CN101706405B - Device and method thereof for acquiring transmission fluctuation spatial correlation spectrum - Google Patents

Abstract

The invention relates to a device and a method thereof for acquiring a transmission fluctuation spatial correlation spectrum. A polychromatic light source is used for irradiation, when the light source passes through a dispersor, the distances between an incident light focus and reflected light focuses with different wavelengths in a measurement region are different, and thus the corresponding spatial correlations are different. An incident light beam and a reflected light beam are dispersed and absorbed in the measurement region under the action of particles, thereby causing extinction. A split light beam passes through a half reflecting and half transparent plain glass and is focused on a light sensing element by a lens, thereby obtaining a transmission correlation spectrum. The invention effectively solves the problem that the particle measurement range is limited because of mechanical operation in the measurement process. A transmission fluctuation spatial correlation spectral method is irrelevant to the flow field of the particles, has simple structure and can be used for detecting a particle system in laminar flow and onflow states in real time and on line, thereby testing the particle size distribution and the concentration of micron-sized particles. The invention can be widely applied to various fields of scientific research, production and process control of chemical industry energy sources, environment protection, water quality detection and particle measurement.

Description

Obtain the devices and methods therefor of transmission fluctuation spatial correlation spectrum

Technical field

The invention belongs to the transmitance field of measuring technique, particularly a kind of devices and methods therefor that obtains transmission fluctuation spatial correlation spectrum.

Background technology

The transmission fluctuation spatial correlation spectrum method adopts the narrow laser beam of the identical parallel placement of two bundles, obtains relevant frequency spectrum by the space interval (promptly postponing parameter) that changes light beam.Its advantage is the measuring accuracy height, can measure the micron order granule, and the flow field of gained transmission fluctuation relevant frequency spectrum and particle (comprising that flow direction, velocity field distribute and fluctuating) is irrelevant.Therefore, need not to consider whether the setting of two-beam is consistent with the particle flow direction; Can measure the particle system under laminar flow and the turbulence state.Yet beam spacing requires and can change in measuring process, and this relates to mechanically actuated, when grain diameter hour requires beam spacing less than grain diameter, is difficult to accomplish mechanical positioning accurately in little interval.The corresponding same particulate samples of each sampling request pairing transmission fluctuation spatial correlation spectrum of different beam spacings, this requires sampling to finish in the short as far as possible time interval, and beam spacing must Fast Adjustable.In addition, also require detector can with the light beam synchronization action; Require two light beams as far as possible in light distribution, beam size unanimity; It is very difficult to satisfy above requirement simultaneously.Therefore, utilizing simple mechanism to obtain transmission fluctuation spatial correlation spectrum, is the difficulty that overcomes the mechanical adjustment aspect with the key that realizes utilizing the transmission fluctuation spatial correlation spectrum method to measure particle size distribution and granule density.

In the transmission fluctuation spatial correlation spectrum method, the transmission fluctuation relevant frequency spectrum is:

$e\left\{T_a{T}_b\right\}=\underset{t_s\→\∞}{\lim }\frac{1}{t_s}\underset{0}{\overset{t_s}{\∫}}{T}_a\left(t\right)T_b\left(t\right)\mathrm{dt}---\left(3\right)$

$\ln e\left\{T_a{T}_b\right\}=-\frac{1.5}{D_P}\mathrm{\ΔZ}\·C_V[2-\mathrm{\χ}(\mathrm{\Δ},\mathrm{\Λ})]---\left(4\right)$

Wherein, T _a, T _bBe respectively the transmitances of two parallel narrow light beams through measurement zone, t _sBe sample time, D _PBe grain diameter, C _VBe solids volume concentration, Δ Z is a light path.Wherein (Δ Λ) is described the particle size distribution information that comprises in the transmitance spatial correlation spectrum to fundamental function χ.Can be expressed as:

