Optical antenna structure with wide temperature application range and assembly method thereof

Abstract

The invention provides an optical antenna structure with a wide temperature adaptation range, which comprises a plurality of optical lenses, each optical lens is sleeved with a gasket, the optical lenses provided with the gaskets are fixed in a lens barrel through a pressing ring, a space ring for separating the optical lenses is further arranged in the lens barrel, and a solar optical filter is arranged at the front end of the lens barrel; the optical lens is made of optical glass with low heat sensitivity, the lens cone is made of an aluminum alloy material, the space ring is made of an invar steel material, the gasket is a graphene gasket subjected to anti-oxidation treatment, and the solar optical filter is made of microcrystalline glass and is coated with an aluminum film. The athermalization design is carried out by selecting an optical structure material with a low thermal expansion coefficient, so that the optical antenna structure can keep stable performance in a larger temperature range, and the possibility of mechanical deformation or rigid body displacement of the optical antenna structure in a space extreme temperature environment is further reduced.

Description

Technical Field

[0001] This invention relates to the field of optical antenna technology, and in particular to an optical antenna structure with a wide temperature adaptability range and its assembly method. Background Technology

[0002] Space laser communication is a communication method that uses laser light as a carrier to transmit data. Compared with microwave communication, it has advantages such as high data transmission rate, high security, and strong anti-interference capabilities. As a crucial component of satellite optical communication terminals, the optical antenna experiences significant temperature variations due to the combined effects of external space heat flow, the cold black background of space, and thermal radiation from the satellite payload. This can cause rigid body displacement or mirror distortion of the optical mirror of the receiving antenna relative to its ideal mirror surface, causing the antenna to deviate from its ideal operating state and ultimately affecting the link's aiming, acquisition, tracking, and communication performance.

[0003] Since the payload operates in the shadow area most of the time, existing technologies mainly rely on reasonable heat dissipation and heating compensation, and thermal wrapping for constant temperature thermal control, which can ensure that the optical components of the payload can work normally within a range of about 20℃±5℃. However, with the increase in the number of satellites and the densification of orbits, the design of optical antennas and connecting trusses needs to have higher sensitivity and anti-interference capabilities. Therefore, it is urgent to design the optical antenna structure with a wide temperature range to ensure its stable performance over a wider temperature range. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the above-mentioned technologies and provide an optical antenna structure with a wide temperature adaptability range and its assembly method.

[0005] Therefore, the present invention provides an optical antenna structure with a wide temperature adaptability range, including multiple optical lenses, each optical lens having a spacer fitted on it, the optical lens with the spacer fixed to the lens barrel by a pressure ring, a spacer between two adjacent optical lenses, and a solar filter installed at the front end of the lens barrel; the optical lenses are made of optical glass with low thermal sensitivity, the lens barrel is made of aluminum alloy, the spacer is made of Invar steel, the spacer is an anti-oxidation treated graphene spacer, and the solar filter is microcrystalline glass with an aluminum coating.

[0006] Preferably, the optical glass includes H-FK61 optical glass, H-ZF73 optical glass, H-ZLAF53B optical glass, and H-ZF12 optical glass.

[0007] Preferably, the lens barrel is made of 6061 aluminum alloy with a wall thickness of 2.5-3mm and a flatness of ≤0.02mm, and its surface is blackened.

[0008] Preferably, the axial thermal expansion coefficient of the graphene gasket is 8 × 10⁻⁶. -6 / K, the radial thermal expansion coefficient is 25×10-6 / K, with a temperature range of -180℃ to 650℃.

[0009] An assembly method for an optical antenna structure with a wide temperature adaptability range includes the following steps: S1. Match the ambient temperature of the optical antenna structure assembly with the thermal control reference for the satellite's on-orbit operation; S2. Clean and activate the outer surface of the lens barrel, then uniformly spray a polyimide heat insulation coating onto its surface and perform gradient temperature curing treatment. S3. Place a shim on the contact surface between the optical lens and the lens barrel; S4. Install H-ZF12 optical glass, H-ZLAF53B optical glass, H-ZF73 optical glass and H-FK61 optical glass in the lens barrel in sequence, and install Invar spacers between each optical glass. S5. Install the solar filter at the front end of the lens barrel at a 2° angle; S6. Conduct the final inspection.

[0010] Preferably, in step S3, a preload of 1.8 N·m is applied to the clamping ring that fixes the H-FK61 optical glass using a torque feedback wrench, a preload of 1.5 N·m is applied to the clamping ring that fixes the H-ZF73 and H-ZLAF53B optical glasses, and a preload of 1.2 N·m is applied to the clamping ring that fixes the H-ZF12 optical glass.

[0011] Preferably, the ambient temperature in step S1 is 23℃±5℃.

[0012] Preferably, in step S4, a laser interferometer is used to detect the wavefront error of the optical glass during the installation process, and the wavefront error is less than λ / 10 (@632.8nm).

[0013] Preferably, the activation process in step S2 involves etching the surface of the lens barrel with an acidic solution to remove oxide films, grease, and other impurities from its surface.

[0014] Preferably, the thickness of the heat-insulating coating is 0.1 mm.

[0015] The beneficial effects of the present invention are as follows: The present invention provides an optical antenna structure with a wide temperature adaptability range and its assembly method, which has the following beneficial effects.

[0016] (1) By selecting optical structural materials with low thermal expansion coefficients for athermal design, the optical antenna structure can maintain stable performance over a wider temperature range, further reducing the possibility of mechanical deformation or rigid displacement of the optical antenna structure in extreme space temperature environments. This solves the problem of insufficient adaptability of optical antennas to work in a wide temperature range in space in laser communication systems, and provides effective method support for the stable on-orbit operation of high-performance satellite laser communication systems. (2) The lens barrel is made of aluminum alloy, which, compared with traditional titanium alloy, has the advantages of being lightweight and inexpensive while ensuring thermal stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical antenna structure; Figure 2 This is a cross-sectional view of the optical antenna structure; Figure 3 This is a schematic diagram of the graphene gasket structure; Figure 4 It is a displacement diagram of the surface in the X, Y, and Z directions of an optical antenna structure without pyrolysis design at a temperature of -100℃; Figure 5 It is a displacement diagram of the surface of an athermalized optical antenna structure in the X, Y, and Z directions when the temperature is -100℃; Figure 6 It is a displacement diagram of the surface in the X, Y, and Z directions of an optical antenna structure without pyrolysis design at a temperature of 100℃; Figure 7 It is a displacement diagram of the surface in the X, Y, and Z directions of an athermalized optical antenna structure at a temperature of 100℃.

[0018] The markings in the diagram are: 1. Optical lens; 11. Primary lens; 12. Secondary lens; 13. Third lens; 14. Fourth lens; 2. Gasket; 3. Pressure ring; 4. Lens barrel; 5. Spacer; 6. Solar filter. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments to aid in understanding its content. Unless otherwise specified, the methods used in this invention are conventional methods; the raw materials and apparatus used, unless otherwise specified, are conventional commercially available products. Example

[0020] like Figures 1-3As shown, the present invention provides an optical antenna structure with a wide temperature adaptability range, including multiple optical lenses 1, each optical lens 1 having a gasket 2 fitted on it, the optical lens 1 with the gasket 2 fixed in the lens barrel 4 by a pressure ring 3, a spacer 5 between two adjacent optical lenses 1, and a solar filter 6 installed at the front end of the lens barrel 4; the optical lenses 1 are made of optical glass with low thermal sensitivity, the lens barrel 4 is made of aluminum alloy, the spacer 5 is made of Invar steel, the gasket 2 is an anti-oxidation treated graphene gasket, and the solar filter 6 is microcrystalline glass with an aluminum coating.

[0021] In this embodiment, the optical lens 1 includes a primary lens 11, a secondary lens 12, a tertiary lens 13, and a fourth lens 14. The primary lens 11 is made of H-FK61 optical glass, the secondary lens 12 is made of H-ZF73 optical glass, the tertiary lens 13 is made of H-ZLAF53B optical glass, and the fourth lens 14 is made of H-ZF12 optical glass. The primary lens 11 and the tertiary lens 13 are both plano-convex lenses, with their convex surfaces facing the solar filter 6. The secondary lens 12 and the fourth lens 14 are both biconcave lenses.

[0022] Glass transition temperature is an important indicator of the stability of optical glass at high temperatures. A higher glass transition temperature indicates greater stability of the optical glass in high-temperature environments, which is crucial for optical systems in space laser communication. Furthermore, in a wide temperature range, the thermal sensitivity of optical systems, particularly the deformation caused by temperature changes, is mainly related to the material's coefficient of thermal expansion (α).

