Mechanical self-locking large-aperture spatial deformable mirror with rigid body displacement adjustment function

Abstract

The application discloses a large-aperture space variable mirror with a mechanical self-locking rigid body displacement adjustment function, comprising: a lens, a plurality of support components, a driving assembly equal in number to the support components and a mounting base plate; wherein one end of the lens is connected with one end of each driving assembly corresponding to the plurality of support components; and the other end of each driving assembly is connected with the mounting base plate. The application has a simple structure and improves driving control reliability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of space optical remote sensors, and particularly relates to a large-aperture space deformable mirror with mechanical self-locking rigid body displacement adjustment function. BACKGROUND

[0002] In order to realize high-precision imaging, not only the rigid body displacement of the optical element needs to be adjusted, but also the high-order surface error needs to be corrected in a space remote sensing camera. The surface adjustment generally needs to use a deformable mirror. At present, the deformable mirror used in space still needs to solve the problems of power-off self-locking, mechanical performance, large aperture and the like. Moreover, the stack piezoelectric driver commonly used in the deformable mirror is actually a cantilever beam, which cannot completely isolate the transmission of the bending moment of the support to the lens, and there will be a local influence on the lens. On the other hand, the rigid body adjustment technology of different degrees of freedom is relatively mature, and typical examples are one-dimensional focusing and six-degree-of-freedom adjustment mechanism and the like. However, in order to realize the rigid body displacement and surface adjustment of a certain degree of freedom, generally, a plurality of adjustment devices need to be combined or a plurality of functions need to be combined, and the structure form will be very complex, the weight will be large, and the control difficulty will also be great. SUMMARY

[0003] The application solves the technical problem of overcoming the deficiencies of the prior art and providing a large-aperture space deformable mirror with mechanical self-locking rigid body displacement adjustment function, which is simple in structure and improves the driving control reliability.

[0004] The application is achieved by the following technical scheme: a large-aperture space deformable mirror with mechanical self-locking rigid body displacement adjustment function, comprising: a lens, a plurality of support components, a driving assembly equal in number to the support components and a mounting base plate; wherein one end of the lens is connected to one end of each driving assembly corresponding to the plurality of support components through the plurality of support components; and the other end of each driving assembly is connected to the mounting base plate.

[0005] In the above large-aperture space deformable mirror with mechanical self-locking rigid body displacement adjustment function, the driving assembly comprises a pre-tightening support sub-assembly, a driving motor sub-assembly, a motion sub-assembly and a measurement sub-assembly; wherein the driving motor sub-assembly, the motion sub-assembly and the measurement sub-assembly are arranged inside the pre-tightening support sub-assembly; the driving motor sub-assembly and the motion sub-assembly are connected; the motion sub-assembly and the measurement sub-assembly are connected; and the pre-tightening support sub-assembly is connected to the support component.

[0006] The pre-tightening support subassembly includes a main support, a first side support, and a second side support; one open side of the main support is connected with the first side support, and the other open side of the main support is connected with the second side support; one end of the main support is connected with the support component, and the other end of the main support is connected with the mounting base plate.

[0007] The motion subassembly includes a combined differential nut assembly, a support cylinder, and a central shaft; the combined differential nut assembly is arranged inside the support cylinder, one end of the combined differential nut assembly is connected with one end of the support cylinder, and the other end of the support cylinder is connected with the other end of the main support; one end of the central shaft is connected with the internal thread of the combined differential nut assembly, and the other end of the central shaft is connected with one end of the main support.

[0008] The motion subassembly further includes a central shaft pin; the other end of the central shaft is connected with one end of the main support through the central shaft pin.

[0009] The combined differential nut assembly includes a spline sleeve, a circular sheet, an adapter, a nut combination, and a spring; one end of the nut combination is connected with one end of the support cylinder; one end of the central shaft is connected with the nut combination; the spring is arranged inside the nut combination; the protruding end of the nut combination is connected with the adapter through a pin; the circular sheet is sleeved on the outer surface of the spline sleeve, one end of the spline sleeve is connected with the adapter, and the other end of the spline sleeve is connected with the driving motor subassembly.

[0010] The nut combination includes a nut a and a nut b; the external thread of the nut a is connected with the internal thread of one end of the support cylinder; the external thread of the nut b is connected with the internal thread of the nut a; and the internal thread of the nut b is connected with the external thread of one end of the central shaft.

[0011] The driving motor subassembly comprises a step motor, a speed reducer, a motor flange and a motor spline; wherein the step motor is connected with the other end of the main support through the motor flange; the step motor is connected with one end of the speed reducer; the other end of the speed reducer is connected with the motor spline; and the motor spline is connected with the other end of the spline sleeve.

[0012] The driving motor subassembly further comprises a pin; wherein the motor spline is connected with the other end of the spline sleeve through the pin.

[0013] The measurement subassembly comprises a sensor installation base plate, a sensor main body, a sensor support cylinder, an iron core and an iron core fixing screw; wherein the sensor installation base plate is sleeved on the outer surface of the central shaft; the bottom end of the sensor support cylinder is connected with the sensor installation base plate, the sensor main body is arranged in the interior of the sensor support cylinder; one end of the iron core is connected with the sensor main body, and the other end of the iron core is connected with one end of the main support through the iron core fixing screw.

[0014] Compared with the prior art, the present application has the following beneficial effects:

[0015] The present application generates a large torque by a motor and a large speed ratio speed reducer to drive an anti-backlash pre-tightening differential screw pair with different internal and external pitches, realizes high-precision self-locking translation of the central shaft, and simultaneously realizes adjustment of surface correction, translation along the optical axis and rotation in the mirror surface. BRIEF DESCRIPTION OF DRAWINGS

[0016] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not to be considered limitations of the present application. Moreover, in the drawings, like reference numerals refer to similar components throughout the several views. In the drawings:

[0017] Figure 1 is a structural schematic diagram of a large-aperture spatial deformable mirror with mechanical self-locking rigid body displacement adjustment function provided by an embodiment of the present application;

[0018] Figure 2 is an exploded view of a driving assembly provided by an embodiment of the present application;

[0019] Figure 3 is a sectional view of the driving assembly provided by the embodiment of the present application;

[0020] Figure 4 is a perspective view of the driving assembly provided by the embodiment of the present application. DETAILED DESCRIPTION

[0021] Exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and the scope of the present disclosure can be accurately conveyed to those skilled in the art. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0022] Figure 1 is a structural schematic diagram of a large-aperture spatial deformable mirror with mechanical self-locking and rigid body displacement adjustment function provided by an embodiment of the present application. As shown in Figure 1 , the large-aperture spatial deformable mirror with mechanical self-locking and rigid body displacement adjustment function comprises a mirror 1, a plurality of support components, a driving assembly 4 equal in number to the support components, and a mounting substrate 5; wherein one end of the mirror 1 is connected to one end of each driving assembly 4 corresponding to the plurality of support components through the plurality of support components; the other end of each driving assembly 4 is connected to the mounting substrate 5.

[0023] Specifically, the support components are support rods 2 and support sheets 3. The mirror is generally a circular sheet, and the material is microcrystalline glass, ULE or Si, and the diameter-thickness ratio is generally not less than 30:1, and is connected through adhesive bonding and support rod 2 or support sheet 3 bonding surface. Three groups of support sheets 3 are symmetrically distributed along the 120-degree outer edge of the back of the mirror 1, and a plurality of different distributed support rods 2 form a quasi-kinematic layout. The mechanical driving assembly 4 is in the shape of a closed cuboid, one end is connected to the mounting substrate 5, and the other end is connected to the support rod 2 / support sheet 3, which realizes high-precision lockable linear driving through a stepping motor, a large-speed-ratio reducer, a combined differential nut, and a symmetric rectangular bracket, and realizes high-precision feedback of the movement direction through an LVDT.

