JPH0316203Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a movable aperture device that is effective for use in electron microscopes and the like that require ultra-high vacuum.

[Prior Art] Normally, a movable aperture device in an electron microscope or the like has several aperture holes with different diameters drilled in an aperture plate, and the aperture hole is selected according to the purpose by moving the aperture plate. .

[Problems to be solved by the invention] However, in such a structure in which the aperture holes are formed in a row, there is a limit to the distance that the aperture plate can move, so there is a limit to the number of aperture holes that can be formed. The internal vacuum must be broken and the aperture plate replaced with the desired aperture hole.

Incidentally, in recent electron microscopes and the like, ultra-high vacuums are being used to minimize sample contamination. In order to obtain such an ultra-high vacuum, it is necessary to perform a so-called baking process, in which the inside of the mirror body is heated to several hundred degrees or higher while being evacuated, and the evacuating process requires a long time. Therefore, once the inside of the lens barrel has been evacuated to ultra-high vacuum, it is necessary to avoid leakage inside the lens barrel as much as possible.

Therefore, in view of these points, it is an object of the present invention to provide a movable diaphragm device that can be replaced with a large number of diaphragm holes without breaking the vacuum and with a simple operation.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a hollow cylindrical diaphragm body fixed to a mirror body, and a diaphragm body disposed within the body and arranged in a plane perpendicular to the optical axis. A holding cylinder rotatably supported around a certain point, a moving axis to which a diaphragm plate movably inserted into the holding cylinder is fixed, and the moving axis is moved along an axis orthogonal to the optical axis. and a means for rotating the holding cylinder and tilting the movement axis about the center of rotation, the holding cylinder extending radially from the center of rotation of the holding cylinder on the aperture plate. It is characterized in that a plurality of aperture holes are formed on at least two straight lines.

[Embodiment] FIG. 1 is a plan sectional view showing an embodiment of the present invention, and 1 is a mirror body of an electron microscope or the like. 2 is a hollow cylindrical aperture body that penetrates and is fixed to this mirror body,
The axial center thereof is arranged so as to coincide with the X-axis orthogonal to the optical axis Z. 3 is a cylindrical body placed concentrically within this main body 2, and this cylindrical body has a key 4 and a key groove 5.
It is inserted movably in a state in which rotation is prevented via the . Reference numeral 7 denotes a nut screwed onto this threaded portion 6, and since its side surface is in contact with the body 2 and is being moved, by rotating this nut, the cylindrical body 3 can be moved along the X axis. can be done.

Reference numeral 8 denotes a holding cylinder which is inserted concentrically into the space of the cylinder 3 and is rotatably attached via the sphere 9, and a key 10 and a key groove 1 are provided inside the holding cylinder.
1, a support shaft 12 whose rotation is prevented is movably inserted. A diaphragm plate 13 is fixed to one end (inside the mirror body 1) of this support shaft 12 with screws 14, and a female thread 15 is formed at the other end. A male screw 16, which is prevented from moving by contacting the holding cylinder 8, is screwed into the female screw 15, and by rotating this male screw, the support shaft 12 can be moved slightly along the X-axis.

The aperture plate 14 has two straight lines L extending radially from the center of the sphere 9, that is, from the rotation center O of the holding cylinder 8.
1 and L2, three throttle holes 17a, 17b, 17c and 18a, 18b, 1 with different hole diameters.
8c are formed respectively.

Reference numeral 19 indicates the aperture plate 13 by rotating the holding cylinder 8 (moving shaft 12) about the sphere 9.
This is a push screw for moving the optical axis Z in the Y-axis direction perpendicular to the X-axis. A spring 20 is placed on the opposite side of the holding cylinder 8 from the push screw 19, and is used to keep the holding cylinder 8 in constant contact with the push screw 19 via a pin 21. 2
2 is a guide body for holding these springs 20 and pins 21.

23 is a metal bellows for preventing vacuum leakage between the main body 2 and the cylinder 3, between the cylinder 3 and the holding cylinder 8, and between the holding cylinder 8 and the support shaft 12, respectively.

