JPH0656747B2 - Aperture position control device for electron microscope - Google Patents

Description

The present invention relates to an aperture position control device for an electron microscope, which performs remote control of fine adjustment of the aperture position by driving a motor or the like.

[Prior Art] In an electron microscope, diaphragms such as an objective diaphragm are arranged in several places, and the operator performs the work of aligning the center of the diaphragm with the optical axis, that is, the fine adjustment work while observing the screen. It was The structure is shown in FIG. Diaphragms a, b, c having different diameters are formed on the diaphragm plate 1, and the operator operates the adjustment knobs 3 and / or 5 of the fine adjustment mechanism 2 so that the center of the diaphragm coincides with the optical axis 13. Let As shown in FIG. 2, taking an example in which fine adjustment is performed so that the center of the diaphragm a coincides with the optical axis 13, the operator observes a screen (not shown) and moves in the direction indicated by arrow X (X direction). If it is necessary to move it to), turn adjustment knob 3. The adjusting knob 3 is designed so that it only rotates in the direction A at the position shown in the drawing and does not move in the left-right direction in the drawing.
Since it is screwed with the shaft 4 to which is attached,
The shaft 4 can be moved in the X direction by turning the adjusting knob 3. A stopper 10 is provided to prevent the stop plate 1 from tilting the diaphragm plate 1 with respect to the optical axis 13 when the shaft 4 rotates.
When the diaphragm is to be moved in the direction indicated by Y in the figure (Y direction), the adjustment knob 5 is turned. Since the adjusting knob 5 is rotatable on the spot and is screwed with the shaft 6, the shaft 6 moves in the vertical direction in the figure when the adjusting knob 5 is rotated. Since the other side of the support body 7 is supported by the spring 8, the support body 7 moves in the Y direction around the fulcrum 9 formed as a spherical surface as the shaft 6 moves up and down.
Reference numeral 11 denotes a stopper provided so that the shaft 6 does not rotate, and reference numeral 12 in the drawing denotes a container for accommodating the fine adjustment mechanism.

The above is the fine adjustment that has been performed conventionally. In addition to the fine adjustment, a coarse movement mechanism for switching the diaphragm, that is, a mechanism for quickly moving the diaphragm having a desired diameter to the vicinity of the optical axis 13 is usually provided, but it is omitted because it is not related.

[Problems to be Solved by the Invention] However, although it is performed while observing an enlarged image on the screen, it is necessary to manually perform a delicate adjustment such that the center of a diaphragm having a diameter of a micron unit is aligned with the optical axis. Requires skill and its operability is very poor. In addition, there is a problem that the position where the diaphragm is inserted is restricted when the fine adjustment is manually performed as shown in the conventional example. That is, since the operator operates the adjustment knob while observing the screen, there is a constraint that the diaphragm must be placed within reach of the operator while sitting. Of course, since various remote control mechanisms are known, it is possible to perform remote control by an appropriate mechanism, but adjusting the aperture is a very delicate one, so it must be a complicated mechanism. As a result, the cost becomes high.

The present invention is to solve the above-mentioned problems, in which fine adjustment of the aperture position is performed by remote control using a motor or the like, and the moving speed of the aperture at that time is a predetermined value according to the diameter of the aperture. It is an object of the present invention to provide a diaphragm position control device for an electron microscope.

[Means for Solving the Problems] In order to achieve the above object, the aperture position control device for an electron microscope according to the present invention, when performing the control of the aperture position by remote control, adjusts the moving speed during fine adjustment of the aperture. It is characterized in that the predetermined value is determined by the size of the aperture.

[Operation] In the present invention, since the fine adjustment of the diaphragm position is performed by remote control, the operability is of course good, and the speed of the diaphragm at the time of the fine adjustment is a predetermined speed corresponding to the size of the diaphragm diameter. Therefore, the control is easy and can be realized.

[Examples] In recent years, automation has been called for in all fields. Therefore, before explaining the embodiment, let us consider the possibility of automating the fine adjustment of the diaphragm position in the electron microscope. Of course, it is possible to completely automate the adjustment of the diaphragm position. For example, assuming that the diaphragm plate is moved by a motor drive, the diaphragm plate is moved while emitting an electron beam, and the center of the diaphragm is aligned with the optical axis when the current detected by the diaphragm plate becomes minimum. You can think of it as a match. However, such control is technically difficult and, as a result, becomes expensive, which is not a good idea.

The next possibility is remote control using a driving device such as a motor. That is, for example, the fine adjustment of the aperture position can be performed only by pushing the button of the desired movement direction or by instructing the movement direction with the joystick. The problem at this time is how to set the moving speed in the case of fine adjustment of the diaphragm position. First, it can be considered that the moving speed of the diaphragm is always constant. However, setting the constant speed to be relatively high is advantageous for a large-diameter aperture, but it is not useful for a small-diameter aperture of about 10 μm. This is because in the case of a diaphragm with a small diameter, fine adjustment cannot be performed unless it is moved at an ultra-low speed. In that case, it suffices to set the moving speed to an ultra-low speed in accordance with a small-diameter aperture. In that case, it is possible to make fine adjustments, but the position adjustment of a large aperture that does not require fine adjustments of about 100 μm. It will take too much time. It seems that it is better to set an intermediate value, but since the diameter of the diaphragm is very wide, about 5 μm to 100 μm, it is difficult to find an appropriate constant speed for any diaphragm. Therefore, it turns out that it is not a good idea to keep the moving speed of the diaphragm constant.

