US2272843A - Electron microscope specimen chamber - Google Patents

Description

Feb. 10, 1942. J. HILLIER ELECTRON MICROSCOPE SPECIMEN CHAMBER 2 Sheets-Sheet 1 Filed July 31, 1940 ksSk Feb. 10, 1942. I J, L IE 2,272,843

ELECTRON MICROSCOPE SPECIMEN CHAMBER Filed July 51, 1940 2 Sheets-Sheet 2 ELECTRON MICROSCOPE SPECIMEN I CHAMBER James Hillier, Collingswood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application July 31, 1940, Serial No. 348,912

7 Claims. (01. 250-495) This invention relates to improvements in the for the screw it which is operated by handle specimen chambers of electron microscopes and H. A rod H9 in the end of the screw l enespecially to a specimen chamber with provisions gages a block 2| A pair of rods 23 are mounted for maintaining the main vacuum of the microon the block and are also secured to a plate 25 scope during the insertion and removal of speci- 5 which will be hereinafter described. A pair of menssleeves 21 are slidab-ly mounted on the rods re- The electron microscope includes a main spectively and are frictionally retained in posichamber which is evacuated by means of a suittion by the biasing springs 29 which are also able vacuum pump. Inasmuch as the main mounted on the rods. Thus the rods form parchamber requires several minutes for evacual0 eliel guides on Which the sleeves 27 move- Under tion, it is desirable to provide means whereby the influence of the biasing springs 29, the the specimen to be examined may be inserted sleeves move forward or rearward in response within the microscope without impairing the to the movements of the block 2! which is driven main vacuum. This may be done by arranging by the screw l5. Fig. 2 represents the extreme an auxiliary chamber which can be shut off rearward position and Fig. 3 represents the exf m the main chamber and separately evacutreme forward position of the block and sleeves. ated. A lever 3i is pivotally mounted on the block It is an object of the present invention to ju t bel w the p of s on one end of the provide means for inserting and removing a lever is mounted a cradle 33 which carries the specimen to be examined within an electron 90 spec e ho de 3 On e Othe e of the microscope. Another object is to provide means lever an adjus a s p 37 is arranged to whereby the specimen chamber of an electron a a p n 39 Whieh is fastened to the block microscope is provided with interlocking com The fixed portion of the spec me Chamber trols to prevent the unintentional operati within which the rods 23 are mounted, is made thereof. Another object is to provide means p O a ca g which s s y hermetically whereby the specimen chamber of an electron sealed to the main chamber wall l3. The permicroscope is provided with a door through on o t e Cha o th right o the rod which the specimens may be inserted and in mounting inc d s a (1 0 The 01001 is p which the controlling valves are operated by the erably provided With a gasket 45 Which forms door lock. a vacuum tight seal. The door, which is hinged, The invention will be considered in connection is locked in position by means of a locking memth the accompanying drawings in which Figber ll. The locking member 4'! is also in the ure 1 is a View partly in section of the specimen form of a door which cooperates with a locking chamber of the invention; Figure 2 is a sectional handle 9- e handle se ves t d l p p View taken along line II II f Fig, 1; Figure 3 of securing the locking member 4! in its closed is a sectional view corresponding to Fig. 2 with p s n a d a h s me m r ta g 2. double the specimen cradle raised; Figure 4 is an end C m W n e locking member 47 is Closed, view of a portion of the specimen chamber; and a kn d s w located pp s the center f Figure 5 is a sectional view taken along line V he nn r oor 43 en a s and for es he door of Fig. 1. In describing the drawings similar tightly ag ins s as et 4 t ereby lockin the reference numerals will be applied to similar 0100i 43 in place The cam is P S d W th n elements. the outer portion 53 of the locking member. Figure 1.The main chamber 1 of an l t The rotation of the cam acts upon valves which microscope is connected to a mai vacuum pump will now be described. A bellows 55 is locked 3. It should be understood that the microscope Within a recess On pp ends 0 he per se is not the subject matter of this invention bellows are secured discs 59, 6|. These discs are and since the microscope is well known to those p ab y arranged to include gaskets 63, 65 skilled in the art no attempt has been made to which e gage the opp e ends O t e re ess 5'! show the entire microscope structure. The specto form thereby a three Way valve. imen chamber includes the stationary portion 5 When the outer portion of the cam is turned and the movable portion 1 which is included a sl ve 66 s pus d inward y. This m vement within a flexible metallic bellows 9. The bellows opens the valve formed by h right hand disc 9 is fixedly mounted to a member H which is El to thus admit air into the auxiliary chamber suitably fastened to the wall I3 of the main as will be hereinafter described. When the cam microscope cylinder. The member H is threaded 56 is turned in the reverse direction a rod 61, lo-

cated with the bellows 55, is operated by the inner portion of the cam to permit the valve formed by the disc 59 to open, thus connecting the auxiliary vacuum pump 69 to the specimen chamber. Before the last mentioned valve 59 is opened, the first mentioned valve BI is closed. When both valves are closed, the specimen chamber is disconnected from the auxiliary pump and is connected to the main pump 3.

