US3474247A

US3474247A - Automatic airlock structure for corpuscular ray device having a spherical door and specimen holder

Info

Publication number: US3474247A
Application number: US656464A
Authority: US
Inventors: Franz Stocklein
Original assignee: Max Planck Gesellschaft zur Foerderung der Wissenschaften eV
Current assignee: Max Planck Gesellschaft zur Foerderung der Wissenschaften eV
Priority date: 1967-02-24
Filing date: 1967-07-27
Publication date: 1969-10-21
Anticipated expiration: 1986-10-21
Also published as: DE1286239B; NL6802472A; GB1196003A

Description

Qcf. 21. 1969 F. sT'cKLEnN 3,474,247

AUTOMATIC AIRLOCK STRUCTURE FOR CORPUSCULAR RAY DEVICE HAVING A SPHERICAL DOOR AND SPECIMEN HOLDER Filed July 27, 1967 5 Sheets-Sheet 1 Fig.1

Ill

Inventor.-

Uct. 21, 1969 STOCKLEIN 3,474,247

AUTOMATIC AIRLOCK STRUCTURE FOR GORPUSCULAR RAY DEVICE HAVING A SPHERICAL DOOR AND SPECIMEN HOLDER Filed July 27. 1967 5 Sheets-Sheet Fig. 2 I

Inventor- Oct. 21, 1969 sroc 3,474,247 AUTOMATIC AIRLOCK STRUCTURE FOR CORPUSCULAR RAYY DEVICE HAVING A SPHBRICAL DOOR AND SPECIMEN HOLDER Filed July 2'7, 196'? 5 Sheets-Sheet 15 Inventor:

ct 21. 96 F. STOCKLEIN 3,474,247

AUTOMATIC AIRLOCK STRUCTURE FOR CORPUSCULAR RAY DEVICE HAVING A SPHERICAL DOOR AND SPECIMEN HOLDER Filed July 2'7, 1967 5 SheetsSheet 4.

In ventor:

Oct. 21, 1969 F. STOCKLEIN 3,474,247

AUTOMATIC AIRLOCK STRUCTURE FOR CORPUSCULAR RAY DEVICE HAVING A SPHERICAL DOOR AND SPECIMEN HOLDER Filed July 27, 1967 5 Sheets-Sheet Fig.5

lnventon United States Patent Int. Cl. nol 37/26 U.S. Cl. 250-495 25 Claims ABSTRACT OF THE DISCLOSURE A corpuscular ray device, such as an electron microscope, which has a hollow evacuated interior and which is provided with an airlock structure by means of which an object can be introduced into and removed from the hollow evacuated interior of the device. This airlock structure includes an airlock chamber means which defines an elongated bore which has a predetermined axis and which forms the airlock chamber. This bore has an inner end directed toward the hollow evacuated interior of the device and an outer end directed away from the hollow evacuated interior of the device, and at the region of the inner end of the airlock bore there is an annular sealing means having an inner end directed toward the evacuated interior of the device and an outer end directed away from the evacuated interior of the device. An elongated holder means is axially displaceable along the interior of the airlock bore for introducing an object into and removing it from the evacuated interior of the device, and a rotary substantially spherical door means is surrounded and engaged by the sealing means which has a vacuum-tight engagement therewith. This rotary door means has a turning axis which is situated adjacent and extends perpendicularly to the axis of the airlock bore, and the rotary door means responds to insertion of the holder means longitudinally along the interior of the airlock bore to be turned thereby to a position where said holder means is capable of placing an object in the interior of the corpuscular ray device. When the holder means is in this latter position it extends through an opening which is formed in the rotary door means, and a means coacts with this rotary door means and with the holder means for responding automatically to retraction of the holder means outwardly through the airlock bore for automatically returning the rotary door means to a closed position where its opening is situated at a side of the sealing means toward which the outer end thereof is directed.

My invention relates to corpuscular ray devices, such as electron microscopes, in particular, having an airlock structure provided with an elongated airlock bore for receiving an elongated holder for the object which is to be passed through the airlock structure into or out of the evacuated hollow interior of the corpuscular ray device, this airlock structure having at its end which is directed toward the evacuated interior of the device an airlock door which includes a spherical member.

As is well known, one of the' fundamental functions to be performed in connection with corpuscular ray devices, which may include beside electron microscopes such devices as, for example, diffraction devices, ion microscopes, devices for micro-analysis, or devices for working with charge-carrying rays and the like, is to be able to insert any desired object into or out of the evacuated interior of the corpuscular ray device without disturbing the vacuum thereof. When carrying out operations of this type, the

operations may be performed not only on a given object or specimen cartridge, but also on any part of the corpuscular ray device itself, such as, for example, diaphragms, pole shoe components of electromagnetic lenses or other objects.

Because of the fundamental significance of this particular function, a large number of airlock devices are known. An airlock device which is known from German Patent 1,027,815 includes an elongated holder for the object, this holder being insertable into an airlock bore which has arranged at its end which is directed toward the evacuated interior of the device an airlock door which includes a spherical member. The airlock bore includes with this known construction, at its end which is directed toward the evacuated interior of the corpuscular ray device, a component which has a flaring configuration similar to that of a funnel and into which a spherical member is drawn by means of springs when there is a vacuumtight closure of the device. This spherical member, during introduction of the elongated object holder, is pushed laterally away to one side of the path of movement of the holder by the holder itself in opposition to the force of the springs.

