tip portion 35 of the center conductor 32, and the terminal T33, which is the contact surface portion 33 of the conductor case 31, are each a capacitance C.
s and the capacitance Cg are connected to the electrode 4. An AC power supply 9 is connected between the conductor case 31 which is a ground conductor and the electrode 4.

In the non-linear dielectric constant measuring apparatus of the first embodiment configured as described above, the AC power supply 9 applies the AC voltage Vp to the conductor case 31 of the reentrant cavity resonator 30 and the electrode 4. When applied, an alternating electric field Ep is generated in the minute region 2a of the dielectric sample 2 and the region 2b located between the contact surface portion 33 and the electrode 4. Both the minute area 2a and the area 2b are connected to the AC electric field Ep.
As a result, the dielectric constant changes, and the capacitances Cs and Cg change. At this time, since the contact area of the contact surface portion 33 is sufficiently larger than the contact area of the tip portion 35, the capacitance Cg≫the capacitance Cs holds. Further, as shown in FIG. 6, since the capacitance Cg and the capacitance Cs are connected in series, the resonance frequency of the reentrant cavity 30 including the dielectric sample 2 and the electrode 4 changes with the change of the capacitance Cs. However, the influence of the change in the capacitance Cg on the resonance frequency can be ignored.

The above-mentioned reentrant cavity resonator 3
The resonance condition of 0 is given by the following equation 31 as is well known. In Equation 31, Lc is the resonator length of the reentrant cavity resonator 30, vc is the speed of light in vacuum, and Y is the conductor case 31 and the center conductor of the reentrant cavity resonator 30. 32 is a characteristic admittance of the coaxial line when 32 is regarded as a coaxial line, and is represented by the reciprocal of the characteristic impedance Z of the coaxial line represented by Expression 32. Here, a in Equation 32 is the diameter of the center conductor 32, and b is the inner diameter of the conductor case 31. Μ ₀ is the magnetic permeability in a vacuum, and ε ₀ is the dielectric constant in a vacuum.
Furthermore, Equation 31 can be transformed into Equation 33, and Equation 33 can be further transformed as Equation 34. Therefore, from Equation 34, the resonator length Lc is given by Equation 35.

[0068]

Ωr · Cs−Ycot (ωr · Lc / vc) = 0

(32) Z = {1 / (2π)} √ (μ ₀ / ε ₀ ) ln (b / a)

Tan (ωr · Lc / vc) = Y / (ωr · Cs)

Ωr · Lc / vc = tan ⁻¹ {Y / (ωr · Cs)}

Lc = (vc / ωr) tan ^-1 {Y / (ωr · Cs)}

Next, the reentrant cavity resonator 30
Is expressed as in Equation 36, and the angular resonance frequency ωr expressed in Equation 36 and the capacitance Cs expressed in Equation 21 are substituted into Equation 31. Equation 31 is expressed as Equation 37. Is done. Here, in Equation 36, ω ₀ is the angular resonance frequency of the reentrant cavity resonator 30 when the AC voltage Vp is not applied to the dielectric sample 2. Δω is the amount of change in the angular resonance frequency from the angular resonance frequency ω ₀ of the reentrant cavity resonator 30 when the AC voltage Vp is applied to the dielectric sample 2.

[0070]

Ωr = ω ₀ + Δω

(37) (ω ₀ + Δω) (C ₀ + ΔC) −Ycot {(ω ₀ / vc +
Δω / vc) · Lc} = 0

Here, since ω ₀ ≫Δω, C ₀ ≫ΔC, the approximate expression expressed by Expression 38 can be used in Expression 37, and it can be approximated as Δω × ΔC ≒ 0. From the above, Equation 37 can be expressed as Equation 39.

[0072]

38] cot {(ω ₀ / vc + Δω / vc) · Lc} ≒ cot {(ω ₀ /
vc) · Lc} − [cosec ² {(ω ₀ / vc) · Lc}] · (Δω / vc) · Lc

## EQU39 ## ω ₀ C ₀ + ΔωC ₀ + ω ₀ ΔC−Ycot {(ω ₀ / v
c) · Lc} + [Y · cosec ² {(ω ₀ / vc) · Lc}] · (Δω / vc) · Lc
= 0

Equation 39 can be transformed as Equation 40, and Equation 40 can be transformed as Equation 41.

[0074]

Equation 40 Δω [C ₀ + (Lc / vc) Ycosec ² {(ω ₀ / vc) · L
c}] = − ω ₀ · ΔC

Δf / f ₀ = Δω / ω ₀ = −ΔC / [C ₀ + (Lc / vc) Ycosec ² {(ω ₀ / vc) · Lc}]

As described in detail above, when the AC voltage Vp is applied to the conductor case 31 and the electrode 4 of the reentrant cavity resonator 30, the resonance frequency change Δf has a negative slope of the capacitance change ΔC. It is expressed by the following function.
Therefore, the resonance frequency f ₀ of the reentrant cavity resonator 30 changes by the resonance frequency change Δf in proportion to the capacitance change ΔC of the capacitance Cs. Further, the resonance circuit section 10a and the negative resistance circuit 5
Since the oscillator 20a is configured, the oscillator 20a
Oscillates and generates an oscillation signal having an oscillation frequency f _OSC that is the same frequency as the resonance frequency f _0, and outputs the oscillation signal to the FM demodulation circuit 26. Here, as described above, the resonance frequency f ₀ of the reentrant cavity resonator 30 changes by the resonance frequency change Δf in proportion to the capacitance change ΔC of the capacitance Cs, so that the oscillation frequency f _OSC Similarly, the capacitance changes in proportion to the capacitance change ΔC of the capacitance Cs. Further, since the capacitance change amount ΔC is given by Expression 27, the capacitance change amount ΔC has an amplitude proportional to the third-order dielectric constant ε ₃ and the amplitude Ep ₀ of the AC electric field Ep, and changes alternately with the angular frequency ωp. Capacitance change ΔC ₃ , fourth-order permittivity ε ₄ and AC electric field Ep
Including capacitance variation △ C ₄ that varies alternately have a have an amplitude and angular frequency 2ωp proportional to the square of the amplitude Ep _0. Therefore, the oscillation signal has a third order dielectric constant ε ₃ and a signal S having an amplitude proportional to the amplitude Ep ₀ of the AC electric field Ep and having an angular frequency ωp, that is, a frequency fp.
₃ and the fourth order permittivity ε ₄ and the amplitude Ep ₀ of the AC electric field Ep 2
An oscillation signal frequency-modulated by a signal S ₄ having a having an amplitude and angular frequency 2ωp or frequency fp proportional to the multiplication. Therefore, as described above in the description of the basic circuit in FIG. 1, similarly, the tertiary dielectric constant ε ₃ in the electrical region can be measured by demodulating the oscillation signal and performing synchronous detection. tertiary dielectric constant epsilon ₃ of the measurement results based on, can be determined polarization distribution.

In the nonlinear dielectric constant measuring apparatus of the first embodiment, since the reentrant cavity resonator 30 is used, the oscillation frequency of the oscillator 20a is set higher than that of the nonlinear dielectric constant measuring apparatus of the basic circuit. can do. As a result, the maximum frequency shift can be increased, and the third-order permittivity ε ₃ can be measured with higher sensitivity and higher accuracy than the conventional example.

Next, a measurement example using the nonlinear dielectric constant measuring apparatus of the first embodiment will be described. FIG. 7 is a plan view of Z-cut LiNbO ₃ used for the following measurement, and FIG.
7 is a graph showing measurement results obtained by using Z-cut LiNbO ₃ of Example ₁ as a dielectric sample 2. What is Z cut?
It is a crystal cut out on a plane perpendicular to the optical axis.