Having described the essential arrangement of the invention, its operation will be considered by reference to Figures 2 and 3. As the screw I5 is turned in a clockwise direction the block member 2| is forced to the right. This causes the pin 39 to engage the stop 31 because during the initial forward movements of the block 2| the sleeves 2'| stay in their initial position and hence the pin 39 initially engages stop 31 as shown in Fig. 2 and finally brings the stop 31 to the position shown in Fig. 3. As the stop is forced outwardly the lever 3| is raised upwardly until the cradle 33 and specimen holder 35 are raised into a position for entry into chamber 5. After the lever has been raised additional stops H on the member 2| engage the sleeves 21 so that they are forced along the rods 23 to compress the biasing springs 29. This movement of the screw l5 will also force the movable member including the bellows 9 to the right until its end 13 including the gasket 15 engages the exposed end of the chamber 5 to form thereby an airtight joint and an airtight specimen chamber.

The space within the bellows and within the chamber 5 is thus hermetically sealed from the main chambers of the microscope. Because of the vacuum within the auxiliary chamber it is impractical to open the doors 43, 41 without first admitting air into the chamber. This is done by turning the lock 49 until the outer cam 5| forces the valve BI, 65 to the left to admit air into the chamber. It will be observed that the rod 61 maintains the Valve 59, 53 closed so that the auxiliary pump 69 is shut off. It is then possible to open the outer door 41 which releases the inner door 43. The specimen holder 35 may then be removed from the chamber by means of any suitable instrument such as a pair of forceps. The specimen is inserted in the small cap I! which is removably mounted on the end of the specimen holder.

The reverse process, namely, returning the specimen holder to within the microscope, includes the following steps: First, the specimen holder 35 is inserted within the cradle 19. Next, the inner and outer doors are closed. The handle 49 is turned to lock both doors 43 and 41 and at the same time to shut the valve 6|, 65 and open the valve 59, 63. This permits the auxiliary pump to evacuate the auxiliary chamber. After the auxiliary chamber has been evacuated the screw I5 is turned in a counter-clockwise direction so that the bellows 9 is moved to the left. As the bellows moves to th left the biasing springs 29 force the sleeve 21 to the left until they reach the end of their travel. After the sleeves have moved as far to the left as the stops permit, the member 2| will continue to move toward the left carrying with it the pin 39. The movement of the pin 39 causes the lever 3| to pivot and thus the specimen cradle and holder move downwardly until the cradle rests on the plate 8| which locates the specimen at the proper depth within the microscope. The specimen may be moved laterally by the adjusting screws 83, 85 which operate through metallic bellows 81,

89, respectively. Plungers 9|, 93 engage the angles 95, 91 to move the plate BI and with it the specimen holder. Since the movements of the specimen are less than about a sixty-fourth of an inch, it has been found that the play in the lever 3| and other parts is sufiicient to permit the required movement. Since it is not necessary to run the auxiliary pump when the specimen is being observed the valve 59, 63 has been arranged so that a movement of the cam 5| will close the valve thereby disconnecting the auxiliary pump.

Thus the invention has been described as a mechanism for inserting specimens within an electron microscope. The specimen is inserted into the main chamber of the microscope through an auxiliary chamber which may be evacuated independently. A door to the auxiliary chamber is provided with a lock which operates the valve controlling the admittance of air of the evacuation of the auxiliary chamber. For convenience the specimen holder is supported by a cradle which may be lifted from its normal position into the auxiliary chamber at a point where it may be conveniently removed for the insertion or removal of the specimen.

I claim as my invention:

1. A specimen chamber for an electron microscope including in combination means including a bellows for forming an airtight auxiliary chamber, means for moving said bellows into and out of engagement with a portion of said auxiliary chamber, means mounted on a portion of said moving means for supporting a cradle, a specimen holder mounted on said cradle, means operated by said moving means for raising and for moving said cradle supporting means into said portion of the auxiliary chamber, and a vacuum tight door arranged to provide access to said auxiliary chamber.

2. A specimen chamber for an electron microscope including in combination a movable mem ber including a recess, a fixed member including a recess, means for bringing said movable member into engagement with said fixed member so that said recesses form an airtight chamber, a specimen holder, a lever mounted on said movable member and arranged to support said specimen holder, means including said movable member for engaging said lever to raise and to move said specimen holder within said airtight chamber, and an airtight door mounted externally of said microscope and arranged to provide access to said auxiliary chamber.

3. A specimen chamber of the character of claim 2 including a valve arranged to connect said auxiliary chamber to an auxiliary pump or to the outside air, a lock for said door, and means connecting said lock to said valve so that the door and valve positions are interlocked.

4. A specimen chamber of the character of claim 2 including a lock for said door, a valve for connecting said chamber to the outside air, to an auxiliary pump or to shut off the auxiliary pump, and means interconnecting said lock and said valve.

5. A specimen chamber for an electron microscope including a stationary member, a movable member, said members including recesses forming a specimen chamber when the members are brought together, means for making said chamber airtight, a door external to said microscope opening into said chamber for the insertion of specimens, a holder for said specimens, means for moving said holder upon movement of said 7. A specimen chamber of the character of claim 5 including a three position valve for connecting said chamber to the outside air, to an auxiliary pump and to close said auxiliary chamher to said auxiliary pump, a lock for said door and means interconnecting said valve and lock.

JAMES HILLIER.

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