These springs, which are intended to pull the spherical member onto its seat, must have relatively large dimensions, so that they exert a considerable force, since after the elongated object holder is removed, the spherical member must be located on its seat in a highly reliable manner in opposition to the outer air pressure. The significance of this latter requirement resides in the fact that the elongated object holder must itself have a strong robust construction so as to be capable of withstanding the substantial force with which the holder must be operated, so that the spherical member can be pushed to one side out of the path of movement of the object holder. These factors further lead easily to damaging of the exterior surface of the spherical member, and since this exterior surface of the spherical member is required to form the vacuum-tight closure with the flaring extension of the airlock bore after removal of the elongated object holder, this damaging of the exterior surface of the spherical member can result in a highly significant disadvantage with respect to the achievement of the desired seal between the spherical member and its seat. Furthermore, the springs which urge the spherical member against its seat so as to achieve the required seal show fatigue characteristics which have a direct undesirable eifect on the quality of the vacuum-tight closure of the airlock structure.

It is thus a primary object of my invention to avoid these disadvantages, my invention relating not only to the introduction and removal of an object through an airlock structure but also to the airlock structure itself.

An additional object of my invention is to provide a structure of the above general type which will reliably prevent any damaging of the exterior surface of an airlock door.

Also, it is an object of my invention to provide a construction where no springs are required to urge the airlock door to its closed position while if springs are indeed used relatively light springs will sufiice.

In addition, it is an object of m invention to provide a construction which will compel the object holder to be operated in a predetermined manner which will automatically bring about the operations required for introduction and removal of an object into and out of the hollow evacuated interior of a corpuscular ray device.

Furthermore, it is an object of my invention to provide a construction where a valve which is capable of placing an airlock chamber either in communication with the outer atmosphere or in communication with an evac uated space of low pressure is capableof being automatically actuated in response to the operation of the object holder.

Also, the objects of my invention include the provision of a structure which is simple while at the same time being composed of rugged elements which are highly reliable in operation.

Thus, in accordance with my invention the corpuscular ray device includes an airlock structure which has an airlock door in the form of a substantially spherical member which in accordance with one feature of my invention is surrounded by an annular sealing means in the form of a sealing ring which has an inner end directed toward the evacuated interior of the device and an outer end directed away from the evacuated interior of the device. An airlock chamber means defines an elongated bore which forms the airlock chamber and which has an inner end directed toward the annular sealing means, and the spherical door means of the airlock structure is turnable about an axis which is perpendicular to the axis of the airlock bore and which is situated adjacent this latter axis, the rotary airlock door of my invention being turned by the elongated object holder itself during introduction of the latter into the airlock bore. When the elongated object-holding means of my invention has been fully introduced into the device it extends through an elongated opening which is formed in the substantially spherical airlock door. In accordance with a further feature of my invention, a means is provided for automatically turning the airlock door means back to its closed position in response to retraction of the elongated object-holder means outwardly of the airlock bore, and when the airlock door means of my invention is in its closed position the opening which is formed in the door means is situated on that side of the annular sealing means toward which the outer end of the latter is directed. Preferably the airlock door means turns about an axis which extends along a diameter of the sphere which forms the door means.

My invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a longitudinal section of the structure of my invention taken in a vertical plane which contains the axis of the airlock bore, a part of the vertical hollow column which forms the evacuated housing of the corpuscular ray device being shown fragmentarily in dotdash lines in FIG. 1;

FIG. 2 is a horizontal sectional plan view of the structure of FIG. 1 also taken in a plane which contains the axis of the airlock bore;

FIG. 3 shows the structure of FIG. 2 in a position different from that of FIG. 2;

FIG. 4 is a transverse section of the structure taken in a plane which is perpendicular to the axis of the airlock bore and which contains the turning axis of the airlock door, the structure of FIG. 4 being shown as it appears when looking at the structure in a direction which extends outwardly away from the interior of the corpuscular ray device; and

FIG. 5 is a diagrammatic developed representation of camming grooves and cams of the control means of the structure of my invention.

It is to be noted that not only is the entire construction shown in the drawings representative of my invention, but also individual details of the illustrated structure form my invention. The description which follows relates primarily to FIGS. 2 and 3, while FIGS. 1 and 4 serve primarily for further explanations in connection with the construction and assembly of the individual components.

The structure which is illustrated in the drawings provides an embodiment of my invention where the airlock structure is assembled together into a block which includes a valve for the airlock chamber. The entire assembl is mounted in an opening which is formed in the wall of the hollow column which forms the housing of the corpuscular ray device, and within this latter wall opening is situated the seal 1 which surrounds the block. The structure which extends inwardly beyond the seal 1 extends into the evacuated interior of the corpuscular ray device, which in the illustrated example is an electron microscope. Thus, the seal 1 seals the periphery of the block with respect to the surface which defines the opening in the wall of the column of the electron microscope which is fragmentarily indicated in dot-dash lines in FIG. 1. The electron my travels perpendicularly to the plane of FIGS. 2 and 3 over the support means 2 which is provided for the object stage into and out of wh ch a specimen cartridge or any other object carrier are introduced and removed, respectively, by means of the airlock structure described below without any interruption of the degree of vacuum prevailing in the interior of the electron microscope.