It is also conceivable that the moving speed at the time of fine adjustment of the diaphragm position is interlocked with the magnification of the electron microscope and the diaphragm is moved at a speed suitable for the magnification, but this is not a good idea because control becomes complicated.

Therefore, in the present invention, the moving speed of the diaphragm during the fine adjustment is set to a predetermined speed corresponding to the diameter of the diaphragm. That is, for example, when using an aperture having a diameter of 5 μm, the aperture is moved at a speed corresponding to the diameter, and when using an aperture of 100 μm, the aperture is moved at a predetermined velocity different from that of 5 μm. To try. That is, as described above, when the aperture diameter is small, it is necessary to move it at a low speed, and when the aperture diameter is large, it may be faster than that. Therefore, there is an optimum moving speed suitable for the size of the aperture diameter. It is based on the recognition that And such control can be easily realized at low cost.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an aperture position control device for an electron microscope according to the present invention, in which 20 is a CPU, 21.
Is an aperture selection table, 22 is an operation table, 23 and 24 are drive circuits,
25 and 26 are motors, 27 is a rotary encoder, 2
Reference numeral 9 indicates an X drive axis, and 30 indicates a Y drive axis. The same parts as those in FIG. 2 are designated by the same reference numerals and the details thereof will be omitted.

In the configuration of FIG. 1, the aperture selection table 21 is for selecting an aperture, and corresponds to the coarse movement mechanism described above. The aperture is selected by pressing the buttons indicated by 1, 2, 3 and 4 in the figure. It is made possible. For example, 1
The button can be selected as aperture a, the button 2 as aperture b, the button 3 as aperture c, and the button 4 as open. Aperture a has been selected so far, and aperture c now
If the button 3 of the aperture selection table 21 is pressed to select, the CPU 20 compares the position of the aperture c stored in advance with the current position obtained from the rotary encoder 27, and moves the motor 25 in either direction. It is calculated whether it should be rotated, and the result is sent to the drive circuit 23. As a result, the motor 25 starts rotating in a predetermined direction, and thus the diaphragm plate 1 moves in the X direction by the above-mentioned operation. At this time, the CPU 20 uses the rotary encoder 27.
The position is confirmed by the signal from the above, and when it coincides with the predetermined position of the diaphragm c, a signal for stopping the driving of the motor 25 is sent to the drive circuit 23. In this way, the diaphragm c is arranged near the optical axis 13. The above is the coarse movement, that is, the operation of selecting the aperture, but since coarse adjustment needs to be performed quickly no matter which aperture is selected,
It is made to move at a predetermined high speed.

After the aperture selection, fine adjustment is performed using the console 22. Now, a case where fine adjustment is performed in the + X direction will be described as an example. At this time, the operator presses the button marked with "←" on the console 22 while observing the screen, and the CPU
20 detects it and issues a command to the drive circuit 23 to rotate the motor in a predetermined direction, and the shaft 4 starts moving in the + X direction. Then, when the operator stops pressing the button, the movement of the shaft 4 is stopped. In other words, the movement of the axis 4 is the operation console 2
It is designed to be performed only while the second button is being pressed. The moving speed at this time is a speed corresponding to the diameter of the diaphragm. That is, the CPU 20 stores in advance the data of the fine adjustment speed according to the aperture diameter, and on the other hand, it is possible to judge which aperture is near the optical axis 13 from the position data obtained from the rotary encoder 27. If the fine adjustment speed is read out based on, and the read fine adjustment speed is sent to the drive circuit 23, the fine adjustment can be performed at a speed corresponding to the diameter of the diaphragm.

The speed data at the time of fine adjustment stored in the CPU 20 is
Now, let the diameters of the diaphragms a, b, and c be φ _a , φ _b , and φ _c , respectively.
And φ _a > φ _b > φ _c , the speeds V _a , V _b , and V _c at the time of fine adjustment of the respective apertures are set to optimal speeds such that V _a > V _b > V _c. It is what

The above is fine adjustment in the + X direction, but the same applies to fine adjustment in the -X, + Y, and -Y directions.

Further, in the above embodiment, no aperture is specified, but this is because the aperture position control device for an electron microscope according to the present invention can be applied to all apertures used in an electron microscope.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, although the motor is used in the above-mentioned embodiment, other well-known remote control methods may be used. As an example, a piezo element is used, and the slope of the voltage applied to the piezo element is changed. Alternatively, the moving speed may be changed. In addition to the button operation described in the embodiment, a joystick may be used to instruct the direction of fine adjustment.

[Effects of the Invention] As is clear from the above description, according to the present invention, fine adjustment of the aperture position can be performed by remote control, so that operability is good and the aperture position is restricted as in the conventional case. Nor. Moreover, since the speed at the time of fine adjustment is the optimum speed corresponding to the size of the aperture diameter, control is easy and there is no problem in cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of an aperture position control device for an electron microscope according to the present invention, and FIG. 2 is a diagram showing a conventional configuration. 1 ... Aperture plate, 2 ... Fine adjustment mechanism, 13 ... Optical axis, 20
...... CPU, 21 …… Aperture selection table, 22 …… Operation table, 2
3, 24 ... Drive circuit, 25, 26 ... Motor, 27 ...
… Rotary encoder.

Claims (1)

[Claims] 1. A diaphragm position control device for an electron microscope, which controls the diaphragm position by remote control, wherein a moving speed at the time of fine adjustment of the diaphragm is set to a predetermined value determined by the size of the diaphragm diameter. Aperture position control device for electron microscope.