A high-precision, high-stability, large-aperture dual-camera common-shape primary mirror

Abstract

This invention discloses a high-precision, high-stability, large-aperture dual-camera common-shape primary mirror, comprising a dual-primary-mirror body and a primary mirror support. The dual-primary-mirror body is a combination of two mirror-symmetrical, coaxial single primary mirrors. The primary mirror support is used to achieve quasi-statically determinate support for the dual-primary-mirror body. This invention's common-primary-mirror adopts an integrated structure, which can reduce the size of the optomechanical system, improve the overall specific stiffness, and enhance structural accuracy and stability, showing broad application prospects in the field of stereo mapping.

Description

Technical Field

[0001] This invention relates to a high-precision, high-stability, large-aperture dual-camera common-shape primary mirror, belonging to the field of space optical remote sensing technology. Background Technology

[0002] With the improvement of remote sensor development and the gradual improvement of satellite platform design and development, optical remote sensing satellites at home and abroad have made great strides in recent years. Space optical remote sensing systems have also become increasingly complex, developing towards higher spatial resolution, spectral resolution and radiometric resolution.

[0003] Stereo mapping is the process of creating topographic maps of a certain scale from stereo images taken from different camera stations at different perspectives of the same ground scene under the same orbital conditions. As map scales continue to increase, achieving refined mapping inevitably requires ensuring the accuracy of the acquired stereo image location information. This means ensuring both planar positioning accuracy (representing planar position information) and elevation positioning accuracy (representing height position information). Based on the specific working method of the camera to achieve the stereo mapping perspective, mapping cameras can be divided into three types: single-line array stereo mapping cameras, dual-line array stereo mapping cameras, and triple-line array stereo mapping cameras. Single-line array stereo mapping cameras require rapid maneuvering of the satellite platform to complete the stereo mapping process. Under uncontrolled conditions, the elevation positioning accuracy of their stereo images cannot meet the accuracy requirements of large-scale mapping. Triple-line array stereo mapping cameras can achieve higher positioning accuracy, but they require three cameras (forward-looking, front-looking, and back-looking), resulting in a larger size and weight, making them generally unsuitable for agile mapping. Dual-line array stereo mapping cameras can achieve long strip mapping through dual-line array push-broom, improving mapping efficiency and positioning accuracy compared to single-line array mapping cameras.

[0004] Currently, to meet the requirements of high-resolution, wide-swath detection, typical dual-line array stereo mapping cameras both domestically and internationally are generally equipped with two independent high-resolution cameras, with the base-to-height ratio varying by changing the installation angle of the two cameras. Since elevation accuracy is easily guaranteed under large base-to-height ratio conditions, existing dual-line array stereo mapping cameras generally use a fixed base-to-height ratio of 0.6 to 1. High-resolution dual-line array stereo mapping camera systems with this base-to-height ratio are large in size and weight, posing certain challenges for agile detection of key areas.

[0005] To simplify the design of dual-camera combined imaging systems and standardize the assembly and adjustment schemes of the two cameras, both cameras typically employ identical optomechanical support structures and use the same mounting substrate for registration and installation. While dual-camera combined imaging addresses the requirements for high resolution and wide swath, it increases the overall size of the optomechanical imaging system, hindering compact envelope design and satellite-wide motion imaging. Furthermore, the dual-camera design introduces more sources of error and assembly variables during the fabrication and inspection of large optomechanical structures, especially large-aperture mirrors such as the primary mirror, as well as during assembly and adjustment, which is detrimental to rapid convergence and the overall system's high precision and stability. Summary of the Invention

[0006] The purpose of this invention is to overcome the aforementioned shortcomings and provide a high-precision, high-stability, large-aperture dual-camera common-shape primary mirror, solving the technical problem of existing high-resolution dual-line array stereo mapping cameras relying on two independent cameras for imaging. The common-shape primary mirror of this invention adopts an integrated structure, which can reduce the optomechanical scale of the dual-line array camera, improve the overall specific stiffness, and enhance structural accuracy and stability, thus having broad application prospects in the field of stereo mapping.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] A high-precision, high-stability, large-aperture dual-camera common-shape primary mirror, comprising dual primary mirror bodies and a primary mirror support;

[0009] The dual-primary-mirror body is a combination of two mirror-symmetrical, coaxial single-primary-mirrors;

[0010] The primary mirror support is used to achieve quasi-statically determinate support for the dual primary mirror bodies.

