Secondary mirror on-orbit correction and focusing device and method

Abstract

The present application relates to a kind of secondary mirror in-orbit correction and focusing device and method, secondary mirror in-orbit correction and focusing device includes secondary mirror frame, support frame and three support rods, secondary mirror frame is coaxially arranged in the upper side of support frame, three support rods are evenly arranged in the circumferential side of secondary mirror frame and support frame, support rod upper end is connected in the top of secondary mirror frame by joint bearing, support rod lower end is connected in the top of support frame by sliding bearing;Heating film is equipped on the side surface of support rod.The secondary mirror in-orbit correction and focusing device of the present application provides the kinematic installation mode of static for secondary mirror, installs secondary mirror on secondary mirror frame, secondary mirror frame is connected with three support rods by three joint bearings, three support rods are connected with support frame by three sliding bearings, joint bearing can release the three-way rotation degree of freedom of mounting point, sliding bearing can release the one-way rotation degree of freedom of mounting point, to statically determinate support, realize deformation decoupling between secondary mirror frame and support frame.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace technology, in particular to a secondary mirror on-orbit correction and focusing device and method. BACKGROUND

[0002] In recent years, with the development of science and technology, the reliability and precision of space cameras under harsh launch environment and space environment are increasingly required, the space camera will be subjected to vibration and impact during transportation and launch, the space temperature is complex and changeable during on-orbit operation, and the space gravity field is different from the microgravity environment on the earth surface, all these factors may cause the imaging plane of the camera to be not coincident with the focal plane, that is, different degrees of defocus, thereby causing the imaging quality to decrease.

[0003] In order to ensure the imaging quality of the camera, a focusing mechanism needs to be added in the camera system, and a corresponding focusing mechanism is used to fine-tune the position of the light imaging in the optical system, compensate for the defocus of the CCD, and accurately image the nadir standard on the CCD photosensitive surface, so as to correct the defocus, which is beneficial to the reliable operation of the optical remote sensor in harsh environment.

[0004] At present, the secondary mirror focusing method has also been applied, and the secondary mirror focusing is relative to the three-mirror or focal plane focusing, the displacement amount of adjustment is small, generally within 0.3mm, so more precise displacement control precision is required.

[0005] The commonly used secondary mirror focusing method in China is thermal control focusing, and the thermal control focusing method has many advantages, but also has some objective shortcomings: the secondary mirror support is completely fixed with the main load-bearing structure, which will cause the heat of the secondary mirror support to be transferred to the main load-bearing structure to form thermal deformation, causing the deformation stress to be transmitted to the secondary mirror, and affecting the imaging quality. The heating area of the secondary mirror is small, and the distance of active thermal deformation is short, so the secondary mirror cannot be adjusted in the azimuth and on-orbit position. SUMMARY

[0006] The technical problem to be solved by the present application is how to provide a secondary mirror on-orbit correction and focusing device and method.

[0007] The technical solution for solving the above technical problem is as follows: a secondary mirror on-orbit correction and focusing device, comprising a secondary mirror frame, a support frame and three support rods, the secondary mirror frame is coaxially arranged on the upper side of the support frame, the three support rods are uniformly arranged on the circumferential side of the secondary mirror frame and the support frame, the upper end of the support rod is connected to the top of the secondary mirror frame through a joint bearing, and the lower end of the support rod is connected to the top of the support frame through a sliding bearing; a heating film is arranged on one side of the support rod.

[0008] The beneficial effects of the present application are: the secondary mirror on-orbit correction and focusing device provides a statically determinate kinematic mounting method for the secondary mirror, the secondary mirror is mounted on a secondary mirror frame, the secondary mirror frame is connected with three support rods through three joint bearings, the three support rods are connected with a support frame through three sliding bearings, the joint bearings can release the three-direction rotation freedom of the mounting point, the sliding bearings can release the single-direction rotation freedom of the mounting point, and static support is achieved, and deformation decoupling is realized between the secondary mirror frame and the support frame.

[0009] On the basis of the above technical scheme, the present application can also be improved as follows.

[0010] Further, the support rod is a long strip-shaped structure, the secondary mirror frame and the support frame are both circular structures, the outer diameter of the support frame is greater than that of the secondary mirror frame, and the support rod extends along the radial direction of the secondary mirror frame.

[0011] Further, the upper end of the support rod is provided with a bent head, the top of the secondary mirror frame is provided with three first U-shaped supports, the center lines of the open channels of the three first U-shaped supports are arranged along the radial direction of the secondary mirror frame respectively, and the bent head of the upper end of the support rod extends into the open channel of the first U-shaped support and is movably connected with the first U-shaped support through a joint bearing.

[0012] The beneficial effects of the above further scheme are: through the U-shaped support, the joint bearing is facilitated to be installed, and multi-freedom movable assembly between the support rod and the secondary mirror frame is facilitated.

[0013] Further, the top of the support frame is provided with three second U-shaped supports, the center lines of the open channels of the three second U-shaped supports are arranged along the radial direction of the support frame respectively, and the lower end of the support rod extends into the open channel of the second U-shaped support and is rotatably connected with the second U-shaped support through a sliding bearing.

[0014] The beneficial effects of the above further scheme are: through the U-shaped support, the sliding bearing is facilitated to be installed, and single-freedom movable assembly between the support rod and the support frame is facilitated.

[0015] Further, the heating film is a long strip-shaped structure, the long strip-shaped structure is shape-fitted with one side surface of the support rod and is fixed at the middle position of the one side surface of the support rod.

[0016] The beneficial effects of the above further scheme are: it is beneficial to the stable control of the overall expansion and contraction of the support rod.

[0017] Further, the area of the heating film covering the support rod is a thermal control adjustment segment, the length of the thermal control adjustment segment along the length direction of the support rod is L=△L / α*△T, △T is a thermal adjustment temperature range of the heating film, △L is an expansion and contraction amount of the support rod thermal control adjustment, and α is a thermal expansion coefficient of the support rod.

[0018] The beneficial effect of the further scheme is that the heating film with different lengths can be set according to different adjustment requirements.

[0019] Further, the support rod is made of a titanium alloy rod or an aluminum alloy rod, the expansion and contraction amount of the support rod thermal control adjustment is 0-0.1 mm, the thermal expansion system of the titanium alloy rod is 9.0e -6 / K.

[0020] Further, the thermal adjustment temperature range of the heating film is 0-30 DEG C, the adjustment accuracy is 0.2 DEG C, and the support rod displacement adjustment amount corresponding to the adjustment accuracy is 0.66 μm.

[0021] A secondary mirror on-orbit correction method is realized by using the secondary mirror on-orbit correction and focusing device, a secondary mirror is installed on a secondary mirror frame, when the secondary mirror on the secondary mirror frame deflects and the deflection angle is α, the support rod on the lower side of the secondary mirror frame is heated to make the support rod longer, so that the deflection angle α gradually becomes smaller, until the secondary mirror frame meets the optical system accuracy requirement.

[0022] The beneficial effect of the present application is that the secondary mirror on-orbit correction method can correct the slight deformation of the secondary mirror frame in the launch environment through thermal control adjustment, so as to meet the installation accuracy requirement of the secondary mirror.

[0023] A secondary mirror on-orbit focusing method is realized by using the secondary mirror on-orbit correction and focusing device, a secondary mirror is installed on a secondary mirror frame, and three support rods are heated at the same time, the secondary mirror on the secondary mirror frame is lengthened relative to the primary mirror with the lengthening of the support rods, so that the focusing purpose is achieved.