FIG. 8 shows the output voltage | Va | of the lock-in amplifier 27 at a distance X from X0 on the X-axis measured using the Z-cut LiNbO ₃ of FIG. 7, and the oscillation frequency f _{0 of the} oscillation carrier. FIG. Here, the oscillation carrier is an oscillation signal that is not frequency-modulated when the voltage Vp is applied to the dielectric sample 2.
Thus, the oscillating carrier may change due to a change in capacitance without alternating changes. FIG.
As is clear from FIG. 7, the output voltage | Va | of the lock-in amplifier 27 outputs different values depending on the position on the X-axis. This depends on each position
This shows that the third-order permittivity ε ₃ is different. The oscillating frequency of the oscillating carrier has a maximum value at a position where the distance X from X0 on the X axis is about 3 mm, and decreases as the distance from the position increases. This is because the linear dielectric constant, which is the secondary dielectric constant ε ₂ , is small at the center of the Z-cut LiNbO ₃ used as the dielectric sample 2, or the thickness of the sample is large at the center. It is thought to be. As described above, when using a non-linear dielectric constant measuring apparatus of the first embodiment, by separating the linear dielectric constant can be observed cubic dielectric constant epsilon _3, and the third-order dielectric constant epsilon ₃ is It can be observed that it differs depending on each minute region. Thereby, it is possible to observe that the polarization state of each minute region is different.

FIG. 9 shows a dielectric sample 2 having a different polarization state.
Of the lock-in amplifier 2 at each position when is measured using the nonlinear dielectric constant measuring apparatus of the first embodiment.
7 is a graph schematically showing an output voltage Va ₂ of FIG. As is apparent from FIG. 9, the region where the polarization P1 is distributed from the surface in contact with the electrode 4 of the dielectric sample 2 to the other surface in parallel with the thickness direction of the dielectric sample 2, and the dielectric constant epsilon ₃ is positive region, the output voltage Va ₂ of the lock-in amplifier 27 outputs V2 is a negative voltage. Polarization P
2 is a region distributed in parallel with the thickness direction of the dielectric sample 2 from the other surface of the dielectric sample 2 to the surface in contact with the electrode 4, and the tertiary dielectric constant ε ₃ is negative. in some regions, the output voltage Va ₂ of the lock-in amplifier 27 outputs V1 is a positive voltage. A region where the polarization P3 is distributed in parallel from the surface of the dielectric sample 2 in contact with the electrode 4 to the other surface in the thickness direction of the dielectric sample 2, and the tertiary dielectric constant ε ₃ is positive. In a certain area, the output voltage Va ₂ of the lock-in amplifier 27 outputs a negative voltage V ₂ . As described above, when using a non-linear dielectric constant measuring apparatus of the first embodiment, the dielectric Sample 2 cubic dielectric constant epsilon ₃ has positive and negative regions, third-order dielectric constant epsilon ₃ positive And the region where the third-order dielectric constant ε ₃ is negative, the output voltage Va ₂ of the lock-in amplifier 27 is inverted and outputted, so that the third-order dielectric constant ε ₃ of the region can be easily obtained. Positive or negative can be determined. That is, the direction of polarization in the region can be determined.

<Dielectric Recording / Reading Apparatus> FIG. 10 shows that when the third-order permittivity ε ₃ of the above-mentioned electrical region is positive, the phase difference φ between the signal S ₃ of the demodulated signal and the reference signal becomes π. FIG. 4 is a block diagram of a dielectric recording / reading apparatus utilizing the fact that the phase difference φ between the signal S ₃ and the reference signal becomes 0 when the third-order permittivity ε _{3 of} the electrical region is negative. As will be described in detail later, the dielectric recording / reading apparatus has a dielectric tape 100 in which the polarization of the dielectric film 102 is recorded in the thickness direction and in a direction corresponding to digital signals 1 and 0.
Is a dielectric recording and reading device.

The dielectric recording / reading apparatus shown in FIG. 10 generates (a) an AC electric field Ep in the dielectric film 102 by applying an AC voltage Vp having a frequency fp to the metal film 104 and the measurement electrode 50; An AC power supply 9 for outputting the AC voltage Vp as a reference signal, and (b) the dielectric film 10
The oscillation circuit includes a resonance circuit section 10b including the oscillation frequency 2 and the oscillation frequency changes when the AC voltage Vp is applied to the dielectric film 102 in accordance with the frequency fp and the polarization direction of the dielectric film 102. Oscillator 20b for generating a signal
And (c) demodulating the frequency of the oscillation signal to obtain the frequency f
an FM demodulation circuit 26 that outputs a signal having a phase difference φ corresponding to p and the direction of polarization as a demodulated signal, and (d) detecting a phase difference between the demodulated signal and the reference signal based on the reference signal, A phase detector 56 that outputs a phase difference φ corresponding to the polarization direction of the dielectric film 102, and a phase difference φ corresponding to a digital signal recorded on the dielectric film 102;
Is output.

Hereinafter, the configuration of the dielectric recording / reading apparatus will be described in detail with reference to the drawings.

As shown in FIG. 10, the resonance circuit 10
“b” is composed of the dielectric tape 100, the measurement electrode 50, the tape holders 55a, 55b, 55c, and the coil 6. The dielectric tape 100 is composed of a metal film 104 and a dielectric film 102 made of a ferroelectric material. For example, the dielectric film 102 made of a ferroelectric material is formed on the tape-shaped metal film 104 serving as a tape base. It is formed by close contact formation by a known method such as sputtering. In addition, the dielectric tape 100 is formed as follows.
And a digital signal composed of two types of signals, 0 and 0. When the digital signal is 1, the polarization of the dielectric film 2 is caused by the dielectric film 1 in close contact with the metal film 104.
02 from the one surface 102b to the other surface 102a of the dielectric film 102. When the digital signal is 0, the polarization of the dielectric film 2 is
Polarization is performed so as to be directed from the surface 102b toward the surface 102a. The measurement electrode 50 is formed of a conductor having a conical tip 50 a, and is fixed such that the tip 50 a contacts the surface 102 a of the dielectric film 102. Further, the tape holding portions 55a,
55b and 55c are formed of columnar conductors having a predetermined axial length longer than the width of the dielectric tape 100. The tape holding portion 55a and the tape holding portion 55b can be rotated to face each other so that their axes are parallel to the width direction of the dielectric tape 100 and the dielectric tape 100 is sandwiched between the respective circumferential surfaces. Is provided. Further, the tape holding portion 55c is rotatable so that its axis is parallel to the width direction of the dielectric tape, and presses the dielectric tape 100 at a predetermined pressure in opposition to the distal end portion 50a of the measurement electrode 50. Is provided. The tape holding unit 55a and the tape holding unit 55b rotate the dielectric tape 100 in the longitudinal direction in opposite directions to each other while holding the dielectric tape 100 therebetween and pressing the dielectric tape 100 at a predetermined pressure. At a predetermined speed. Here, the tape holding unit 55
“a” contacts the metal film 104 of the dielectric tape 100, while the tape holder 55 b contacts the dielectric film 102.

Further, the coil 6 has an inductance L, one end of which is connected to the measuring electrode 50 and the negative resistance section 5 and the other end of which is connected to the tape holding section 55c. The resonance circuit unit 10b is configured as described above. Further, the AC power supply 9 is connected between the tape holding portion 55a and the ground, and applies an AC voltage Vp to the measurement electrode 50 and the metal film 104 via the tape holding portion 55a to perform the measurement. Small area 1 of dielectric film 102 located between electrode 50 and tape holding portion 55c
An AC electric field Ep is generated at 02a, and the AC voltage Vp is output to the phase detector 56 as a reference signal.

The resonance circuit section 10b configured as described above
, The tip 50a of the measurement electrode 50 and the metal film 10
4, the tip 50a of the measurement electrode 50 and the metal film 1
04 forms a capacitance Cs. Further, since the coil 6 is connected in parallel with the capacitance Cs as described above, the capacitance Cs and the coil 6 are connected to the LC resonance circuit. Is configured. This LC resonance circuit is connected to the negative resistance circuit 5 and forms the oscillator 20b. The oscillator 20b oscillates and generates an oscillation signal frequency-modulated in accordance with the change in the capacitance Cs, and outputs the oscillation signal to the FM demodulation circuit 26, as described in detail later. The FM demodulation circuit 26 demodulates the frequency-modulated oscillation signal and outputs the demodulated signal to the phase detector 56. The phase detector 56 includes, for example, the lock-in amplifier 27, and
The phase difference φ is calculated from the output voltages Va ₁ and Va ₂ of Equation (4) using Equation 4 and output.