[0023] The glass transition temperature and coefficient of thermal expansion of the four types of optical glass are shown in Table 1: Table 1 Thermal properties of optical lenses

[0024] Where Tg represents the glass transition temperature, α -30 / 70℃ α represents the coefficient of thermal expansion of an optical lens in the temperature range of -30℃ to 70℃. 100 / 300℃ It represents the coefficient of thermal expansion of an optical lens in the temperature range of 100℃ to 300℃.

[0025] As shown in Table 1, the four types of optical glass selected in this application all have low coefficients of thermal expansion, which can effectively reduce deformation caused by temperature changes and ensure the stability of the optical system. Furthermore, they exhibit good stability at both low temperatures (-30℃) and high temperatures (300℃). In summary, by appropriately matching their coefficients of thermal expansion and high glass transition temperatures, these four types of optical glass can achieve low thermal sensitivity of the optical antenna structure in a wide temperature range, reducing the impact of temperature changes on optical performance and thus ensuring high system stability.

[0026] Furthermore, the lens barrel 4 is made of 6061 aluminum alloy with a wall thickness of 2.5mm and a flatness of ≤0.02mm, and its surface is blackened. Multiple annular reinforcing ribs are provided inside the lens barrel 4, increasing the overall rigidity of the structure. This not only improves the deformation resistance of the optical antenna structure but also serves to fix the optical lens 1.

[0027] Blackening the surface of the lens barrel 4 refers to forming an oxide layer on its surface through oxidation treatment. As a result, the surface of the lens barrel 4 will absorb more light, reduce internal and external reflections and stray light, and the black surface has a stronger heat absorption capacity than the glossy surface, which can help optical equipment better cope with temperature changes and reduce optical performance fluctuations caused by temperature differences.

[0028] Furthermore, an Invar spacer 5 is provided between two adjacent optical lenses 1. The coefficient of thermal expansion of Invar is 1.2 × 10⁻⁶. -6 / k Suitable for precision systems, it has high mechanical strength and low coefficient of thermal expansion, and can maintain good morphological stability in high or low temperature environments. It is used to compensate for differences in thermal deformation between materials, reduce interfacial shear stress, and bear thermal deformation in layers.

[0029] Furthermore, the axial thermal expansion coefficient of the graphene gasket is 8 × 10⁻⁶. -6 / K, the radial thermal expansion coefficient is 25×10 -6 / K, with a temperature range of -180℃ to 650℃. Its coefficient of thermal expansion is −67 × 10⁻⁶ K in the range of room temperature to 150°C. −6 / °C, this negative coefficient of thermal expansion helps reduce the difference in thermal expansion between the lens barrel 4 or the optical lens 1 caused by temperature changes, suppresses thermal stress, and avoids deformation or distortion of the optical system caused by inconsistent thermal expansion of different materials.

[0030] According to Fourier's law of heat conduction, heat flow With thermal conductivity and temperature gradient

[0031] There is a linear relationship between them, that is:

[0032] High thermal conductivity of graphene oxide This enables it to efficiently transfer heat from high-temperature areas to low-temperature areas, significantly improving thermal management efficiency and reducing the risk of displacement and optical path drift caused by thermal stress.

[0033] Furthermore, in this embodiment, the pressure ring 3 includes pressure ring one, pressure ring two, and pressure ring three. Pressure ring one is used to fix the primary mirror 11, pressure ring two is used to fix the secondary mirror 12 and the tertiary mirror 13, and pressure ring three is used to fix the tertiary mirror 14. Since the secondary mirror 12 is a biconcave lens and the tertiary mirror 13 is a plano-convex lens, one of the concave surfaces of the secondary mirror 12 mates with the convex surface of the tertiary mirror 13. Pressure ring two is used to press and fix the secondary mirror 12 on the side closest to the primary mirror 11.

[0034] Furthermore, the solar filter 6 is made of microcrystalline glass and coated with an aluminum film, which enables it to have good thermal stability and reflective properties in a wide temperature environment. It can maintain its optical performance basically unchanged in the range of -150℃ to +90℃, effectively suppressing the impact of solar stray light on the system signal-to-noise ratio.