[0011] Furthermore, the dual primary mirror body has a ULE sandwich structure, including a mirror panel, an inner sandwich layer, and a mirror back plate; the mirror back plate is fixedly connected to the primary mirror support.

[0012] Furthermore, the single primary mirror in a dual-primary-mirror body has a configuration that is thicker at the center and thinner at the edges.

[0013] Furthermore, the optical axis angle between the two single primary mirrors in the dual-primary-mirror body is 16° to 20°, the distance between the vertices of the two single primary mirrors is 600 to 1000 mm, and the aperture of a single primary mirror is 1 to 1.6 m.

[0014] Furthermore, the two single primary mirrors in the dual-primary-mirror body share a mirror backplate, which provides the same processing, inspection, and assembly reference for the two single primary mirrors.

[0015] Furthermore, the primary mirror support includes a nested adapter, a flexible support rod, and a support base;

[0016] The flexible support rod is connected to a nested adapter and a support base at both ends, respectively; the support base is connected to the main load-bearing structure, and the back plate of the reflector is provided with a reflector nest at the support point. The nested adapter is used to connect the reflector nest.

[0017] Furthermore, the two primary mirror supports form a Bipod structure, and the three Bipod structures are distributed in an equally spaced circular pattern to achieve quasi-statically determinate support. The two flexible support rods in each Bipod structure are at 90° in space; the two ends of the flexible support rods are flexible links.

[0018] Furthermore, the three Bipod structures contain a total of 6 primary mirror supports, forming 6 support points for the primary mirror body. The 6 support points are mirror symmetrical, with four support points being 0.65R away from the center of the single primary mirror and the other two support points being 0.5R away from the center of the single primary mirror.

[0019] R is the radius of a single primary mirror.

[0020] Furthermore, the backplate of the reflector is reinforced with support at the connection point with the nested adapter.

[0021] Furthermore, the dual primary mirror bodies are integrated into a single structure, and the dual primary mirror bodies are simultaneously matched with the optical systems of two cameras.

[0022] Compared with the prior art, the present invention has at least one of the following advantages:

[0023] (1) This invention creatively proposes a high-precision, high-stability, large-aperture dual-camera common irregular-shaped primary mirror, which can reduce the scale of the optical engine and improve the specific stiffness of the whole machine: the dual-camera system shares a common irregular-shaped primary mirror, and the corresponding primary mirror support and lens support are simplified into an integrated support form, the whole machine is compact, and the scale of the optical engine is greatly reduced.

[0024] (2) The common-shaped primary mirror of the present invention can reduce the sources of error and simplify the development process: the common primary mirror adopts an integrated structure, which enables the two primary mirrors in the dual system to achieve a common reference for processing, testing and assembly, reducing the sources of error and improving the structural accuracy and stability; in the assembly and adjustment process of the dual optical system, the system assembly and adjustment variables are reduced, which greatly improves the assembly and adjustment efficiency of the dual camera system.

[0025] (3) This invention provides the optical structure, support method and specific design parameters of the common-shaped primary mirror, which is beneficial to the optimized design of high-resolution dual-line array stereo mapping camera. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a high-precision, high-stability, large-aperture dual-camera common-shape primary mirror of the present invention;

[0027] Figure 2This is a diagram showing the included angle between the two support rods inside a single Bipod of the dual primary mirrors of the present invention;

[0028] Figure 3 This is a diagram showing the angular relationship between the three sets of Bipods in this invention;

[0029] Figure 4 This is a diagram showing the location of the dual primary mirror support points of the present invention;

[0030] Figure 5 Figure (a) is a bottom view and Figure (b) is a cross-sectional view of Figure (a).

[0031] Figure 6 This is a schematic diagram of the ULE sandwich structure of the dual primary mirror body of the present invention;

[0032] Figure 7 This is a schematic diagram of a single support rod structure of the Bipod of the present invention. Detailed Implementation

[0033] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0034] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0035] This invention provides a high-precision, high-stability, large-aperture dual-camera common-shape primary mirror. This irregularly shaped primary mirror is a combination of two mirror-symmetrical coaxial single primary mirrors, suitable for dual-camera systems and simultaneously compatible with the optical systems of both cameras. It exhibits high relative accuracy between the primary mirrors and high overall mechanical and thermal stability, solving the problem of relative positioning accuracy within dual-camera systems.