In the dielectric recording / reading apparatus having the above-described structure, the AC power supply 9 applies the AC voltage V to the metal film 104 via the measuring electrode 50 and the tape holder 55a.
When an AC electric field Ep is generated in the minute region 102a of the dielectric film 102 located between the measurement electrode 50 and the tape holder 55c by applying p, as described above in the description of the basic circuit in FIG. In addition, the oscillator 20
b has an amplitude proportional to the tertiary dielectric constant ε _{3 of the} minute region 102a and the AC voltage Vp, and has the frequency fp
Generated by oscillating an oscillation signal frequency-modulated by a signal S ₃ which includes a signal having a. Here, when the tertiary dielectric constant ε ₃ is a positive real number, that is, when the digital signal is 1, the phase difference φ between the signal having the frequency fp and the reference signal is π, and the tertiary dielectric constant ε ₃ is π. When the rate ε ₃ is a negative real number, that is, when the digital signal is 0, the phase difference φ between the signal having the frequency fp and the reference signal is 0. Next, the FM demodulation circuit 26 demodulates the oscillation signal to have a third-order dielectric constant ε _{3 of the} minute region 102 a and an amplitude proportional to the AC voltage Vp and the same frequency fp as the AC voltage Vp. Further, a demodulated signal including a signal having a phase difference φ corresponding to the above digital signal is generated. Further, the phase detector 56 synchronously detects the demodulated signal based on a reference signal having a frequency fp,
A phase difference φ of 0 or π is output in accordance with the sign of the third-order dielectric constant ε ₃ of the minute region 102a. Therefore, the dielectric tape 100 is caused to travel by rotating the tape holding portions 55a and 55b at a predetermined speed,
By sequentially changing the position of the minute area 102a, the phase difference φ
, It is possible to observe the sign of the third-order dielectric constant ε ₃ of each minute region 102 a by the value of the phase difference φ. Further, as described above, the third-order dielectric constant ε ₃
Is a polarization having a direction from the measurement electrode 50 toward the metal film 104, and a negative value of the third order dielectric constant ε ₃ is a polarization having a direction from the metal film 104 toward the measurement electrode 50. Corresponding. That is, each of the minute regions 102a
Can be detected, and the digital signal can be read. Here, the dielectric film 102
The recording of the digital signal into the measuring electrode 5 is performed, for example, so that a DC electric field is generated in the minute area 102a.
0 and a polarization process such as applying a DC voltage to the metal film 104 are used.

<Second Embodiment> FIG. 11 is a block diagram showing a configuration of a dielectric recording and reading apparatus according to a second embodiment.
The dielectric recording / reading apparatus of the second embodiment shown in FIG.
The resonance circuit section 10c is provided with a reentrant cavity resonator 30 in place of the LC resonance circuit of the application circuit of (1). Reentrant cavity resonator 3 of FIG.
Numeral 0 is configured similarly to the reentrant cavity resonator 30 of the first embodiment shown in FIGS. The tape holding portions 55a and 55c are made of a columnar conductor having a predetermined axial length longer than the width of the dielectric tape 100, and each axis is parallel to the width direction of the dielectric tape 100. And a reentrant cavity resonator 30
The surface contact portion 33 is rotatably provided so as to hold the dielectric tape 100 between the surface contact portion 33 and the surface contact portion 33. Then, the tape holding portions 55a and 55c rotate at a predetermined number of rotations so that the dielectric tape 1 is rotated.
00 at a predetermined speed in its longitudinal direction.

The AC power supply 9 is connected to the tape holding unit 5.
By applying an AC voltage Vp to the cavity 5a and the reentrant cavity 30, a minute region 102a of the dielectric film 102 sandwiched between the tip portion 35 and the metal film 104, the contact surface portion 33, and the metal film 104 are sandwiched. An AC electric field Ep is generated in the region 102b of the dielectric film 102 thus formed. Moreover,
In the dielectric recording / reading apparatus of the second embodiment, a lock-in amplifier 27a is provided instead of the phase detector 56 of the dielectric recording / reading apparatus of FIG. The lock-in amplifier 27a is configured so that only the output voltage Va ₂ is outputted. Resonant circuit section 10c and lock-in amplifier 27
Configurations other than a are the same as those of the above-described dielectric recording and reading apparatus of FIG.

In the dielectric recording / reading apparatus of the second embodiment configured as described above, when the AC power supply 9 applies an AC voltage Vp to the reentrant cavity resonator 30 and the tape holder 55a, An AC electric field Ep is generated in the minute region 102a and the region 2b of the dielectric film 102.
In both the minute region 102a and the region 102b, the dielectric constant changes due to the AC electric field Ep, and the capacitances Cs and Cg change.

As described above, the resonance frequency of the reentrant cavity resonator 30 changes in accordance with the change in the capacitance Cs associated with the change in the dielectric constant of the minute region 102a. As a result, the oscillator 20c has the capacitance Cs
Oscillates and generates an oscillation signal that has been frequency-modulated in response to the change in. Therefore, by the tape holding unit 55a, 55c is rotated, by driving the dielectric tape 100 in the longitudinal direction, by measuring the output voltage Va ₂ sequentially changing the position of the minute regions 102a, each the third order of the positive and negative permittivity epsilon ₃ of the small regions 102a may be determined by the sign of the output voltage Va _2. That is, as described above, the direction of polarization of each of the minute regions 102a corresponding to the digital signal can be detected, and the digital signal can be read.

In the dielectric recording / reading apparatus of the second embodiment, since the above-mentioned reentrant cavity resonator 30 is used, the oscillation frequency of the oscillator 20c is compared with that of the dielectric recording / reading apparatus of the application circuit of FIG. And can be set higher. As a result, the maximum frequency shift can be increased, so that a dielectric recording / reading device having higher sensitivity and higher accuracy than the dielectric recording / reading device of FIG. 1 can be configured.

FIG. 12 is a view showing an example of measurement using the dielectric recording and reading apparatus of the second embodiment, and shows a dielectric tape 1
00 from start point and lock-in amplifier 27a
5 is a graph showing a relationship between the output voltage Va ₂ and the output voltage Va ₂ . Here, the tip 35 of the reentrant cavity resonator 30 is used.
Is configured so that the diameter D is a circle having a diameter of 1.6 mm, the distance from the starting point of the dielectric tape 100 is expressed in units of 1.6 mm, which is the diameter. As is apparent from FIG. 12, in the region where the polarization direction of the dielectric film 102 is polarized in the direction from the surface 102d of the dielectric film 102 to the surface 102c of the dielectric film 102, the lock-in amplifier is used. output voltage Va ₂ of 27a is a negative, the polarization direction is, the surface 10
The output voltage Va ₂ is positive in a region where the polarization process is performed in the direction from 2c to the surface 102d. As described above, by using the dielectric recording and reading system of the second embodiment, since the information recorded by the direction of polarization is output as the sign of the output voltage Va ₂ of the lock-in amplifier 27a, facilitating the information Can be read.

<Third Embodiment> FIG. 13 is a block diagram showing a configuration of a nonlinear dielectric constant measuring apparatus according to a third embodiment which is another applied example. As will be described in detail later, when an AC electric field Ep is applied to a dielectric sample 2 made of a ferroelectric substance, the reflectivity of the dielectric sample 2 changes to the AC electric field Ep as described later in detail. Therefore, a non-linear dielectric constant measuring apparatus that measures the Pockels constant, which is one of the non-linear dielectric constants in the optical region of the dielectric sample 2, utilizing the change.