Now, by operating the push screw 19 and rotating the holding cylinder 8 counterclockwise, the support shaft 1
2 (diaphragm plate 13) in the Y direction so that, for example, the straight line L1 coincides with the optical axis Z, that is, with the X axis, by turning the nut 7, the cylinder body 3
Even if (sphere 9) is moved left and right, this straight line L1
deviates from the X-axis, that is, the straight line L1 does not deviate from the optical axis Z. This is because the straight line L1 extends radially from the center O of the sphere 9, and the sphere moves in parallel along the X axis. Therefore,
As shown in FIG. 2, once the straight line L1 is aligned with the optical axis Z, any aperture holes 17a to 17c provided on the straight line L1 can be positioned on the optical axis simply by operating the nut 7. can. Similarly, if the other straight line L2 is aligned with the optical axis Z, any aperture hole 18a on the straight line L2 can be adjusted by simply operating the nut 7.
18c can be positioned on the optical axis.

Incidentally, in order to actually make the straight lines L1 and L2 coincide with the optical axis Z, the push screw 19 and the nut 7 are
(male screw 16) to project an image of an arbitrary aperture hole on a desired straight line onto the fluorescent screen, and press screw 19 until the center of the image of the aperture hole is located at the center of the fluorescent screen (optical axis Z). All you have to do is operate Natsuto 7.

In addition, in the above explanation, when replacing the aperture holes in each row, the nut 7 is operated to move the sphere 9 along the Therefore, even if the aperture hole is replaced by moving the support shaft 12, it will not have much of an adverse effect on observation. In other words,
When replacing the aperture hole on the support shaft 12, the straight line L1
Since the intersection of and L2 shifts from the center O of the sphere,
As the support shaft moves, this straight line L1 or L
2 is shifted from the X-axis, and the center of the aperture hole is deviated from the optical axis Z. At this time, the moving distance of each row of aperture holes (for example, the distance between aperture holes 17a and 17c)
However, since the distance from the optical axis Z to the center O of the sphere 9 is very long, the deviation of each of the aforementioned straight lines L1 and L2 from the optical axis is almost negligible, and does not interfere with actual observation. It was confirmed through experiments that there was no Therefore, there is no problem even if the mechanism for moving the sphere 9 is omitted.

Furthermore, in the above description, the push screw 19 was used to switch the aperture holes in each row, but the invention is not limited to this; the distance corresponding to the angle formed by the straight lines L1 and L2 is determined in advance, and two positions corresponding to that distance are determined. If the holding tube 8 is alternately rotated using a position switching knob that can regulate the position, the two rows of aperture holes can be switched in a short time. Furthermore, although the aperture plate has two rows of aperture holes, the present invention is not limited to this, and the aperture holes may be formed in three or more rows.

[Effect of the invention] With the above configuration, it is possible to introduce a large number of aperture holes into the mirror body without breaking the vacuum.
Furthermore, it is possible to provide a movable diaphragm device that can easily replace each row of diaphragm holes provided in the diaphragm plate in a short time.

[Brief explanation of the drawing]

FIG. 1 is a plan sectional view showing one embodiment, and FIG. 2 is a diagram for explaining the operation. 1: Mirror body, 2: Diaphragm body, 3: Cylindrical body, 4,1
0: Key, 5, 11: Keyway, 6: Threaded part, 7:
Nut, 8: Holding tube, 9: Sphere, 12: Support shaft,
13: Aperture plate, 15: Female thread, 16: Male thread, 1
7a, 17b, 17c: throttle hole, 18a, 18
b, 18c: throttle hole, 19: push screw, 20: spring, 23: metal bellows.

Claims (1)

[Scope of utility model registration request] A hollow cylindrical diaphragm body fixed to the mirror body, a holding cylinder disposed within the main body and supported rotatably about a point in a plane perpendicular to the optical axis, and a a moving shaft to which a movably inserted aperture plate is fixed; a means for moving the moving shaft along an axis perpendicular to the optical axis; an electron microscope, etc., characterized in that a plurality of aperture holes are formed on at least two straight lines extending radially from the center of rotation of the holding tube on the aperture plate, respectively. movable diaphragm device.