[0024] The driving assembly 4 comprises a pre-tightening bracket sub-assembly, a driving motor sub-assembly, a movement sub-assembly, and a measurement sub-assembly; wherein the driving motor sub-assembly, the movement sub-assembly, and the measurement sub-assembly are all arranged inside the pre-tightening bracket sub-assembly; the driving motor sub-assembly and the movement sub-assembly are connected; the movement sub-assembly and the measurement sub-assembly are connected; and the pre-tightening bracket sub-assembly is connected to the support component.

[0025] As shown in Figure 2 ,Figure 3 and Figure 4 As shown in

[0026] As shown in Figure 2 , Figure 3 and Figure 4 As shown in

[0027] As shown in Figure 2 , Figure 3 and Figure 4 As shown in

[0028] Further, the nut combination includes nut a 435 and nut b 437; wherein the outer thread of nut a 435 is connected with the inner thread of one end of the support cylinder 431; the outer thread of nut b 437 is connected with the inner thread of nut a 435; the inner thread of nut b 437 is connected with the outer thread of one end of the center shaft 438.

[0029] As shown in Figure 2 , Figure 3 and Figure 4As shown, the driving motor subassembly includes a stepper motor 421, a reducer 422, a motor flange 423, a motor spline 424, and a pin 425; wherein the stepper motor 421 is connected to the other end of the main support 411 through the motor flange 423; the stepper motor 421 is connected to one end of the reducer 422; the other end of the reducer 422 is connected to the motor spline 424; the motor spline 424 is connected to the other end of the spline sleeve 432 through the pin 425.

[0030] As shown in Figure 2 , Figure 3 and Figure 4 , the measurement subassembly includes a sensor mounting base plate 441, a sensor main body 442, a sensor support cylinder 443, an iron core 444, and an iron core fixing screw 445; wherein the sensor mounting base plate 441 is sleeved on the outer surface of the central shaft 438; the bottom end of the sensor support cylinder 443 is connected to the sensor mounting base plate 441, and the sensor main body 442 is arranged inside the sensor support cylinder 443.

[0031] One end of the iron core 444 is connected to the sensor main body 442, and the other end of the iron core 444 is connected to one end of the main support 411 through the iron core fixing screw 445.

[0032] In view of the over-constraint problem of the mirror surface caused by the actuator equivalent to a cantilever beam in the traditional piezoelectric deformable mirror, a coupling mode of multiple support rods and three support sheets is adopted to realize quasi-kinematic support of the lens; in view of high-resolution driving of the deformable mirror, a combination of a stepper motor, a large-speed-ratio reducer, a differential nut, and a symmetric pre-tightening support is adopted; in view of the power-down self-locking problem, pre-tightening spring and pre-tightening support and high driving torque are adopted to realize it; in order to realize the compactness of the design space, an embedded design mode is adopted for the motor driving; by adopting the above mode, the translation in the optical axis direction and the rotation adjustment around the two axis directions in the mirror surface are realized, and the surface shape correction ability is also achieved, avoiding the complexity of multi-device or multi-function coupling in the traditional design, and the driving of the stepper motor also reduces the requirement for driving control.

[0033] The outer thread and inner thread of the nut a and the nut b can realize the differential effect of the screw rod movement by adopting different pitches; at the same time, according to the resolution requirement of use, select the appropriate stepping motor and the speed ratio of the reducer. And the motor and the reducer should meet the requirements of light weight and compactness. In this embodiment, the German phytron VSS19 vacuum motor and the reducer with a reduction ratio of 196 are selected, and the inner and outer threads are 0.6mm and 0.7mm pitch respectively, so that sub-nanometer resolution can be realized. The size and stiffness of the corrugated spring 436 are selected according to the machining accuracy of the inner and outer threads, and the deformation of the general pre-tightening force is more than 1.5 times the maximum tooth gap in the effective working section. In addition to the threaded material, all other materials are recommended to select titanium alloy; the selection of threaded material should consider hardness matching and coating treatment, and the material of the nut a and the nut b in the scheme diagram is beryllium bronze, the material of the matched threaded pair is stainless steel, the coating material is molybdenum disulfide, and the thickness is greater than 30um. The selection of the sensor is to realize the self-feedback of the driving mechanism, in order to realize the surface shape level feedback accuracy, the scheme diagram selects the LVDT sensor of MHR010 type, so that high-precision feedback in the axial 500um translation range can be realized. The working stroke of the actuator is limited by the measuring element. When using open-loop driving, a larger adjustment range can be realized.

[0034] The assembly method is: first, complete the assembly of the driving assembly 4. Place the spring 436 and the appropriate gasket in the cavity of the nut a 435 and the nut b 437, and fasten them into one body through the assembly pin. The setting of the gasket is determined according to the maximum gap of the inner and outer threads. After the assembly screw is fastened, the pin hole is matched and the pin is installed. The adapter 434 is fastened through three pins and the protruding end of the nut a 435. The protruding lug of the adapter 434 is threadedly connected with the round plate 433; the other two holes of the round plate and the key sleeve lug are bolted. This assembly body is placed in the hole of the adapter 434 according to the size of the hole, and the adapter 434 is fastened through the three pins and the protruding end of the nut a 435. The protruding lug of the adapter 434 is threadedly connected with the round plate 433; the other two holes of the round plate and the key sleeve lug are bolted. This assembly body is placed in the hole of the adapter 434 according to the size of the hole, and the adapter 434 is fastened through the three pins and the protruding end of the nut a 435. Figure 3Screw the connection into the support cylinder 431. Then, screw the threaded end of the central shaft 438 into the appropriate position from the nut b437 side. Remove the assembly screws. Then, rotate the support cylinder 431 and the central shaft 438 relative to each other, ensuring that the rotation is smooth and free of slippage or wobbling; otherwise, replace the shims and repeat the above process. In addition, apply appropriate vacuum grease before inserting each threaded pair. The completed assembly is assembly A. Screw the sensor core screw 445 into the threaded hole on the inner side of the upper end face of the bracket 411, and tighten the core 444 at the other end. The sensor center body 442 is placed into the sensor bracket 443 by gluing or pre-tightening, and then connected to the support plate 441 by bolts. Assembly B is formed. Insert the central shaft 438 of assembly A into the center hole of the sensor substrate of assembly B from the cylindrical end. Place the composite assembly of parts A and B into bracket 411. Insert the lower flange of support cylinder 431 into the hole at the lower end of bracket 411. Insert the sensor center hole into the iron core 444. Insert the cylindrical end of the central shaft 438 into the center hole at the upper end of bracket. Adjust the positions of the above parts. Then, bolt the lower flange of support cylinder 431 to the lower end of bracket 411, the upper flange of support cylinder 431 to sensor base plate 441, and the central shaft fastening pin in sequence. Insert the motor spline 424 of the drive motor sub-assembly into the spline sleeve 432, and then bolt the motor bracket flange 423 to the lower end of bracket 411. The assembly of the mechanical drive assembly is completed through the above operations.

[0035] After assembling the drive assembly 4, the support rod 2 or support plate 3 is installed into the upper end face of the bracket and secured with pins 425, thus forming an assembly with the support rod or plate. Then, the mounting base plate is installed as follows: Figure 1 As shown, place the assembly onto the mounting base, starting from the center and proceeding outwards. The perpendicularity of the assembly to the mounting surface is ensured by the machining accuracy of the two mating surfaces, while the lateral positional accuracy within the mounting plane is ensured by auxiliary tooling. Next, the height error of the bonding surfaces of all support holes / rods needs to be checked using a coordinate measuring machine or other high-precision displacement monitoring methods. Adjustment is achieved by applying an electric motor to ensure that the height error of all bonding surfaces is within 1 micrometer. Then, apply adhesive at the center of each bonding surface. Here, domestically produced SE-14-80 epoxy structural adhesive is used, with the amount controlled based on a thickness of approximately 0.1mm. The lens is then pressed from top to bottom onto the bonding surface of the support rod / piece. A suitable weight can be placed at the center of the lens to promote bonding. The bonding time meets the requirements of the bonding tester. To ensure the positional accuracy of the lens during placement, appropriate markings can be made on the back of the lens. After the adhesive has cured, remove the counterweight and check the surface shape. Perform subsequent optical processing such as coating as needed.

[0036] All actuators synchronize output displacement amount, can realize along the optical axis of the translation adjustment; all actuators along the optical surface in a certain direction linear input displacement amount, can realize around the angle adjustment of the direction; and according to high order aberration input, each actuator input opposite displacement amount, can realize high order surface correction. Adjust well, turn off the motor power, the mechanism can realize high precision mechanical locking.

[0037] The embodiment realizes quasi-kinematic support for the ultra-thin lens by the combination of the support rods and the support sheets, reduces the influence of the additional bending moment on the lens, the mechanical driving assembly of the embodiment has high rigidity and can withstand the mechanical launch environment, meanwhile, the combination of the stepping motor, the speed reducer and the differential nut can realize high driving precision and power-off self-locking capability, has the ability of translation along the optical axis direction and rotation adjustment capability around two axes in the lens surface and surface correction capability. Meanwhile, the embodiment avoids the high voltage driving mode of the traditional piezoelectric, the driving circuit has high reliability, and the driving multiplexing technology further reduces the demand for driving control resources. The embodiment can meet the requirements of space launch and on-orbit environment, has important practical value in the field of space optical remote sensors.

[0038] Although the present application has been disclosed with reference to the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A mechanical self-locking large-aperture spatial deformable mirror with rigid body displacement adjustment function, characterized in that The lens (1), a plurality of support components, a driving assembly (4) equal in number to the support components, and a mounting base plate (5); wherein One end of the lens (1) is connected to one end of each driving assembly (4) corresponding to the support components through the plurality of support components; The other end of each driving assembly (4) is connected to the mounting base plate (5); The driving assembly (4) comprises a pre-tightening bracket sub-assembly, a driving motor sub-assembly, a motion sub-assembly, and a measurement sub-assembly; wherein The driving motor sub-assembly, the motion sub-assembly, and the measurement sub-assembly are all arranged inside the pre-tightening bracket sub-assembly; The driving motor sub-assembly and the motion sub-assembly are connected; The motion sub-assembly and the measurement sub-assembly are connected; The pre-tightening bracket sub-assembly is connected to the support components; The pre-tightening bracket sub-assembly comprises a main bracket (411), a first side bracket (412a), and a second side bracket (412b); wherein One open side of the main bracket (411) is connected to the first side bracket (412a), and the other open side of the main bracket (411) is connected to the second side bracket (412b); One end of the main bracket (411) is connected to the support components, and the other end of the main bracket (411) is connected to the mounting base plate (5); The motion sub-assembly comprises a combined differential nut assembly, a support cylinder (431), and a central shaft (438); wherein The combined differential nut assembly is arranged inside the support cylinder (431), one end of the combined differential nut assembly is connected to one end of the support cylinder (431), and the other end of the support cylinder (431) is connected to the other end of the main bracket (411); One end of the central shaft (438) is connected to the internal thread of the combined differential nut assembly, and the other end of the central shaft (438) is connected to one end of the main bracket (411); The combined differential nut assembly comprises a spline sleeve (432), a disc (433), an adapter (434), a nut combination, and a spring (436); wherein The nut combination is connected to one end of the support cylinder (431); One end of the central shaft (438) is connected to the nut combination; The spring (436) is arranged inside the nut combination; The protruding end of the nut combination is connected to the adapter (434) through a pin; The disc (433) is sleeved on the outer surface of the spline sleeve (432), one end of the spline sleeve (432) is connected to the adapter (434), and the other end of the spline sleeve (432) is connected to the driving motor sub-assembly; The driving motor sub-assembly comprises a stepper motor (421), a reducer (422), a motor flange (423), and a motor spline (424); wherein The stepper motor (421) is connected to the other end of the main bracket (411) through the motor flange (423); The stepper motor (421) is connected to one end of the reducer (422); ​ The other end of the decelerator (422) is connected with the motor spline (424); The motor spline (424) is connected with the other end of the spline sleeve (432); The motion subassembly further comprises a center shaft pin (439); wherein the other end of the center shaft (438) is connected with one end of the main support (411) through the center shaft pin (439); The nut combination comprises nut a (435) and nut b (437); wherein, The outer thread of the nut a (435) is connected with the inner thread of one end of the support cylinder (431); The outer thread of the nut b (437) is connected with the inner thread of the nut a (435); The inner thread of the nut b (437) is connected with the outer thread of one end of the center shaft (438); The drive motor subassembly further comprises a pin (425); wherein, The motor spline (424) is connected with the other end of the spline sleeve (432) through the pin (425); The measurement subassembly comprises a sensor mounting base plate (441), a sensor main body (442), a sensor support cylinder (443), an iron core (444) and an iron core fixing screw (445); wherein, The sensor mounting base plate (441) is sleeved on the outer surface of the center shaft (438); The bottom end of the sensor support cylinder (443) is connected with the sensor mounting base plate (441), and the sensor main body (442) is arranged in the interior of the sensor support cylinder (443); One end of the iron core (444) is connected with the sensor main body (442), and the other end of the iron core (444) is connected with one end of the main support (411) through the iron core fixing screw (445).

2. The mechanical self-locking large-aperture spatial deformable mirror assembly method of claim 1, wherein It comprises: Firstly, the assembly of the drive assembly is completed: the nut a and the nut b are opposite to each other, the spring and the appropriate gasket are placed in the cavities, and the assembly pin is fastened into one body; after the assembly screw is fastened, the pin hole is matched, and the pin is installed; the adapter is fastened through the three pins and the protruding end of the nut a, the protruding lug and the round piece of the adapter are threadedly connected; the other two holes of the round piece and the lug bolt of the spline sleeve are bolted, and the assembly body is rotated into the interior of the support cylinder; then, the threaded end of the center shaft is screwed into the appropriate position from one side of the nut b, and the assembly screw is removed; Then, relative rotation of the support cylinder and the center shaft, ensure that the rotation of no slip and shaking, the above completed assembly becomes assembly A; the sensor core screw into the screw hole in the inside of the upper end face of the bracket, and in the other end of the core, the sensor center body by cementing or pre-tightening put into the sensor bracket, and then through the bolt connection to the support plate, forming assembly B; the center shaft of assembly A by the cylindrical end inserted into the sensor substrate of assembly B center hole, the assembly of assembly A and B is put into the bracket, the support cylinder flange inserted into the lower end face hole of the bracket, the sensor center hole inserted into the core, the center shaft cylindrical end inserted into the center hole of the upper end face of the bracket; then, in turn, bolt connection of the support cylinder flange and the lower end face of the bracket, the support cylinder flange and the sensor substrate and the center shaft fastening pin; drive motor subassembly motor spline inserted into the spline sleeve inside, and then the motor bracket flange and the lower end face of the bracket bolt connection; After the completion of the drive assembly, the installation of the support rod or the support piece to the upper end face hole of the bracket, and through the pin fastening, so as to form the assembly with support rod or piece; then, the assembly is placed on the installation base plate, from the center to the outer ring, one by one installation; Next, it is necessary to test the height error of the cementing surface of all support holes / rods by three coordinate test or other high precision displacement monitoring means, through the motor power driven adjustment, to ensure that the height error of all cementing surfaces is within 1 micron; then, in the center of each cementing surface, glue is applied, and then the lens is placed on the adhesive surface of the support rod / piece from top to bottom, and appropriate weight is placed at the center of the lens to promote cementing.

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