Hereinafter, the configuration of the nonlinear dielectric constant measuring apparatus according to the third embodiment will be described with reference to the drawings. As shown in FIG. 13, the reflected light measuring unit 60 includes a capacitor unit 1, a laser diode 21, an AC power supply 9, a half mirror 57,
Focus lens 58, mechanism section 7, mechanism control section 25
And a photoelectric converter 51. The capacitor section 1 is configured by sandwiching a dielectric sample 2 between transparent electrodes 3 and electrodes 4 facing each other. The laser diode 21 generates a light beam of a predetermined wavelength, and irradiates the light beam to the surface of the minute region 2a which is a part of the dielectric sample 2 via the half mirror 57, the focus lens 58, and the transparent electrode 3. An AC power supply 9 is connected to the transparent electrode 3 and the electrode 4 to supply the dielectric sample 2 with 100 MHz.
While applying an AC voltage Vp having a predetermined frequency of between 1000 MHz and 1000 MHz as a reference signal to the mixer 53b. The half mirror 57 transmits the light beam generated by the laser diode 21 through the focus lens 58 so as to converge on the surface of the minute area 2a of the dielectric sample 2, while the half mirror 57 transmits the light beam.
After being reflected by the surface a, the light beam incident through the focus lens 58 is reflected, and the reflected light, which is a light beam signal, is emitted to the photoelectric converter 51. Here, the reflected light is a light beam signal having the same frequency as the AC voltage Vp and being intensity-modulated by a signal including a signal having an amplitude proportional to the amplitude of the AC voltage Vp, as described later. . The photoelectric converter 51 photoelectrically converts a light beam signal, which is input reflected light, to obtain the AC voltage Vp.
And generates an electric signal including a signal having an amplitude proportional to the amplitude of the AC voltage Vp, and outputs the generated electric signal to the mixer 53a of the electric signal processing unit 70 via the amplifier 52.

The mechanism section 7 mounts and holds the capacitor section 1 on its surface, and in response to a control signal from the mechanism control section 25, switches the capacitor section 1 to the laser diode 21.
Is moved in a one-dimensional direction or a two-dimensional direction in a direction perpendicular to the direction in which the light beam is irradiated. By moving the capacitor unit 1 by the mechanism unit 7 in this manner, the minute region 2a of the dielectric sample 2 to be irradiated with the light beam is moved in a one-dimensional direction or a two-dimensional direction. Mechanism control unit 2
5 generates the above-mentioned control signal, generates a position signal indicating the movement position of the minute area 2a of the above-mentioned dielectric sample 2 corresponding to the above-mentioned control signal, and outputs it to the display control unit 28.

The electric signal processing unit 70 includes an amplifier 52
, A local oscillator 54, mixers 53 a and 53 b, a lock-in amplifier 27, a display controller 28, and a display 29. The local oscillator 54 oscillates and generates a local oscillation signal having a predetermined local oscillation frequency lower than the frequency fp of the AC voltage Vp, and outputs the signal to the mixers 53a and 53b. The mixer 53a mixes the electric signal from the amplifier 52 and the local oscillation signal, converts the frequency of the electric signal to a signal having a frequency of the sum and difference of the frequency of the electric signal and the local oscillation frequency, and performs a band-pass filter 59a. Output to The band-pass filter 59a
The terminal of the lock-in amplifier 27 passes only the signal having the frequency of the difference between the frequency fp and the local oscillation frequency among the signals having the frequency of the sum and the difference between the frequency of the electric signal and the local oscillation frequency. Output to T1. On the other hand, the mixer 53b mixes the input reference signal and the local oscillation signal, frequency-converts the signal into a signal having a frequency that is the sum and difference of the frequency fp of the reference signal and the local oscillation frequency, and Output to the filter 59b. The band-pass filter 59b passes only a signal having a frequency equal to the difference between the frequency fp of the reference signal and the local oscillation frequency, and outputs the signal to the terminal T2 of the lock-in amplifier 27.
Further, the lock-in amplifier 27, the display control unit 28, and the display 29 are configured similarly to the nonlinear dielectric constant measuring apparatus of the first embodiment.

When the dielectric sample 2 is irradiated with a light beam in the nonlinear dielectric constant measuring apparatus according to the third embodiment having the above-described configuration, the light beam is irradiated with the dielectric sample 2.
Is reflected on the surface of the minute region 2a. At this time, the reflectance R of the light of the dielectric sample 2 can be expressed as in Equation 42 using the refractive index n of the dielectric sample 2. Also,
The refractive index n can be expressed as in Equation 43 using the dielectric constant εs of the dielectric sample 2 and the dielectric constant ε ₀ in vacuum.

[0098]

R = {(1-n) / (1 + n)} ²

[Mathematical formula-see original document] n = √ (εs / ε ₀ )

The AC power supply 9 applies an AC voltage Vp, which is a sine wave having a frequency fp, to the transparent electrodes 3 and 4.
Is applied, in parallel with the thickness direction of the dielectric sample 2,
An AC electric field Ep that is a sine wave having an amplitude proportional to the amplitude of the AC voltage Vp and the same frequency as the frequency fp of the AC voltage Vp is generated. As a result, the refractive index n and the reflectance R change by the refractive index change Δn and the reflectance change ΔR, respectively, according to the AC electric field Ep, as described later. Here, assuming that the refractive index when the AC voltage Vp is not applied is n ₀ , the refractive index n can be expressed by the following equation 44, and when the AC voltage Vp is not applied to the dielectric sample 2. Assuming that the reflectance is R ₀ , the reflectance R is given by
5 can be represented.

[0100]

N = n ₀ + Δn

R = R ₀ + ΔR

Next, the refractive index n expressed by Expression 44 and Expression 45
By substituting the reflectivity R expressed by Eq. Into Equation 42 and deforming, the reflectivity R can be expressed as shown in Equation 46.

[0102]

R ₀ + ΔR = {(1−n ₀ ) / (1 + n ₀ )} ² [{1-
Δn / (1−n ₀ )} / {1 + Δn / (1 + n ₀ )}] ²

Here, since the refractive index change Δn≪n ₀ and the refractive index change Δn≪1, it is possible to set (Δn) ² = 0. Further, as is apparent from Equation 42, the reflectance R ₀ can be expressed as Equation 47 using the refractive index n ₀ . From the above, Equation 46 can be rewritten as Equation 48 below. Further, from Expression 48, the reflectance change amount ΔR can be expressed as Expression 49 and Expression 50.

[0104]

R ₀ = {(1−n ₀ ) / (1 + n ₀ )} ²

R ₀ + ΔR = R ₀ (1-2Δn / (1-n ₀ ) -2)
Δn / (1 + n ₀ )}

ΔR = R ₀ {−2Δn / (1−n ₀ ) −2Δn / (1 + n ₀ )}

ΔR = −4R ₀ Δn / (1-n ₀ ² )

On the other hand, the AC voltage Vp is applied to the transparent electrodes 3 and 4.
When an AC electric field Ep is generated in the minute region 2a of the dielectric sample 2 by applying
Changes the permittivity εs by the permittivity change amount Δε. Assuming that the dielectric constant when no AC voltage Vp is applied is εs ₀ , the dielectric constant εs can be expressed by the following equation 51. Further, when the dielectric constant εs expressed by Expression 51 is used, the refractive index when the AC voltage Vp is applied is expressed by Expression 5
2 can be represented.

[0106]

[Equation 51] εs = εs ₀ + Δε

N ₀ + Δn = {(εs ₀ + Δε) / ε ₀ } ^1/2

Since Δε≪εs ₀ in Equation 52, Equation 52 can be written as Equation 53 using approximation. When the refractive index n ₀ expressed by Expression 54 in Expression 53 is used, the refractive index change Δn can be expressed as Expression 55.

