US3745341A

US3745341A - Specimen positioning device for electron microscope and the like

Info

Publication number: US3745341A
Application number: US00283294A
Authority: US
Inventors: Y Sakitani
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1971-08-25
Filing date: 1972-08-24
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10
Also published as: NL7211495A; JPS4830860A

Abstract

A specimen positioning device for an electron microscope or the like is provided which comprises a rectilinear motion mechanism and a rotating mechanism. A movable member in the rectilinear motion mechanism and a rotary member in the rotating mechanism are selectively coupled under the Coulomb force to a driven member which carries a specimen holder, so that the rectilinear or rotary motion may be transmitted to a specimen.

Description

United States Patent 1 Sakitani SPECIMEN POSITIONING DEVICE FOR ELECTRON MICROSCOPE AND THE LIKE [75] Inventor: Yoshio Sakitani, Katsuta-shi, Japan [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: Aug. 24, 1972 [21] App]. No.: 283,294

[30] Foreign Application Priority Data Aug. 25, 197] Japan .46/64441 52 us. (:1 .Q 250 495 B [51] Int. Cl. HOlj 37/20 [58] Field of Search 250/495 B [56] Y i References Cited UNITED STATES PATENTS 3,628,013 12/1971 Heide 250/495 B 3,678,270

7/1972 Braun 250/495 B [111 3,745,341 [451 July 10,1973

Primary Examiner-Archie R. Borchelt Assistant Examiner-C. E. Church Attorney-Paul M. Craig, Jr., Donald R. Antonelli et a1.

[5 7] ABSTRACT A specimen positioning device for an electron microscope or the like is provided which comprises a rectilinear motion mechanism and a rotating mechanism. A movable member in the rectilinear motion mechanism and a rotary member in the rotating mechanism are selectively coupled under the Coulomb force to a driven member which carries a specimen holder, so that the rectilinear or rotary motion may be transmitted to a specimen.

3 Claims, 4 Drawing Figures Patented July 10, 1973 5 Sheets-Sheet 1 F/Gn Patented July 10, 1973 3,745,341

3 Sheets-Sneet 2'3 Patented Jul 10, 1973 3,745,341

3 Sheets-Snet :5

SPECIMEN POSITIONING DEVICE FOR ELECTRON MICROSCOPE AND THE LIKE BACKGROUND OF THE INVENTION In the prior art a specimen positioning device used in an electron microscope generally comprises a compound mechanism for imparting the rectilinear motion and rotation to a specimen. The rectilinear motion mechanism and the tilting mechanism are mounted upon the rotating mechanism or the rotating and tilting mechanisms are mounted on the rectilinear motion mechanism. Thereforce, the prior art specimen positioning devices have distinct defect that the axis of rotation or tilting of the specimen is displaced when the rectiliniear movement and tilting of the specimen are displaced when the specimen is rotated. Since various mechanisms such as universal joints, strings and the like are used in order to transmit the motions to the mechanisms mounted on the other mechanism, the prior art specimen positioning devices have defects that they are large in size and that the range within which the specimen may be moved is limited.

SUMMARY OF THE INVENTION The present invention has for its object to provide a specimen positioning device for an electron microscope and the like which may selectively impart to a specimen a rectilinear motion, a rotary motion or tilting motion and which is very simple in construction and compact in size.

Briefly stated, the present invention is characterized by the provision of means for selectively coupling a rectilinear motion mechanism and a rotating mechanism to a specimen holder through Coulomb electrostatic attraction, and means for rotating both said rectilinear motion mechanism and said rotating mechanism in unison with each other.

The above and other objects, features, and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a sectional view of a prior art specimen positioning device;

FIG. 2 is a perspective view of another prior art specimen positioning device;

FIG. 3 is a sectional view of a first embodiment of the present invention in which a specimen positioning device is used as a specimen fine adjustment of an electron microscope; and g FIG.'4 is a longitudinal sectional view of a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the preferred embodiments of the present invention, the prior art specimen positioning devices will be briefly described with reference to FIGS. 1 and 2 in order to distinctly point out the problems and defects encountered in the prior art devices.

