US3405264A

US3405264A - Specimen injector for electron microscopes with a rotatable specimen holder

Info

Publication number: US3405264A
Application number: US482105A
Authority: US
Inventors: John R Fairbanks; Bruno F Melchionni
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1965-08-24
Filing date: 1965-08-24
Publication date: 1968-10-08
Anticipated expiration: 1985-10-08
Also published as: GB1167323A; DE1564538B1; GB1167322A

Description

Oct. 85 1968 N Mmm www Kum NES ARE mnu wwwa J. R FAIRBANKS ET Al. 3,405,264 SPECIMEN INJECTOR FOR ELECTRON MICROSCOPES WITH A ROTATABLE SPECIMEN HOLDER 3 Sheets-Sheet 2 Oct. 8, 1968 uml-m.

Filed Aug. 24, 1955 J. R. FAIRBANKS ET AL 3,405,264 SPECIMEN INJECTOR FOR ELECTRON MICROSCOPES Oct. s, 196s WITH A ROTATABLE SPECIMEN HOLDER 5 Sheets-Sheet 3 Filed Aug. 24, 1965 .mw mw ...NN

United States Patent O 3 40s 254 SPECIMEN INJECTOR FR ELECTRON MICRO- SCOPES WITH A ROTATABLE SPECIMEN HOLDER John R. Fairbanks, Cherry Hill, and Bruno F. Melchionni,

Camden, NJ., assignors to Radio Corporation of America, a corporation of Delaware Filed Aug. 24, 1965, Ser. No. 482,105 3 Claims. Cl. Z50-49.5)

ABSTRACT or THE DISCLOSURE Aspecimen injector is provided for an electron microscope comprising a turret which is vrotatable with respect to a closure plate for the specimen chamber ofthe microscope. The turret has ahole therethrough which registers at a certain rotated psitionfof the turret with a hole through the plate. At otherrotatedI positionsof the-turret, the hole in the plate 'is sealed by the turret-A grasping member is insertable into the specimen chamber through the registered holes of the turret and of the plate "to grasp a specimen holder in a certain position thereof..The specimen holder is moveable between two positions. In one position thereof it may be grasped by the specimen holder grasping member. In the second position thereof, the

specimen holder is in a position where the specimen held thereby is in the electron beam of the microscope.

This invention relates to apparatus for inserting a specimen into and taking a specimen out of an evacuated chamber, such as the specimen chamber of an evacuated electron microscope, Without breaking the vacuum.

Prior art apparatuses for inserting a specimen into or taking a specimen out of an electron microscope are known. Such apparatuses are generally quite complicated in structure and operation since they usually require an auxiliary chamber which must be evacuated each time a specimen is taken out of the microscope or put into it. Also, a partition between the auxiliary chamber and the microscope must be opened and closed during each loading and unloading operation. The exhausting of the auxiliary chamber and the opening and closing of the partition takes considerable time. Furthermore, errors in operation may result in the breaking or impairing the vacuum of the electron microscope.

It is an object of this invention to provide an improved apparatus for inserting a specimen into or removing a specimen from an evacuated chamber such as the specimen chamber of an electron microscope.

It is a further object of this invention to provide apparatus for easily and expeditiously inserting into or removing a specimen from an evacuated chamber which does not require an auxiliary evacuated chamber.

Another object of the invention is to provide a specimen changing apparatus for an electron microscope which does not require a partition between the microscope and an auxiliary evacuated chamber.

According to this invention, a hole is provided in the door of the specimen chamber which comprises part of an electron microscope enclosure. A turret having a portion which closely ts the outside of the door is pivoted thereon. A vacuum tight seal is provided between the turret and door. A hole is provided in a thick portion of the turret, which at one angular position thereof with respect to the door registers with the hole in the door. A specimen injector rod which forms a vacuum tight t within the hole in the turret is slidably mounted therein. The injector rod may be moved into the microscope enclosure to engage a specimen holder and then may be drawn back to the point where the specimen holder is completely within the hole in the thickened portion of the turret. Since the thick- 3,405,264 Patented Oct. 8, 1968 y CC ness of the thickened portion of the turret is great enough so that a portion of the injector rod still closes the hole in the turret when the specimen holder is wholly within the hole therein, the vacuum is not broken by drawing the specimen holder into the hole in the turret. The turret may then be turned to the point where another ange portion thereof fits over and closes the hole in the door. At this rotated position of the turret the hole with the specimen holder therein is beyond the door and at a position where the specimen holder is accessible and may be changed. To return the changed specimen holder into the evacuated microscope, the specimen holder is pulled wholly into the hole in the turret and the turret is rotated until the hole in the turret vregisters with the hole in the door. Then the injector may move the specimen holder into the chamber of the microscope. If desired, a plate may be xed to the door and the turret may rotate with respect to the plate. Provision of the plate permits adjustment of the position of the turret with respect to the microscope.

