JPS5856950B2 - Aperture device for electron microscopes, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to alignment of an aperture hole in an aperture device used in an electron microscope or the like.

The aperture holes used in electron microscopes are, for example, several tens to several hundred microns in size.
Since the aperture hole is extremely small such as m, it is necessary to align the center of the aperture hole with high precision with respect to the optical axis.

Therefore, the aperture device incorporates a fine adjustment mechanism for minutely moving the aperture plate.

However, as such fine adjustment mechanisms, mechanical ones using an index mechanism have generally been used, which has the disadvantage that the mechanism is complicated and large, and fine adjustment operations are extremely difficult. Was.

The present invention aims to solve such inconveniences, and will be explained in detail below with reference to the drawings.

FIG. 1 is a plan sectional view showing the basic configuration of the present invention, and 1 is a mirror body of an electron microscope or the like.

Reference numeral 2 denotes a holder attached to the side wall of the mirror body 1 through a spherical bearing 3 so as to be movable and rotatable, and the axis of the holder is aligned with the X axis perpendicular to the optical axis Z of the electron beam. Buttoned to match.

A diaphragm plate 6 having several diaphragm holes 5a, 5b, 5c is attached to one end (vacuum side) of the holder via a piezoelectric element 4, which will be described later.

The calibration holes 5a, 5b, and 5c are formed at approximately equal intervals along the X-axis.

A gripping portion 7 is provided at the other end (atmospheric side) of the holding body 2, and a pin 8 is implanted in the gripping portion 7.

The pin 8 is engaged in an E-shaped guide groove 10 formed in a guide body 9 fixed to the side wall 1, thereby regulating the positions of the calibration holes 5a, 5b, and 5c.

1. When the repin 8 is set at the position shown by the solid line in the figure, the center of the aperture hole 5b is located approximately on the optical axis, and the grip portion 7
When the pin 8 is set in the position indicated by number a or b in the guide groove 10, the center of the aperture hole 5c or u5a is located approximately on the optical axis 2, respectively.

Reference numeral 11 denotes a push rod placed inside the mirror body 1. One end of the push rod is in contact with the holder 2, and the other end is connected to the inner wall of the mirror body 1 via a piezoelectric element 12, which will be described later. Fixed.

The piezoelectric elements 4 and 12 described above are formed of a material that causes mechanical strain when a voltage is applied, and each piezoelectric element has two electrode plates 13a, 13b and 14a and 14, respectively.
b is attached, and a DC variable power supply 15 is attached between each electrode plate.
The piezoelectric elements 4 and 12 are configured to expand or contract in the longitudinal direction of the aperture plate 6 and the push rod 11, respectively, by applying voltages from the piezoelectric elements 4 and 16.

Therefore, when the piezoelectric element 4 is expanded or contracted by the DC variable power source 15, the aperture plate 6 moves slightly in the X-axis direction.

Furthermore, if the piezoelectric element 12 is expanded or contracted by the other DC power source 16, the push rod 11 moves in the same direction, and thereby the holding rod 2
rotates about the spherical bearing 3 in a plane perpendicular to the optical axis Z, so the diaphragm plate 6 slightly moves approximately in the Y-axis direction.

As a result, by appropriately adjusting the DC variable power supplies 15 and 16, the diaphragm plate 6 can be horizontally slightly moved in any direction.

After operating the grip part 7 to set the desired aperture hole approximately on the optical axis, the two variable DC power supplies 15 and 16 are adjusted while observing the image of this aperture projected on a fluorescent plate (not shown). In this way, the desired center of the aperture hole can be precisely aligned with the optical axis Z.

FIG. 2 shows an embodiment of the present invention, which is characterized in that the aperture hole position is automatically finely adjusted in conjunction with the replacement operation of each calibration hole. In the figure, the same numbers as in FIG. 1 indicate the same components.

In FIG. 2, numeral 17 is a memory circuit, and the memory circuit stores the deviation between the center of each calibrating hole and the optical axis when each calibrating hole 5a, 5b, 5c is set on the optical axis Z by the grip part 7. A signal for correcting the amount is stored, and the stored signal is used for position detection such as a Maro cross inch installed in the guide groove 10 portion for regulating the position of each calibration hole 5a, 5b5c. The position signals are read out based on the position signals from the devices 18a, 18b, and 18c.

The signal continued from the memory circuit 17 is sent to the X and Y direction DC power supplies 19 and 20 to control the power supplies and correct the amount of deviation between each electrode plate 13a and 13b and 14a and 14b. Apply voltage.

Now, if you operate the grip part 7 and set the aperture hole 5b on the optical axis Z as shown by the solid line in the drawing,
Since the pin 8 provided on the grip portion 7 engages with the position detector 18b, a position signal is generated from the position detector 18b and sent to the memory circuit 17.

As a result, a signal corresponding to a voltage value for correcting the amount of deviation from the optical axis at the aperture hole 5b is read out from the memory circuit 17, and is passed through the DC power supplies 19 and 20 to the electrode plates 13a and 13b.
and 14a and 14b, so each voltage element 4
and 12 expand or contract, respectively, in the direction to correct the deviation from the optical axis of the aperture hole 5b, and the center of the aperture hole 5b is automatically positioned on the optical axis Z.

Furthermore, if the other aperture holes 5a and 5c are set on the optical axis Z using the gripping part 7, the pins 8 will engage with the position detectors 18a and 18c, respectively, so that the centers of the aperture holes 5a and 5c can be set by the same operation as described above. is automatically located on the optical axis Z.

By configuring as described above, the present invention has an extremely simple and compact structure, and can align the aperture hole with the optical axis with high precision, and furthermore, can perform fine adjustment of the aperture hole position extremely easily. I can do it.

In addition, by using a signal memory circuit that corrects the amount of misalignment between each calibration hole and the optical axis, it becomes possible to automatically align the aperture center with the optical axis in conjunction with the operation of replacing the aperture holes. It is possible to further improve the handling operation and has a great practical effect.

Please note that the above description is an example of the present invention, and many modifications may be made to its implementation.

For example, in the above description, the case where three aperture holes are provided in the aperture plate is described, but the number is not limited to this.

Also, although I have described the case where the aperture hole is replaced manually,
For example, it is also possible to perform this electrically using a motor or the like.

[Brief explanation of the drawing]

FIG. 1 is a sectional plan view showing the basic configuration of the present invention, and FIG. 2 is a sectional plan view showing an embodiment of the present invention. In Fig. 1, 1 is the mirror body of an electron microscope, 2 is a holder, 3 is a spherical bearing, 4 and 12 are piezoelectric elements, 5a, 5b
and 5cu aperture hole, 6 is the aperture plate, γ is the grip part, 8 is the pin, 9 is the guide body, 10 is the guide groove, 11 is the push rod, 13a,
13b, 14a and 14b are electrode plates, and 15 and 16 are DC variable power supplies.

Claims (1)

[Claims] 1. A diaphragm plate having a plurality of diaphragm holes, a holding member for holding the diaphragm plate on a mirror body, and an arbitrary one of the diaphragm holes being selectively fixed by moving the holding member. A mechanical positioning device for positioning on the optical axis, a member that is attached to the holding member and generates mechanical strain by applying a voltage; and a member that generates mechanical strain by applying a voltage to the member. a storage means for storing a signal for correcting deviation from the optical axis when each of the apertures is positioned by the mechanical positioning means; means for reading out a corresponding correction signal from the storage means based on a signal indicating whether the aperture hole is arranged on the optical axis, and controlling the output of the power supply based on the read-out correction signal. A diaphragm device for an electron microscope, etc., characterized by: