An external drive mechanism for ultra-high vacuum

Abstract

The present invention discloses an external driving mechanism for ultra-high vacuum, comprising a vacuum chamber assembly and a driving assembly connected to the outside of the vacuum chamber assembly via a connecting assembly. The driving assembly can achieve large-stroke movement of the driven part and resetting with sub-micron precision. The output end of the driving assembly is connected to the driven part, and the driven part can extend into the vacuum chamber assembly. In the present invention, by designing the driving mechanism outside the ultra-high vacuum and using bellows connection and knife-edge sealing, not only can the contamination of the ultra-high vacuum by the driving mechanism be avoided, but also flexible driving of the driven part can be achieved. At the same time, the driving assembly is directly mounted on the vacuum chamber assembly, eliminating the error caused by the independent support of the driving part. Through the provision of the bolt adjustment assembly, the driving assembly can be used to drive the driven part to move or rotate relative to the vacuum chamber assembly, thereby adapting to the actual orientation requirements of the passive driving part.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-high vacuum, precision displacement and real-time monitoring of key features of optical elements in a vacuum chamber, and more specifically to an external drive mechanism for ultra-high vacuum with a large stroke. Background Art

[0002] In synchrotron accelerators, free electron lasers, and various beamline devices, it is often necessary to precisely position a probe, sample, pinhole, optical mirror, or slit in five or six dimensions within an ultra-high vacuum. During operation, the positioned object must be withdrawn from the working position over a large distance. When necessary, it must be precisely returned to the working position. This process is repeated repeatedly as the work progresses. For example, the pop-in probe in the oscillator of a free electron laser device, see Figure 1 The probe is a triangular electron beam trajectory position calibration device with a small hole for calibrating the electron trajectory and a yttrium aluminum garnet (YAG) crystal target for displaying the electron position. To precisely calibrate the electron beam trajectory, the centerline of the probe's small hole must be installed and adjusted to be concentric with the theoretical laser optical axis of the free electron laser oscillator, with a linear position error within ∅25μm and an angular error less than 5mrad. The probe's drive mechanism must be adjustable in five dimensions during installation (position adjustment along the optical axis is not required). After the electron trajectory centerline is calibrated, the probe is moved 60mm out of the oscillator's optical path. If the electron trajectory needs to be recalibrated later in operation, the probe must accurately return to the theoretical calibration position. Therefore, the drive mechanism must be adjustable in five dimensions during installation and must demonstrate extremely high repeatability after a large range of motion and return. Furthermore, the internal components are located in an ultra-high vacuum chamber, making direct measurement of the position parameters of key features difficult. Multiple targets, fixedly linked to and measurable from key device features within the vacuum chamber, are required outside the vacuum chamber. The driving mechanism can accurately implement the precise installation positioning, driving and repeated positioning functions required by the probe.

[0003] Patent publication number CN 209216588 U discloses a long-stroke precision piezoelectric displacement stage for ultra-high vacuum applications, comprising a stage base and a movable table that moves relative to the stage base. Two sets of cross-ball guide rail assemblies are disposed between the stage base and the movable table, each set of cross-ball guide rail assemblies comprising two mutually coupled cross-ball guide rails. One cross-ball guide rail in each set of cross-ball guide rail assemblies is fixedly connected to the stage base, while the other cross-ball guide rail in each set of cross-ball guide rail assemblies is fixedly connected to the movable table. The long-stroke precision piezoelectric displacement stage for ultra-high vacuum applications disclosed in this proposal is suitable for ultra-high vacuum and ultra-low temperature environments. While ensuring movement in the stroke direction, it avoids shaking in other directions, thereby ensuring absolute nanometer-level motion accuracy. However, it is not suitable for moving components such as probes and for positioning key elements, such as the axial position requirements of the probe center hole. Summary of the Invention

[0004] The technical problems to be solved by the present invention are:

[0005] 1. How to avoid the contamination of ultra-high vacuum by the drive mechanism;

[0006] 2. Ability to adjust the actual position of the driven parts in 5 dimensions and meet the precision positioning requirements of key elements;

[0007] 3. It can make the driven part withdraw from the working position with a large stroke and return to the original working position with high precision;

[0008] 4. Accurately confirm the exact location of key features of the probe inside the vacuum chamber by measuring the position of external targets at any time;

[0009] 5. The driving mechanism is compact and can be directly installed on the vacuum chamber.

[0010] The present invention solves the above technical problems through the following technical means: an external drive mechanism for ultra-high vacuum, comprising a vacuum chamber assembly, a target ball, a fixed base plate fixed to the flange of the vacuum chamber assembly, and a drive assembly connected to the outside of the vacuum chamber assembly through an adjustment assembly, the output end of the drive assembly is connected to a driven part, the driven part can extend into the vacuum chamber assembly, the drive assembly can be coupled to the vacuum chamber assembly by welding a bellows, avoiding contamination of the ultra-high vacuum by the drive mechanism, flexibly realizing long-range drive of the driven part along the axial direction of the bellows and precise five-dimensional installation adjustment. Flexible drive; the adjustment assembly includes a vertical adjustment screw group and a lateral horizontal adjustment group; the vertical adjustment screw group can drive the assembly to move in the Z direction and rotate around the X axis; the lateral horizontal adjustment group can drive the drive assembly to move in the X direction and rotate around the Y and Z axes relative to the vacuum chamber assembly; the drive assembly is used to withdraw the driven part from the working position or return it to the working position; the target ball is fixed on the drive assembly and is located outside the vacuum chamber, and the orientation of the key features of the probe connected to the vacuum chamber assembly can be obtained by measuring the center position of the target ball; the drive assembly is installed on the knife-edge flange of the vacuum chamber assembly.

[0011] As a preferred technical solution, the adjustment assembly includes a vertical adjustment screw group and a lateral horizontal adjustment group. The vertical adjustment screw group includes two fine-thread adjustment screws arranged at the bottom of the fixed base plate and an elastic plunger screw at the top. The elastic plunger screw is used to drive the adjustment base plate on the driving assembly to close contact with the two fine-thread adjustment screws at the bottom. The vertical adjustment screw group is used to drive the driving assembly to translate in the Z direction and rotate around the X axis.

[0012] As an optimal technical solution, the lateral horizontal adjustment group includes three bolt adjustment assemblies, the bolt adjustment assembly includes a concave conical gasket, an adjusting thread sleeve, a locking nut, a rectangular coil spring, and a tightening screw, the concave conical gasket can contact the floating plane of the fixed base plate; the end spherical surface of the adjusting thread sleeve presses against the conical surface of the concave conical gasket; the adjusting thread sleeve is screwed into the screw hole of the adjusting base plate of the drive assembly; the adjusting thread sleeve is screwed onto the locking nut; the tightening screw passes through the rectangular coil spring, and the adjusting thread sleeve and the concave conical gasket are screwed into the screw hole of the fixed base plate; the compression amount of the rectangular coil spring here is adjusted during installation, and its elastic force ensures that the drive assembly does not overturn due to gravity, and allows the vertical adjustment screw group to verify the installation adjustment of the drive assembly; the three bolt adjustment assemblies are arranged in a triangle, and adjusting the corresponding bolt adjustment assemblies can realize two-dimensional rotation and one-dimensional translation adjustment of the drive assembly connected to the adjustment base plate relative to the fixed base plate assembly.

[0013] By adjusting the amount of tightening screws screwed in, the tightening force can be adjusted through the rectangular coil spring to ensure that the drive assembly can still be firmly fixed on the vacuum chamber under the action of gravity. At the same time, due to the existence of elasticity, the vertical adjustment screw group can be allowed to adjust the Z direction or rotation around the X axis of the drive assembly.

[0014] As a preferred technical solution, the output end of the drive assembly is connected to the driven part through a transmission shaft, and the fixed base plate is bolted to press the knife-edge flange onto the sealing copper gasket of the vacuum chamber assembly to achieve vacuum sealing; the knife-edge flange is seal-welded to one end of the bellows, and the other end of the bellows is seal-welded to the end of the transmission shaft; the bellows acts as a flexible coupling connector that ensures the vacuum sealing of the vacuum chamber and allows the driven part to be installed and adjusted to the working position, withdrawn from the working position over a long stroke, and reset flexibly.

