JPS5916256A - Field of view setting device in electron microscope - Google Patents

Abstract

PURPOSE:To make the operation of visual field setting in an electron microscope performable in a speedy and easy manner, by setting up an instantaneous selector mechanism for both field shifting cases, one using an electron beam deflecting device and the other using a mechanical sample movement. CONSTITUTION:A sample 1 is irradiated by electron beams 3 emitted out of an electron gun 2 through a converging lens 4 in a state of being paralleled. Deflecting electrodes 18X and 19Y lead the electron beams, transmitting a specific spot of the sample 1, into an optical axis in an image formation system below intermediate lenses, and forms an image on a phosphor plate by the way of supplying each of two-step deflecting coils 20X, 21X and 20Y, 21Y, with a DC de- flecting current respectively. Information concerning the electrical field shifting stored in a memory is converted into a control signal to be fed to a pulse motor 23X for Y-direction drive use and a pulse motor 24Y for 24Y for Y-direction drive use and feeds the signal to these pulse motors 23X and 24Y. Since this conversion takes place so as to accord with direction and quantity of the field shifting by the electrical field shifting and the sample's mechanical shifting, a visual field on a phosphor plate 8 before and after pressing an S button is kept ever so constant except for a short time immediately after pressing the S button.

Description

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

In a transmission molecular microscope, an electron beam transmitted through a sample is imaged on a fluorescent plate by an imaging lens system. In order to move the field of view of this microscope image, a sample moving mechanism is usually used that mechanically moves the position of the sample that is irradiated with the electron beam. Operation of the sample moving mechanism (J manual C' or pulse motor is used, but as the observation magnification increases, the amount of sample movement becomes extremely small (it becomes small, causing vibrations, etc.).
The specimen had to be carefully moved little by little to avoid any damage, and as the observation magnification decreased, the amount of specimen movement increased, so it took a considerable amount of time to move the field of view. Therefore, the so-called field-of-view search operation that searches for the target part of the observation sample involves repeating this type of field-of-view movement many times.
'K L], it was a troublesome operation. on the other hand,
Another method for moving the field of view is to use a deflection coil installed at an appropriate position within the C imaging lens system, and to direct only the electron beam that has passed through a specific part of the sample to the deflection coil. There is a method using a deflection movement mechanism consisting of means for supplying a deflection current so as to guide it near the optical axis.
It is used for the purpose of smoothly moving minute samples. (Refer to Japanese Patent Publication No. 48-33903 for details.) However, as the observation magnification becomes lower, even in the h method of electric field movement, even in the first transmitted electron beam, the imaging lens system is far out from the optical axis. It is almost never used to search the field of view in low-magnification images because it has the disadvantage of increasing image distortion due to the effects of lens aberrations. What happened?

The present invention aims to eliminate the troublesome operation of searching the field of view as described above. In a device that implements a deflection movement mechanism that moves a field of view by electromagnetic deflection of an electron beam or a sample-transmitting electron beam, there is provided means for replacing the movement of the field of view moved by operating the deflection movement mechanism with the movement of the field of view by the sample movement mechanism. It is characterized by the fact that

The drawing is a schematic diagram showing an embodiment of an apparatus in which the present invention is applied to a transmission electron microscope. In the figure, reference numeral 1 represents a thin film sample, and the sample has an electron beam 3 emitted from an electron gun 2.
are irradiated in parallel by the converging lens 4. The electron beam transmitted through the sample 1 is passed through the objective lens 5. A microscopic image is formed on a fluorescent plate 8 by an imaging lens system consisting of an intermediate lens 6 and a projection lens 7. In order to avoid changing the image magnification of this microscope image, it is done by operating the magnification specifying means 9 and changing the output point of the lens power supply 10 of the C imaging lens system, but to change the field of view of the microscope LT image, This is done by operating the knobs on the operation panel 11 shown in FIG. For example, if you want to move the microscope image displayed on the fluorescent plate 8 left and right in the X direction, press knob 12X and 13X a number of times according to the amount of movement, and move it 1-'F in the Y direction. If so, turn knob 14Y.

By pressing 15Y a number of times according to the moving vehicle (designating the direction and place of the field of view movement), the signal generated by pressing the knob is sent to the central control circuit 17 via the signal generation circuit 16, The circuit 17 deduces to which value the outputs of the deflection power supplies IE3X and 19Y should be changed together with the signal from the magnification specifying means 9, and based on the result of
, 19Y. Deflection power supply 18X, 19
Y are respectively - two-stage deflection coils 2ox, 21X and 20Y
.

By supplying one current and one direction current to 21Y, the electron beam that passes through a specific portion of test 11 is guided to the optical axis of the imaging lens system below the intermediate lens, and is imaged onto the fluorescent plate. As described above, this electrical visual field movement operation is quick and easy, so it is extremely convenient for moving the visual field many times to search for visual fields.

When the operation of searching the visual field by electrical visual field movement is completed in the above manner, the knob S on the operation panel 11 is pressed. When the signal (g) from the signal generation circuit 16 generated by pressing the knob S is applied to the central control circuit 17, the deflection power source 1
The values of the signals supplied to 8X and 19Y are stored in the main memory, and the signals of the deflection power supplies 18X and 19Y are supplied to the deflection coils 20X, 20Y, 21X, and 21.
Let the electric field of view shift due to Y be A). At the same time,
The information related to the electrical field of view movement stored in the memory is transferred to the X-direction driving pulse motor 23X of the sample moving device @22.
and convert it into a control signal that should be supplied to the Y-direction drive pulse motor 24Y, and then convert the converted control signal to the pulse motor 24Y.
Supply to 3X and 24Y. This conversion is for the short time after J, uni tJ4', +neru (・, press the S button) where nl matches the direction of field movement due to electrical field movement and mechanical movement of the sample. Except for the time, the field of view 1 of the fluorescent plate 81 that moves back and forth by pressing the S button is maintained at a constant value. However, the distortion and aberrations of the microscope image have been improved compared to before pressing the button S, making it suitable for taking photographs and observing with the naked eye.

As described above, in the present invention, the instant 1 of the field of view movement using the electron beam width plane means and the field of view movement using the mechanical sample movement
With the establishment of the 7J Katsukisha, the electronic W1 microscope (which makes it easy to quickly and easily find the field of view)
S1j Hi yell.

[Brief explanation of drawings]

The drawing is a schematic illustration of an embodiment of the present invention.

Claims (1)

[Claims] In the apparatus comprising a sample moving mechanism that moves the field of view of an electron microscope image by moving a sample irradiated with an electron beam, and a deflection movement mechanism that moves the field of view by deflecting a sample-preparing electron beam or a sample-transmitting electron beam, A field of view setting device for an electron microscope, characterized in that a means is provided for replacing the field of view movement by operating the deflection movement mechanism and moving the field of view by the movement of the field of view by the sample movement mechanism.