An important component of the airlock structure of my invention is formed by the elongated holder means 3 which is provided at its inner end with a hook 4 to be fastened to the object-carrier 5 in an eye of the latter, this hook 4 and object-carrier 5 being situated within a hollow tubular enclosure 6 of the holder means 3 situated in the region of the inner end portion of the latter. This elongated hollow tubular enclosure 6 is provided at its inner end with a substantially spherically shaped, convexly curved end surface 7 which coacts with part of the spherical member 8 which forms the airlock door means of my invention. The sealing of the door means is achieved by way of an annular sealing means 9 in the form of a circular sealing ring which has an inner end directed toward the evacuated interior of the corpuscular ray device, an outer end directed away from this latter evacuated interior, and which fluid-tightly engages the exterior surface of the sphere 8.

The substantially spherical door means 8 of the airlock structure of my invention is turnable about an axis 10, and when the door means 8 is in the position shown in FIG. 3 an elongated opening 11 which is formed in the spherical door means is traversed by the tubular enclosure 6 which extends axially completely through and beyond the opening 11. In this latter position of the parts which is illustrated in FIG. 3 the axis 10 is precisely tangent to the left limiting line at the exterior surface of the tubular enclosure 6, as viewed in FIGS. 2 and 3. Starting from the position of the tubular enclosure 6 which is illustrated in FIG. 2, when this tubular enclosure 6 is advanced 1nwardly into engagement with the surface 12 of the door 8 which defines the innermost part of the opening 11 thereof, the convexly curved end surface 7 of the tubular enclosure 6 has a substantially rolling contact with the surface 12, and during the further advancing of the tubular enclosure 6 toward the interior of the corpuscular ray device the spherical door means 8 turns about its axis 10 until the axis of the opening 11 reaches the position shown in FIG. 3 where this axis of the opening 11 coincides with the axis of the hollow tubular enclosure 6 and the elongated holder means 3.

The turning axis 10 of the door means 8 is formed by the common axis of the pair of

pivotal supports

10a and 10b which are provided for the door as shown in FIG. 1. The ends of the coaxial pivot pins 10a and 10b which project beyond the spherical door 8, are received in suitable openings formed in the rigid block structure, and the axis 10 preferably extends along a diameter of the sphere 8.

Considering the driving mechanism of the airlock structure in connection with operations which take place during introduction of an object into the corpuscular ray device, there is initially an insertion of the elongated holder means 3 with its inner tubular enclosure 6 and its outer sleeve assembly 13 into the airlock bore 14, so that there is a first initial axial movement of the drive 13 to the position thereof which is illustrated in FIG. 2. The components which are assembled together to form the stationary structure of FIGS. 14 form an airlock chamber means which defines the elongated airlock bore 14 having an axis adjacent which the axis is situated, this latter axis 10 extending peripendicularly with respect to the axis of the airlock bore 14. The sleeve assembly or drive means 13 is provided in the illustrated example with the control means of my invention which includes three camming grooves which respectively coact with three cams. In order to carry out the airlock operations, only the first camming groove 15 and the second camming groove 16 are of interest. This first camming groove 15 coacts with a cam 17 in the form of a roller carried by the tube 18 the interior of which defines the bore 14, this stationary tube 18 being fixedly carried by the block component 19 which is fixed to the housing column of the electron microscope, so that

elements

18 and 19 form part of the airlock chamber means and part of the block assembly of the invention. Thus, the cam 17 is a stationary cam.

FIG. 2 shows the position of the parts when the initial axis increment of movement of the sleeve assembly 13 has been terminated by the action of the cam 17 which acts as a stop. Thus, when the holder means 3 is initially introduced into the airlock bore 14, the parts can advance up to the position shown in FIG. 2 in an axial direction until the inner end of the sleeve assembly 13, which surrounds the outer end of the tube 18, engages the cam 17. This initial axial increment of movement is followed in the illustrated example by a first angular increment of rotary movement, in a clockwise direction, for example, this first angular increment of rotary movement being of interest in connection with the valve adjustment in a manner described in greater detail below. This first increment of angular turning movement is initially interrupted by the action of a detent structure formed by the

ball members

20 and 21 shown in FIG. 1, this detent structure including springs which act on the

ball members

20 and 21 thereof and which urge these ball members into detent recesses formed at the inner surface of the slidable sleeve 22 which forms part of the sleeve assembly or drive means 13. As is further explained below, the

detent devices

20 and 21 serve to indicate a predetermined valve position.

Upon further turning of the sleeve assembly 13, the movement thereof is limited by the action of a further stop location of the camming groove 15. At this time there is a further axial introduction of the elongated holder means 3 with its inner tubular enclosure 6 resulting from the second increment of axial inward movement of the sleeve assembly 13. At the end of this second increment of inward axial movement, the parts take the position shown in FIG. 3, this position being determined by a further stop formed by a part of the camming groove 15.

One of the further features of my invention resides in the provision of a means which will respond automatically to retraction of the holder means 3 for turning the door means 8 to its closed position, and this latter means which responds automatically to the retraction of the holder means 3 includes an elongated guide 24 which receives a pin which is fixed to the door means 8. This elongated guide 24 is in the form of an axially extending notch which is formed in an exterior side surface portion of the tubular enclosure 6, this notch of guide 24 being limited at its ends by an outer end surface 23 and an inner end surface 31. The pin 25 is fixed to the spherical member 8 at a predetermined radial distance from its axis 10 and extends into the opening 11 in the manner shown most clearly in FIG. 4, so as to be received in the notch or guide 24. When the parts have the position shown in FIG. 3, the outer end surface 23 of the notch 24 has the illustrated position with respect to the pin 25, although a certain additional play can be provided between the pin 25 and the end surface 23 when the parts have the position shown in FIG. 3, if desired.