[0015] As a preferred technical solution, the driving assembly includes an adjusting base plate, a displacement platform base, a precision displacement platform, a coupling, a stepper motor, a movable plate, a transmission shaft, a knife-edge flange, and a bellows; the displacement platform base is fixedly mounted on the adjusting base plate with screws, the precision displacement platform is mounted on the displacement platform base, the two movable sliders of the precision displacement platform are fixedly connected with a displacement plate, the displacement plate is connected to the driven part through a transmission shaft, the stepper motor is mounted at the end of the precision displacement platform, and the output shaft of the stepper motor is transmission-connected to the screw input shaft of the precision displacement platform through a coupling; when the stepper motor rotates, the driving screw of the precision displacement platform drives the two sliders to perform translational motion, thereby driving the displacement plate, the connecting shaft and the driven part to perform translational motion.

[0016] As a preferred technical solution, the drive mechanism also includes a Renishaw grating scale assembly, a travel switch assembly, and a controller; the controller is electrically or communicatively connected to the precision displacement platform, the absolute grating scale assembly, and the travel switch assembly; the linearity of the motion of this drive mechanism can be met by selecting the accuracy level of the precision drive platform as needed; the motion step length of this drive mechanism can be met by selecting the drive screw pitch of the precision drive platform, the stepper motor, and the number of differential drive microsteps of the motor driver as needed; the repeatability of the positioning accuracy of this drive mechanism can be determined by selecting the appropriate accuracy level of the precision drive platform and the appropriate accuracy level of the grating scale assembly as needed.

[0017] As a preferred technical solution, the absolute grating scale assembly includes a grating scale reading head and a grating scale. The grating scale reading head is fixedly connected to the displacement platform base, and the grating scale is fixedly connected to the displacement plate. When the displacement plate drives the grating scale, the grating scale reading head scans the grating scale and accurately reads the displacement. The accuracy of the characteristic grating of closed-loop control represents the repeatability of the drive mechanism.

[0018] As a preferred technical solution, the travel switch assembly includes a travel switch paddle and a travel switch. The travel switch paddle is fixedly connected to the displacement plate, and the two travel switches are fixedly connected to the base of the displacement platform. When the displacement plate drives the travel switch paddle to move to trigger one travel switch, the movement in this direction is stopped, and the reverse movement is stopped to trigger the other travel switch.

[0019] As a preferred technical solution, the displacement plate can also form a hard stop for the drive assembly. If the travel switch fails, the displacement plate's forward motion is halted until one end abuts the adjustment plate; its retraction motion is halted until the other end abuts the rear step of the displacement platform. The hard stop serves to limit the drive travel in the event of a travel switch failure, thereby protecting the driven components and the bellows (vacuum system) from damage.

[0020] As a preferred technical solution, the displacement plate is provided with a target ball seat that is compatible with the target ball. The target ball seat has a 90° concave cone surface. The target ball can be installed on the target ball seat with ultra-high repeatability at any time. The driven part and the four target balls outside the vacuum have a fixed positional relationship. After calibrating this relationship with an appropriate instrument (such as an articulated arm), the actual position of the driven part in the vacuum can be obtained at any time by measuring the positions of the four target balls outside the vacuum using CAD means.

[0021] As a preferred technical solution, the precision displacement platform uses the THK KR2001B-0035-P0 motion platform, the stepper motor uses the Oriental Motor model PKP523N12B, the grating scale assembly uses the Renishaw ResoluteTM absolute grating scale, and the limit switch assembly uses the Omron D2MQ-1-TR micro limit switch. These are combined into a closed-loop controlled precision drive positioning system to ensure that the position repeatability accuracy of the driven part when it withdraws from the workbench position and returns reaches the micron level.

[0022] The beneficial effects of the present invention are:

[0023] (1) In the present invention, by designing the drive mechanism outside the ultra-high vacuum and coupling it with a welded bellows, not only can the drive mechanism avoid contamination of the ultra-high vacuum, but it can also achieve long-stroke precision driving of the driven part, ensuring the flexibility of precision driving. The drive of the driven part here includes five-dimensional installation adjustment drive and long-stroke exit working position and precision return drive.

[0024] (2) In the present invention, by setting up the vertical adjustment screw group and the lateral horizontal adjustment group, the five-dimensional installation adjustment of the driven part in the vacuum chamber assembly can be achieved, so that the center line of the probe hole can be installed to the theoretical position, and then a large stroke displacement and precise reset can be achieved through the precision displacement platform.

[0025] (3) In the present invention, the entire drive mechanism is directly mounted on the vacuum chamber flange to avoid the large position error caused by independent support on the ground.

[0026] (4) In the present invention, a THK KR2001B-0035-P0 motion platform, a stepper PKP523N12B Oriental motor, a Renishaw ResoluteTM absolute grating scale, and an Omron D2MQ-1-TR micro-stroke switch are used to form a closed-loop controlled precision drive positioning system to ensure the linearity of the motion of the driven part, to ensure ultra-high repeatability when withdrawing from the working position to the accurate specified position, and to return.

[0027] (5) In the present invention, the movement data of the displacement platform can be obtained based on the reading of the grating ruler, thereby obtaining the movement of the driven component and achieving real-time reading. The repeatability of the positioning accuracy of this drive mechanism depends on the reading accuracy of the grating ruler, which is on the micron level.

[0028] (6) In the present invention, a combination of micro-travel switches is used to limit the translational motion operating range; the length of the displacement plate is used to rigidly limit the stroke when the travel switch fails to protect the driven part from being damaged due to excessive stroke.

[0029] (7) In the present invention, multiple target ball seats are provided and rigidly connected to the driven part. By calibrating the relative position relationship between the four target balls and the driven part, such as the probe, the coordinates of the center positions of the four target balls can be measured at any time outside of a vacuum to check the orientation of the driven part.

[0030] (8) In the present invention, the drive mechanism can be mounted on the blade mounting flange of any vacuum system. By adjusting the length of the drive shaft and the welded bellows and the stroke of the THK precision motion platform, the drive mechanism can be adapted to different drive strokes and driven component positions. The driven component can be an optical mirror mount, a fluorescent target, a target ball, or a slit, i.e., the two mechanisms are combined to form a scannable slit with adjustable slit width. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the probe structure provided as the background technology of the present invention;

[0032] Figure 2 A schematic diagram of a half-section structure provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of an axonometric structure provided in an embodiment of the present invention;

[0034] Figure 4 An axonometric diagram of a drive assembly provided in an embodiment of the present invention;

[0035] Figure 5A schematic cross-sectional view of an adjusting bolt assembly according to an embodiment of the present invention;

[0036] Figure numbers: 1. Vacuum chamber assembly; 11. Vacuum chamber body; 12. Mounting flange; 13. Sealing copper gasket; 2. Fixed base plate; 3. Vertical adjustment screw group; 31. Elastic plunger screw; 32. Fine-thread adjustment screw; 33. Screw locking nut; 4. Horizontal adjustment group; 41. Concave conical gasket; 42. Adjusting threaded sleeve; 43. Locking nut; 44. Rectangular coil spring; 45. Clamping screw; 5. Drive assembly; 501. Adjusting base plate; 502. Displacement platform base; 503. Precision displacement platform; 504. Coupling; 505. Stepper motor; 506. Displacement plate; 507. Drive shaft; 508. Knife-edge flange; 509. Welded bellows; 510. Travel switch paddle; 511. Travel switch; 512. Target ball seat; 513. Grating scale reading head; 514. Grating scale; 6. Probe; 7. Target ball. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] See Figure 2 、 3 In this embodiment, the length direction of the vacuum component 1 is the Y direction, the height direction is the Z direction, the width direction is the X direction, and the optical axis direction of the laser is the Y direction.

[0039] See Figure 2 、 Figure 3 A large-stroke ultra-high vacuum external drive mechanism includes a vacuum chamber assembly 1, a vertical adjustment screw group 3, a lateral horizontal adjustment group 4, a drive assembly 5, a driven part 6, and a target ball 7; the drive assembly 5 is connected to the outside of the vacuum chamber assembly 1 through a connecting assembly, and the drive assembly 5 is provided with a target ball 7. The output end of the drive assembly 5 is connected to the driven part 6, and the driven part can be extended into the vacuum assembly 1. The drive assembly 5 is mainly used to drive the operation, withdrawal, and reset of the probe 6 in the vacuum chamber assembly 1. It should be noted that the probe 6 can also be a required sample, small hole, mirror holder, slit, etc.; the driven part is the probe 6, and the probe 6 is a POP IN probe;

[0040] The vacuum chamber assembly 1 includes a vacuum chamber body 11, a mounting flange 12, and a sealing copper gasket 13. The mounting flange 12 is fixedly connected to the end of the vacuum chamber body 11 facing the probe 6, and the sealing copper gasket 13 is fixedly connected to the end of the mounting flange 12 facing the fixed base plate 2.

[0041] The connection assembly includes a fixed base plate 2, a vertical adjustment screw assembly 3, a lateral adjustment group 4, an adjustment base plate 501, and a welded bellows 509. The fixed base plate 2 is fixed to the vacuum chamber flange of the vacuum chamber assembly 1. One end of the welded bellows 509 is connected to the knife-edge flange 508, and the other end is connected to the drive shaft 507. The welded bellows 509 provides both a flexible connection between the vacuum chamber assembly 1 and the drive shaft 507 and a vacuum seal. The lateral adjustment group 4 and the vertical adjustment screw assembly 3 can adjust the position of the external drive mechanism as required, thereby installing and positioning the drive assembly 5.

[0042] See Figure 2 、 Figure 3 、 Figure 4 The fixed base plate 2 is fixedly installed on the mounting flange 12 of the vacuum chamber assembly 1 by six groups of bolts, nuts and gaskets. The fixed base plate 2 compresses the knife-edge flange 508 on the drive assembly 5 and the sealing copper gasket 13 on the vacuum chamber assembly 1 to perform ultra-high vacuum sealing. Two fine-thread screw holes are opened at the lower part of the fixed base plate 2 for installing two fine-thread adjustment screws 32 in the vertical screw group 3. A screw hole is opened at the upper part of the fixed base plate 2 for installing the elastic plunger screw 31 in the vertical screw group 3. Three screw holes are opened on the plane of the fixed base plate 2 to match the clamping screw 45 on the horizontal adjustment group 4.

[0043] See Figure 2 、 Figure 3, In this embodiment, the vertical adjustment screw group 3 includes two fine-thread adjustment screws 32 at the bottom and an elastic plunger screw 31 at the top. The two fine-thread adjustment screws 32 and the elastic plunger screw 31 are respectively screwed into three corresponding screw holes on the fixed base plate 2, and the heads of the two fine-thread adjustment screws 32 are against the lower surface of the adjustment base plate 501 of the drive assembly 5; the heads of the elastic plunger screws 32 elastically press the displacement platform base 502 on the drive assembly 5 to keep the adjustment base plate 501 in close contact with the fine-thread adjustment screws 32; by adjusting the two fine-thread adjustment screws 32 at the bottom simultaneously, in the same direction, and by the same amount, the linear vertical position (Z coordinate) of the drive assembly 5 can be adjusted. The pitch of the fine-thread adjustment screws 32 is 0.5mm, and the linear adjustment step is 0.5mm / 360°, which is equal to 1.4 μm / °; when the adjustment amounts of the two fine-thread adjustment screws 32 are different, the rotation of the drive assembly 5 around the X-axis can be adjusted, and the rotation step is 1.4 μm / ° / 100mm (the distance between the two fine-thread adjustment screws 32), equal to 0.014mrad / °; when adjusted to the correct position, the two fine-thread adjustment screws 32 and the elastic plunger screw 31 are locked with the lock nut 33 to maintain position stability;

[0044] See Figure 2 、 Figure 3 、 Figure 5 In this embodiment, the lateral level adjustment group 4 includes three groups of identical bolt adjustment components; the bolt adjustment components include a concave conical gasket 41, an adjusting threaded sleeve 42, a locking nut 43, a rectangular coil spring 44, and a tightening screw 45. The concave conical gasket 41 is in plane contact with the fixed base plate 2, the adjusting threaded sleeve 42 is threadedly connected to the adjusting base plate 501, the adjusting threaded sleeve 42 and the locking nut 43 are threadedly matched, the arc-shaped bottom surface of the adjusting threaded sleeve 42 is matched with the groove surface inside the concave conical gasket 41, and the rectangular coil spring 44 is sleeved between the tightening screw 45 and the adjusting threaded sleeve 42. One end of the tightening screw 45 can pass through the adjusting threaded sleeve 42 and be threadedly connected to the fixed base plate 2, and the other end presses the rectangular coil spring 44. Tightening the tightening screw 45 can compress the rectangular coil spring 44, the adjusting threaded sleeve 42 and the concave conical gasket 41.

[0045] See Figure 5The plane of the concave conical gasket 41 in the bolt adjustment assembly contacts the fixed base plate 2 and is movable within the plane; the ball head of the adjusting threaded sleeve 42 rests against the inner conical surface of the concave conical gasket 41, and the ball head and the inner conical surface will maintain stable contact no matter how the adjustment is made; the adjusting threaded sleeve 42 is screwed into the corresponding screw hole of the adjusting base plate 501, and rotating the adjusting threaded sleeve 42 can change the distance between the adjusting base plate 501 and the fixed base plate 2, and the locking nut 43 is used to lock the adjusting threaded sleeve after adjusting it into place and then rotate it; the two ends of the rectangular coil spring 44 are respectively against the adjusting threaded sleeve 42 and the tightening screw 45; the tightening screw 45 passes through the rectangular coil spring 44, the adjusting threaded sleeve 42, and the concave conical gasket 41 and is screwed into the corresponding screw hole of the fixed base plate 2; by adjusting the screw-in depth of the tightening screw 45, the elastic force of the rectangular coil spring 44 can be adjusted so that the ball head of the adjusting threaded sleeve 42 always keeps in contact with the concave conical gasket 41.

[0046] Due to the elasticity of the rectangular coil spring 44, the adjustment base plate 501 can still move appropriately in the vertical direction under the action of the vertical adjustment screw group 3. The three sets of bolt adjustment components are arranged in a triangle. When adjusted simultaneously, linear adjustment in the X direction can be achieved. The pitch of the adjusting threaded sleeve 42 is adjusted to 0.5mm, and the adjustment step size is 1.4 μm / °. Adjusting the three sets of horizontal adjustment components 4 can achieve rotational adjustment of the drive component 5 around the Y and Z axes, with an adjustment step size of 0.014 mrad / °.

[0047] In this way, we can obtain Z-direction translation and two-dimensional adjustment around the X-axis from the vertical adjustment screw assembly 3; from the horizontal adjustment assembly 4, we can perform X-direction translation and three-dimensional adjustment around the Y-axis and Z-axis, which together can obtain five-dimensional installation adjustment.

[0048] The vacuum chamber assembly 1 is a six-way structure, consisting of three interconnected pipes whose axes intersect at a central point, forming a chamber. The driven component can move from the center of the chamber into the pipes. The actual shape of the vacuum chamber does not affect the use of this mechanism; any vacuum chamber in practical applications can be used. The drive mechanism can be installed and used by matching the blade of the mounting flange 12 with the blade flange 508 of the drive assembly 5. Furthermore, a welded bellows 509 of appropriate length and a precision displacement platform 503 of appropriate travel range can be selected based on the required travel range of the drive mechanism.

[0049] See Figure 2 、 Figure 3 、 Figure 4 The driving assembly 5 includes an adjusting base plate 501, a displacement platform base 502, a precision displacement platform 503, a coupling 504, a stepping motor 505, a displacement plate 506, a transmission shaft 507, a knife-edge flange 508, a welding bellows 509, a limit switch paddle 510, a limit switch 511, a target ball seat 512, a grating scale reading head 513, and a grating scale 514.

[0050] See Figure 4 The adjustment base plate 501 is the supporting structure of the entire drive assembly 5, the displacement platform base 502 is fixed to the adjustment base plate 501 with two screws, and the precision displacement platform 503 is fixed to the displacement platform base 502 with six screws. The precision displacement platform 503 is a commercially available part, and the coupling 504 is used to connect the drive shaft of the precision displacement platform 503 and the output shaft of the stepper motor 505. The stepper motor 505 is a commercially available Oriental motor with a model of PKP523N12B, which takes 500 steps per revolution; the displacement plate 506 is fixed to the two sliders of the precision displacement platform 503 with eight screws; the rotation of the stepper motor 505 can drive the displacement plate 506 to move horizontally through the lead screw, nut, and slider on the precision displacement platform. There is a precision guide rail between the slider and the base of the precision displacement platform 503 to ensure the linearity of the movement of the slider and the displacement plate 506; the model of the precision displacement platform 503 is commercially available THK KR2001B-0035-P0, its driving screw pitch is 1mm, the moving step length of the displacement plate 506 is 1mm / 500 steps, which is equal to 2μm / step. When the stepper motor 505 is driven by 1 / 10 microstep, the moving step length of the displacement plate 506 can reach 0.2μm / microstep.

[0051] One end of the transmission shaft 507 is fixed to the displacement plate 506 with two screws and moves with the displacement plate 506; the other end of the transmission shaft 507 passes through the adjustment base plate 501, the knife-edge flange 508, and the welded bellows 509; one end of the welded bellows 509 is sealed and welded to the end of the transmission shaft 507, and the other end is vacuum-sealed and welded to the knife-edge flange 508; the end of the transmission shaft 507 is designed with a suitable mounting platform for mounting the driven part; in this way, even if the knife-edge flange 508 is fixed on the vacuum chamber mounting flange 12, the driven part can still be adjusted to the ideal mounting position through the adjustment base plate 501 through the vertical adjustment screw group 3 and the lateral horizontal adjustment assembly 4; the probe 6 is driven long-range in the X direction by the stepping motor 505, and the stroke in this embodiment is 60 mm.

[0052] See Figure 3 , Figure 4 The grating scale reading head 513 on the drive assembly 5 is fixedly mounted on the displacement platform base 502 with two screws; the grating scale 514 is fixedly bonded to the displacement plate 506, so that when the stepper motor 505 drives the displacement plate 506 and the probe 6 to move, the grating scale reading head 513 scans the grating scale 514 to accurately detect the amount of probe movement; the grating scale 514 is a commercially available Renishaw ResoluteTM absolute grating scale with a reading step of 0.1μm and a reading accuracy of 1 micron; the probe on the drive shaft 507 can be accurately reset to an accuracy of 1μm.

[0053] See Figure 4, two limit switches 511 are installed on the displacement platform base 502 with screws, and the displacement switch paddle 510 is fixedly installed on the displacement plate 506. The two limit switches 511 are respectively used to limit the two extreme positions of the probe movement. When the displacement plate 506 drives the limit switch paddle 510 to trigger one of the limit switches 511 contacts, the limit switch 511 sends a signal to the control system to cut off the power supply of the stepper motor 505. When the reverse movement triggers the other limit switch 511 contact, the power supply of the stepper motor 505 is also cut off; in this way, the entire stroke is limited to the area specified by the two limit switches 511; the limit switch component is a commercially available Omron D2MQ-1-TR micro limit switch, and its stop position accuracy is 2μm.

[0054] See Figure 4 , the displacement plate 506 also serves as a hard stop in this embodiment; the function of the hard stop is to prevent the probe from feeding or withdrawing too much when the limit switch 511 fails, thereby damaging precision components, such as the probe 6 and the welding bellows 509 in this embodiment; assuming that the limit switch 511 fails, the displacement plate 506 drives the probe 6 to feed beyond the position of the limit switch 511 to a certain amount, and the left end of the displacement plate 506 will press against the adjustment base plate 501 to forcibly prevent the probe from continuing to feed; on the contrary, when withdrawing beyond the limit position of the limit switch 511, the end face of the groove at the right end of the displacement plate 506 will press against the rear end step of the precision displacement platform 503 to forcibly prevent the probe from further withdrawing.

[0055] See Figure 4 The displacement plate 506 is provided with multiple target ball seats 512 for mounting target balls 7. In this embodiment, four target balls 7 are positioned at the four corners of the displacement plate 506. In this embodiment, the probe 6, connecting shaft 507, displacement plate 506, and four target ball seats 512 are fixedly connected. Regardless of how the probe 6 is adjusted or driven, its positional relationship with the center of the target balls mounted on the four target ball seats 512 remains constant. At any time, by measuring the center positions of the four target balls 7 with a laser tracker, the real-time position of the driven component (probe) can be determined using CAD. The target balls 7 are commercially available optical components of a laser tracker.

[0056] The above embodiments are merely intended to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. For example, the driven member may also be an optical lens holder, a fluorescent target, a slit, a target, etc., without limitation thereto. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An external drive mechanism for ultra-high vacuum, characterized in that: The invention comprises a vacuum chamber assembly (1), a target ball (7), a fixed base plate (2) fixed on a flange of the vacuum chamber assembly (1), and a driving assembly (5) connected to the outside of the vacuum chamber assembly (1) through an adjusting assembly, wherein the output end of the driving assembly (5) is connected to a driven member, the driven member can extend into the vacuum chamber assembly (1), and the driving assembly (5) can be coupled to the vacuum chamber assembly (1) through a welded bellows (509); the adjusting assembly comprises a vertical adjusting screw group (3) and a horizontal adjusting group (4); the vertical adjusting screw group (3) and the horizontal adjusting screw group (4) are connected to the vertical adjusting screw group (3). The screw group (3) can drive the component (5) to move in the Z direction and rotate around the X axis; the horizontal adjustment group (4) can drive the drive component (5) to move in the X direction relative to the vacuum chamber component (1) and rotate around the Y axis and the Z axis; the drive component (5) is used to withdraw the driven part from the working position or return it to the working position; the target ball (7) is fixed on the drive component (5) and is located outside the vacuum chamber, and the position of the driven part can be obtained by measuring the center position of the target ball (7); the drive component (5) is installed on the mounting flange (1) of the vacuum chamber component (1) 2); the driving assembly (5) includes an adjusting base plate (501), a displacement platform base (502), a precision displacement platform (503), a coupling (504), a stepping motor (505), a displacement plate (506), a transmission shaft (507), a knife-edge flange (508), and a welded bellows (509); the displacement platform base (502) is fixedly mounted on the adjusting base plate (501) with screws, the precision displacement platform (503) is mounted on the displacement platform base (502), and the two The movable slider is fixedly connected to a displacement plate (506), and the displacement plate (506) is connected to the driven part through a transmission shaft (507). The stepper motor (505) is installed at the end of the precision displacement platform (503). The output shaft of the stepper motor (505) is transmission-connected to the lead screw input shaft of the precision displacement platform (503) through a coupling (504). The knife-edge flange (508) is seal-welded to one end of the welding bellows (509), and the other end of the welding bellows (509) is seal-welded to the end of the transmission shaft (507).

2. The ultra-high vacuum external drive mechanism according to claim 1, characterized in that: The adjustment assembly comprises a vertical adjustment screw group (3) and a horizontal adjustment group (4), wherein the vertical adjustment screw group (3) comprises two fine-thread adjustment screws (32) arranged at the bottom of the fixed base plate (2), an elastic plunger screw (31) at the top and a screw locking nut (33), wherein the elastic plunger screw (31) is used to drive the adjustment base plate (501) on the driving assembly (5) to be in close contact with the two fine-thread adjustment screws (32) at the bottom, and the vertical adjustment screw group (3) is used to drive the driving assembly (5) to translate in the Z direction and rotate around the X axis.

3. The ultra-high vacuum external drive mechanism according to claim 1, characterized in that: The lateral level adjustment group (4) includes three bolt adjustment components, and the bolt adjustment components include a concave conical gasket (41), an adjusting threaded sleeve (42), a locking nut (43), a rectangular coil spring (44), and a clamping screw (45). The concave conical gasket (41) can contact the floating plane of the fixed base plate (2); the end spherical surface of the adjusting threaded sleeve (42) presses against the concave conical gasket (41); the adjusting threaded sleeve (42) is screwed into the screw hole of the adjusting base plate (501) of the driving component (5); the adjusting threaded sleeve (42) is screwed externally on the locking nut (43); the clamping screw (45) passes through the rectangular coil spring (44), and the adjusting threaded sleeve (42) and the concave conical gasket (41) are screwed into the screw hole of the fixed base plate (2).

4. The ultra-high vacuum external drive mechanism according to claim 1, characterized in that: The output end of the driving assembly (5) is connected to the driven component via a transmission shaft (507), and the fixed base plate (2) is connected by bolts to press the knife edge flange (508) onto the sealing copper gasket (13) of the vacuum chamber assembly (1).

5. The ultra-high vacuum external drive mechanism according to claim 1, characterized in that: The drive assembly (5) further comprises a Renishaw grating scale assembly, a travel switch assembly, and a controller; the controller is electrically or communicatively connected to the precision displacement platform (503), the absolute grating scale assembly, and the travel switch assembly.

6. The ultra-high vacuum external drive mechanism according to claim 5, characterized in that: The absolute grating ruler assembly comprises a grating ruler reading head (513) and a grating ruler (514), wherein the grating ruler reading head (513) is fixedly connected to the displacement platform base (502), and the grating ruler (514) is fixedly connected to the displacement plate (506).

7. The ultra-high vacuum external drive mechanism according to claim 5, characterized in that: The travel switch assembly comprises a travel switch paddle (510) and a travel switch (511), wherein the travel switch paddle (510) is fixedly connected to the displacement plate (506), and the two travel switches (511) are fixedly connected to the displacement platform base (502).

8. The ultra-high vacuum external drive mechanism according to claim 1, characterized in that: The displacement plate (506) can also form a hard stop for the movement of the drive assembly (5).

9. The ultra-high vacuum external drive mechanism according to claim 1, characterized in that: A target ball seat (512) adapted to the target ball (7) is provided on the displacement plate (506).

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