US2220973A - Electron microscope - Google Patents

Description

Nov. 12, .1940. L. MARTON ELECTRON MICROSCOPE 2 Sheets-Sheet 1 2 Filed March 31, 1939 Nov. 12, 1940. L. MARTON ELECTRON MICROSCOPE Filed March 31, 1939 2 Sheets-Sheet 2 Patented Nov. 12, 1940 a 1 2,220,973

UNITED STATES PAT NT OFFICE ELECTRON MICROSCOPE Ladislaus .Marton, Collingswood, N. 5., assignor to Radio Corporation of America, acorporation of Delaware 'ADDliCflfiOll March 31, 1939, Serial No. 265.375

9 Claims. (Cl. 250-460) This invention relates to a device for inserting source 23 of refrigerant used in freezing the specimens or objects into a vacuum chamber. specimen. The threaded pipe is soldered to a In one embodiment of the invention, the device bellows or Sylphon 25 which is in turnsoldered is associated with an electronic microscope, which to a disc or plate. 21 in the hinged portion 5. is so arranged that the "vacuum of the main The'disc may include a thermal insulator 29. chamber is not disturbed when a specimen is The pipe 2| is connected through a ,.second inserted into the chamber. I Sylphon 3| toa second pipe 33' terminating in a In a number of instruments, such as electronic specimen holder 35. The second pipe and specimicroscopes, after a main chamber has been men holder extend through the opening lfi'int'o. evacuated, it is. desirable to be able to insert the main chamber. i r specimens into the main chamber without de- Referring to Fig. 2, the specimen holder 35is stroying or reducing the vacuum. It is also deinserted intoa cutaway portion of the disc 3?. sirable to provide means for moving the speci- The disc 31 may be made of a single piece, if a men within the. vacuum so that its image may be heat-insulating material is used. If non-insu- H focused. lating materials are employed, it is preferable to Q5 The present invention has for one of its objects include heat-insulating rings 391:0 prevent conthe Provision of e s o t ng a O j duction losses in the refrigerant. The central into a vacuum. Another object is to provide portion of the disc is reduced in thicknessto permeans for moving an object withina vacuum. mit suitable spacing of thepole pieces M of the Another object is to provide'means for cooling a electronic lens of the microscope proper. The

p i n w i h has een inser ed i o a vacu m. disc 31 is seated on ball bearings 43 and is held An additional object is toprovide an electronic i engagement therewith by springs 45, which microscope w an auxiliary C be y means may bear upon the upper pole piece structure.

o w specimens may be inserted into a n The ball bearings are suitablymounted on an ev e C a W ut impairing t main annulus 41 whose inner portion 49 is threaded1 V uu and Whose outer portion 5| is slidably. mounted The invention will be described by reference to on pins 53. The pins prevent rotation of the he c mp ny n r wins i w h Figure 8 annulus. The threaded portion 49 en ages a. a P View, p y in Section, Of 0116 embodiment male thread 55 on a second annulus 51. The

0f e invention; Figure 2 s & Sectional .ViBW second annulus-is mounted on a circulartrack (.2

t k n along h line 1; Figure 3 is a 59, which may be a portion of the lower pole t o w taken along the line and piece structure. The second'annulus includes a Fi re 4 i n v al vi w f he sp n skirt portion 6| on which is formed a circular holder. Similar reference numerals are used to ;1 63, Thecircular rack is engaged by '9, pin. indicate similar elements in theseveral views. i 65, The pinion is mounted on a shaft 61.235

Referring o an auxiliary Chamber I is Referring to Fig. 1, the shaft 67 is extended attached to the main chamber 3 of an electronic through the ma i chamberfs to u t t microscope. Since the microscope itself is well fitting 5 A sylphon is solderedto the fittin known to those skilled in h it is unneces" and is closed at its free end. 'Ihe'sha'ft 6'! is Sary to Show the details which Way bent along the portion remote fromthe main 14. may be found m copindmg apphcatmn chamber. The bent portion is included within .senal 2 i, Method the Sylphori Tljwl'iich terminates in an eccentric mg electrom? photographs filed December aperture 13 in a knob 15. The knobis rotatably 1938 by Lgshslaus Marton' mounted on the fitting 69. The foregoing arauxfl-lary cha-mber 1S provlded with rangement makes a vacuum-tight connection for hinged portion 5 which may be sealed to a base the shaft Without th addition of stuffing o s" orion i b means of a asket 9 and a lock H. $11; base p rtionincludes anopening I3 into the or e like- The Shaft 15 rotated by mtiatmg e.

main chamber and a' cover 15 operated by an knob such rotation i Permitted by h external control H which will be hereinafter deflexibility i t y n o Rotation of t scribed. knob 75 raises and lowers j the first annulus 41 The end of the hinged portion 5 includes a and the disc 31 carrying the specimen holder 35. heat-insulating nut! 9 which is rotatably mount- The flexibility of the pipe 33 and the clearance at ed. The threaded portion of the nut l9 engages opening l3 are designed to permit this 'move-.

a threaded pipezl which may be connected to a merit.

ratus.

In order that the specimen holder may be shifted with respect to the center line of the microscope or located with respect thereto, a pair of pins 11 are arranged within the main chamber 5 opposite the opening I3. Inasmuch as the pins may be identical, only one will be described. The pin extends through a vacuum-tight fitting l9 and terminates in the far end of a Sylphon 8|. The near end of the Sylphon BI is soldered to the 10 fitting. The elasticity of the Sylphon makes it possible to move the pin inwardly or outwardly. These movements may be effected by a plunger 83 which is threaded into an adjusting knob 85. The plunger 83 is keyed .81 to prevent rotation. The adjusting knob 85 is also threaded into the fitting I9. A different number of threads per inch is preferably used on the adjusting knob and plunger so that a differential action or vernier movement results.

- 31. The movements of the pins are accompanied by movements of the disc because the latter is continuously pressed against the pins by virtue of the atmospheric pressure applied through the tube 2|, 33 and transmitted by the second-mentioned Sylphon 3! which is interposed in the pipe line 2|, 33. The clearance in the opening [3 prevents interference with movements of the disc.

. It should be understood that a careful fit of the specimen holder 35 within the disc ensures not only an accurate location of the specimen but also that movements of the disc are accompanied by corresponding movements of the specimen holder. The cover l5 arrangement is illustrated in Fig.

35 3. The opening) is surrounded by a suitable gasket 89. The cover I5 is mounted on a crank shaft 9|. The crank shaft is supported by bear- ,ings in the hinged portion 5 of the auxiliary chamber. One end of the crank shaft extends 50 tion Serial No. 258,887, filed February 28, 1939 en-v titled Photographic device for vacuum appa- While any type of specimen holder may' be used,

a preferred type has been illustrated in Fig. 4. 55 The second pipe 33 is soldered or otherwise secured to the holder 35. The second pipe may be appropriately guided within the second Sylphon to maintain alignment with the first pipe. Stops may be used to limit the Sylphon deflection. The

0 holder may be made of a pair of spring metal strips 91. A hole 99 is made through the strips 91. The specimen may be clamped between the strips and aligned with the hole.

The operation of the device is as follows: We shall assume that the main chamber has been closed by clamping the cover l5 over the opening l3,- and that the main chamber has beenevacuatedb It follows that the specimen holder 35 has been withdrawn from the main chamber by withdrawing the pipe portion 33. Suitable clearance for such movement has been noted by the breaks in the hinged portion of the auxiliary chamber. Air may be admitted into the auxiliary chamber, which may be. opened to make the 75 specimen holder accessible.

The two pins 1'! engage a shoulder on the disc through the wall of the hinged portion 5 and is A specimen is inserted within the holder and is aligned with the aperture 99. The specimen may be cooled or frozen by admitting the refrigerant which may be circulated through the pipes 2|, 33. The auxiliary chamber I is closed and the hinged portion 5 is clamped securely l l. The auxiliary chamber is then evacuated by a pump P. After or during evacuation, the cover l5 may be removed from the opening l3 to permit the insertion of the specimen holder 35 into the disc 31. The insertion is accomplished by turning the nut l9 which advances the threaded pipe 2 l. After the specimen holder has reached its seat in the disc, an image of the specimen may be focused by raising or lowering the disc, by means of knob 15. Such movements are possible because of the elasticity of the relatively long pipes 2 I, 33. Furthermore, the guiding means within the second Sylphon 3| is also designed to permit movements. It should be realized that the movements are of the order of a few hundredths of an inch.

The specimen holder may be moved with respect to the central axis of the microscope by means of the adjusting knobs 85.

Thus, the invention has been described as a device for inserting a specimen into a vacuum. The device includes anauxiliary chamber, connected to a-main chamber, through a coverable opening. This arrangement makes it practical to insert an object or specimen Without impairing the vacuum of the main chamber. Means external to the main chamber are disclosed for shifting the specimen with respect to the axis of the chamber and for moving the specimen with respect to a focal point. The several adjusting means are operable without the use of stuiiing boxes. While the device has been described in connection with an electronic microscope, it should be understood that the invention may be applied to other vacuum-operated instruments.

Iclaim: e

1. In an electronic microscope, a main vacuum.

chamber, an auxiliary; chamber, said auxiliary chamber being independently evacuated, means for evacuating said chambers, a wall including an opening between said chambers, said wall being located between said chambers, a vacuum tight cover for said opening, a holder for supporting a specimen to be examined within said electronic microscope, movable means for inserting said specimen holder from said auxiliary chamber through said opening without impairing the Vacuum of the main chamber, and supplemental adjusting means external to both chambers for moving said specimen holder.

2. In an electronic microscope a main vacuum chamber, an auxiliary chamber, said auxiliary chamber being independently evacuated, means for evacuating said auxiliary chamber, a passageway between said chambers, a vacuum tight cover for closing said passageway, mechanical means external to said chambers for opening and closing said cover, a holder supported partly within said auxiliary chamber and arranged to support a specimen to be examined within said electronic microscope, movable means for inserting said holder through said passageway into said main chamber, and supplemental adjusting means external to said chambers for moving said holder later-ally with respect to the axis of the main chamber.

3. In an'electronic microscope, a main vacuum chamber, an auxiliary chamber, said auxiliary chamber supporting a vacuum independent from said main chamber, means for evacuating said auxiliary chamber, a passageway between said chambers, a vacuum tight cover for closing said passageway, means external to said chambers for operating said cover, a holder supported partly within said auxiliary chamber and arranged to support a specimen to be examined within said electronic microscope, movable means for inserting said holder through said passageway into said main chamber, means external to said chambers for moving said holder with respect to the axis of the main chamber, and supplemental adjusting means external to said chambers for moving said holder along said axis.

4. In an electronic microscope, a main vacuum chamber, an auxiliary chamber, said auxiliary chamber being constituted to support a vacuum independent of said main chamber, means hinging said auxiliary chamber on said main chamber, a clamp for securing said auxiliary cham-w her to said main chamber so as to sustain said vacuums, a holder supported partly within said main chamber and adapted for supporting a specimen to be examined electronically, movable means for inserting said specimen holder into said main chamber through an opening therein, a vacuum tight cover for closing said opening, mechanical means external to said chambers for operating said cover, and means for evacuating said auxiliary chamber so that the vacuum of the main chamber is not impaired during the insertion of said holder.

5. In an electronic microscope, a main vacuum chamber, means located within said chamber for receiving a specimen holder, means external to said chamber for raising or lowering said firstnamed means, means external to said chamber for moving-said first-named means with respect to the axis of said chamber, said last-named means being operable through vacuum-tight connections, a holder for supporting a specimen to be examined, an auxiliary vacuum tight chamber partly supporting said holder, a common wall for said chambers including an aperture permitting said holder to be inserted through said wall and into engagement with said first-named means, means for evacuating said auxiliary chamber independently of said main chamber, and movable means external to said chambers for inserting said holder into said main chamber.

6. In an electronic microscope, a main vacuum chamber, an auxiliary chamber, said auxiliary chamber being constituted to support a vacuum independent of said main chamber, means hinging said auxiliary chamber on said main chamber, a clamp for securing said auxiliary chamber to said main chamber so as to sustain said vacuums, a holder supported partly within said main chamber and adapted for supporting a specimen to be examined electronically, movable means for inserting said specimen holder into said main chamber through an opening therein,

a vacuum tight cover for closing said opening, mechanical means external to said chambers for operating said cover, means for evacuating said auxiliary chamber so that the vacuum of the main chamber is not impaired during the insertion of said holder, means for raising or lowering said holder with respect to a point within said main chamber, and means external to the main chamber for operating said raising or lowering means.

7. In an electronic microscope, a main vacuum chamber, an auxiliary chamber, said auxiliary chamber being constituted to support a vacuum independent of said main chamber, means hinging said auxiliary chamber on said main chamber, a clamp for securing said auxiliary chamber to said main chamber so as to sustain said vacuums, a holder supported partly within said main chamber and adapted for supporting a specimen to be examined electronically, movable means for inserting said specimen holder into said main chamber through an opening therein, a vacuum tight cover for closing said opening, mechanical means external to said chambers for operating said cover, means for locating said holder withrespect to the axis of said main I chamber, and means external to the main chamber for operating said locating means.

8. In an electronic microscope, a main Vacuum chamber, an auxiliary chamber, said auxiliary chamber ibeing independently evacuated, means for evacuating said chambers, a wall including an opening between said chambers, said wall being located between said chambers, a vacuum tight cover for said opening, a holder for supporting a specimen to be examined within said electronic microscope, movable means for inserting said specimen holder from said auxiliary chamber through said opening without impairing the vacu-.

um of the main chamber, supplemental adjusting means external to both chambers for moving said specimen holder, means external to said chambers and connected to said specimen holder for cooling said specimen within said main chamber, and means intermediate said support and said chambers for heat insulating said specimen holder from said chambers.

9. In an electronic microscope, a main vacuum chamber, means located within said chamber for receiving a specimen holder, means external to said chamber for raising or lowering said firstnamed means, means external to said chamber for moving said first-named means with respect to the axis of said chamber, said last-named means being operable through vacuum-tight connections, a holder for supporting a specimen to be examined, an auxiliary vacuum tight chamber partly supporting said holder, 2. common wall for said chambers including an aperture permitting said holder-to be inserted through said wall and into engagement with said first-named means, means for evacuating said auxiliary chamber independently of said main chamber, movable means external to said chambers for inserting said holder into said main chamber, a vacuum tight cover for closing the aperture in said common wall, and mechanical means external to said chambers for moving said cover into and out of place.

LADISLAUS MARTON.

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