Expandable partitioned reflecting mirror with hollow center

Abstract

The invention discloses an expandable partitioned reflecting mirror with a hollow center. The expandable partitioned reflecting mirror comprises a primary mirror bearing cylinder, partitioned sub-mirrors, a primary mirror folding state locking device, a primary mirror expansion mechanism and an expansion in-place locking device, the central part of the primary mirror adopts a hollow design; before being unfolded, the partitioned sub-mirrors are installed on the outer wall of the main mirror force bearing cylinder through the main mirror unfolding mechanism, the adjacent sub-mirrors are sequentially folded upwards and downwards, the upwards-turned sub-mirrors are mutually connected and fixed through the main mirror folding state locking device, and the downwards-turned sub-mirrors are fixed to the outer wall of the main mirror force bearing cylinder through the main mirror folding state locking device. When the primary mirror is unfolded, the locking device in the folded state of the primary mirror is unlocked in an electric explosion mode, the upward-turning sub-mirror is turned over downwards through the primary mirror unfolding mechanism, the downward-turning sub-mirror is turned over upwards through the primary mirror unfolding mechanism, the primary mirror is coplanar, and after the primary mirror is unfolded in place, the sub-mirror blocks are fixed through the in-place unfolding locking device.

Description

Technical Field

[0001] The invention relates to a centrally hollowed-out deployable segmented reflector, and belongs to the field of space optical remote sensing system design. Background Art

[0002] Ultra-large aperture reflectors are mainly used in space optical remote sensing imaging systems, such as earth observation systems, astronomical telescopes, etc. Their main forms include integral type, block-deployable type, block-assembly type, sparse aperture interferometric type, etc. The present invention belongs to the block-deployable large aperture splicing method.

[0003] At present, the successful application forms of the main mirror of the ultra-large aperture space remote sensing system mainly include integral reflectors (such as the US Keyhole series satellites) and split reflectors (such as the US James Webb Telescope). Among them, the integral structure has the advantages of simple structure, stable system, and high wavefront control accuracy, but it is limited by the fairing envelope of the launch vehicle and cannot achieve a larger aperture. With the continuous development of technologies such as active optics, computer science and advanced optical processing, the block mirror splicing technology has become the main technical means for space optical remote sensors to increase the effective aperture under the constraints of the launch envelope and the mass of the main mirror. At present, only the US JWST telescope has successfully applied similar block splicing in orbit. The block-type deployable main mirror is composed of 18 hexagonal sub-mirrors. Each main mirror wing (one on each side, each containing 3 sub-mirrors) is folded and retracted by the main mirror deployment mechanism during launch, and is deployed and locked after entering orbit. The main mirror wings on both sides are adjusted into position and spliced ​​in orbit in a honeycomb shape with the 12 sub-mirrors fixed in the center. The shape and splicing method of the block mirror are relatively fixed, which is difficult to adapt to the requirements of different optical systems. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a centrally hollowed-out deployable segmented reflector, to solve the engineering implementation problem of increasing the effective aperture of the optical system under the limitation of the existing rocket launch envelope, and to further promote the development of my country's large-aperture space optical remote sensing system.

[0005] The technical solution of the present invention is: a centrally hollowed-out deployable segmented reflector, comprising: a main mirror bearing tube, segmented sub-mirrors, a main mirror folding state locking device, a main mirror unfolding mechanism, and an unfolding locking device; the central part of the main mirror adopts a hollow design; before the segmented sub-mirrors are unfolded, they are installed on the outer wall of the main mirror bearing tube through the main mirror unfolding mechanism, and adjacent sub-mirrors are folded upward and downward in sequence, wherein the upward-folding sub-mirrors are mutually connected and fixed through the main mirror folding state locking device, and the downward-folding sub-mirrors are fixed to the outer wall of the main mirror bearing tube through the main mirror folding state locking device; when the main mirror is unfolded, the main mirror folding state locking device is electrically unlocked, the upward-folding sub-mirror is folded downward through the main mirror unfolding mechanism, and the downward-folding sub-mirror is folded upward through the main mirror unfolding mechanism, so that the main mirror is coplanar, and after being unfolded into place, each segmented sub-mirror is fixed by the unfolding locking device.

[0006] The reflector uses N blocks of sub-mirrors, each of which has the same physical properties and is independent of each other; wherein N is an even number and is greater than or equal to 4.

[0007] The N is an even number greater than or equal to 4.

[0008] The primary mirror support cylinder is a cylindrical structure, and its horizontal cross section is a circle or a centrally symmetrical N-gon.

[0009] A main mirror unfolding mechanism is arranged on the outer wall of the main mirror bearing cylinder, which is used to connect the bearing cylinder and the segmented sub-mirrors, and can also drive the segmented sub-mirrors to fold upward or downward and unfold.