[0024] The beneficial effect of the present application is that the secondary mirror on-orbit focusing method can use the heating support rod of the heating film to realize stable focusing. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a perspective structural schematic view of the secondary mirror on-orbit correction and focusing device of the present application;

[0026] Figure 2 It is a front view structural schematic view of the secondary mirror on-orbit correction and focusing device of the present application;

[0027] Figure 3 It is a front view structural schematic view of the focusing process of the secondary mirror on-orbit correction and focusing device of the present application;

[0028] Figure 4 This is a schematic top view of the structure of the on-track correction and focusing device for the secondary mirror of the present invention.

[0029] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0030] 1. Secondary mirror frame; 11. First U-shaped support; 2. Support frame; 21. Second U-shaped support; 3. Support rod; 31. Bending head; 4. Spherical bearing; 5. Sliding bearing; 6. Heating film. DETAILED DESCRIPTION

[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0032] like Figures 1-4 As shown, a secondary mirror on-track correction and focusing device of this embodiment includes a secondary mirror frame 1, a support frame 2 and three support rods 3. The secondary mirror frame 1 is coaxially arranged on the upper side of the support frame 2, and the three support rods 3 are evenly arranged on the circumference of the secondary mirror frame 1 and the support frame 2. The upper end of the support rod 3 is connected to the top of the secondary mirror frame 1 through a joint bearing 4, and the lower end of the support rod 3 is connected to the top of the support frame 2 through a sliding bearing 5; a heating film 6 is provided on one side surface of the support rod 3.

[0033] like Figures 1-4 As shown, the support rod 3 of this embodiment is a long strip-shaped sheet structure, the secondary mirror frame 1 and the support frame 2 are both circular structures, the outer diameter of the support frame 2 is larger than the outer diameter of the secondary mirror frame 1, and the support rod 3 extends along the radial direction of the secondary mirror frame 1.

[0034] like Figures 1-4 As shown, in this embodiment, the upper end of the support rod 3 is provided with a bending head 31, and the top of the secondary mirror frame 1 is provided with three first U-shaped supports 11. The center lines of the openings of the three first U-shaped supports 11 are arranged along the radial direction of the secondary mirror frame 1. The bending head 31 at the upper end of the support rod 3 extends into the opening of the first U-shaped support 11 and is movably connected to the first U-shaped support 11 via the spherical bearing 4. The U-shaped support facilitates the installation of the spherical bearing and facilitates the multi-degree-of-freedom movable assembly between the support rod and the secondary mirror frame.

[0035] like Figures 1-4As shown, the top of the support frame 2 of the embodiment is provided with three second U-shaped supports 21, the center lines of the open channels of the three second U-shaped supports 21 are arranged along the radial direction of the support frame 2 respectively, and the lower end of the support rod 3 extends into the open channel of the second U-shaped support 21 and is rotationally connected with the second U-shaped support 21 through a sliding bearing 5. Through the U-shaped support, the sliding bearing is facilitated to be installed, and the single-degree-of-freedom movable assembly between the support rod and the support frame is facilitated.

[0036] As shown, Figures 1-3 The heating film 6 of the embodiment is a long strip-shaped structure, which is adapted to the shape of one side of the support rod 3 and is fixed at the middle position of the one side of the support rod 3. This is advantageous for stable control of the overall expansion and contraction of the support rod.

[0037] As shown, Figures 1-3 The region of the support rod 3 covered by the heating film 6 of the embodiment is a thermal control adjustment section, the length L of the thermal control adjustment section along the length direction of the support rod 3 is △L / α*△T, △T is the thermal adjustment temperature range of the heating film 6, △L is the expansion and contraction amount of the support rod 3 for thermal control adjustment, and α is the thermal expansion coefficient of the support rod 3. Different lengths of the heating film can be set according to different control requirements.

[0038] Specifically, the support rod 3 is made of a titanium alloy rod or an aluminum alloy rod, and other metal materials can also be used, the expansion and contraction amount △L of the support rod 3 for thermal control adjustment is 0-0.1 mm. Further preferably, the support rod 3 can be made of titanium alloy TC4; when the titanium alloy rod is made of titanium alloy TC4, the thermal expansion system α is 9.0e -6 / K. Regardless of the metal material used for the support rod 3, the structure needs to have good stability, high rigidity and high strength.

[0039] Specifically, the thermal adjustment temperature range △T of the heating film 6 is 0-30℃, the adjustment accuracy is 0.2℃, and the displacement adjustment amount of the support rod 3 corresponding to the adjustment accuracy is 0.66μm.

[0040] Preferably, when the support rod 3 is made of titanium alloy TC4, the expansion and contraction amount △L of the support rod 3 for thermal control adjustment is 0.1 mm, the thermal adjustment temperature △T of the heating film 6 is 30℃, and the length L of the thermal control adjustment section along the length direction of the support rod 3 is △L / α*△T=370mm.

[0041] Generally, the range of the travel of the secondary mirror for thermal control focusing is about 30 μm, and the total travel of the support rod of the secondary mirror can reach 100 μm, and the extra travel is used for the in-orbit position correction of the secondary mirror. According to the accuracy of 0.2℃ of the thermal control adjustment, the corresponding adjustment amount of the support rod displacement is 0.66 μm, and the adjustment accuracy requirement of the secondary mirror is ±0.8 μm, so the accuracy of the thermal control adjustment can fully meet the requirement.

[0042] In the structural design with higher dimensional stability requirement, in order to avoid the influence of the external deformation on the dimensional stability of the high-stability structure, the high-stability structure and the external spacecraft structure must be decoupled in deformation. Generally, the high-stability structure is required to be static, and this static installation mode is referred to as kinematic installation. The in-orbit correction and focusing device of the secondary mirror of the present embodiment provides a static kinematic installation mode for the secondary mirror, and the secondary mirror is installed on the secondary mirror frame, the secondary mirror frame is connected with three support rods through three joint bearings, and the three support rods are connected with the support frame through three sliding bearings. The joint bearings can release the three-direction rotation degrees of freedom of the installation point, the sliding bearings can release the single-direction rotation degree of freedom of the installation point, the static support is achieved, and the deformation decoupling between the secondary mirror frame and the support frame is achieved. A remarkable advantage of the in-orbit correction and focusing device of the secondary mirror of the present embodiment is that, because it is a static structure, the bending moment of the bearing can be eliminated, and the deformation caused by temperature is only generated on the secondary mirror support rod, and does not affect the secondary mirror frame and the support frame.

[0043] The present embodiment also provides an in-orbit correction method of a secondary mirror, which is implemented by using the in-orbit correction and focusing device of the secondary mirror. The secondary mirror is installed on the secondary mirror frame 1. When the secondary mirror on the secondary mirror frame 1 deflects and the deflection angle is α, the support rod 3 on the lower side of the secondary mirror frame 1 is heated to make the support rod 3 longer, so that the deflection angle α gradually becomes smaller, until the secondary mirror frame 1 meets the accuracy requirement of the optical system. According to the foregoing in-orbit adjustment amount of 0.1 mm, the in-orbit correction range of the present embodiment is ±3' (3 seconds), and the deflection angle is 1 / 60 degree per second, which can basically cover the errors caused by the structural processing, assembly and vibration environment. Generally, after the in-orbit correction error is completed, the thermal control focusing is performed.

[0044] In the process of ground assembly, transportation and launching, the position of the secondary mirror relative to the primary mirror will introduce certain errors, and if the error is too large, it will cause the optical imaging quality to decrease, and even cannot meet the functional requirements. Therefore, the secondary mirror support structure needs to have good stability, and the relative position does not change substantially before and after the vibration test, which has very high requirements on the structure and adjustment, and often requires very high precision and repeated grinding and adjustment. However, for some support structures, even if the precision on the ground is very good, the position changes after experiencing the launch environment, and this change cannot be eliminated in orbit. The secondary mirror in-orbit correction method of the embodiment can correct the slight deformation of the secondary mirror frame caused by the launch environment or other reasons in orbit through thermal control adjustment, so as to meet the installation precision requirements of the secondary mirror.