When the parts have the position shown in FIG. 3, the tubular enclosure 6 engages at an outer annular shoulder which is adjacent its outer end a stop 27 formed at the outer end surface of a stationary inner block member carried by the block member 19 and itself provided at its inner end with an annular edge of V-shaped configuration which extends into an annular groove formed in the outer end of the sealing ring 9. The stop 27 is of circular configuration and takes the form of a circular lip projecting from this inner block and slidably surrounding and engaging the tubular enclosure 6, so that inward movement of the tubular enclosure 6 cannot take place beyond the position thereof shown in FIG. 3.

Now a second increment of angular turning of the sleeve assembly 13 takes place, and at this time a portion of the camming groove 16 which has a predetermined inclination or pitch becomes effective to coact with a cam 29 in the form of a suitable ball bearing or roller connected to an inner part of the sleeve assembly 13 adjacent its outer end to advance an inner rod of the holder means 3 axially with respect to the tubular enclosure 6 inwardly toward the evacuated interior of the corpuscular ray device while this inner rod, which terminates at its inner end in the hook 4, slides through a bore 30 situated in the region of the outer end of the tubular enclosure 6. This relative movement between the inner rod of the holder means and the tubular enclosure 6 results in movement of the object carrier 5 inwardly beyond the tubular enclosure 6 to a location where the object is situated at the object stage.

The elongated guide or notch 24 is required to fulfill the following function:

During retraction of the elongated holder means 3, the tubular enclosure 6 of the latter is also retracted, and as a result the inner end surface 31 of the notch or guide 24 engages and turns the pin 25 of the door means 8 so as to turn the door means 8 from the open position thereof illustrated in FIG. 3 to the closed position thereof illustrated in FIG. 2 where the door means 8 engages, at the right end of its opening 11, as viewed in FIG. 2, a stop pin 31a. At this time, as a result of the clockwise turning of the door means 8 as viewed in FIG. 2, the pin 25 advances to the left along the end surface 31 of the guide 24. At the left of this end surface 31, and forming a continuation of the notch or guide 24 is an elongated axially extending space 32 which extends along the exterior surface of the tubular enclosure 6 all the way up to the end 7 thereof, so that When the pin 25 reaches the space 32, simultaneously with engagement of the door 8 with the stop 31a, the tubular enclosure 6 is free to continue its outward retracting movement while the space 32 is axially retracted along and beyond the pin 25. Thus, at the region of its inner end 7, the tubular enclosure 6 is formed at its exterior surface with an L-shaped shoulder having a transversely extending edge which defines the end 31 of the notch or guide 24 and an axially extending edge which defines the right limit for the axially extending space 32, as viewed in FIGS. 2 and 3.

In the illustrated example the support means 2 for the object stage is itself carried by the block assembly of the airlock structure. This support or bearing provided for the support means 2 in the block assembly includes

springs

33 and 34 as well as

rollers

35, 36 and 37 which guide the support means 2 for movement in such a way that the movement of the object by way of corresponding movement of the object stage is possible in a plane which extends perpendicularly with respect to the electron ray. Thus, as is particularly apparent from FIGS. 24, the support means 2 is of substantially U-shaped configuration and has a pair of opposed parallel legs of circular cross section, the left leg rotatably carrying the roller 35 which engages a surface of an axially extending bore formed in the outer block 19, while the right leg of the support means 2, as viewed in FIGS. 2-4 is guided between the pair of

rollers

36 and 37 which have stationary turning axes and which are supported for rotary movement by the block 19. At the inner ends of its opposed legs, the substantially U-shaped support means 2 has a transverse portion which extends transversely across the axis of the airlock bore 14 and which is formed with an opening which receives the inner end of the tubular enclosure 6 when it has the position shown in FIG. 3, as indicated in FIG. 3.

The sleeve assembly or drive means 13 has an outer sleeve 38 which is provided with a third camming groove 39 of the control means of my invention, this camming groove coacting with a cam 40 which also takes the form of a roller in the form of a ball bearing for reducing the friction of the camming structure. This cam 40 is directly carried by the valve means 41. The valve means 41 serves, depending upon the position of the holder means 3, to bring about an evacuation of, and admission of air into, or a vacuum-tight closure of the airlock chamber which is defined between the door 8 and seal 9, on the one hand, and the circular sealing ring 42 which slidably and fluid-tightly surrounds the inner rod of the holder means 3, so that the airlock chamber proper extends between the sealing ring 9 and the sealing ring 42.

The valve means 41 includes a valve housing formed by the block assembly, and the valve means 41 further includes a sealing ring 43 which is situated with its outer periphery engaging the inner surface of the valve hous ing and with its inner periphery slidably and fluid-tightly engaging the valve stem 49 at the exterior surface of the latter, this sealing ring 43 dividing the interior of the valve housing into a pair of valve chambers. One of these valve chambers is formed by the inner valve chamber 44 which communicates with a conduit 45 which in turn communicates with an unillustrated evacuated space of low pressure so that a pre-evacuation may be provided through the conduit 45 and the valve chamber 44. The ring 43 also provides the valve housing with an outer valve chamber 46 which through apassage 47 communicates with the airlock chamber proper 48. The valve stem 49 is formed with a pair of axially extending passages or bores 50 and 51. These bores 50 and 51 extend inwardly along the axis of the valve stem from the opposed outer ends thereof and at the region of their inner ends the

bores

50 and 51 respectively communicate with transverse openings 52 and 53 which extend through the wall of the valve stem. Thus, the transverse openings 52 and 53 are situated at those ends of the

bores

50 and 51 which are nearest and directed toward each other. When the valve stem 49 has the position shown in FIG. 2, as a result of the actuation derived from the sleeve assembly 13, its passage 51 and the valve chamber 46 bring about admission of air from the exterior into the airlock chamber 48 proper. When the valve stem 49 has been displaced outwardly to its unillustrated outer end position, the other passage or axial bore 50 provides through the transverse bore 52 and valve chamber 46 a communication between the airlock chamber 48 proper and the vacuum conduit 45. FIG. 3 shows the valve stem 49 at an intermediate position between its inner end position shown in FIG. 2 and its unillustrated outer end position where the valve means 41 provides a vacuum-tight closure of the airlock chamber 48 proper, and this closure is augmented by way of the sealing ring 42 which at this time is located across and closes, in a fluid-tight manner, the end 54 of the passage 47 which extends between the chamber 48 and the valve chamber 46. It is to be noted that the distance between the inner ends of the

bores

50 and 51, where they are nearest to each other, and thus the distance between the transverse bores 52 and 53, is greater along the axis of the valve stem 49 than the axial length of the valve chamber 46, so that both of the

passages

50 and 51 cannot simultaneously communicate with the chamber 46.

By providing the

camming grooves

15, 16 and 39 of the control means of my invention with a suitable configuration, it is possible to achieve axial increments of movement of the sleeve assembly 13 and angular turning increments of movement thereof, in the same direction, which will provide all of the required steps in connection with introduction and removal of an object from the evacuated interior of the corpuscular ray device, including actuation of the valve. A developed illustration of the primary portions of the three

camming grooves

15, 16 and 39 of the sleeve assembly 13, as they extend through a turning angle a of the sleeve assembly 13 is illustrated in FIG. 5. At the position I indicated at the left in FIG. 5 the parts have the position shown in FIG. 2 where as a result of the initial increment of axial movement the cam 17 has become effective as a stop, in cooperation with the camming groove 15, so as to terminate the initial increment of inward axial movement of the hollow tubular enclosure 6 and the remainder of the elongated holder means 3 into the airlock bore 14. During the next following increment of angular turning movement of the sleeve assembly 13 from position I to position III, which is the first increment of angular turning movement, the axial positions of the corresponding regions of the

camming grooves

15 and 16 do not change, since this first increment of angular turning movement serves only to control the valve. The valve means 41 is situated at instant I, as a result of the coaction of the cam 40 and the camming groove 39 at the position shown in FIG. 2 where the valve stem 49 is located at its inner end position situated nearest to the evacuated hollow interior of the corpuscular ray device, and at this inner end position of the valve stem 49 the bore 51 thereof and the transverse bore 53 which communicates therewith provide admission of air from the exterior into the airlock chamber proper 48.

When position II resulting from a first portion of the first increment of angular turning of the drive means 13 has been reached, the valve stem 49 has been axially displaced outwardly to its unillustrated outer end position where the other axial bore of the stem 49 provides through its transverse bore 52 a communication between the airlock chamber 48 and the unillustrated evacuated space of low pressure, such as, for example, a pre-evacuated container, this connection being provided through the conduit 45. Thus, when the valve stem 49 has been displaced to the position II indicated in FIG. 5, there will take place an evacuation of the airlock chamber 48 before the spherical door means 8 has been opened. This position of the parts is indicated to the operator and is determined in the illustrated example by means of the

releasable detent device

20, 21. The operator can feel the

ball members

20 and 21 snap into the detent recesses, and when this position is achieved the operator will pause in the turning of the sleeve assembly 13 so that the parts will remain for a given interval at the position II in order to assure reliable evacuation of the airlock chamber 48 which has a small cross section of fiow.

The second part of the first increment of angular turning movement extends from position II up to position III, shown in FIG. 5, and also serves to control the valve means 41. Before the door 8 is turned to its position permitting the passage of the holder means 3 and in particular of the hollow tubular enclosure 6 thereof through the opening 11 of the door 8, the valve must provide a vacuum-tight closure of the airlock chamber. For this purpose the stem 49 must be axially displaced into the position shown in FIG. 3, and in order to reach this intermediate position the camming groove 39 has the configuration shown in FIG. 5 extending between positions II and III.

After this movement of the valve stem from the airadmitting position I through the evacuating position II into the closure position III, brought about by the first increment of angular turning of the drive means 13, the second increment of axial advance of the holder means takes place, this axial advance taking place from the position III to the position IV indicated in FIG. 5. At this time the configuration of the camming groove is such, as is apparent from FIGS. 3 and 5, that this portion of the camming groove 15 extends parallel to the axis of the holder means 3 and thus extends in the direction of the second increment of axial movement.

Also, the camming groove 39 for actuating the valve stem 49 has at this region a portion extending in the direction of axial movement of the holder means, as is also indicated in FIG. 3. Therefore, at this time the position of the valve stem 49 does not change as a result of the second increment of axial advance of the holder means 3. Thus, at this time the holder means 3 is advanced inwardly through its second increment of axial movement until the parts have the position shown in FIG. 3.

This second increment of axial movement from the position III to position IV is followed-by a second increment of angular movement from position IV to position V, during which the sleeve assembly 13-is turned to provide by way of the camming groove 16 and cam 29 an advance of the inner rod of the holder means 3 with respect to the outer tubular enclosure 6 thereof which is held stationary at this time by the stop27 so that the enclosure 6 is prevented from participating in this movement. During the second increment of angular turning of the sleeve assembly 13 neither the axial position of the latter or the axial position of the valve stem 49 changes, so that the

camming grooves

15 and 39 have at their portions extending between positions IV and V circumferential parts respectively located in planes normal to the axis of bore 14. Only the camming groove 16 is inclined and has a predetermined pitch to provide for axial displacement of the cam 29 during turning from position IV to position V.

When the parts have reached the position V the object which is to be introduced into the evacuated interior of the corpuscular ray device has reached its operating position. This is brought about by the continued inward displacement of the inner rod of the holder means 3 with respect to the tubular enclosure 6 beyond the position of the parts shown in FIG. 3, and this relative movement of the inner rod with respect to the enclosure 6 is brought about by the coaction of the cam 29 with the inclined portion of the groove 16. It may be desirable to provide for the position Va a detent device releasably holding the parts in a position where the inner rod of the holder means 3 is retracted through a slight distance and is mechanically uncoupled from the object which has been introduced.

During the further continued turning of the sleeve assembly 13 in the same direction the camming groove 16 is displaced from position V to position VI where the camming groove is provided with an inclined portion of pitch which is a mere image of the portion thereof extending between positions IV and V. As a result the inner rod of the holder means 3 has been outwardly displaced relative to the hollow tubular enclosure 6 to again reach the position shown in FIG. 3, and beyond position VI all of the components of the holder means 3 again move together. During this phase of the operation, up to position VI, the valve stem 49 remains in its vacuum-tight closure position providing a reliable closure for the airlock chamber 48 proper (FIG. 3), and the camming groove 15 is provided with a circumferential extension of the circumferential portion thereof extending between positions IV and V, so that there is no axial retraction of the sleeve assembly 13 at this time.

The retraction of the sleeve assembly 13 takes place during the next increment of axial movement from position VI to position VII, whereupon the valve stem 49 again must be placed in the position of FIG. 2 for admitting air. This latter positioning of the valve stem 49 takes place during turning from position VII to position VIII. During this latter increment of turning there is no axial displacement of the holder means 3.

The second part of the final increment of turning from position VIII to position IX may serve to provide an interval for admission of air into the airlock chamber proper 48. Position VIII can, however, be immediately followed by a further axial retraction of the holder means 3 together with its tubular enclosure 6 outwardly from the position shown in FIG. 2 (corresponding to position VII). In this case the positions I and VIII will coincide.

It is however also possible to bring about the airlock operations by moving the parts in the reverse series of operations back from positions Va or V to position I.

Of course, it is also possible to utilize valve constructions different from that illustrated in the drawings, such as, for example, a valve construction where the

valve chambers

44 and 46 are not separated by a ring 43 which is fixed in the valve housing but instead are defined by a sealing ring which is fixed on the valve stem 49 and moves relative to the valve housing together with the second valve seal shown in FIGS. 2 and 3. Also, additional detent devices can be provided, such as a detent device which indicates position IV and which is situated between a fixed part of the device which surrounds the tubular enclosure 6, on the one hand, and a component which participates in the axial movement, on the other hand.

As is apparent from FIGS. 1-3, it is preferred to provide a resilient yieldable support for the holder means 3 by way of the spring 55 to achieve the possibility of adapting the position of the holder means with respect to the particular position in which the object stage is located.

The valve means can also be provided with an electromagnetic or motor drive in whose circuit are located contacts which are controlled from the sleeve assembly 13 by way of suitable cams or other means.

Thus, while with known constructions the airlock door is moved in opposition to the action of springs, when the holder is introduced, such movement of the components with the airlock structure of my invention is avoided by providing the spherical door 8 which is turnable about the axis 10 and which is formed with the opening 11 which receives the holder means 3 to be turned by the latter into a position where the holder means extends through the opening of the sphere 8.

While in this position of the airlock structure, shown in FIG. 3, a connection between the evacuated interior of the corpuscular ray device and the airlock bore 14 is provided through the opening 11, at all operating positions where the elongated holder means 3 does not extend into the evacuated interior of the corpuscular ray device, the opening 11 is situated only at that side of the seal 9 toward which its outer end is directed, so that at this time the opening 11 of the door 8 does not extend through the seal 9.

As is apparent from the above description, the sealing surface of the sphere 8 which coacts with the sealing ring 9 and the surface thereof which is engaged by the holder means 3 are not identical so that even if there should be damaging of the surface 12 by the pressure of the holder means 3, this factor will have no undesirable influence on the seal of the door 8. Furthermore, the forces required to turn the door 8 to its closed position are only those which are required for the turning of the door 8 itself, since the door 8 need not be held in its closed position in opposition to the pressure of the outer atmosphere. The force resulting from the pressure of 'the outer atmosphere acts only on the turning axis of the sphere 8, namely on the

pins

10a and 10b. After the door 8 has been turned to its closed position, the friction resulting from the engagement of the seal 9 with the sphere 8 is adequate for holding the sphere in its closed position. If desired, however, a detent ball device or the like may be provided for holding the spherical door 8 in its closed position.

Also, in order to contribute to the movement of the door 8 to its closed position, relatively weak springs may be provided, these springs seeking to press the door 8 in opposition to the force acting thereon from the elongated holder means 3 into engagement with the stop 31a.

The spherical or convexly curved end 7 of the holder means 3 reduces the frictional engagement between the latter and the door to a minimum, and this inner end 7 has a substantially rolling contact with the surface 12 during turning of the door to its open position where the axis of the opening 11 coincides with the axis of the bore 14. The dimensions of the components can be maintained particularly small by providing for the spherical door means 8 a radius which is approximately equal to the largest cross sectional dimension of that region of the elongated holder means 3 which is received in the opening 11. Thus, the door means 8 has in cross section a form of a door which is swingable about the axis 10 and which has a maximum thickness corresponding to the radius of the sphere.

It is to be noted that the hollow tubular enclosure 6 serves to protect the object which is to be introduced into and removed from the interior of the corpuscular ray device. Because of the telescopic coaction between the inner rod of the holder means and the hollow tubular enclosure 6 thereof, there is a protection of the object against mechanical damage during introduction and removal of the object, and this protection is required only as long as the holder means is in the region of the opening 11 while the door is turned by the holder means.

It is also apparent from the above description that the control means of my invention need only include three camming grooves and cams in order to bring about all of the desired operations by way of a single manually operable sleeve assembly 13, these operations including the actuation of the valve means.

The axial bores of the valve stem and the transverse openings which communicate therewith can be replaced, if desired, with axially extending grooves formed at the exterior surface of the valve stem.

The structure can of course be operated by adjusting motors which will automatically carry out the airlcok operations in such a way that the continued operation after the second increment of angular turning brings about the retraction of the elongated holder means with the operations carried out during retraction of the object being mirror image movements of those carried out during introduction of the object. For example, by way of a single revolution of the drive means 13 there can be provided a complete introduction and retraction cycle. During operation with the object situated in the interior of the corpuscular ray device, the elongated holder means 3 may remain connected to the object. However, by providing a yieldable mounting for the holder means 3, by way of the spring 55, it is possible to separate the holder means from its connection with the object which has been introduced, and then the continued operation after the second increment of angular turning of the holder means can uncouple the latter from the object. The illustrated example of a hook and eye connection lends itself to this type of operation. In the case where the holder means remains connected with the object during operation of the corpuscular ray device, the eye and hook will have with respect to each other a play which takes into consideration the movement required for the object at the operating position of the latter. Spring-means 56 will diminish the force exerted by the ambient air pressure.

I claim:

1. In a corpuscular ray device, such as an electron microscope, which has a hollow evacuated interior, airlock chamber means defining an elongated bore which has a predetermined axis and which forms an airlock chamber, said bore having an inner end directed toward the evacuated hollow interior of the device and an outer end directed away from said evacuated hollow interior of the device, elongated holder means for holding an object which is to be introduced into and removed from the hollow evacuated interior of the device, said holder means being longitudinally insertable axially through said airlock bore beyond said inner end thereof during introduction of an object into the device and axially retractable out of said bore during removal of an object from the hollow interior of the device, annular sealing means having an outer end directed toward said bore and an inner end directed toward the hollow interior of the device, rotary, substantially spherical door means surrounded and engaged by said annular sealing means for providing a vacuum-tight closure therewith, said rotary door means having a turning axis perpendicular to and situated adjacent said bore axis and said door means responding to insertion of an object by said holder means to be turned by the latter to a position introducing the object into the interior of the device, said rotary door means being formed with an opening through which said holder means extends when an object has been introduced thereby into the hollow interior of the corpuscular ray device, and means responding to retraction of said holder means outwardly along the interior of said bore for automatically turning said door means to a closed position where said opening thereof is situated at a side of said annular sealing means toward which said outer end of the latter is directed.

2. The combination of claim 1 and wherein said rotary door means turns about an axis which coincides with a diameter of said substantially spherical door means.

3. The combination of claim 1 and wherein a spring means coacts with said door means for urging the latter to turn in a direction opposed to the direction in which it is turned by said holder means during introduction of an object into the device, and stop means toward which said door means is urged by said spring means.

4. The combination of claim 1 and wherein a stop means is situated in the path of closing movement of said rotary door to engage the latter and determine its closed position, said means which responds automatically to retraction of said holder means for turning said door to said closed position thereof including a pin carried by said door means and an elongated guide formed in said holder means and receiving said pin for engaging and guiding the latter to turn said door to said closed position thereof during retraction of said holder means, said pin turning about the axis around which said door turns during closing of the latter to a location located beyond said guide when said stop means engages said door to determine the closed position thereof, so that when the door is in its closed position said pin and guide no longer are in cooperative relationship with respect to each other.

5. The combination of claim 4 and wherein said holder means is formed next to said guide with a free space receiving said pin when said door engages said stop means and said free space of said holder means extending up to an inner end of said holder means so that when said door is in its closed position said holder means can be retracted beyond said pin while displacing said free space therealong.

6. The combination of claim 1 and wherein said holder means has an inner end of convexly curved configuration engaging said door in said opening thereof during insertion of said holder means into said bore, said opening of said door being elongated and having a predetermined axis and said inner end of said holder means turning said door while said holder means advances toward the hollow interior of the device to a location where said axis of said opening coincides with said axis of said bore while said holder means extends through said opening of said door, said inner, convexly curved end of said holder means having substantially rolling contact with said door in said opening thereof during turning of said door to the position where the axis of said opening concides with the axis of said bore.

7. The combination of claim 1 and wherein said holder means has at an inner end portion which is directed toward said door an elongated outer tubular enclosure and said holder means having within :said tubular enclosure a means for engaging and holding the object which is to be introduced into and removed from the device.

8. The combination of claim 4 and wherein said holder means includes at the region of its inner end an outer tubular enclosure which is formed at an exterior surface portion thereof with said guide which coacts with said pin, and means situated within said enclosure for holding an object which is to be introduced into and removed from the hollow interior of the corpuscular ray device.

9. The combination of claim 7 andwherein a stop means limits the movement of said tubular enclosure toward the interior of the corpuscular ray device while said means within said enclosure for holding the object continues to advance with respect to said enclosure along the interior of and beyond the latter into the hollow interior of the corpuscular ray device.

10. The combination of claim 1 and wherein a second sealing means surrounds said holder means in a vacuumtight manner outwardly of said annular sealing means to define with the latter an airlock chamber proper which is situated between said annular sealing means and said second sealing means, and valve means communicating with said airlock chamber proper for placing the latter in one position of said valve means in communication with the outer atmosphere and in another position of said valve means in communication with an evacuated space of low pressure.

11. The combination of claim 10 and wherein a displacing means coacts with said valve means fordisplacing the latter between said positions thereof, and said holder means actuating said displacing means during movement of said holder means in said bore for determining the position of said valve means according to the position of said holder means in said bore.

12. The combination of claim 1 and wherein said holder means includes at an outer end portion thereof which is directed away from said door means an elongated sleeve which forms an actuating handle, and control means including a pair of camming grooves and earns situated therein for controlling said holder means to first move axially inwardly toward the interior of the corpuscular ray device through a predetermined increment, to then be turned angularly through a given angular increment, for then being axially advanced toward the interior of the corpuscular ray device through a second increment, and for then being angularly turned through a second angular increment for locating said holder means at an inner end position where the object has been introduced into the corpuscular ray device.

13. The combination of claim 12 and wherein said control means includes an inner camming groove which coacts with a stationary cam to act as a stop for limiting the extent of the first increment of inward movement of said holder means.

14. The combination of claim 13 and wherein a second sealing means surrounds said holder means and engages the latter in a vacuum-tight manner, said second sealing means being situated outwardly of said annular sealing means and defining with the latter an airlock chamber proper which is situated between both of said sealing means, and valve means communicating with said airlock chamber proper and having one position for placing the latter chamber proper in communication with the outer atmosphere and another position for placing the latter chamber proper in communication with a space which is evacuated and at a low pressure, said valve means having an elongated axially movable stem which is axially displaced to locate said valve means in said positions thereof and said control means including a third camming groove located at said sleeve and a cam carried by said stem and engaged in said third groove for automatically displacing said valve means between said positions thereof during axial movement of said holder means.

15. Thecombination of claim 1 and wherein a valve means coacts with said airlock chamber for placing the latter in one position of said valve means in communication with the outer atmosphere and in another position of said valve means in communication with an evacuated space of low pressure, said valve means including an elongated axially movable stem, a valve housing, and a sealing ring in said housing fluid-tight and slidably surrounding said stem and dividing said housing into a pair of chambers one of which communicates with said airlock chamber and the other of which communicates with said evacuated space of low pressure, said stem being formed with a pair of elongated axially extending passages one of which communicates with said housing chamber which communicates with said evacuated space of low pressure and the other of which communicates with the outer atmosphere, and said passages being spaced from each other longitudinally of said stem at ends of said passages which are nearest to each other by a distance which is greater than the axial length of said housing chamber which communicates with said airlock chamber.

16. The combination of claim 12 and wherein said control means provides for said holder means after said second angular increment of movement thereof a further movement forming a continuation of said second angular increment of movement and providing for uncoupling of said holder from the object which has been introduced into the hollow interior of the corpuscular ray device.

17. The combination of claim 14 and wherein said third camming groove acts to displace said valve means during said first increment of angular turning of said holder-means from a position where said valve means places said airlock chamber in communication with said evacuated space of low pressure to a position where said airlock chamber is closed in a vacuum-tight manner.

18. The combination of claim 17 and wherein the vacuum-tight closure of said airlock chamber is further enhanced by said second sealing means-which closes a communication between the airlock chamber and a valve chamber.

19. The combination of claim 17 and wherein said third camming groove controls said valve means for placing said airlock chamber in communication with the outer atmosphere after said :rotary door means has reached its closed position.

20. The combination of claim 1 and wherein a valve means coacts with said bore for placing the latter in communication with an evacuated space of low pressure in one position of said valve means and in communication with the outer atmosphere in another position of said valve means, and detent means coacting with said valve means for releasably holding the latter in said positions thereof.

21. The combination of claim 1 and wherein said holder means includes a hook while the object held thereby is formed with an eye which receives said hook with a predetermined play in accordance with the movement of the object at its location within the hollow interior of the corpuscular ray device.

22. The combination of claim 1 and wherein said holder means includes an exterior portion by which said holder means is actuated and a yieldable spring means for transmitting movement from said exterior portion of said holding means to the remainder of the latter.

23. The combination of claim 1 and wherein a sup port means for supporting an object stage is itself supported for movement by said airlock chamber defining means.

24. The combination of claim 23 and wherein said support means has a substantially U-shaped configuration providing said support means with a pair of free legs movably carried by said airlock chamber defining means for longitudinal movement, and spring means situated between said legs and airlock chamber defining means for yieldably and resiliently opposing movement of said support means, and said support means having between said legs a transverse portion eXtending approximately perpendicularly with respect to said elongated holder means.

25. The combination of claim 1 and wherein said rotary door means has a radius which is approximately equal to the largest cross-sectional dimension of said holder means at the region of the latter which is received in said opening of said door means.

References Cited UNITED STATES PATENTS 2,845,540 5/1958 Franken et al. 25049.52

10 RALPH G. NILSON, Primary Examiner C. E. CHURCH, Assistant Examiner