[0108]

[Expression 53] n ₀ + Δn = (εs ₀ / ε ₀ ) ^1/2 {1+ (1/2) (Δε / εs ₀ )}

N ₀ = (εs ₀ / ε ₀ ) ^1/2

[Expression 55] Δn = (1/2) n ₀ (Δε / εs ₀ )

Next, the refractive index change amount Δn represented by Expression 55
Is substituted into the reflectance change amount ΔR expressed by Expression 50, the reflectance change amount ΔR can be expressed by the following Expression 56.

[0110]

ΔR = −4R ₀ {(1/2) n (Δε / εs ₀ )} Δ
^{_{n / (1-n 0 2}} )

As is well known, the dielectric constant variation Δ
ε is a Pockels constant r which is a first-order electro-optical constant and 2
Using the Kerr constant g, which is the following electro-optic constant, can be expressed as in Equation 57. Here, the Pockels constant r is a kind of the third-order dielectric constant ε ₃ , and the Kerr constant g
Is a kind of fourth-order permittivity ε ₄ . Therefore, the Pockels constant r and the Kerr constant g are a kind of nonlinear dielectric constant. The non-linear dielectric constant referred to here is a non-linear dielectric constant in an optical region since the response to light is observed. Further, the dielectric constant change amount Δ expressed by the following equation 57
Using ε, the reflectance change ΔR expressed by Expression 56 can be written as Expression 58. Furthermore, Equation 5
8 is the AC electric field E expressed by the equation 59.
With reflectance change amount [Delta] R ₂ is proportional to the square of the AC electric field Ep represented by reflectance change amount [Delta] R ₁ to the number 60 which is proportional to p, it can be expressed as Expression 61.

[0112]

Δ５７ = − (εs ₀ ² / ε ₀ ) (rEp + gEp ² )

Equation 58] ^{_{ΔR = 2 {n 0 3 /}} (1-n 0 2)} R 0 (rEp + gEp 2)

Equation 59] ^{_{ΔR 1 = 2 {n 0 3}} / (1-n 0 2)} R 0 rEp

Equation 60] ^{_{ΔR 2 = 2 {n 0 3}} / (1-n 0 2)} R 0 gEp 2

ΔR = ΔR ₁ + ΔR ₂

As shown in Equation 61, the reflectance change amount ΔR is expressed in the form of the sum of a term ΔR ₁ proportional to the AC electric field Ep and a term ΔR ₂ proportional to the square of the AC electric field Ep. Accordingly, the reflectance change ΔR of the minute region 2a of the dielectric sample 2 has a Pockels constant and an amplitude proportional to the amplitude Ep ₀ of the AC electric field Ep, and a reflection that changes alternately with the angular frequency ωp. the rate variation △ R _1, including reflectance change amount △ R ₂ which changes alternately have a and angular frequency 2ωp an amplitude proportional to the square of the amplitude Ep ₀ of the Kerr constant and alternating electric field Ep Therefore, the light beam signal that is the reflected light is reflected by the reflectance change amount ΔR ₁
And the intensity changes in accordance with the reflectance change amount ΔR ₂ .
Therefore, the light beam signal as the reflected light has a signal S ₃ having an amplitude proportional to the Pockels constant and the amplitude Ep ₀ of the AC electric field Ep, and having the angular frequency ωp, that is, the frequency fp.
And an angular frequency 2ωp, that is, a frequency fp, having an amplitude proportional to the square of the Kerr constant and the amplitude Ep ₀ of the AC electric field Ep.
Becomes a light beam signal intensity-modulated by the signal S ₄ having

The photoelectric converter 51 photoelectrically converts the intensity-modulated light beam signal, has a Pockels constant, an amplitude proportional to the amplitude Ep ₀ of the AC electric field Ep, and has an angular frequency ωp, that is, a frequency fp. the signal S _3, into an electric signal including a signal S ₄ having a and angular frequency 2ωp or frequency fp an amplitude proportional to the square of the amplitude Ep ₀ of the Kerr constant and alternating electric field Ep, the amplifier 52 Output to the mixer 53a via the The mixer 53a mixes the local oscillation signal input from the local oscillator 54 and the electric signal input via the amplifier 52, and calculates a sum of the frequency of the electric signal and the frequency of the local oscillation signal. The signal is frequency-converted into a signal having a difference frequency and output to the band-pass filter 59a. The above bandpass filter 59
a, among the signals having the frequency of the sum and difference between the frequency of the electric signal and the frequency of the local oscillation signal, passing only the signal having the frequency of the difference between the frequency fp and the frequency of the local oscillation signal. , Terminal T of the lock-in amplifier 27
Output to 1. Here, among the electric signals, the signal S ₃ having the frequency fp has an amplitude proportional to the Pockels constant and the amplitude Ep ₀ of the AC electric field Ep, as described above, so that the frequency fp and the local oscillation signal Is also a signal having an amplitude proportional to the Pockels constant and the amplitude Ep ₀ of the AC electric field Ep.

On the other hand, the mixer 53b mixes the input reference signal and the local oscillation signal, frequency-converts the mixed signal into a signal having a frequency that is the sum and difference between the frequency of the reference signal and the local oscillation frequency, and Output to the band-pass filter 59b. The band-pass filter 59a includes only a signal having a frequency equal to the difference between the frequency fp of the reference signal and the local oscillation frequency among signals having a frequency equal to the sum of the frequency fp of the reference signal and the local oscillation frequency. And output to the terminal T2 of the lock-in amplifier 27.

The lock-in amplifier 27 converts the signal having the frequency difference between the frequency fp input from the terminal T1 and the frequency of the local oscillation signal into the frequency difference between the frequency fp of the reference signal and the frequency of the local oscillation signal. , And outputs the output voltage | Va | sin φ to the display control unit 28 via the terminal T3, and outputs the output voltage | Va
| Cosφ is output to the display control unit 28 via the terminal T4. Since the signal having the frequency of the difference between the frequency fp and the frequency of the local oscillation signal is a signal having an amplitude proportional to the Pockels constant and the amplitude Ep ₀ of the AC electric field Ep, the output voltage Va ₁ and the output voltage Va ₂ are The voltage is proportional to the Pockels constant and the amplitude Ep ₀ of the AC electric field Ep.

Next, the display control unit 28 calculates the phase difference φ and the voltage | Va | from the input voltages Va ₁ and Va ₂ , and outputs the position signal input from the mechanism control unit 25 and the voltage V
The display 29 is controlled so that parameters designated from among a ₁ , Va ₂ , | Va | and the phase difference φ are displayed on the display 29. Display 2 above
9 displays a parameter specified from the voltages Va ₁ , Va ₂ , | Va | and the phase difference φ on a two-dimensional plane in accordance with the position of the dielectric sample 2 in accordance with the instruction of the display control unit 28. I do.

As described in detail above, the AC voltage Vp is applied to the transparent electrodes 3 and 4 while irradiating the light beam.
When an AC electric field Ep is generated in the minute region 2a of the dielectric sample 2, the minute region 2a causes the input light beam to have an amplitude proportional to the Pockels constant of the minute region 2a and the amplitude of the AC voltage Vp; The light is reflected as a light beam signal whose intensity is modulated according to a signal having the same frequency fp as the AC voltage Vp. Next, the photoelectric converter 51 photoelectrically converts the intensity-modulated light beam signal, and
It is converted into an electric signal having a Pockels constant of a and an amplitude proportional to the amplitude of the AC voltage Vp and including a signal having the same frequency fp as the AC voltage Vp. Further, the lock-in amplifier 27 synchronously detects the electric signal based on the reference signal and outputs a DC signal proportional to the Pockels constant of the minute area 2a and the amplitude of the AC voltage Vp. Therefore, by scanning the irradiation position of the light beam by the mechanism unit 7 and the mechanism control unit 25 and measuring the DC signal, the difference in the Pockels constant of the minute area 2a is observed based on the value of the DC signal. be able to. Also,
The Pockels constant is a third-order tensor like the third-order permittivity ε _3, and does not exist in a material having a center of symmetry. In addition, for example, a material with sufficiently polarized polarization and a material with less polarization have greatly different values of the Pockels constant. When the polarization becomes zero, the Pockels constant also becomes zero. When the polarization direction is reversed, the sign of the Pockels constant changes. Furthermore, when the crystal state is disturbed, it is considered that the anisotropy of the crystal is reduced in the disturbed portion, and the Pockels constant, which is also the third-order tensor amount, is reduced.
Therefore, by observing the difference in the fine region 2a of the Pockels constant, it is possible to judge the non-uniformity of the crystal state and the microscopic distribution of the permanent polarization.