[0035] An assembly method for an optical antenna structure with a wide temperature adaptability range includes the following steps: S1. Assembly Environment Preparation. The assembly and calibration of the optical antenna structure must be carried out in a temperature-controlled, dust-free workshop, with the ambient temperature strictly controlled within the range of 23℃±5℃. This temperature matches the thermal control baseline for satellite operation in orbit, aiming to minimize the structural deformation differences caused by drastic temperature field changes when switching from the ground assembly environment to the space in-orbit environment.

[0036] S2. Pretreatment and Coating of Lens Barrel 4. Before assembling optical components, the outer surface of the 6061 aluminum alloy lens barrel 4 is cleaned and activated. Then, a polyimide heat-insulating coating is uniformly coated using a spraying process. The thickness of the heat-insulating coating is controlled at 0.1 mm, and it needs to undergo a gradient temperature curing process (for example, slowly increasing the temperature from 80°C to 300°C and holding it at that temperature) to ensure that the heat-insulating coating has strong adhesion under extreme temperature alternation environments and does not crack or peel off.

[0037] The activation process involves etching the aluminum alloy surface with an acidic solution (such as sulfuric acid or phosphoric acid) to remove oxide films, grease, and other impurities. Acid etching improves the surface roughness and cleanliness of the aluminum alloy, making it more suitable for subsequent coatings or bonding.

[0038] The heat insulation coating is made of polyimide (PI) material. The selected polyimide material has a low coefficient of thermal expansion and excellent high temperature resistance. The thickness of the polyimide coating is optimized to 0.1 mm, which can effectively reduce the impact of temperature changes on the lens barrel 4 and improve the on-orbit stability of the optical antenna.

[0039] S3. Place a graphene pad on the contact surface between the optical lens 1 and the lens barrel 4, and use its anisotropic thermal expansion characteristics to adapt to deformation and absorb thermal stress.

[0040] S4. The four mirrors 14, three mirrors 13, two mirrors 12 and the main mirror 11 are sequentially fixed in the predetermined position inside the lens barrel 4 by applying the corresponding pre-tightening force to the titanium alloy thermal compensation pressure ring 3 using a torque feedback wrench. Invar spacers 5 are installed between each optical glass to achieve matching of thermal expansion coefficients and stress buffering between materials.

[0041] Specifically, a torque feedback wrench is used to apply a preload of 1.8 N·m to the clamping ring 3 that fixes the primary mirror 11, thus securing the primary mirror 11. A preload of 1.5 N·m is applied to the clamping rings 3 that fix the secondary mirror 12 and the tertiary mirror 13, thus securing them. A preload of 1.2 N·m is applied to the clamping ring 3 that fixes the fourth mirror 14, thus securing the fourth mirror 14. During this process, a laser interferometer is used to monitor the surface shape of the optical lens 1 in real time to ensure that the wavefront error is less than λ / 10 (@632.8 nm), in order to avoid surface shape distortion of the optical lens 1 caused by accumulated stress.

[0042] λ / 10 (@632.8nm) indicates that the shape change of the optical lens in the laser interferometer at a spectrum of 632.8nm is less than λ / 10. λ is 632.8nm.

[0043] S5. The solar filter at the front end of the lens barrel is installed at a 2° angle using adhesive. The 2° angle ensures that stray light reflected from its surface will not return along the optical axis to the surface of the primary mirror 11, thereby effectively avoiding the formation of interfering interference fringes within the optical system and improving the system's signal-to-noise ratio.

[0044] S6. Final Inspection and On-Orbit Preparation. After the assembly of all components is completed, the complete optical antenna is subjected to final wavefront error detection using precision instruments such as a laser interferometer in a constant temperature environment of 23℃±5℃ to ensure that the optical performance of the entire system meets the standards. Subsequently, random vibration and thermal vacuum environment tests are conducted to verify its mechanical and thermal stability. After the tests, the optical performance is verified to meet the standards again.

[0045] The aforementioned materials and structures work together to form a heatless design, i.e., a temperature-insensitive design.

[0046] Taking room temperature (20℃) as the starting temperature as an example, Figure 4 From left to right, these represent the surface displacements in the X, Y, and Z directions of an optical antenna without athermal design at a temperature of -100℃. Figure 5 From left to right, these represent the surface displacements in the X, Y, and Z directions of the optical antenna when the temperature is -100℃ after the anechoic design. Figure 6 From left to right, these represent the surface displacements in the X, Y, and Z directions of an optical antenna without athermal design at a temperature of 100°C. Figure 7 From left to right, these represent the surface displacements in the X, Y, and Z directions of the optical antenna when the temperature is 100℃ after the anechoic design.