The novel features of the invention, both as to its organization and method of operation, as well as additional objects and advantages thereof, will be understood more readily from the following description when read in conjunction with the accompanying drawing in which:

FIGURE l is a sectional view through the specimen chamber of an electron microscope, showing the specimen changer of this invention in inoperative position, portions of the apparatus being broken away,

FIGURE 2 is a section on line 1-1 of FIGURE 1,

FIGURE 3 is a fragmentary sectional view of the apparatus of FIGURE l showing another position thereof, and

FIGURE 4 is an elevation or front view of the turret and plate, comprising part of the specimen changer, mounted on the door of the specimen chamber of a microscope.

Referring first to FIGURE 1, a door 10 is hermetically sealed to the wall 12 of a specimen chamber of an electron microscope. The cathode and electromagnetic lens (not shown) of the microscope project a beam 5 of electrons (see FIGURE 2) through a specimen holder 14. This specimen holder 14, which is better shown in FIGURE 2, is supported on a microscope stage by a hinged adapter 17. The stage is supported on the objective lens 18 of the microscope. A winding 20 (FIGURE 2) comprises part of the objective lens 1S.

The hinged adapter 17 comprises a seat portion 22 and a hinged portion 24 pivoted on the seat portion 22 by a pin 26. The seat portion 22 has a conical lower outer portion 28 (as viewed in FIGURE 2) which tits a conical hole through the stage 16. A conical hole 30 is provided through the seat 22 to receive a mating portion of the hinged portion 24. An upstanding lug 32 is provided at the left end of the seat portion 22. A portion of the lug 32 is cut away at 34 as shown in FIGURE 1.

The hinged portion 23 comprises a flat bar having a hollow generally conic'ally shaped dependent portion 38 (FIGURE 2). The outside portion of the dependent portion 38 near the top thereof is made to tit the conical hole 30 in the seat 22. The remainder of the dependent portion 3-8 is also conical and of small enough diameter so that it clears the hole 30 as the hinged portion 24 rotates on-its pivot 26. The bottom part of the dependent portion 38 is partially closed but a conical hole 40= is provided in the bottom part of the dependent portion 38 for receiving the specimen holder 14. A spring 42, which is wound around the pin 26 in the hole 314 in the lug 32, biases the hinged portion 24- to the position where the upper part of the dependent portion 38 is seated in the conical hole in the stage 16. At this position, the specimen holder 14 holds the specimen (not shown) in the path of the electron beam 15. A rod or bar 41 fixed to the 3 hinged portion 24 extends laterally thereof for a purpose to be explained.

The specimen holder 14 is of generally conical shape and tits the hole in the hinged portion 24. The specimen holder 14 has a conical hole therethrough and the specimen is held on a grid (not shown) closing the bottom of the conical hole 44. An end portion of the specimen holder 14 is cut away to receive spring lingers 45 as will be explained.

The pivoted portion 24 of the hinged adapter 17 may be moved from a position where the specimen holder 14 holds the specimen (not shown) in the path as the beam to a position where the specimen holder 14 may be removed from the microscope. This means comprises a rod which is slidable in through a hole in the door 10. An airtight gland 48 prevents leakage around the rod 46 as it slides through the door 10. A handle 50 is provided for the outside end of the rod 46. One end of a wire 52 extends t-hrough `a hole in the other end of the rod 46. The other end of the wire 52 extends through a flange portion 54 of a clip 56. The clip 56 surrounds an end of the rod or bar 41. The wire 52 is mounted so that it can rotate with respect to the rod 46 and so that it has nearly universal motion with respect to the llange 54. Therefore, when the handle 50 is pulled away from the plate 10, the hinged portion 24 will be moved to the position shown in solid lines in FIGURE 2 and up against a stop 57. In this position of the hinged portion 24, the specimen holder 14 may be removed from the microscope as will be explained.

A plate 58 is mounted on the door 10. The plate 58 has a projecting hollow cylindrical portion 60 which fits into a hole `62 in the door 10. This plate 58 is lixed to the door in any desired manner for slidable adjustment with respect thereto. A threaded hole 64 is provided in the plate 58 at one side of the hollow cylinder 60. An O-ring 59 may be provided between door 10 and the plate 58 to provide a vacuum tight joint therebetween. The outside surface of the plate 58 is made quite smooth so that a vacuum tight sliding junction m-ay be made thereto.

A turret 66 is mounted on the plate 58 by means of a bolt 68. The bolt 68 extends through a hole 69 in a thickened portion 70 of the turret 66 and is threaded into the hole 64. The -shank of the bolt 68 lits a small diameter portion of t-he hole 69. The larger diameter portion of the hole 69 contains la compression spring 71 surrounding a portion of the bolt 68. The outer end of the bolt 68 is threaded and a nut 72 which is threaded on the outer end of the bolt 68 may be adjustably positioned to provide proper compression between the turret 66 and the plate 58. A further hole 76 is made through the thickened portion 70 of the turret `66. The hole 76 is placed so that in one rotary position of the turret 66 the hole 76 registers wvith the inside of the hollow cylinder 60. This position of the turret 66 is shown in FIGURE 2. A vacuum tight gland 78 is fitted into the thickened portion 70 of the turret 66 surrounding the outer end of the hole 76. A spring pressed detent 80 is threaded into the thickened portion 70, the end of the detent extending into the hole 76. A vacuum tight seal is provided between the detent 80 and the turret 66. Therefore, the turret 66 may be rotated about bolt 68 between the positions shown in FIGURES 2 and 3. O-rings 63, 63 may be provided between the plate 58 and the door 10` to provide a vacuum tight joint therebetween.

An injector assembly 82 is slidably mounted in the hole 76. This injector assembly `82 comprises a hollow rod 84 having a handle 86 at t-he outer end thereof and spring lingers extending inwardly from the inner end thereof. (The rod 84 is broken oil in FIGURE 1 for clarity of illustration.) The spring fingers 45 are shaped to lit into the cut away portion of the specimen holder 14 as shown in FIGURE 2 and to be readily engageable and disengageable therefrom. A vacuum tight gland 88 is provided in the outer end of the handle 86, the hole through the gland 88 registering with the hole through the hollow rod 84. An annular groove 89 is provided near the inner end of the rod 84 to receive the detent 80. This grove may have a vertical inner wall to prevent pulling the rod 84 out of the hole 76. An ejector rod 90 extends through the hollow rod 84. The inner end 92 of the ejector rod 90 slidably ts inside of the rod 84. The outer portion of the rod 90 slidably ts the gland 88. A knob 96 is fixed to the outer end of the rod 90 and a compression spring 98 is positioned around the rod 90 between the knob 96 and the gland 88 to urge the rod 90 outward, that is, to the left as viewed in FIGURE 2. A stop pin 160 extends through the inner end of the rod 90 to prevent the rod 90 from sliding out of the hollow rod 84.

During the operation of the electron microscope, the hinged portion 24 and the specimen holder 14 are in the position shown in FIGURE l and in dotted lines in FIG- URE 2, where the beam 5 passes through the specimen (not shown). When it is desired to remove the specimen, the handle 52 is pulled until the hinged portion 24 pivots to the position shown in solid lines in FIGURE 2, by means of the rod 46, the wire 52, the clip 54 and the bar 41. The handle 46 is pushed in until the springs 45 grasp the holder 14. Then the handle 86 is pulled out until the detent 88 enters the groove 89 in the rod 84. At this time, the specimen holder is wholly within the thickened portion of the turret as shown in solid lines in FIGURE 3. Then the turret 66 is rotated until the injector assembly 82 is below the plate 58 and the door 10, as viewed in FIGURE 3. Since a thinner portion of the turret 66 covers the hole in the plate 58 during this turning movement of the turret 66, the vacuum in the electron microscope is not broken. Then the handle 86 is pushed in until the specimen holder 14 is in the position shown in dotted lines in FIGURE 3. The knob 96 is moved inwardly and the inner end of the rod pushes the specimen holder 14 out of the spring fingers 45. To replace the specimen, the operation is reversed.

The portion of the hole 76 containing the specimen holder 14 will till with air when the specimen is changed. However, this portion of the hole 76 may be made so small, just slightly bigger than the specimen holder 14, that the amount of air leaked into the microscope upon change of the specimen is not sufficiently great as to impair the vacuum. Furthermore, the turret automatically maintains the vacuum in the microscope as the turret is rotated as noted above and no auxiliary partition is needed. Finally, the specimen changing apparatus does not contact the specimen holder while the microscope is in operation and therefore heating thereof during operation of the microscope cannot affect the position of the specimen with respect to the electron beam.

The plate 58 is provided so as to permit lateral adjustment of the injector assembly 82 with respect to the specimen holder 14 when in the position shown in solid lines in FIGURE 2.

Although only a single specimen changer structure has been described, variations thereof are possible within the spirit of the present invention. Hence, it should be understood that the foregoing description and illustration are to be considered as illustrative and not in a limiting sense.

What is claimed is: 1. A specimen injector for an electron microscope having a specimen chamber comprising a plate having a hole therethrough, said plate comprising a wall of the specimen chamber of said microscope,

a turret mounted for rotation about its axis on said plate, there being a vacuum-tight slidable joint between said turret and said plate,

said turret having a thickened portion with a second hole extending through said thickened portion parallel to said axis,

said second hole being positioned so that in one rotated position of said turret said first-mentioned and said second holes are inregistry, a portion of said turret covering said first-mentioned hole in other positions of said turret,

an injector rod slidably mounted in said second hole, there being a vacuum-tight slidable joint between said rod and the inside of said second hole,

specimen holder grasping means on one end of said injector rod, the thickness of said thickened portion of said turret in a direction parallel to said axis being great enough to contain a specimen holder and at least a portion of said injector rod,

a hinged adapter adapted to be mounted in said specimen chamber,

said hinged adapter comprising a seat portion and a hinged portion pivotally mountedl on said seat portion,

said hinged portion being movable between two positions in one of which a specimen holder supported thereby is in the path of the electron beam ofV said microscope and in the other of which the specimen holder is in position to be grasped by said specimen holder grasping means and means to move said hinged portion between its two positions.

2. In an electron microscope having a stage and having a door with a hole therethrough,

a hinged adapter for holding a specimen holder mounted on said stage,

means for pivoting said adapter between two positions in one of which it holds said specimen holder in position for the specimen held thereby to be traversed by the beam of said electron microscope and in the other position of which it holds said specimen holder in a position adjacent said door where it can be removed from said microscope through said hole in said door,

means for removing said specimen holder from said microscope without breaking the vacuum in said microscope comprising a turret mounted for rotation about its axis on said door, there being a vacuum-tight slidable joint between said turret and said door,

said turret having a thickened portion,

a second hole extending through said thickened portion parallel to said axis, said second hole and said first-mentioned hole registering at one position of said turret, and a portion of said turret covering said hole at other positions of said turret,

specimen holder grasping means on one end of said injector rod, the thickness of said thickened portion in a direction parallel to said axis being great enough to contain a specimen holder and a suicient portion of said rod so that the vacuum-tight joint between said rod and the inner surface of said second hole is not broken,

said injector rod being insertable into said microscope through said hole in said door when said first and second holes are in registry whereby a specimen holder may be inserted into said microscope and removed from said microscope by said injector rod.

3. In an electron microscope including an evacuable chamber having a door with a hole therethrough, means for removing a specimen holder from said microscope without breaking the vacuum comprising,

a turret mounted for rotation about an axis therethrough on said door, there being a vacuum-tight seal between said door and said turret,

said turret having a thickened portion with a second hole through said thickened portion parallel to said axis,

said irst-mentioned and second holes registering in one rotary position of said turret, and said turret closing said hole in said door in other positions of said turret,

an injector rod extending through said second hole, there being a vacuum-tight sliding joint between said rod and the inside of said second hole,

specimen holder grasping means on an end of said injector rod,

said end of said rod being insertable into said microscope through the hole in said door when said iirst and second holes register to cause said grasping means to grasp a specimen holder in said microscope and being withdrawable to the point where a specimen is wholly contained in said second hole,

a specimen holder in the said evacuable chamber,

means for moving said specimen holder between two positions, said specimen holder in one of said positions being graspable by said specimen holder grasping means and in its other position presenting a specimen held thereby to the electron beam of said microscope,

said thickened portion of said turret being so thick in a direction parallel to said axis as to contain a specimen holder and suicient of said injector rod to preserve the vacuum-tight seal between said rod and the inside of the second hole,

said turret being rotatable to a position where a specimen holder in the turret may be removed from said second hole.

References Cited UNITED STATES PATENTS 2,508,317 5/ 1950 Verhoeff. 3,073,951 1/ 1963 Burdg. 3,117,223 1/ 1964 Brunnee.

RALPH G. NILSON, Primary Examiner.

S. C. SHEAR, Assistant Examiner.