JPS5858779B2 - Field of view moving device for electron microscopes, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for moving a field of view of a microscope image in a transmission imaging electron microscopy or a scanning electron microscope.

The field of view of a microscope image in an ordinary electron microscope is moved by mechanically horizontally moving a means for holding a sample.

However, it is difficult to accurately control microscopic amounts using mechanical sample movement mechanisms, and special care is required when setting the field of view of a high-magnification microscope image to a desired location. .

In order to solve these problems, in scanning electron microscopes, the field of view is moved by electrically deflecting the entire deflection range of the electron beam irradiating the sample, and in transmission imaging type electron microscopes, As shown in Publication No. 33903, a deflection coil is provided in the imaging lens system, and the field of view is moved by deflecting the electron beam that is transmitted outside the electron beam optical axis of the sample-transmitting electron beam in a direction that allows image formation. ing.

However, since the control knobs for electrically moving the field of view and the knobs for mechanically moving the field of view in low magnification areas are provided separately, it is cumbersome to operate the microscope's field of view. It had some drawbacks.

The purpose of the present invention is to solve these drawbacks and to perform highly accurate visual field movement by appropriately switching between electrical visual field movement and mechanical visual field movement with a single operation knob. An electron optical system for displaying a microscopic image of a sample to be irradiated, a mechanical field of view moving means for mechanically moving the sample position, and an electron beam deflection means incorporated in the electron optical system An apparatus comprising an electric field moving means for moving an image in a field of view, and a magnification control means for controlling a magnification of the microscope image,
A field of view movement operating means for specifying a field of view movement, and when a magnification signal from the magnification control means is lower than a fixed magnification value, the mechanical field of view movement means is controlled by a signal from the field of view movement operation means, and the mechanical field of view movement means is controlled by a signal from the field of view movement operation means, The present invention is characterized in that a central control circuit is provided which controls the electric field of view moving means by a signal from the field of view movement operation means when the magnification signal from the control means is higher than a fixed magnification value.

FIG. 1 is a schematic diagram showing an embodiment in which the present invention is applied to a transmission imaging type electron microscope.

In the figure, numeral 1 represents an electron gun that generates an electron beam 2, and two-stage focusing lenses 3 and 4 irradiate the thin film sample 5 with the electron beam 2 in a substantially parallel state.

The electron beam transmitted through the sample 5 is directed to a fluorescent plate 9 by an imaging lens system consisting of an objective lens 6, an intermediate lens 7, and a projection lens 8.
A microscopic image is formed on top.

The magnification of the microscope image is determined by the lens control means 10 of the imaging lens system.
The field of view is set to an arbitrary value by operating the sample 5, and the general field of view is moved by operating the sample moving mechanism 11 that holds the sample 5.

Further, as shown in the above-mentioned Japanese Patent Publication No. 48-33903, a two-stage deflection coil 12 X t is provided behind the objective lens 6.
12 y is provided, and the field of view is minutely moved by adjusting the deflection power source 13 so as to move the electron beam passing through the area off the optical axis of the objective lens 5 in the optical axis direction. There is.

Reference numeral 15 represents a knob for moving the field of view provided on the operation panel of the electron microscope, and a rotary encoder 1 generates an electric signal according to the amount of rotation of the knob 15.
It is attached to 6.

The central control circuit 14 to which signals from the rotary encoder 16 are supplied includes a rotating section for controlling the deflection power source 13 and moving the electric field of view, a pulse smoke 17,
A built-in circuit unit is controlled by a transmission 18 to transmit the circuit of the pulse motor 17 to the sample moving mechanism 11 via a rotary encoder 19 and a mechanical conversion mechanism 20 to mechanically move the field of view.

In the apparatus shown in FIG. 1, the only operation part for moving the field of view is the knob 15, and when the knob 15 is rotated,
The amount of rotation is converted into an electrical signal by the rotary encoder 16 and transmitted to the central control circuit 14.

The central control circuit 14 receives a magnification signal indicating the operational setting value of the image magnification from the lens control means 10, and when the magnification value is low, operates a circuit for mechanical visual field movement and controls the pulse motor 17. At the same time as giving a rotation signal according to the electric signal from the rotary encoder 16, the transmission 18
is controlled to increase the gear ratio when the magnification value is low;
When a high magnification value is used, the gear ratio is set to be low, and when a constant rotation amount is given to the knob 15 at one stroke speed, the microscopic image formed on the fluorescent plate 9 is adjusted regardless of the image magnification. It is configured such that the visual field movement speed is always approximately constant.

That is, in the case of high magnification, even if the pulse motor 17 rotates by a certain amount, the amount of sample movement can be kept low.

A rotary encoder 19 provided between the transmission 18 and the conversion mechanism 20 generates a signal for monitoring the position of the sample held in the sample moving mechanism 11.