[0010] In the folded state, folded state locking devices are arranged on both sides of the top of all the upward-folding sub-mirrors, which can realize the mutual fixation and locking of all the upward-folding sub-mirrors; folded state locking devices are arranged on the backs of all the downward-folding sub-mirrors, which can realize the fixation and locking of the downward-folding sub-mirrors and the load-bearing cylinders.

[0011] In the unfolded state, after each segmented sub-mirror is unfolded into place, the segmented sub-mirror and the support tube are fixed and locked by the unfolded locking device arranged at the top of the support tube, so that the segmented sub-mirrors form a complete main mirror.

[0012] The shape of each sub-mirror block is an isosceles trapezoid, a fan, a polygon or a circle.

[0013] The ratio of the inner diameter D1 of the central hollow area of ​​the main mirror to the effective aperture D2 of the main mirror formed after the divided sub-mirrors are unfolded, i.e. D1 / D2, is between 0.3 and 0.6 to ensure the imaging performance of the optical system and the stability of the optomechanical structure.

[0014] In the hollow of the primary mirror, three mirrors or a focal plane can be placed according to the design requirements of the optical system.

[0015] The advantages of the present invention compared with the prior art are:

[0016] 1) The present invention can increase the effective aperture of the optical system by splicing blocks under the existing envelope limitation;

[0017] 2) The present invention can be applied to compact coaxial optical systems, and adopts a hollow design at the center of the primary mirror, which greatly reduces the weight of the spliced ​​primary mirror and has the advantage of being lightweight;

[0018] 3) The block primary mirror and bearing tube structure of the present invention can be adapted to any shape and number of splicing according to the requirements, thereby improving the flexibility of system design. Therefore, the splicing method proposed in the present invention has high innovation and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a schematic diagram of the folding, unfolding and splicing process of the fan-shaped segmented mirror under the design method of the present invention.

[0020] Figure 2 It is a schematic diagram of the division method of the fan-shaped segmented mirror under the design method of the present invention. DETAILED DESCRIPTION

[0021] The present invention proposes a design method for splicing a centrally hollowed-out deployable segmented reflector, which adopts a segmented folded launch, on-orbit deployable and spliced ​​large-aperture main mirror assembly, which consists of a main mirror load-bearing tube structure, segmented sub-mirrors, a main mirror folding state locking device, a main mirror deployment mechanism, a deployment-in-place locking device, etc.

[0022] The segmented sub-mirrors are fixed to the outer wall of the main mirror bearing tube structure through the main mirror deployment mechanism, and the segmented sub-mirrors can be folded upward or downward through the main mirror deployment mechanism; in the folded and retracted state, the segmented sub-mirrors are folded upward or downward in sequence. All the upward folding sub-mirrors are arranged with folding state locking devices on both sides of their tops, and the adjacent upward folding sub-mirrors are connected and fixed to each other by "hand in hand" in the folded state, and all the downward folding sub-mirrors are fixed to the outer wall of the main mirror bearing tube through the folding state locking devices arranged on their backs; in the deployed state: the main mirror folding state locking devices of all the segmented sub-mirrors are unlocked, the segmented sub-mirrors that are folded upward are folded downward through the main mirror deployment mechanism, and the segmented sub-mirrors that are folded downward are folded upward through the main mirror deployment mechanism, and after being deployed in place, that is, all the segmented sub-mirrors are coplanar, the deployed in place locking devices fix all the segmented sub-mirrors to the main mirror bearing tube structure.

[0023] like Figure 1 As shown, N (N is an even number) sub-mirrors are spliced ​​to form a large-diameter primary mirror. Each sub-mirror has the same physical properties such as shape and volume. The sub-mirrors are independent of each other and are installed on the outer wall of the primary mirror bearing tube through the primary mirror deployment mechanism. Figure 1 The upper part shows the way of unfolding and splicing the sub-mirrors when the sub-mirrors are isosceles trapezoidal or fan-shaped. The number and the inner diameter of the hollow area can be further designed according to the optical system and specific task requirements (it is necessary to ensure that the ratio D1 / D2 of the inner diameter D1 of the central hollow area to the effective aperture D2 of the unfolded main mirror is between 0.3 and 0.6); Figure 1 The lower part shows the unfolded state of the equilateral hexagonal sub-mirror. For any sub-mirror block configuration, the odd-numbered sub-mirrors are flipped up by the unfolding mechanism, and the even-numbered sub-mirrors are folded down by the unfolding mechanism. After this folding, the lateral envelope of the main mirror is reduced, and the longitudinal envelope is affected by the diameter difference between the mirror area and the hollow area and the satellite platform. When designing the shape of the reflector (main mirror aperture, hollow area), attention should be paid to the longitudinal envelope limitation of the launch vehicle. In addition to the envelope limitation, the area of ​​the hollow area and the number of sub-mirror blocks mainly depend on the optical system design and the feasibility of engineering implementation. They are not within the scope of this invention and should be analyzed specifically according to specific engineering requirements.

[0024] like Figure 2 As shown, according to the above method, a design example of applying the method of the present invention is given. Taking the envelope of a certain type of launch vehicle as an example, a spliced ​​reflector with an effective aperture of 6.5m is designed. 12 pieces of 1500mm×1700mm segmented sub-mirrors are spliced ​​to form a large-aperture reflector with a circumscribed circle of Φ6500mm. The sub-mirrors are equilateral trapezoidal in shape. The segmented sub-mirrors are independent of each other and are installed in the main mirror bearing cylinder structure through the main mirror deployment mechanism. The bearing cylinder is a 12-sided axisymmetric polygonal barrel structure with a circumscribed circle size of Φ3200mm. The ratio of the inner diameter of the central hollow area to the effective aperture of the main mirror after deployment is 0.49. The following is a detailed description of two types of states:

[0025] State 1: Folded during launch phase

[0026] Each sub-mirror is flipped upside down and folded during the launch phase through the main mirror deployment mechanism. The upward-flipped and folded sub-mirror is locked "hand in hand" through the main mirror folded state locking device, and the downward-flipped and folded sub-mirror is locked to the load-bearing tube structure through the main mirror folded state locking device. The outer envelope of the main mirror in the folded state is less than Φ4200mm, which meets the size envelope of the Long March 5 rocket.

[0027] State 2: 12 primary mirrors are spliced ​​together

[0028] In order to meet the requirements of high-precision posture maintenance and rigidity when deployed, a deployment locking device is used to provide locking force for the deployment mechanism, ensure good contact between positioning points, and improve the deployment rigidity of the system. After the satellite enters the predetermined orbit, the main mirror is deployed, the locking device of the main mirror in the folded state is unlocked by electric explosion, and the up-flip sub-mirror and the down-flip sub-mirror are deployed through the folding and deployment mechanism. After the action is completed and deployed in place, the coplanarity is achieved through the locking mechanism at the connection between the load-bearing cylinder and the segmented sub-mirror.

[0029] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A centrally hollowed-out deployable segmented reflector, characterized in that: include: A main mirror bearing tube, divided sub-mirrors, a main mirror folding state locking device, a main mirror unfolding mechanism, and a unfolding locking device; the central part of the main mirror adopts a hollow design; before the divided sub-mirrors are unfolded, they are installed on the outer wall of the main mirror bearing tube through the main mirror unfolding mechanism, and adjacent sub-mirrors are folded upward and downward in sequence, wherein the upward-folding sub-mirrors are connected and fixed to each other through the main mirror folding state locking device, and the downward-folding sub-mirrors are fixed to the outer wall of the main mirror bearing tube through the main mirror folding state locking device; when the main mirror is unfolded, the main mirror folding state locking device is unlocked by electric explosion, the upward-folding sub-mirror is folded downward by the main mirror unfolding mechanism, and the downward-folding sub-mirror is folded upward by the main mirror unfolding mechanism, so that the main mirror is coplanar, and after being unfolded into place, each divided sub-mirror is fixed by the unfolding into place locking device.

2. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: The reflector uses N blocks of sub-mirrors, each of which has the same physical properties and is independent of each other; wherein N is an even number and is greater than or equal to 4.

3. The centrally hollow deployable segmented reflector according to claim 2, characterized in that: The N is an even number greater than or equal to 4.

4. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: The primary mirror support cylinder is a cylindrical structure, and its horizontal cross section is a circle or a centrally symmetrical N-gon.

5. The centrally hollow deployable segmented reflector according to claim 4, characterized in that: A main mirror unfolding mechanism is arranged on the outer wall of the main mirror bearing cylinder, which is used to connect the bearing cylinder and the segmented sub-mirrors, and can also drive the segmented sub-mirrors to fold upward or downward and unfold.

6. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: In the folded state, folded state locking devices are arranged on both sides of the top of all the upward-folding sub-mirrors, which can realize the mutual fixation and locking of all the upward-folding sub-mirrors; folded state locking devices are arranged on the backs of all the downward-folding sub-mirrors, which can realize the fixation and locking of the downward-folding sub-mirrors and the load-bearing cylinders.

7. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: In the unfolded state, after each segmented sub-mirror is unfolded into place, the segmented sub-mirror and the support tube are fixed and locked by the unfolded locking device arranged at the top of the support tube, so that the segmented sub-mirrors form a complete main mirror.

8. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: The shape of each sub-mirror block is an isosceles trapezoid, a fan, a polygon or a circle.

9. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: The ratio of the inner diameter D1 of the central hollow area of ​​the main mirror to the effective aperture D2 of the main mirror formed after the divided sub-mirrors are unfolded, i.e. D1 / D2, is between 0.3 and 0.6 to ensure the imaging performance of the optical system and the stability of the optomechanical structure.

10. The centrally hollow deployable segmented reflector according to claim 1, characterized in that: In the hollow of the primary mirror, three mirrors or a focal plane can be placed according to the design requirements of the optical system.

Images