First referring to FIG. 1 illustrating the prior art spec imen positioning device of the type in which both a specimen and a fine adjustment may be simultaneously replaced, a compound fine adjustment proper 41 is placed in a magnetic path 37 with a pivot pin 34, a pivot bearing 39, a spring 40 and a ball joint 52 with 0-

rings

53 and 54. As the fine adjustment proper 41 is moved into and out of the magnetic path 37 through the ball joint 52, the fine translation of a specimen 44 may be effected in the direction indicated by the double-pointed arrow X. When the fine adjustment proper 41 together with the ball joint 52 is swung in the direction indicated by the double-pointed arrow Y, a sub stantially rectilinear fine movement of the specimen 44 may be effected in the direction Y. When the fine adjustment proper 41 is rotated in the ball joint 52 in the direction indicated by the double-pointed arrow T, a fine tilting movement of the specimen 44 may be effected. When a rotary table or stage 43 upon which is mounted the specimen 44 is rotated from the exterior, the rotation of the specimen 44 may be effected.

Next the mechanism for rotating the specimen 44 will be described in detail hereinafter. The rotary table 43 is rotatably fixed to the fine adjustment proper 4K in such a manner that the specimen 44 may be placed substantially at the center of the magnetic path 37. A drum 49 is rotatably mounted on a stationary table 91 of the fine adjustment proper 4ll extended outwardly of the magnetic path 37. A string 46 whose both ends are fixed to pins 46 and positioned at both ends of the stationary table 91, is wrapped around the rotary table 43, a pin 42 extending from the end close to the pivot 38 of the fine adjustment proper 41, and the drum 49. The drum 49 is normally so biased as to move away from the rotary table 43 through a :sliding bearing mem ber 48 under the force of a tension spring 47 loaded in a guide groove 92 of the fine adjustment proper 44 so that the string 45 may be always imparted with a uniform tension, thereby producing the frictional force between the string 45 and the rotary table 43. A fine adjustment rod 51 is moved in the direction indicated by the arrow R so that the string 45 is moved against the tension spring 47 thereby causing the rotary table 43 and hence the specimen 44 in the direction indicated by the arrow R.

In summary, the specimen 44 is rectilinearly translated in the X and Y directions with respect to the magnetic path 37, is tilted in the direction T and is rotated in the direction R.

Next referring to FIG. 2, another prior art specimen positioning device will be described in which only the specimen 3 upon a specimen holder 4 may be replaced.

A fine moving plate 1 is located in the magnetic path with respect to a lens 2 and is translated in the X and Y direction by a spring l3, and fine adjustment rods l l and 12. Means are provided on the plate 4 for tilting and rotating the specimen 3.

The rotation of a tilting shaft 117 is transmitted to a tilting table 5 through a universal joint 16, a worm 8, a gear 20 and a slide 24. disposed on the plate ll, thereby tilting the specimen 3. The fine adjustment in a tilted plate of the specimen supporting tube 4 is made by a fine adjustment table 6 which is disposed on the tilting table 5 and to which is transmitted the rotation of a rotary shaft 19 through a universal joint 14, a worm W and a spring 22. Upon the adjustment plate 6 is disposed a rotary table 7 provided with a bevel gear for supporting the specimen supporting tube 4. The rotation of the rotary shaft 18 is transmitted to the rotary table 7 and hence the specimen 3 through a universal joint and a bevel gear 9 in mesh with the bevel gear of the rotary table 7.

In summary, the second prior art specimen positioning device is of the so-called stacking type in which the rectilinear motion mechanism, the tilting mechanism and the rotating mechanism are stacked in the order named.

THE INVENTION, FIGS. 3 AND 4 The specimen positioning device in accordance with the present invention shown in FIG. 3 may selectively translate and rotate a specimen. The speciment positioning device is disposed in an opening 23' of a supporting member 23 made of an electrically insulating material. A specimen holder 26 adapted to hold a specimen 27 is fitted into a center opening of a metallic driven disk 33 which is interposed between a pair of upper and lower metallic disks 24 and 30. Thin disks 28 and 32 made of a semiconductive ferroelectric material with a specific volume resistivity ranging from to 10 ohm-cm are bonded to the metallic disks 24 and 30 respectively with electrically conductive adhesive 25 and 31. The driven disk 33 and the disks 24 and 30 are coupled to a voltage source 93 through

lead wires

94, 95, and 96 respectively so that the same voltage may be impressed between the disk 24 and the driven disk 33 and between the disk 30 and the driven disk 33. A switch 36 is inserted between the voltage source 93 and the lead wires 95 and 96 so one of the pair of disk 24 and 30 may be selectively coupled to the voltage source 93.

The thin disks 28 and 32, the disks 24 and 30 are provided with center openings 28', 32, 24 and 30', respectively which are in line with one another when assembled. The diameters of these openings 28', 32, 24' and 30' are so selected that the specimen holder 26 may move in a plane within these openings.

The flange of the upper disk 24, which is the fine adjustment disk, is fitted into an annular groove 97 formed in the inner wall of the opening 23' of the supporting member 23. The flange of the lower disk 30, which is the rotary disk, is placed upon an annular stepped portion 98 formed in the opening 23 of the supporting member 23.

The rectilinear translation of the fine adjustment disk 24 may be effected by a pair of

fine adjustment rods

34 and 35 whereas the rotation of the rotary disk 30 may be effected by a rotary driving shaft 29' which carries a driving gear 29 in mesh with a pinion or driven gear 99. mounted upon the undersurface'of the rotary disk 30.

Next the mode of operation will be described. The movable contact of the switch 36 is made into contact with the fixed contact connected to the lead wire 95 so that the d-c voltageranging from 200 to 700 volts is impressed between the rotary disk 30 and the driven disk 33 so that the driven disk 33 may rotate in unison with the rotary disk 30 through the Coulomb electrostatic attraction whereas the driven disk 33 is operatively disconnected from the fine adjustment disk 24. Next the rotary disk 30 is rotated by the rotary shaft 29' through the gear 29 and the pinion 99, thereby adjusting the angular position of the specimen holder 26 and hence the specimen 27.

In order to adjust the position of the specimen 27 by the rectilinear movement, the movable contact of the switch 36 is made into contact with the fixed contact connected to the lead wire 96 so the d-c voltage may be applied between the fine adjustment disk 24 and the driven disk 33, thereby causing the latter to move in unison with the fine adjustment 24 while operatively disconnecting the driven disk 33 from the rotary disk 30. When the fine adjustment rods 34 and 35 are actuated, the fine adjustment disk 24 is caused to make a rectilinear movement, thereby reciprocating the specimen holder 26 in a plane. Thus the fine adjustment of the specimen 27 in the lateral direction may be accomplished.

Next the second embodiment of the present invention will be described hereinafter with reference to FIG. 4. The second embodiment is different from the first embodiment in that it further comprises a mechanism for tilting the specimen.

The specimen positioning device together with the specimen 59 is directly inserted into a space of a lens 56 held in position'by a lens holder 78 at the center of a magnetic path 55. The specimen positioning device generally comprises an insulator 57, a holder 8 and a sealed block 71. At one end of the insulator 57 is disposed a specimen fine adjustment mechanism comprising a driven disk 64 carrying a specimen holder 58 which in turns holds the specimen 59, a rotary disk 61, a fine adjustment disk 60, and a retainer 77. The driven disk 64 is interposed between the rotary disk 61 and the fine adjustment disk 60.

Disks

63 and 62 made of a semiconductive ferroelectric material are bonded to the rotary disk 61 and the fine adjustment disk 60, respectively, with electrically

conductive adhesives

85 and 86. The rotary disk 61 is rotated about the axis of the lens 56 through a gear 84, a rotary shaft 65, a spring 67 and a vacuum proof rotating shaft 70. The rectilinear translation of the fine adjustment disk 60 may be effected by a mechanism comprising a spring 72 which is coupled to a pin 83 extending from the fine adjust ment disk 60 with a string 82, a guide plate 74, a connecting rod 68 and a fine adjustment rod 69. The specimen holder 58, the specimen 59 and the driven disk 64 are electrically grounded through a lead wire 76, a contact 75 and the magnetic path 55, and the rotary disk 61 and the fine adjustment disk 60 are connected to a switch 81 through lead wires 66 and 73, respectively.