In the above third embodiment, the frequency f
Although the Pockels constant is configured to be observable by performing synchronous detection using a reference signal having p, the present invention is not limited to this, and the synchronous detection is performed based on a reference signal having a frequency of 2 × fp. It may be configured so that the Kerr constant can be observed. As described above, the nonlinear dielectric constant in the optical region can be measured.

<Fourth Embodiment> FIG. 14 is a block diagram showing a configuration of a nonlinear dielectric constant measuring apparatus according to a fourth embodiment. The difference between the nonlinear dielectric constant measuring apparatus of the fourth embodiment and the nonlinear dielectric constant measuring apparatus of the third embodiment is that a transparent electrode 4a is provided in place of the electrode 4 and a transparent electrode is provided in place of the mechanical unit 7. This is a point that it is provided with a mechanical portion 7a composed of a body. With the above-described configuration, a light beam signal, which is transmitted light passing through the transparent electrode 3, the dielectric sample 2, the transparent electrode 4a, and the mechanism 7a, is converted into an electric signal, and an optical signal is formed based on the electric signal. The method is characterized in that a nonlinear dielectric constant in a region is measured.

Hereinafter, the configuration of the nonlinear dielectric constant measuring apparatus according to the fourth embodiment will be described with reference to the drawings. As shown in FIG. 14, the nonlinear dielectric constant measuring apparatus of the fourth embodiment replaces the reflected light measuring section 60 of the third embodiment with a capacitor section 1, a laser diode 21, an AC power supply 9, A mechanism section 7a;
It is provided with a transmitted light measuring unit including the mechanism control unit 25 and the photoelectric converter 51. The capacitor section 1 is configured by sandwiching a dielectric sample 2 between a transparent electrode 3 and a transparent electrode 4a facing each other. The laser diode 21 generates a light beam having a predetermined wavelength, and irradiates the light beam to the minute area 2 a which is a part of the dielectric sample 2 via the transparent electrode 3. The AC power supply 9 includes the transparent electrode 3 and the transparent electrode 4.
a to the minute region 2a of the dielectric sample 2 by applying an AC voltage Vp having a frequency fp to
, And outputs the AC voltage Vp to the mixer 53b as a reference signal. Here, the frequency fp ranges from 100 MHz to 1000 MHz.
It is set to a predetermined frequency between z. Here, the transmitted light is a light beam signal which has the same frequency as the AC voltage Vp and is intensity-modulated by a signal including a signal having an amplitude proportional to the amplitude of the AC voltage Vp, as described later. . The photoelectric converter 51 photoelectrically converts a light beam signal, which is input transmitted light, into an electric signal including a signal having the same frequency as the AC voltage Vp and having an amplitude proportional to the amplitude of the AC voltage Vp. The signal is generated by the amplifier 5
2 to the mixer 53a. The above mechanism 7
a is made of a transparent body, the capacitor unit 1 is placed and held on its surface, and in response to a control signal from the mechanism control unit 25, the capacitor unit 1 is moved in the direction in which the light beam is emitted from the laser diode 21. Are moved in a one-dimensional direction or a two-dimensional direction in a direction perpendicular to. Capacitor part 1 is mechanism part 7
As a result, the minute region 2a of the dielectric sample 2 to which the light beam is irradiated is moved in one-dimensional direction or two-dimensional direction. The mechanism control unit 25 includes:
In addition to generating the control signal, it generates a position signal indicating the movement position of the minute area 2a of the dielectric sample 2 corresponding to the control signal, and outputs the position signal to the display control unit 28.

In the nonlinear dielectric constant measuring apparatus according to the fourth embodiment having the above-described configuration, the dielectric sample 2
When an AC voltage Vp is applied to the transparent electrodes 3 and 4 by the AC power supply 9, an amplitude proportional to the amplitude of the AC voltage Vp and the AC voltage Vp are applied in parallel with the thickness direction of the dielectric sample 2.
An AC electric field Ep having the same frequency as the frequency fp of p is generated. Thereby, as described above, the reflectance change amount Δ
R changes. Here, as is well known, there is a relationship shown in Expression 62 between the reflectance R of the dielectric sample 2 and the light transmittance T of the dielectric sample 2. Therefore, there is a relationship shown in Expression 63 between the reflectance change amount ΔR and the transmittance change amount ΔT.

[0123]

T = 1-R

ΔT = −ΔR

As is apparent from Equations 63 and 61, the transmittance change ΔT has an amplitude proportional to the Pockels constant and the amplitude Ep ₀ of the AC electric field Ep and has an angular frequency ωp, and Since it includes the transmittance change amount that changes and the transmittance change amount ΔT that has an amplitude proportional to the square of the Kerr constant and the amplitude Ep ₀ of the AC electric field Ep and that alternately changes with the angular frequency 2ωp, the light beam signal is the transmitted light, and a signal having the Pockels constant and alternating electric field having an amplitude proportional to the amplitude Ep ₀ of Ep and the angular frequency ωp or frequency fp, the Kerr constant and alternating electric field Ep of the amplitude Ep ₀ A light beam signal having an amplitude proportional to the square and being intensity-modulated by a signal having an angular frequency 2ωp, that is, a frequency fp.

Therefore, by subjecting the electric signal obtained by photoelectrically converting the light beam signal to the same processing as in the fifth embodiment, it is possible to observe the difference in the Pockels constant of each minute area 2a based on the value of the DC signal. it can. As described above, the electric field Ep to which the light transmittance T of the dielectric sample 2 is applied
The difference in Pockels constant of each minute region 2a can be observed by utilizing the fact that the Pockels constant varies in each micro region 2a.

In the fourth embodiment, the frequency f
Although the Pockels constant is configured to be observable by performing synchronous detection using a reference signal having p, the present invention is not limited to this, and the synchronous detection is performed based on a reference signal having a frequency of 2 × fp. It may be configured so that the Kerr constant can be observed.

In the third and fourth embodiments, the output of the lock-in amplifier 27 is observed. However, the present invention is not limited to this, and the electric signal output from the photoelectric converter 51 is observed. Alternatively, the Pockels constant in the minute region 2a of the dielectric sample 2 may be measured. In this case, the nonlinear dielectric constant measuring apparatus includes a band-pass filter that selectively filters only the signal of the frequency fp from the electric signals output from the photoelectric converter 51,
An oscilloscope for measuring the waveform of a signal having a frequency of 000 MHz is provided. With the above configuration, the Pockels constant and the amplitude Ep of the AC electric field Ep are obtained.
_The power value proportional to ₀ can be obtained, and the Pockels constant can be measured. The Kerr constant can be measured by using a band-pass filter that selectively filters and outputs only a signal having a frequency of 2 fp. As described above, the nonlinear dielectric constant in the optical region can be measured as in the above-described nonlinear dielectric constant measuring apparatus of the third embodiment.

<Fifth Embodiment> FIG. 15 shows a fifth embodiment utilizing the fact that the polarity of the Pockels constant r is inverted depending on the direction of polarization of the dielectric film 102 in the same manner as the above-described third-order dielectric constant ε ₃ . 1 is an embodiment of a dielectric recording and reading apparatus according to an embodiment. FIG.
The dielectric recording / reading apparatus 5 includes a dielectric tape 100, a laser diode 21, a half mirror 57, a focus lens 58, an AC power supply 9, a tape holding unit 55a,
It is constituted by 55b, 55c, 55d, the photoelectric converter 51, and the phase detector 56. Dielectric tape 100
A dielectric film 102 made of a ferroelectric is formed on a metal film 104 formed in a tape shape by a known method such as sputtering, and a transparent electrode 103 such as ITO is formed on the dielectric film 102. For example, it is formed by a known method such as sputtering. The laser diode 21 generates a light beam of a predetermined wavelength,
The light beam is applied to the surface of the minute region 102a which is a part of the dielectric film 102 via the half mirror 57 and the focus lens 58. Here, the focus lens 58 transmits the light beam to the minute portion 1 of the dielectric sample 2.
The light is focused so as to irradiate 02a. In addition, AC power supply 9
Generates an AC electric field Ep in the thickness direction of the dielectric film 102 by applying an AC voltage Vp to the tape holder 55c and the tape holder 55d, while using the AC voltage Vp as a reference signal to generate a phase detector. Output to 56. The half mirror 57 transmits the light beam generated by the laser diode 21 so as to irradiate the surface of the minute region 102 a of the dielectric film 102, while the half mirror 57 transmits the light beam
After being reflected by the surface a, the light beam signal incident through the focus lens 58 is reflected, and the light beam signal as the reflected light is radiated to the photoelectric converter 51. Here, the reflected light is a light beam signal that has the same frequency as the AC voltage Vp and is intensity-modulated by a signal including a signal having an amplitude proportional to the amplitude of the AC voltage Vp. The photoelectric converter 51 photoelectrically converts an input light beam signal, which is reflected light, into an electric signal including a signal having the same frequency as the AC voltage Vp and having an amplitude proportional to the amplitude of the AC voltage Vp. A signal is generated and output to the phase detector 56.

Further, the tape holding portions 55a, 55b, 55
Each of c and 55d is a columnar conductor having a predetermined axial length longer than the width of the dielectric tape 100.
The tape holding portion 55a and the tape holding portion 55b can be rotated to face each other so that their axes are parallel to the width direction of the dielectric tape 100 and the dielectric tape 100 is sandwiched between the respective circumferential surfaces. Is provided. Further, the tape holding portion 55c and the tape holding portion 55d face each other such that their axes are parallel to the width direction of the dielectric tape 100 and that the dielectric tape 100 is sandwiched between the respective circumferential surfaces. It is provided rotatably. The dielectric tape 100 is so arranged that its thickness direction always coincides with the irradiation direction of the light beam, and that the distance from the focus lens 58 is a predetermined value. The tape holding portions 55a, 55a,
55b and the tape holding portions 55c and 55d. Here, the tape holder 55c is in electrical contact with the transparent electrode 103, and the tape holder 55d is
Electrical contact with Then, the tape holding portion 55a and the tape holding portion 55b are rotated at a predetermined number of rotations in opposite directions while holding the dielectric tape 100 therebetween and pressing the dielectric tape 100 at a predetermined pressure, thereby moving the dielectric tape 100 in its longitudinal direction. At a predetermined speed. Further, the phase detector 56
For example, it is configured to include a lock-in amplifier 27, and calculates and outputs a phase difference φ from the output voltages Va ₁ and Va _{2 of the} lock-in amplifier 27 using Expression 4.

In the dielectric recording / reading apparatus of the fifth embodiment configured as described above, the dielectric tape 100
Then, when the light beam is irradiated, the light beam is reflected on the surface of the dielectric film 102, and the light beam signal, which is the reflected light, becomes the intensity-modulated light beam signal as described above.

The photoelectric converter 51 photoelectrically converts the intensity-modulated light beam signal to have a Pockels constant, an amplitude proportional to the amplitude Ep ₀ of the AC electric field Ep, and an angular frequency ωp, that is, a frequency fp. The signal is converted into an electric signal including a signal having an amplitude proportional to the square of the Kerr constant and the amplitude Ep ₀ of the AC electric field Ep and having an angular frequency 2ωp, that is, a frequency fp, and outputs the signal to the phase detector 56. . The phase detector 56 detects a phase of a signal having an amplitude proportional to the Pockels constant r and the amplitude Ep ₀ of the AC electric field Ep and having an angular frequency ωp, that is, a frequency fp, of the electric signal based on the reference signal. And output. Here, since n ₀ is larger than 1 in Equation 59, when the Pockels constant r is positive, the reflectance change ΔR ₁ changes in the opposite phase to the AC electric field Ep, that is, the AC voltage Vp. Therefore, when the Pockels constant r is positive, the frequency f
The phase difference φ between the signal having p and the reference signal becomes π. Similarly, when the Pockels constant r is negative, the frequency fp
And the reference signal has a phase difference φ of 0. That is, the phase difference φ is π corresponding to the positive or negative of the Pockels constant.
Or 0 is output. Further, the tape holding portions 55a, 55b, and 55c allow the minute area 10
By sequentially changing the position of 2a and measuring the phase difference φ, the sign of the Pockels constant r of each minute region 102a can be observed by the value of the phase difference φ. That is, since the positive and negative of the Pockels constant correspond to the direction of polarization of the minute region,
The direction of the polarization a can be detected, and the digital signal recorded on the dielectric tape 100 can be read.

In the above-described fifth embodiment, the dielectric reading device is configured by using the light beam signal that is the reflected light. However, the present invention is not limited to this, and the transmitted light can be changed as in the fourth embodiment. Alternatively, the configuration may be made using a light beam signal.

As the ferroelectric material used in the dielectric recording and reading devices of the second and fifth embodiments, for example, the following materials are used. (A) PZT which is a solid solution of PbTiO ₃ -PbZrO ₃
material. (B) Lead titanate represented by PbTiO ₃ . (C) Lead zirconate represented by PbZrO ₃ . (D) Barium titanate represented by BaTiO ₃ . (E) Lithium niobate represented by LiNbO ₃ . (F) A PLZT material which is a solid solution of lead (Pb), lanthanum (La), zirconium (Zr), and titanium (Ti). (G) Bismuth (Bi), sodium (Na), lead (P
b) a ferroelectric material such as a BNPB material which is a barium (Ba) -based solid solution; As the above-mentioned material, any material of ceramics, single crystal or a thin film formed can be used. Piezoelectric polymer materials such as polyvinylidene fluoride (PVDF), copolymers of vinylidene fluoride and ethylene trifluoride, copolymers of vinylidene fluoride and ethylene tetrafluoride, and copolymers of cyanovinylidene and vinyl acetate Etc. can also be used. Further, a material obtained by combining a plurality of the above materials can also be used.

In the dielectric recording and reading devices of the second and fifth embodiments described above, the dielectric tape 100 is used. However, the present invention is not limited to this, and a disk-shaped dielectric disk may be used. Good.

[0135]

As described above in detail, according to the nonlinear dielectric constant measuring apparatus of the present invention, a predetermined frequency is applied to a minute region of the dielectric located between the first electrode and the second electrode. And a resonance circuit configured to include the two electrodes and the dielectric. When the AC signal is applied to a minute area of the dielectric, the frequency of the AC signal is increased. Then, after generating an oscillation signal whose oscillation frequency changes in accordance with the nonlinear dielectric constant of the minute region, the oscillation signal is frequency-demodulated to obtain the frequency of the AC signal and the nonlinear dielectric constant of the minute region of the dielectric. An electric signal having a corresponding amplitude is output, and a nonlinear dielectric constant of a minute region of the dielectric is measured based on the electric signal. by this,
It is possible to measure a nonlinear dielectric constant in an electric region of a minute region of the dielectric which could not be measured conventionally.

Further, an AC signal having a predetermined frequency is applied to a minute region of the dielectric located between the first electrode and the second electrode made of a transparent material. Irradiating the minute area of the dielectric with a light beam, and electrically reflected light having an intensity corresponding to the nonlinear dielectric constant of the minute area of the dielectric reflected by the surface of the minute area and the frequency of the AC signal. Photoelectrically converts it into a signal,
A non-linear dielectric constant of a minute region of the dielectric is measured based on the electric signal. This makes it possible to measure the non-linear dielectric constant in the optical region of the minute region of the dielectric, which could not be measured conventionally.