On the other hand, when the magnification signal given from the lens control means 10 is higher than a certain value (for example, 100,000 times) and reaches a region where accurate visual field movement cannot be achieved by mechanical visual field movement, the central control circuit 14 performs electrical visual field movement. A control signal for moving the field of view is sent to the deflection power source 13 by operating the circuit section for this purpose.

In this case as well, as in the case of mechanical visual field movement control, it is desirable to control the amount of deflection current to a lower value for a given amount of signal from the rotary encoder 16 as the magnification value increases.

As described above, according to the apparatus of the embodiment shown in FIG. 1, not only can the field of view be moved from low magnification to high magnification with a single knob operation, but also the field of view of the microscope image can be moved if the operating conditions applied to the knob are the same. Since the operation is always performed in substantially the same state regardless of the magnification value, the operability is significantly improved compared to the conventional method.

In the embodiment shown in FIG. 1, only the part relating to movement of the field of view in one direction is shown, but it goes without saying that the same control method is normally carried out in two directions orthogonal to each other.

FIG. 2 is a schematic diagram showing an embodiment in which the present invention is applied to a scanning electron microscope.

1 in the figure represents an electron gun that generates an electron beam 2 as in FIG.
It is narrowly focused on 1.

The sample irradiation position of the electron beam is determined by the deflection coil 24 supplied with the output of the scanning signal generation circuit 23 via the magnification control circuit 22.
However, this change is synchronized with the screen scanning of a cathode ray tube 26 equipped with a deflection coil 25 to which the output of the scanning signal generating circuit 23 is also supplied.

Signals such as secondary electrons generated from the sample 21 are detected by the detector 27 and used as a brightness modulation signal for the cathode ray tube 26, so that a sample scanning image is displayed on the cathode ray tube screen.

By operating the sample moving mechanism 28 on which the sample 21 is placed, the field of view of the scanned image can be mechanically moved.As a control means, a pulse motor 17 and a transmission 18 having the same functions as those shown in FIG. 1 are used. , rotary, encoder 1
9. A mechanical conversion mechanism 20 is provided.

As a means for electrically moving the field of view, a deflection coil 28 and its deflection power supply 29 are provided for moving the entire scanning range of the electron beam that irradiates the sample, and these field of view moving means are connected to a magnification control circuit. 22 output and knob 15
Rotary encoder 1 that converts the rotation of
It is controlled by a central control circuit 30 based on the output of 6.

The control system in the central control circuit 30 is similar to that of the apparatus shown in FIG. 1, in which mechanical visual field movement is performed in low magnification areas and electrical visual field movement is performed in high magnification areas.

Even if the output from the rotary encoder 16 is the same for W, the movement control is changed according to the magnification signal so that the field of view movement caused by the operation of the knob 15 always maintains a constant relationship. .

As detailed above, according to the present invention, the field of view movement in an electron microscope can be controlled accurately and reliably.
This has a significant effect on improving the operability of electron microscopes.

In the above embodiment, the amount of mechanical change in the knob 15 is once converted into an electrical signal by the encoder 16, but the amount of mechanical change in the knob 15 is
5 is connected directly to the sample moving mechanism 11, and a switching flange is provided in the middle, so that the knob 15 is connected to the deflection power source 13 at high magnification.
Alternatively, the switching may be linked to the variable magnification.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment in which the present invention is applied to a transmission imaging electron microscope, and FIG. 2 is a schematic diagram showing an embodiment in which the present invention is applied to a scanning electron microscope. 1...Electron gun, 2...Electron beam, 3,4
...Focusing lens, 5,21...Sample,
11, 29...Sample movement mechanism, 10...
- Lens control means, 12X. 12Y, 2B... Deflection coil, 13, 29...
... Deflection power supply, 14, 30 ... Central control circuit, 15 ... Knob, 16, 19 ...
Rotary encoder, 17...Pulse smoke, 18...Transmission, 20...Mechanical conversion mechanism, 22...Magnification control circuit, 23...
...Scanning signal generation circuit.

Claims (1)

[Scope of Claims] 1. An electron optical system for displaying a microscopic image of a sample irradiated with an electron beam; a mechanical field of view moving means for mechanically moving the sample position; A field of view for specifying the field of view movement in an apparatus comprising an electric field of view movement means for moving the field of view of the microscope image by a built-in electron beam deflection means, and a magnification control means for controlling the magnification of the microscope image. When the magnification signal from the movement operation means and the magnification control means is lower than a fixed magnification value, the mechanical field of view movement means is controlled by the signal from the field of view movement operation means, and the magnification signal from the magnification control means is controlled. 1. A field-of-view moving device for an electron microscope, etc., characterized in that a central control circuit is provided for controlling the electrical field-of-view moving means by a signal from the field-of-view moving operation means when the magnification is higher than a certain magnification value. 2. When controlling the electrical visual field moving means or the mechanical visual field moving means by the output signal from the visual field moving operation means, the central A field-of-view moving device for an electron microscope or the like according to claim 1, characterized in that it comprises a control circuit.