$\mathrm{\χ}(\mathrm{\Δ},\mathrm{\Λ})=\underset{0}{\overset{+\∞}{\∫}}{F}_C\·F_S\·F_P\·\mathrm{du}---\left(5\right)$

Wherein, F _CBe space correlation factor J ₀(2u Δ), J ₀It is first kind zero Bessel function; F _SBe the distribution factor of incident beam intensity on the cross section, be applicable to the light beam of multiple distribution form, as circular Gaussian beam and circular uniform beam, for Gaussian beam F _SBe exp[-(u Λ/u Λ)] ², for the equally distributed circular light beam F of light intensity _SBe [2J ₁(u Λ)/u Λ] ², J ₁It is first kind first-order bessel function; F _PBe particle shape factor, exist for spheric grain $F_P=2J_1^2\left(u\right)/u.$ Λ=D _B/ D _PBe the zero dimension beam diameter, the ratio of expression beam diameter and grain diameter; Δ=L/D _PBe the relevant spacing of zero dimension, L is a spacing between two parallel beams.Transmission fluctuation spatial correlation spectrum is the function of beam spacing L, when beam diameter is D _B, when light path Δ Z is known, can gets particle size distribution information and obtain granule density information thus.

Summary of the invention

In order to improve measuring accuracy, to realize that the transmission fluctuation spatial correlation spectrum method is real-time, on-line measurement micron order granule, overcome in measuring process because of the difficulty aspect the mechanically actuated, the invention provides a kind of devices and methods therefor that obtains transmission fluctuation spatial correlation spectrum.Make reflected light in measurement zone, form focus sequence according to Wavelength distribution, interval wavelength basis between reflected light focus and the incident light focus distributes, there is spatial coherence in light beam between the transmitance when the measurement zone and the transmitance during for the second time through measurement zone for the first time, the light correspondence that wavelength is different different focal point interval and different spatial coherences; Gather wavelength optical signals and transfer electric signal to by photo-sensitive cell, and send Computer Processing.The transmitance signal expectation value correspondence of different wave length different focal point interval be different spatial coherences, transmitance signal expectation value by different wave length constitutes transmission fluctuation spatial correlation spectrum, and the spectrum signature that is embodied has reflected particle grain size information and granule density information in the measurement zone.

For achieving the above object, the present invention adopts following technical scheme:

A kind of device that obtains transmission fluctuation spatial correlation spectrum comprises the light source module, measurement zone, chromatic dispersion module, detection and the signal processing module that are positioned at successively on the light path, wherein:

Described light source module is used for producing at measurement zone the secondary color Gaussian beam of a beam convergence;

Described measurement zone is located at the zone with a tight waist of described secondary color Gaussian beam;

Described chromatic dispersion module is used for and will be collimated into the directional light back reflection through the secondary color Gaussian beam of measurement zone, and once more at the measurement zone inner focusing, and the directional light of different wave length reflection back along different directions at the measurement zone inner focusing, the position of focus has nothing in common with each other;

Survey and signal processing module, be used to receive the light signal behind the measurement zone inner focusing once more, and this light signal is changed into electric signal handle.

Further, on the light path between described light source module and the measurement zone, also be provided with the half-reflection and half-transmission flat glass, be used to reflect the light behind the measurement zone inner focusing once more, described detection and signal processing module are used to receive the light signal through the reflection of half-reflection and half-transmission flat glass.

Further, described light source module comprises secondary color light source, first convex lens, spatial filter, second convex lens that are positioned at successively on the light path.

Further, also be provided with convergent bowl at described secondary color light source place.

Further, described chromatic dispersion module comprises: collimation lens and dispersor, described collimation lens be used for the first time transmitted light be collimated into directional light and shine dispersor, the directional light that is reflected by dispersor through collimation lens once more at the measurement zone inner focusing.

Further, described detection and signal processing module comprise: receiver lens, photo-sensitive cell and computing machine, through the light beam after the reflection of half-reflection and half-transmission flat glass, converged on the described photo-sensitive cell by described receiver lens, described photo-sensitive cell changes into electric signal with light signal and send described Computer Processing.

Further, described photo-sensitive cell is a ccd array, and the thickness of described measurement zone is 2mm～10mm.

The present invention also provides a kind of method of obtaining transmission fluctuation spatial correlation spectrum, may further comprise the steps:

1) adopts a secondary color light source, obtain the Gaussian beam of a beam convergence at measurement zone; For the incident light of certain wavelength, its intensity is I ₀(λ), when the secondary color light beam passes through measurement zone, particle scattering and absorption in the measured district, transmitted intensity is T ₁(λ, t) I ₀(λ), wherein, T ₁(λ t) is the transmitance that light beam passes through measurement zone for the first time;

2) transmitted light of process measurement zone is collimated into the directional light back reflection for the first time, and once more at the measurement zone inner focusing, this moment, the light beam transmitted intensity was T ₁(λ, t) T ₂(λ, t) I ₀(λ), wherein, T ₂(λ t) is the transmitance that light beam passes through measurement zone for the second time;

3) detect the light signal strength CT that passes through measurement zone once more ₁(λ, t) T ₂(λ, t) I ₀(λ), wherein C is a decay factor because grain flow has random character through measurement zone, total transmitance T (λ, t) random fluctuation, corresponding expectation value be expressed as e{T (λ, t) }:

$e\left\{T(\mathrm{\λ},t)\right\}=e\left\{T_1(\mathrm{\λ},t)T_2(\mathrm{\λ},t)\right\}=\underset{t_s\→\∞}{\lim }\frac{1}{t_s}{\∫}_0^{t_s}{T}_1(\mathrm{\λ},t)T_2(\mathrm{\λ},t)\mathrm{dt}---\left(1\right)$

Transmitance signal expectation value e{T (λ by each different wave length _i, t) } and constituted transmission fluctuation spatial correlation spectrum, its spectrum signature has reflected particle grain size information and granule density information in the measurement zone, i=1 wherein, 2 ... n.

Further, the direction of propagation of the Gaussian beam of assembling in the described step 1) is vertical with the particle flow direction.

Further, described step 2) adopts collimation lens and dispersor in, make for the first time angle of deviation θ of generation between parallel beam that transmitted light through measurement zone is collimated into parallel back reflection and the incident parallel beam, the size of angle of deviation is relevant with light wavelength, the light beam that returns produces between the focus of focus that collimation lens forms in measurement zone and incident beam and departs from, and its corresponding focal point interval L (λ) is:

$L\left(\mathrm{\λ}\right)=\mathrm{\θ}\·f=\frac{\mathrm{d\θ}}{\mathrm{d\λ}}\·|\mathrm{\λ}-{\mathrm{\λ}}_0|\·f---\left(2\right)$

Wherein θ is the angle of deviation behind the light beam process dispersor, and f is the collimation lens focal length, and d θ/d λ is the characteristic parameter of dispersor, and the expression angle of deviation is with the change rate of wavelength, and lambda1-wavelength λ equals certain particular value λ ₀The time, light beam returns along former road, and focus corresponding in measurement zone overlaps with the focus of incident beam, and the interval L (λ) that the focus that light beam passes through measurement zone for the first time and light beam pass through between the focus of measurement zone for the second time changes because of wavelength is different, when focus overlaps is L (λ) when being zero, transmitance T ₁(λ is t) with transmitance T ₂(λ, t) in full accord, have strongest correlation between two transmitances, along with the increase correlativity of L (λ) weakens gradually, when L (λ) during greater than grain diameter correlativity reduce to 0, this spatial coherence by transmitance expectation value e{T (λ, t) } embody.

The present invention utilizes the secondary color light source irradiation, through dispersor, makes the interval difference in measurement zone between the reflected light focus of incident light focus and different wave length, corresponding spatial coherence difference.Incident beam and folded light beam are subjected to the particle effect simultaneously, in measurement zone scattering and absorption, cause delustring.The beam split light beam focuses on the photo-sensitive cell through the half-reflection and half-transmission flat glass and by receiver lens, obtains the transmission relevant frequency spectrum thus.Can be used for utilizing micron particles size distribution and concentration under transmission fluctuation spatial correlation spectrum method measurement laminar flow, the turbulence state.Efficiently solve the problem that in measuring process, causes to the restriction of particle sizing scope because of mechanically actuated.And this acquisition methods and measurement mechanism are simple; improved measuring accuracy, realized that the transmission fluctuation spatial correlation spectrum method is real-time, on-line measurement micron order granule; and the flow field of transmission fluctuation spatial correlation spectrum method and particle (comprising that flow direction, velocity field distribute and fluctuating) is irrelevant; be not subjected to influence on flow field, can be widely used in a plurality of fields of scientific research, production of chemical energy and process control, environmental protection, water quality detection and particle sizing.

Description of drawings

Fig. 1 transmission fluctuation spatial correlation spectrum method of the present invention particle measurer synoptic diagram;

The synoptic diagram at interval between the reflected light focus of incident light focus and different wave length in Fig. 2 measurement zone;

Light path synoptic diagram when Fig. 3 dispersor adopts dispersing prism;

Label declaration:

1 secondary color light source, 6 half-reflection and half-transmission flat glasss

2 convergent bowls, 7 measurement zones

3 convex lens, 8 collimation lenses

4 spatial filters, 9 dispersors

5 convex lens, 10 receiver lenss

11 photo-sensitive cells, 13 reflective dispersing prisms

The reflecting surface of 12 computing machines, 14 dispersing prisms

Embodiment

Embodiment one

As shown in Figure 1, a kind of device that obtains transmission fluctuation spatial correlation spectrum comprises light source module, half-reflection and half-transmission flat glass 6, measurement zone 7, chromatic dispersion module, detection and signal processing module.

Described light source module is used for producing the secondary color Gaussian beam of a beam convergence at measurement zone 7;

Measurement zone 7 is located at the zone with a tight waist of described secondary color Gaussian beam;

The chromatic dispersion module, be used for and be collimated into the directional light back reflection through the secondary color Gaussian beam of measurement zone 7, and once more at measurement zone 7 inner focusings, and the directional light of different wave length reflection back along different directions at measurement zone 7 inner focusings, the position of focus has nothing in common with each other, that is to say that make to produce an angle of deviation θ between the parallel beam of reflection and the incident parallel beam, the size of angle of deviation is relevant with light wavelength;

Described half-reflection and half-transmission flat glass 6 is used to reflect the light behind measurement zone 7 inner focusings once more;

Survey and signal processing module, be used to receive light signal, and this light signal is changed into electric signal handle by described half-reflection and half-transmission flat glass 6 reflections.

Further, described light source module comprises secondary color light source 1, convex lens 3, spatial filter 4, second convex lens 5 that are positioned at successively on the light path.

Further, 1 place also is provided with convergent bowl 2 at described secondary color light source, is used for optically focused, to increase the intensity of the secondary color Gaussian beam that produces.

Further, described chromatic dispersion module comprises: collimation lens 8 and dispersor 9, collimation lens 8 transmitted lights for the first time are collimated into directional light and shine on the dispersor 9, the directional light that is reflected by dispersor 9 through collimation lens 8 once more at measurement zone 7 inner focusings.

Further, described detection and signal processing module comprise: receiver lens 10, photo-sensitive cell 11 and computing machine 12, through the light beam after 6 reflections of half-reflection and half-transmission flat glass, converged on the described photo-sensitive cell 11 by described receiver lens 10, described photo-sensitive cell 11 changes into electric signal with light signal and send described computing machine 12 to handle.The directional light of different wave length is reflected the back along different directions process collimation lens 8 by dispersor 9, the position of focus has nothing in common with each other in measurement zone 7, the corresponding focus of the light of each wavelength, distance between these focuses and the incident light focus is relevant with the focal length and the light wavelength of collimation lens 8, and corresponding different probe unit on the photo-sensitive cell 11.

Wherein, described photo-sensitive cell 11 preferred ccd array.

Wherein, the thickness of measurement zone 7 is 2mm～10mm.

Embodiment two

A kind of method of obtaining transmission fluctuation spatial correlation spectrum adopts embodiment one described device, may further comprise the steps:

Adopt a secondary color light source 1, the secondary color light beam that secondary color light source 1 sends is after convergent bowl 2 and 3 convergences of first convex lens, handle by spatial filter 4, assemble by second convex lens 5 again, convergent beam is positioned at the center of measurement zone 7 by its focuses of half-reflection and half-transmission flat glass 6 back, obtains the Gaussian beam of a beam convergence.Direction of beam propagation is vertical with the particle flow direction, and for the incident light of certain wavelength, its intensity is I ₀(λ), when the secondary color light beam passes through measurement zone 7, particle scattering and absorption in the measured district 7, transmitted intensity is T ₁(λ, t) I ₀(λ), T wherein ₁(λ t) is the transmitance that light beam passes through measurement zone 7 for the first time;

Collimation lens 8 transmitted lights for the first time is collimated into directional light and shines on the dispersor 9, the directional light that is reflected by dispersor 9 through collimation lens 8 once more at measurement zone 7 inner focusings.For the second time by particle scattering and absorption, transmitted intensity is T to the light beam of Hui Juing in measurement zone 7 once more ₁(λ, t) T ₂(λ, t) I ₀(λ), T wherein ₂(λ t) is the transmitance that light beam passes through measurement zone 7 for the second time.Consider the attenuation of the optical element of light beam process, the transmitted intensity that specific probe unit receives at last on the photo-sensitive cell 11 is CT ₁(λ, t) T ₂(λ, t) I ₀(λ), wherein C is a decay factor.When not having particle in the measurement zone 7, the signal that photo-sensitive cell 11 corresponding probe units receive is CI ₀(λ), therefore, in the measurement zone 7 the particle scattering and absorb the total transmitance cause the detector received signal be T (λ, t)=T ₁(λ, t) T ₂(λ, t).When having particle in the measurement zone 7, grain flow has random character through measurement zone 7, total transmitance T (λ, t) random fluctuation, corresponding expectation value be expressed as e{T (λ, t) }:

$e\left\{T(\mathrm{\λ},t)\right\}=e\left\{T_1(\mathrm{\λ},t)T_2(\mathrm{\λ},t)\right\}=\underset{t_s\→\∞}{\lim }\frac{1}{t_s}{\∫}_0^{t_s}{T}_1(\mathrm{\λ},t)T_2(\mathrm{\λ},t)\mathrm{dt}---\left(1\right)$

Dispersor 9 can be dispersing prism or reflective gratings, its effect is to make to produce an angle of deviation θ between the parallel beam of reflection and the incident parallel beam, the size of angle of deviation is relevant with light wavelength, the light beam that returns produces between the focus of focus that collimation lens 8 forms in measurement zone 7 and incident beam and departs from, and its corresponding focal point interval L (λ) can be expressed as:

$L\left(\mathrm{\λ}\right)=\mathrm{\θ}\·f=\frac{\mathrm{d\θ}}{\mathrm{d\λ}}\·|\mathrm{\λ}-{\mathrm{\λ}}_0|\·f---\left(2\right)$

Wherein θ is the angle of deviation behind the light beam process dispersor 9, and f is collimation lens 8 focal lengths, and d θ/d λ is the characteristic parameter of dispersor 9, and the expression angle of deviation is with the change rate of wavelength, and lambda1-wavelength λ equals certain particular value λ ₀The time, light beam returns along former road, and focus corresponding in measurement zone 7 overlaps with the focus of incident beam.

As shown in Figure 2, light beam changes because of wavelength is different through the interval L (λ) that the focus of measurement zone 7 and light beam pass through between the focus of measurement zone 7 for the second time for the first time, and note is made L (λ), when the focus coincidence is L (λ) when being zero, and transmitance T ₁(λ is t) with transmitance T ₂(λ, t) in full accord, have strongest correlation between two transmitances, along with the increase correlativity of L (λ) weakens gradually, when L (λ) during greater than grain diameter correlativity reduce to 0, this correlativity is called spatial coherence, by transmitance expectation value e{T (λ, t) } embody.

The transmitance signal expectation value e{T (λ of different wave length, t) } corresponding different focal point interval L (λ) and different correlativitys, and by photo-sensitive cell 11 corresponding probe units receptions, constitute transmission fluctuation spatial correlation spectrum, its spectrum signature that embodies has reflected particle grain size information and granule density information in the measurement zone 7.

As shown in Figure 3, be example with dispersing prism 13, parallel beam I shines on the dispersing prism 13, and after reflecting surface 14 reflections of chromatic dispersion and dispersing prism, wavelength is λ ₁, λ ₂Reflected light II, III and the angle of deviation of incident light I be respectively θ ₁, θ ₂, in measurement zone 7, the focus spacing of reflected light II, III and incident light I is L (λ ₁), L (λ ₂), and all satisfy formula (2).As λ=λ ₀The time, light beam returns along incident light I, and corresponding focus overlaps with the focus of incident beam in measurement zone 7.Photo-sensitive cell 11 corresponding probe units have received transmitance signal expectation value e{T (λ ₁, t) }, e{T (λ ₂, t) }, by the transmitance signal expectation value e{T (λ of each different wave length _i, t) } (i=1 wherein, 2 ... n) constituted transmission fluctuation spatial correlation spectrum, its spectrum signature has reflected particle grain size information and granule density information in the measurement zone 7.

Above-described embodiment only is used to illustrate technological thought of the present invention and characteristics, its purpose is to make those skilled in the art can understand content of the present invention and implements according to this, can not only limit claim of the present invention with present embodiment, be all equal variation or modifications of doing according to disclosed spirit, still drop in the claim of the present invention.

Claims (9)

1. a device that obtains transmission fluctuation spatial correlation spectrum is characterized in that comprising the light source module, measurement zone (7), chromatic dispersion module, detection and the signal processing module that are positioned at successively on the light path, wherein:

Described light source module is used for the secondary color Gaussian beam in measurement zone (7) generation one beam convergence;

Described measurement zone (7) is located at the zone with a tight waist of described secondary color Gaussian beam;

Described chromatic dispersion module, be used for and be collimated into the directional light back reflection through the secondary color Gaussian beam of measurement zone (7), and once more at measurement zone (7) inner focusing, and the directional light of different wave length reflection back along different directions at measurement zone (7) inner focusing, the position of focus has nothing in common with each other;

Survey and signal processing module, be used for receiving the light signal behind measurement zone (7) inner focusing once more, and this light signal is changed into electric signal handle;

On the light path between described light source module and the measurement zone (7), also be provided with half-reflection and half-transmission flat glass (6), be used for the reflection light behind measurement zone (7) inner focusing once more, described detection and signal processing module are used for receiving the light signal through half-reflection and half-transmission flat glass (6) reflection.

2. the device that obtains transmission fluctuation spatial correlation spectrum according to claim 1 is characterized in that:

Described light source module comprises secondary color light source (1), first convex lens (3), spatial filter (4), second convex lens (5) that are positioned at successively on the light path.

3. the device that obtains transmission fluctuation spatial correlation spectrum according to claim 2 is characterized in that:

Locate also to be provided with convergent bowl (2) at described secondary color light source (1).

4. the device that obtains transmission fluctuation spatial correlation spectrum according to claim 3 is characterized in that:

Described chromatic dispersion module comprises: collimation lens (8) and dispersor (9), described collimation lens (8) is used for that the secondary color Gaussian beam that described light source module produces at measurement zone (7) is collimated into directional light and shines dispersor (9), by the directional light of dispersor (9) reflection through collimation lens (8) once more at measurement zone (7) inner focusing.

5. the device that obtains transmission fluctuation spatial correlation spectrum according to claim 4 is characterized in that:

Described detection and signal processing module comprise: receiver lens (10), photo-sensitive cell (11) and computing machine (12), through the light beam after described half-reflection and half-transmission flat glass (6) reflection, converged on the described photo-sensitive cell (11) by described receiver lens (10), described photo-sensitive cell (11) changes into electric signal with light signal and send described computing machine (12) to handle.

6. the device that obtains transmission fluctuation spatial correlation spectrum according to claim 5 is characterized in that:

Described photo-sensitive cell (11) is a ccd array, and the thickness of described measurement zone (7) is 2mm～10mm.

7. method of obtaining transmission fluctuation spatial correlation spectrum is characterized in that may further comprise the steps:

1) adopts a secondary color light source (1), obtain the Gaussian beam of a beam convergence at measurement zone (7); For the incident light of certain wavelength, its intensity is I ₀(λ), when the secondary color light beam passes through measurement zone (7), particle scattering and absorption in measured district (7), transmitted intensity is T ₁(λ, t) I ₀(λ), wherein, T ₁(λ t) is the transmitance that light beam passes through measurement zone (7) for the first time;

2) transmitted light of process measurement zone (7) is collimated into the directional light back reflection for the first time, and once more at measurement zone (7) inner focusing, this moment, the light beam transmitted intensity was T ₁(λ, t) T ₂(λ, t) I ₀(λ), wherein, T ₂(λ t) is the transmitance that light beam passes through measurement zone (7) for the second time;

3) detect the light signal strength CT that passes through measurement zone (7) once more ₁(λ, t) T ₂(λ, t) I ₀(λ), wherein C is a decay factor because grain flow has random character through measurement zone (7), total transmitance T (λ, t) random fluctuation, corresponding expectation value be expressed as e{T (λ, t) }:

Transmitance signal expectation value e{T (λ by each different wave length _i, t) } and constituted transmission fluctuation spatial correlation spectrum, its spectrum signature has reflected particle grain size information and granule density information in the measurement zone (7), i=1 wherein, 2 ... n.

8. the method for obtaining transmission fluctuation spatial correlation spectrum according to claim 7 is characterized in that:

The direction of propagation of the Gaussian beam of assembling in the described step 1) is vertical with the particle flow direction.

9. the method for obtaining transmission fluctuation spatial correlation spectrum according to claim 7 is characterized in that:

Described step 2) adopts collimation lens (8) and dispersor (9) in, make for the first time angle of deviation θ of generation between parallel beam that transmitted light through measurement zone (7) is collimated into parallel back reflection and the incident parallel beam, the size of angle of deviation is relevant with light wavelength, the light beam that returns produces between the focus of focus that collimation lens (8) forms in measurement zone (7) and incident beam and departs from, and its corresponding focal point interval L (λ) is:

Wherein θ is the angle of deviation behind the light beam process dispersor (9), and f is collimation lens (a 8) focal length, and d θ/d λ is the characteristic parameter of dispersor (9), and the expression angle of deviation is with the change rate of wavelength, and lambda1-wavelength λ equals certain particular value λ ₀The time, light beam returns along former road, focus corresponding in measurement zone (7) overlaps with the focus of incident beam, the interval L (λ) that the focus that light beam passes through measurement zone (7) for the first time and light beam pass through between the focus of measurement zone (7) for the second time changes because of wavelength is different, when focus overlaps is L (λ) when being zero, transmitance T ₁(λ is t) with transmitance T ₂(λ, t) in full accord, have strongest correlation between two transmitances, along with the increase correlativity of L (λ) weakens gradually, when L (λ) during greater than grain diameter correlativity reduce to 0, this spatial coherence by transmitance expectation value e{T (λ, t) } embody.

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