[0137] Further, there is provided a detecting means for synchronously detecting the electric signal based on the AC signal and outputting a DC signal corresponding to the electric signal, and a non-linear dielectric in a minute region of the dielectric based on the DC signal. Measure the rate. Therefore, since the electric signal is synchronously detected, other unwanted noise not synchronized with the AC signal is removed, and the signal-to-noise power ratio S / N of the DC signal obtained after the synchronous detection is greatly improved. Therefore, the measurement accuracy of the nonlinear dielectric constant can be improved.

Furthermore, the dielectric is one-dimensionally moved so that the second electrode scans on the second surface of the dielectric or perpendicular to the light beam irradiated by the light irradiating means. Since the moving means for moving in the direction or the two-dimensional direction is provided, the relative change in the nonlinear dielectric constant of each of the minute regions is measured by changing the position of the minute region of the dielectric and performing the measurement. Therefore, the relative micro-distribution of the nonlinear dielectric constant of the dielectric can be known.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a basic circuit of a nonlinear dielectric constant measuring apparatus according to the present invention.

FIG. 2 is a block diagram of the lock-in amplifier 27 showing a detailed configuration of the lock-in amplifier 27 of FIG.

FIG. 3 is a block diagram illustrating a configuration of a nonlinear dielectric constant measuring apparatus according to a first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a reentrant cavity resonator 30 of the nonlinear dielectric constant measuring apparatus according to the first embodiment of the present invention.

5 is a plan view of the reentrant cavity resonator 30 of FIG. 4 as viewed from the direction of the dielectric sample 2. FIG.

FIG. 6 shows a capacitor unit 1 and an AC power supply 9 when the reentrant cavity 30 shown in FIG.
FIG. 3 is a circuit diagram of an equivalent circuit including the following.

FIG. 7 is a plan view of a dielectric sample 2 made of Z-cut LiNbO ₃ used to obtain the measurement results of FIG.

8 shows the output voltage | Va | of the lock-in amplifier 27 and the oscillation frequency f ₀ of the oscillation carrier at a distance X from X0 on the X axis in the dielectric sample 2 made of Z-cut LiNbO ₃ of FIG. It is a graph.

FIG. 9 is a cross-sectional view schematically showing a dielectric sample 2 having regions with different polarization states, and the output voltage Va ₂ of the lock-in amplifier 27 in each of the measurement positions corresponding to the cross-sectional views. 6 is a graph showing the measurement results of FIG.

FIG. 10 is a block diagram of an application circuit of a dielectric recording / reading apparatus to which the principle of the nonlinear dielectric constant measuring apparatus according to the present invention is applied.

FIG. 11 is a block diagram illustrating a configuration of a dielectric recording and reading apparatus according to a second embodiment.

FIG. 12 is a graph showing an output voltage of a lock-in amplifier 27a at a distance from a start point of a dielectric tape 100, which is a measurement example of the dielectric recording and reading apparatus of the second embodiment.

FIG. 13 is a block diagram illustrating a configuration of a non-linear dielectric constant measuring apparatus according to a third embodiment.

FIG. 14 is a block diagram illustrating a configuration of a nonlinear dielectric constant measuring apparatus according to a fourth embodiment.

FIG. 15 is a block diagram illustrating a configuration of a dielectric recording and reading apparatus according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Capacitor part, 2 ... Dielectric sample, 2a, 102a ... Micro area, 2b, 102b ... Area, 3, 4a ... Transparent electrode, 4 ... Electrode, 5 ... Negative resistance circuit, 6 ... Coil, 7, 7a ... 9: AC power supply, 10, 10a, 10b, 10c: Resonance circuit unit, 20, 20a, 20b, 20c: Oscillator, 21: Laser diode, 25: Mechanism control unit, 26: FM demodulation circuit, 27, 27a ... lock-in amplifier, 28 ... display control unit, 29 ... display, 30 ... reentrant cavity resonator, 31 ... conductor case, 32 ... center conductor, 33 ... opening, 35, 50a ... tip, 50 ... measuring electrode 51, a photoelectric converter, 53a, 53b, 277a, 277b, a mixer, 55a, 55b, 55c, 55d, a tape holder, 57, a half mirror, 58, a lens, 56: phase detector, 60: reflected light measurement unit, 100: dielectric tape, 102: dielectric film, 103: transparent electrode film, 104: metal film, 271: amplifier, 272: waveform shaper, 273, 274 ... In-phase distributor, 275 ... 90 degree phase shifter, 278a, 278b ... Low pass filter.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 27/26

Claims (6)

(57) [Claims] 1. A non-linear dielectric constant measuring apparatus for measuring a non-linear dielectric constant in a minute region which is a part of a dielectric having a first surface and a second surface opposed to each other, comprising: A first electrode formed on the surface of the first electrode, a second electrode having a tip portion provided to be in contact with the second surface of the dielectric, and the first electrode and the second electrode. A voltage applying means connected to the terminal for applying an alternating current signal having a predetermined frequency to the minute area of the dielectric; and a voltage applying means for sandwiching the minute area of the dielectric sandwiched between the first electrode and the second electrode. An LC resonance circuit including a capacitor and an inductor is provided. When the AC signal is applied to a minute region of the dielectric, the LC signal corresponds to the frequency of the AC signal and the nonlinear dielectric constant of the minute region. To generate an oscillation signal whose oscillation frequency changes And a demodulating unit that frequency-demodulates the oscillation signal and outputs a signal having an amplitude corresponding to the frequency of the AC signal and the nonlinear dielectric constant of the minute region as an electric signal, based on the electric signal. A non-linear dielectric constant measuring device for measuring a non-linear dielectric constant of a minute region of the dielectric material. 2. A non-linear dielectric constant measuring apparatus for measuring a non-linear dielectric constant in a minute region which is a part of a dielectric having a first surface and a second surface opposed to each other, wherein: A first electrode formed on a surface of the dielectric, a second electrode formed of a transparent material formed on a second surface of the dielectric, connected to the first electrode and the second electrode, Voltage applying means for applying an AC signal having a predetermined frequency to the minute area of the dielectric, light irradiating means for applying a light beam to the minute area of the dielectric via the second electrode, and the light beam And a photoelectric conversion unit that photoelectrically converts reflected light reflected from the minute area of the dielectric when the light is irradiated, and outputs an electric signal. Based on the electric signal, a non-linear area of the minute area of the dielectric is provided. Nonlinear dielectric characterized by measuring permittivity Rate measuring device. 3. The non-linear dielectric constant measuring device further comprises: a detecting means for synchronously detecting the electric signal based on the AC signal and outputting a DC signal corresponding to the amplitude of the electric signal. 3. The nonlinear dielectric constant measuring apparatus according to claim 1, wherein the nonlinear dielectric constant of the minute region of the dielectric is measured based on the following equation. 4. The conductor circuit according to claim 1, wherein the resonance circuit has a cylindrical shape having two bottom surfaces facing each other, and one bottom surface of the cylindrical shape is short-circuited and terminated, and an opening is formed in the other bottom surface. And connected to the center of one bottom surface of the conductor case, and provided in the conductor case such that the tip extends from the connection portion along the axial center of the conductor case to the opening. 2. The nonlinear dielectric constant according to claim 1, further comprising a second electrode having a columnar shape, wherein the other bottom surface of the conductor case is a reentrant cavity resonator in contact with an upper surface of the dielectric. 3. measuring device. 5. The non-linear dielectric constant measuring apparatus according to claim 1, further comprising: moving the dielectric in a one-dimensional direction or a two-dimensional direction such that the second electrode scans on a second surface of the dielectric. 5. The non-linear dielectric constant measuring apparatus according to claim 1, further comprising means. 6. The non-linear dielectric constant measuring device further includes a moving means for moving the dielectric in a one-dimensional direction or a two-dimensional direction perpendicular to the light beam irradiated by the light irradiating means. The nonlinear dielectric constant measuring apparatus according to claim 2 or 3, wherein: