US2418317A - Electronic gun adjustment - Google Patents

Description

April 1, E RUNGE ELECTRONIC GUN ADJUSTMENT Filed April 27, 1944 3 Sheets-Shet 1 INVENTOR.

ME BY m'men/zr April 1947- F. E. RUNGE E 2,418,317

ELECTRONIC GUN ADJUSTMENT Filed April 27, 1944 :5 Sheets-Sheet 2 IN VEN TOR.

Y EMZW April 1, 1947. RUNGE A I 2,418,317

ELECTRONIC GUN ADJUSTMENT Filed April 27, 1944 5 Sheets-Sheet 5 mum Q INVENTOR. anil i' BYQM Patented Apr. 1, 1947 UNITED STATES PATENT, OFFICE ELECTRONIC GUN ADJUSTMENT Frank E. Runge, Haddon Heights, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application April 27, 1944, Serial No. 533,073

7 Claims.

1 The present invention relates to electronic devices such as electron microscopes and more particularly to adjustments of the electron gun or source of the electron beam.

In adjustments of the character here under consideration it has heretofore been customary to shift the gun and its associated parts laterally ,by thrust screws acting through the gun support against alined or diametrically opposed biasing springs. Such arrangements require four points of contact, two by thrust screws and two by biasing springs and while capable of making a desired adjustment, fail to make any provision to prevent spurious movements of the parts during alinement of the gun. This is due to the fact that two biasing springs of necessity must be adjacent to each other and hence the gun or its support has no positive means to react against and thus prevent these disturbing movements.

Some of the objects of the present invention are: to provide an improved adjusting means for an electronic gun; to provide means for adjusting the radiating mechanism of an electronic microscope to bring the electron beam into coincidence with the optical axis of the condensing lens of the instrument; to provide a positive mechanism for tilting an electron gun or radiating mechanism relative to the axis of the electronic lenses; to provide a positive mechanism for shifting an electron gun transversely to the axis of the system for purposes of exact adjustment; to provide means in an electron microscope for adjusting the electron beam in such a man:

ner that spurious movements of the parts during operation of the microscope cannot take place; to provide a novel pivotal control functioning in associationwith an adjustment for an electron beam; and toprovide other improvements as will hereinafter appear.

In the accompanying drawings, Fig. 1 represents a plan of an electron gun embodying one form of the present invention; Fig. 2 represents a section on line IIII ofFig. 1; Fig. 3 represents a section on line III-III of Fig. 2; Fig. 4 represents a detail section on line IV-IV of Fig. 1; and Fig. 5 represents a section on line VV of Fig. 1.

Referring to the drawings one form of the present invention is shown as assembled in the gun endof an electron microscope. The parts shown are those forming the portion of the colsuperposed adjustable unit II and glass or other insulated support I2. The support I2 is closed at the upp r end by an annular head 13 'from umn including the condenser lens frame It, a'

which the electronic gun M is held coaxially within the insulated support l2, while at the lower end the support l2 seats upon anannular ring 15 seating on the unit I l with an interposed gasket it for sealing purposes. The gun [4 has a flanged base I! seating on the head IS with an interposed gasket ill for sealing purposes, and compressed under the tension of screws 9.

The adjustable unit I l is formed of an annular base orstage 29 seated upon the lens frame [0 and including a gasket 2| for sealing the joint between these parts. Screws 22 or other fastening means are employed to prevent displacement of the base Bil. Thebase 29 is formed with an upstanding centrally located hub 23 forming a chamber 2i, coaxially of the column and gun l4, in which the inclined fluorescent face 25 of theaperture member 26 is located. A window 21 is provided in the side of the hub 23 for registry with the face25 so that the projected beam can be observed for adjustment purposes. This hub 23 serves to support a flexible bellows element comprising abottom head 26, a top head 3!, an interposed bellows 32 and a compression spring The head 28 is attached to the hub 23 by screws 2!! or the like, while a gasket 30 is interposed between the parts for sealing purposes. The spring 33 presses agasket 34 against an inturnedannular flange 35 on thehub 35 of an inverted cup-shaped member 3?, which forms the upper movable portion of the unit H. Thismember 37 is provided with a groove 38 to receive the gasket IB.

For adjusting the member 3! laterally, that is transversely with respect to the axis of the column, aring 39 of larger internal diameter than the hub 23 encircles the hub 23 and is seated upon thebase 26. It preferable to provide at least two safety screws 40 for holding the ring 38 in approximate contact with thebase 29. A clearance is provided in the base 28 to permit the required relative movement of thering 39, andthe clamping action of the screws :33 is obtained by a washer 6| bridging such clearance, as will be seen in Fig. 5. Projecting radially outward from the periphery of thering 39 are three tubular bosses 42, 2 and G3, the bosses {i2 and 62 being apart and the boss e3 being from both the bosses 42 and 62'. The two bosses 32 and 42 are provided with like coopcrating-parts as shown in Fig. 3, the same consisting of a radially disposed internally threadedhole 34 which receives an externally threaded plunger 45 having a connected removable keyed stem 46 protruding from thering 39 to terminate 7 end of the plunger in a knurled head M for operating purposes. The inner end of the plunger 45 is alined with and is arranged to bear against a hardenedsteel anvil 48 fixed as an insert upon the side of the hub 23. Theboss 43 is provided with a radially disposed hole 56 which receives a plunger 5| having astem 52 of reduced diameter to accommodate an encirclingcompression biasing spring 53. An externally threadedbushing 54 is threaded into the outer end of thehole 50 to form an abutmentmaintaining thespring 53 under such compression as will project the plunger 5| into contact with an alined hardened steel vertically grooved anvil 55 on the side of the hub 23. The bushing 54 forms a bearing guide for the outer Also the exposed end of thebushing 54 is slotted or otherwise shaped for turning movement when engaged by a suitable implement, such as a screw driver. From the foregoing it will be seen that the plunger '5! bearing against the anvil 55 forms a pivot about which thebase 26 can swing when pressure is applied to either side of the base 28 by one or the other of the adjusting plungers 45. Thus to move the gun H5 in a plane normal to .the electron beam to bring about coincidence of the beam and the optical axis of the magnifying system, the plunger 45, which will give the required movement is screwed in and since pivot 5| is yieldable the assembly has a combined lateral and angular motion which is positive and not susceptible to other movements of a spurious nature which ordinarily creep in where direct line thrust is depended upon for adjustment. In this way spurious movements, ordinarily present where biasing springs are opposite to but alined with adjustin plungers, are entirely eliminated.

In order to adjust the gun l4 angularly to bring about coincidence between the electron beam and the optical axis of the magnifying system, the upper portion of the ring 33 is formed as a depressed spherical face 56, which serves as a seat for a complemental face 5! on the bottom portion of the member t'l. Themember 31 is given an accurate movement by one or the other of two plungers 58 threaded respectively into the bosses 42 and lz in superposed relation to the plungers 45. Eachplunger 53 is arranged to be turned for feeding movement by its removable keyed stern til which projects exteriorly of the boss and carries an operating knurled head 6!. The inner ends of the respective plungers 58 bear against hardened steel anvils 62 inserted in the juxtaposed face of themember 31. The thrust of the member 3'! is taken by a plunger 63 biased by a compression spring 65 against a hardened steel vertically grooved anvil $5 on the juxtaposed side of the member 3i. The lunger 63 rides in a through hole it in theboss 43 located above the hole til, and having a bushing 61 threaded into its outer end as a guide bearing for the stern of theplunger 83 and as a means to." adjust the pressure of the biasing spring 64. The plunger t3 and the anvil 65 thus give a pivoted action about which the angular swing of the member 3'! takes place.

. From the foregoing it will be seen that if either of the adjusting plungers it are operated, thering 39 will slide relative to the base 28 and thus carry the membert'l and the gun parts support- .ed thereby laterally at right angles to the axis of. the lens system. This sliding movement is under thecontro-l of the biasing pivot 5| so that the lateral travel is accompaniedby a relatively parallel side flats it.

minute arcuate swing of the parts about the pivot 5| as a center. Furthermore, if one or the other of the plungers 58 is operated, the lateral thrust causes themember 31 to react against the pivot plunger 63 and thereby bring about through a spherical movement, the desired angular movement which tilts the gun with respect to the axis of the condensing lens. In bothadjustments there is a three-point contact with the parts which serves to resist and eliminate all-anomalous movements which for some unexplainable reason ordinarily develops during adjustments of this kind.

While the adjustments described pertain particularly to shifting the gun assembly relative to the axis of the lens system, the invention comprehends also a novel means for adjusting the cathode or heater 78 with respect to the anode 8!. In the preferred form the cathode assembly includes an insulating tube 82, fitted within and projecting from asleeve 83, which sleeve terminates in a removable head 8'1 which function as a stop. Thestop 34 prevents damage tofilament 18 whensleeve 83 is adjusted to its extreme lower position and 130- thus prevent interference of the filament "8 with theaperture 89. This projecting portion of thesleeve 83 is externally threaded to receive a hub it of a gear l l. Als-oattached to the hub it is a disc l2 having atransverse slot 13 which serves'to prevent rotation of thesleeve 83 when the gear H is given a rotary motion while transmitting axial movement to thesleeve 83. This action is made possible by providing the co-acting part of thesleeve 83 with The gear II is in mesh with aworm gear 15 keyed to a shaft H5 as an extension of an insulated and removable shaft 11 leading to a convenient location for remote control. remote control to turn the gear ii, that the sleeve can be axially raised or lowered to adjust the filament 78 with respect to the anode Bl.

Thus, in addition to a means for adjusting the beam laterally with respect to the axis of the system and means for adjusting the beam angularly with respect to the axis, there is a third adjustment to correlate properly the cathode filwhich block the one side of the filament holder 88 is removably mounted. The other side of the holder 88 is removably mounted in the block which forms the return connection. 1

I claim as my invention:

1. In an electron microscope having a column to be evacuated and an electron lens system, the combination of an electron gun for discharging a beam of electrons into said column, an annular unit mounted for movement transverse to the axis of said system, two independently operable thrust plungers engaging said unit at spaced locations at one side of said unit, and a spring biased pivot angularly disposed to said 'plungers and engaging the opposite side of said unit to oppose the thrust of either plunger, the relation of said pivot to both plungers being such that the thrust of either plunger" causes said unit to swing on an arc transversely of the column about said pivot as a center. 1

. 2. In an electron microscopa the combination 7 of an electron gun, an adjustable unitsupporting said gun and forming a portion of the microscope column, a'frame supporting said-unit and It will thus be seen, by operating the' forming a continuation of said column, means in eluding two independently operable plungers for shifting said unit relative to said frame and transversely with respect to the axis of said column, and a yieldable pivot opposing the thrust of either plunger but out of alinement with both plungers, whereby said unit can be swung on an arc to adjust the optical axis to the electron beam and anomalous movements be prevented during adjustments.

3. In an electron microscope, the combination of an electron gun, an adjustable unit supporting said gun and forming a portion of the microscope column, a frame supporting said unit and forming a continuation of said column, abutment means including a yieldable pivot engaging one side of said unit, and adjustable thrust means engaging said unit in opposed angular relation to said pivot for tilting said unit with respect to the axis of said column, whereby said unit is positively controlled and anomalous movements prevented during adjustments.

4. In an electron microscope, a column having ring for radial contact with said hub at the opposite side of said plane to form a laterally fixed pivot about which said ring swings on an are when either thrust plunger thrusts against said hub, whereby said column can be laterally addusted. i

5. In an electron microscope, a column having as alined portions thereof an annular frame and an annular base, a ring slidably mounted on said base and having an arcuate concave upper face,

an annular member having a lower face seated on said ring face and of complemental contour, an electron gun supported by said member for coaxial alinement with said column, two thrust plungers axially adjustable through said ring for contact with said member at the same side of the medial plane thereof, and a spring biased plunger slidable in said ring to contact said member at the opposite side of said plane to form a laterally fixed pivot about which said member swings when either thrust plunger thrusts against said member, whereby said arcuate faces impart a tilt to said member and gun.

6. In an electron microscope having a column to be evacuated and an electron lens system, the combination of an electron gun for discharging a beam of electrons into said column, an annular unit mounted for movement transverse to the axis of said system to adjust said unit with respect to said axis, and means for simultaneously moving said unit linearly and rotatively transversely of the column.

7. In an electron microscope having a column to be evacuated and an electron lens system, the combination of an electron gun for discharging a beam of electrons into said column, an annular unit mounted for movement transverse to the axis of said system to adjust said unit with respect to said axis, and means for moving said unit linearly and rotatatively transversely of the column.

FRANK E. RUNGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,305,458 Ruska et a1 Dec. 15, 1942 2,277,024 Ruska et a1 Mar. 17, 1942 2,220,973 Marton Nov. 12, 1940 2,266,717 Von Borries et a1. Dec. 16, 1941 2,086,546 George July 13, 1937 2,208,406 Benedict July 16, 1940 2,268,539 Von Borries et a1. Dec. 30, 1941 OTHER REFERENCES Zworykin and, Morton, Applied Electron Optics," pages 182, 183 of J. O. S. A., April 1936, 25049.5.

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