[0036] The dual-camera system comprises two coaxial four-reflector optical systems, with the primary mirrors of both systems integrated into a single unit, forming a common-shape primary mirror. This primary mirror is achieved through a single, lightweight ULE (ultra-low expansion glass) sandwich structure. The irregular-shape primary mirror is supported by an inverted six-bar support, with two bars forming a bipod (two-legged support), for a total of three sets. Each support bar has flexible links at both ends to ensure high axial stiffness and low lateral stiffness. By comprehensively optimizing the common-shape primary mirror configuration and support point positions, the surface accuracy of the common-shape primary mirror is effectively improved.

[0037] The dual primary mirrors employ a lightweight ULE sandwich structure, where the upper and lower panels are sealed to a middle sandwich layer. The sandwich layer uses hexagonal honeycomb or triangular reinforcing ribs, with additional local reinforcing ribs near the support points to enhance support strength. The entire dual primary mirror body is thicker at the center and thinner at the edges to improve edge stiffness and ensure the support surface shape. Due to the dual primary mirror configuration and elongated shape, six-bar supports are used to improve stability. The support point positions (the distance between the support point and the center of the nearest single primary mirror) are between 0.5 and 0.65R (R is the radius of a single mirror). The six-bar supports are arranged in pairs to form a Bipod, with three groups in total. Within each group, the two bars form a 90° angle, and the three groups of Bipods are distributed at a 60° angle, forming a quasi-statically determinate support structure.

[0038] Example:

[0039] The large-aperture dual-camera common-form primary mirror in this invention is a common-prime mirror structure of a certain remote sensing camera. The specific implementation of this invention will now be described using the design of this camera's primary mirror as an example.

[0040] This remote sensing camera is a high-resolution dual-line array stereo mapping camera, consisting of two mirror-symmetrical coaxial four-reflector optical systems. The optical axis angle between the primary mirrors of the two optical systems is 16.2°, the distance between the vertices of the primary mirrors is 920mm, and the primary mirror diameter is 1.5m. Based on the characteristics of this dual optical system, and considering the compact design of the optomechanical structure and the simplification of the optical assembly and adjustment of the dual system, the camera adopts a shared primary mirror design, that is, the two primary mirrors are combined into one, using an integrated irregular primary mirror structure.

[0041] The implementation method of the dual-camera common-shape primary mirror based on the method of the present invention is described in detail below:

[0042] The primary mirror is mainly composed of two parts: the dual primary mirror body 1 and the primary mirror support 2;

[0043] The dual primary mirror body 1 includes: a mirror panel 1.1, an internal sandwich layer 1.2, a mirror back plate 1.3, and a support reinforcement 1.4;

[0044] The primary mirror support 2 consists of six identical support structures. Each primary mirror support 2 includes a nested adapter 2.1, a flexible support rod 2.2, and a support base 2.3. The six primary mirror supports 2 are arranged in pairs to form a Bipod structure, with a total of three sets. Within a single set, the two rods form a 90° angle, and the three sets form a 60° angle, forming a Bipod quasi-statically indeterminate support form.

[0045] like Figure 1 The dual primary mirror assembly consists of a dual primary mirror body 1 and six primary mirror supports 2.

[0046] like Figure 2 , Figure 3The primary mirror support 2 is an inverted six-bar support. The six bars are paired to form a Bipod structure, with a total of three groups. Within each group, the two support bars are at a 90° angle in space. The three Bipods... Figure 3 The first Bipod group 3, the first Bipod group 4, and the first Bipod group 5 are at 60° to each other, thus realizing the Bipod quasi-statically determinate support of the primary mirror body 1.

[0047] like Figure 4 There are six support points on the primary mirror body 1, which are mirror symmetrical. The four first support points 6 are located at 0.65R (R is the radius of a single primary mirror), and the two second support points 7 are located at 0.5R.