Next the mode of operation will be described. The switch 81 is so switched that the d-c voltage ranging from 200V to 700V from a voltage source 89 is applied between the fine adjustment disk 60 and the driven disk 64 so that the great Coulomb electrostatic attraction produced in the contact surface between the driven disk 64 and .the semiconductive ferroelectric disk 62 serves to cause the driven disk 64 to move in unison with the fine adjustment disk 60. Therefore, the rectilinear translation ofthe specimen 59 may be effected through the fine adjustment rod 69, th connecting rod 68 and the guide plate 74. Next the switch 81 is so switched that the d-c voltage is applied between the driven disk 64 and the rotary disk 61 so that the Coulomb electrostatic attraction produced in the contact surface between the driven disk 64 and the semiconductive ferroelectric disk 61 serves to cause the driven disk 64 to move in unison with the rotary disk 61. Therefore, the specimen 59 is rotated about the axis of the lens 56 by the rotating mechanism'comprising the vacuum proof rotating shaft 70, the spring 67, the rotary shaft 65 and the gear 84, independently of the rectilinear movement described above.

When it is desired to tilt the specimen 59, the specimen positioning device may be tilted by a knob 87 formed at the outer end of the block 71.

From the foregoing description, it is seen that according to the present invention, the positioning mechanisms may be individually actuated to determine the position of the specimen. The mechanisms for transmitting the motion to the specimen does not include universal joints, drums and strings so that the specimen positioning device may be made compact in size and that the specimen positioning range may be increased.

When the specimen positioning device in accordance with the present invention is used in an electron microscope, the position of a specimen may be adjusted in a reference plane so that the image with a higher degree of accuracy may be formed. Furthermore the specimen holder is electrically grounded so that the effects upon the electrostatic lens by the driving mechanisms due to the electron beams may be prevented.

What is claimed is. t

l. A specimen positioning device for an electron microscope or the like comprising a. means for supporting a specimen;

b. a driven member into a center opening of which is fitted said specimen supporting means;

0. a rectilinear motion imparting member disposed in closely spaced apart relation with said driven member on one side thereof;

d. a rotary 'motion imparting member disposed in closely spaced apart relation with said driven'member on the other side thereof;

e. means drivingly coupled to said rectilinear motion imparting member for causing the fine motion thereof;

f. means drivingly coupled to said rotary motion imparting member for causing the rotation thereof; and

g. a voltage source one terminal of which is connected to said driven member and the other terminal of which is selectively connected through a switch to either of said rectilinear motion imparting mechanism or said rotary motion imparting mechanism so that Coulomb electrostatic attraction is produced between said driven member and said rectilinear motion imparting member or said rotary motion imparting ,member, thereby causing said driven member and hence said specimen holder to move in unison with said rectilinear motion imparting member or said rotary motion imparting member.

2. A specimen positioning device as set forth in claim 1 further comprising a. means for causing said rectilinear motion imparting member and said rotary motion imparting member to rotate in unison with each other about an axis other than the axis of said rotary motion imparting member, thereby causing said driven member and hence said specimen holder to tilt.

3. A specimen positioning device as set forth in claim 1 wherein on the side surfaces of said rectilinearmotion imparting member and said rotary motion imparting member in opposed relation with said driven disk are fixed members made of semiconductive ferroelectric material.

Claims

1. A specimen positioning device for an electron microscope or the like comprising a. means for supporting a specimen; b. a driven member into a center opening of which is fitted said specimen supporting means; c. a rectilinear motion imparting member disposed in closely spaced apart relation with said driven member on one side thereof; d. a rotary motion imparting member disposed in closely spaced apart relation with said driven member on the other side thereof; e. means drivingly coupled to said rectilinear motion imparting member for causing the fine motion thereof; f. means drivingly Coupled to said rotary motion imparting member for causing the rotation thereof; and g. a voltage source one terminal of which is connected to said driven member and the other terminal of which is selectively connected through a switch to either of said rectilinear motion imparting mechanism or said rotary motion imparting mechanism so that Coulomb electrostatic attraction is produced between said driven member and said rectilinear motion imparting member or said rotary motion imparting member, thereby causing said driven member and hence said specimen holder to move in unison with said rectilinear motion imparting member or said rotary motion imparting member.

3. A specimen positioning device as set forth in claim 1 wherein on the side surfaces of said rectilinear motion imparting member and said rotary motion imparting member in opposed relation with said driven disk are fixed members made of semiconductive ferroelectric material.