[0045] The embodiment also provides a secondary mirror in-orbit focusing method, as shown in Figure 3 The secondary mirror in-orbit focusing method of the embodiment can realize stable focusing by heating the support rods by using the heating film.

[0046] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0047] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0048] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0049] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0051] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A secondary mirror on-track correction and focusing device, characterized in that: The invention comprises a secondary mirror frame, a support frame and three support rods, wherein the secondary mirror frame is coaxially arranged on the upper side of the support frame, and the three support rods are evenly arranged on the peripheral sides of the secondary mirror frame and the support frame, the upper ends of the support rods are connected to the top of the secondary mirror frame through joint bearings, and the lower ends of the support rods are connected to the top of the support frame through sliding bearings; a heating film is provided on one side surface of the support rod; The support rod is a long strip-shaped sheet structure, the secondary mirror frame and the support frame are both circular structures, the outer diameter of the support frame is larger than the outer diameter of the secondary mirror frame, and the support rod extends along the radial direction of the secondary mirror frame; The upper end of the support rod is provided with a bending head, and the top of the secondary mirror frame is provided with three first U-shaped supports, the center lines of the opening channels of the three first U-shaped supports are respectively arranged along the radial direction of the secondary mirror frame, and the bending head at the upper end of the support rod extends into the opening channel of the first U-shaped support and is movably connected to the first U-shaped support through a joint bearing; Three second U-shaped supports are provided on the top of the support frame, and the center lines of the opening channels of the three second U-shaped supports are respectively arranged along the radial direction of the support frame. The lower end of the support rod extends into the opening channel of the second U-shaped support and is rotatably connected to the second U-shaped support through a sliding bearing; The area where the heating film covers the support rod is the thermal control adjustment section, and the length of the thermal control adjustment section along the length direction of the support rod is L=△L / α*△T, △T is the thermal adjustment temperature range of the heating film, △L is the expansion and contraction amount of the support rod thermal control adjustment, and α is the thermal expansion coefficient of the support rod.

2. The on-track correction and focusing device for a secondary mirror according to claim 1, characterized in that: The heating film is a long strip sheet structure, which is adapted to the shape of a side surface of the support rod and is fixed at a middle position of the side surface of the support rod.

3. The on-track correction and focusing device for a secondary mirror according to claim 1, characterized in that: The support rod is made of titanium alloy rod or aluminum alloy rod, and the expansion and contraction amount of the support rod is adjusted by thermal control ΔL=0-0.1mm; the thermal expansion coefficient of the titanium alloy rod is α=9.0e -6 / K.

4. The on-track correction and focusing device for a secondary mirror according to claim 1, characterized in that: The heat adjustment temperature range of the heating film is ΔT=0°C to 30°C, and the adjustment accuracy is 0.2°C. The adjustment amount of the support rod displacement corresponding to the adjustment accuracy is 0.66 μm.

5. A secondary mirror on-orbit correction method, characterized in that: The on-track correction and focusing device for the secondary mirror according to any one of claims 1 to 4 is adopted, and the secondary mirror is installed on the secondary mirror frame. When the secondary mirror on the secondary mirror frame is deflected and the deflection angle is β, the support rod on the lower side of the secondary mirror frame is heated to lengthen the support rod, so that the deflection angle β gradually becomes smaller until the secondary mirror frame meets the accuracy requirements of the optical system.

6. A secondary mirror on-track focusing method, characterized in that: The on-track correction and focusing device for the secondary mirror according to any one of claims 1 to 4 is adopted, the secondary mirror is installed on the secondary mirror frame, and the three support rods are heated simultaneously. As the temperature of the support rods increases, they become longer, so that the position of the secondary mirror on the secondary mirror frame relative to the primary mirror becomes longer, thereby achieving the purpose of focusing.

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