[0048] like Figure 5 , Figure 6 The dual-primary-mirror body 1 is a lightweight ULE sandwich structure. The reflector (dual-primary-mirror body 1) is composed of two mirror-symmetrical single primary mirrors. The reflector consists of three parts: a reflector panel 1.1, an inner sandwich layer 1.2, and a reflector back plate 1.3. The combined dual-primary-mirror body 1 is elongated racetrack-shaped. To improve the specific stiffness of the mirror body and ensure the support surface shape of the reflector edges, each single primary mirror adopts a wedge-shaped configuration that is thicker at the center and thinner at the edges. The center thickness of the reflector is 0.15R (R is the radius of the single primary mirror), and the reflector back plate dimensions are 1.5R × 1.3R with a wedge angle of 23°. Simultaneously, to ensure the local surface shape near the support points, local radial reinforcing ribs 1.4 are added near the reflector support points to improve support strength. The shared reflector back plate 1.3 for both primary mirrors provides the same processing, inspection, and assembly reference for both primary mirrors.

[0049] like Figure 7 The primary mirror support 2 comprises a nested adapter 2.1, a flexible support rod 2.2, and a support base 2.3. The nested adapter 2.1 connects the Bipod to the nested mirror; the flexible support rod 2.2 has flexible ends to ensure high axial stiffness and low lateral stiffness; the support base 2.3 connects the dual primary mirror assembly to the main load-bearing structure. Two primary mirror supports 2 form a Bipod, and three Bipods provide quasi-statically determinate support.

[0050] The primary mirror of this invention weighs 125 kg, a single support weighs 2.2 kg, and the total weight of the primary mirror assembly is 138 kg. When the optical axis of the primary mirror is horizontally adjusted, the surface shape can reach 1 / 50λ (λ is the light source wavelength of the interferometer of the surface shape detection equipment, 632.8 nm).

[0051] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0052] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-precision, high-stability, large-aperture dual-camera common-shape primary mirror, characterized in that, It includes a dual primary mirror body (1) and a primary mirror support (2); The dual-primary-mirror body (1) is a combination of two mirror-symmetrical single-primary-mirrors; The primary mirror support (2) is used to achieve quasi-statically determinate support for the dual primary mirror bodies (1); The optical axis angle between the two single primary mirrors in the double primary mirror body (1) is 16°~20°, the distance between the vertices of the two single primary mirrors is 600~1000mm, and the aperture of the single primary mirror is 1~1.6m; The two single primary mirrors in the dual primary mirror body (1) share a mirror back plate (1.3), and the mirror back plate (1.3) provides the same processing, inspection and assembly reference for the two single primary mirrors; Two primary mirror supports (2) form a set of Bipod structures. The three sets of Bipod structures are distributed in an equally spaced circular pattern to achieve quasi-statically determinate support. The two flexible support rods (2.2) in each set of Bipod structures are at 90° in space. The two ends of the flexible support rods (2.2) are flexible links. The three Bipod structures contain a total of 6 primary mirror supports (2), forming 6 support points on the primary mirror body (1). The 6 support points are mirror symmetrical, with four support points being 0.65R away from the center of the single primary mirror and the other two support points being 0.5R away from the center of the single primary mirror. R is the radius of a single primary mirror; The dual primary mirror body (1) is an integral structure, and the dual primary mirror body (1) is matched with the optical systems of two cameras at the same time.

2. The high-precision, high-stability, large-aperture dual-camera common-shape primary mirror according to claim 1, characterized in that, The dual primary mirror body (1) is a ULE sandwich structure, including a mirror panel (1.1), an inner sandwich layer (1.2) and a mirror back plate (1.3); the mirror back plate (1.3) is fixedly connected to the primary mirror support (2).

3. The high-precision, high-stability, large-aperture dual-camera common-shape primary mirror according to claim 1, characterized in that, The single primary mirror in the double primary mirror body (1) has a configuration that is thick in the center and thin at the edge.

4. The high-precision, high-stability, large-aperture dual-camera common-shape primary mirror according to claim 1, characterized in that, The main mirror support (2) includes a nested adapter (2.1), a flexible support rod (2.2), and a support base (2.3). The flexible support rod (2.2) is connected to a nested adapter (2.1) and a support base (2.3) at both ends respectively; the support base (2.3) is connected to the main load-bearing structure, and the back plate of the reflector (1.3) is provided with a reflector nest at the support point. The nested adapter (2.1) is used to connect the reflector nest.

5. A high-precision, high-stability, large-aperture dual-camera common-shape primary mirror according to claim 4, characterized in that, The backplate of the reflector (1.3) is provided with a support reinforcement (1.4) at the connection with the nested adapter (2.1).

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