[0047] The lens barrel 4 of the optical antenna structure without pyrolysis is made of titanium alloy, while the lens barrel 4 of the optical antenna structure with pyrolysis is made of aluminum alloy. The aluminum alloy, after pyrolysis, has thermal stability similar to that of the titanium alloy in the optical antenna structure, and its advantages lie in its smaller size and lower price.

[0048] pass Figure 4 It can be seen that, at a temperature of -100℃, the maximum displacement of the surface of the optical antenna structure without pyrolysis design is 68.5079μm and the minimum is -78.1526μm in the X direction; the maximum displacement in the Y direction is 146.695μm and the minimum is -185.201μm; and the maximum displacement in the Z direction is 68.7491μm and the minimum is -68.9788μm.

[0049] pass Figure 5 It can be seen that, for an optical antenna structure with a thermal design, at a temperature of -100℃, the maximum displacement of its surface in the X direction is 45.2378μm and the minimum is -47.9571μm; the maximum displacement in the Y direction is 58.0152μm and the minimum is -66.1386μm; and the maximum displacement in the Z direction is 45.2478μm and the minimum is -45.2165μm.

[0050] contrast Figure 4 and Figure 5 The results show that the displacements in the X, Y, and Z directions of the optical antenna structure with athermal design are significantly smaller than those of the optical antenna structure without athermal design at a temperature of -100℃.

[0051] pass Figure 6 It can be seen that, at a temperature of 100℃, the maximum displacement of the surface of the optical antenna structure without pyrolysis design is 36.3029μm and the minimum is -32.1669μm in the X direction; the maximum displacement in the Y direction is 87.5493μm and the minimum is -70.5563μm; and the maximum displacement in the Z direction is 32.5169μm and the minimum is -32.5633μm.

[0052] pass Figure 7It can be seen that, for an optical antenna structure with a pyrolysis design, at a temperature of 100℃, the maximum displacement of its surface in the X direction is 33.3912μm and the minimum is -31.3929μm; the maximum displacement in the Y direction is 49.6116μm and the minimum is -39.1037μm; and the maximum displacement in the Z direction is 31.3747μm and the minimum is -31.3988μm.

[0053] contrast Figure 6 and Figure 7 The results show that the displacements in the X, Y, and Z directions of the optical antenna structure with athermal design are significantly smaller than those of the optical antenna structure without athermal design at a temperature of 100℃.

[0054] In summary, this application reduces the mechanical deformation of the optical antenna caused by the extreme temperature environment of space by using optical structural materials with low thermal expansion coefficients for athermal design. Compared with other transmission optical antennas, the athermal design adopted in this application has a decisive impact on the stability of the optical antenna over a wide temperature range. At the same operating temperatures of -100℃ and 100℃, the traditional structure without athermal treatment exhibits significant thermal displacement and deformation in the X, Y, and Z orthogonal directions. However, after athermal optimization, the thermal displacement in all directions on the surface of the optical antenna is suppressed, and the axial (Y direction) deformation is controlled at a uniform level of -67~59μm and -40~50μm, respectively, improving the response consistency and long-term reliability of the optical antenna in rapidly changing temperature environments.

[0055] In the description of this invention, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0056] However, the above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made in accordance with the scope of protection of the present invention should still fall within the scope of the claims of the present invention.

Claims

1. An optical antenna structure with a wide temperature adaptation range, characterized in that, The application relates to a lens barrel, which comprises a plurality of optical lenses, each of which is sleeved with a gasket, the optical lenses sleeved with the gaskets are fixed in a lens barrel through compression rings, a spacer ring for separating the optical lenses is arranged in the lens barrel, and a solar filter is arranged at the front end of the lens barrel; the optical lenses are made of optical glass with low thermal sensitivity, the lens barrel is made of an aluminum alloy material, the spacer ring is made of a stainless steel material, the gasket is an antioxidant-treated graphene gasket, and the solar filter is a microcrystalline glass coated with an aluminum film.

2. An optical antenna structure with a wide temperature range of adaptation according to claim 1, characterized in that, The optical glass comprises H-FK61 optical glass, H-ZF73 optical glass, H-ZLAF53B optical glass and H-ZF12 optical glass.

3. The optical antenna structure of claim 1, wherein, The lens barrel is made of 6061 aluminum alloy, has a wall thickness of 2.5-3mm, a flatness of less than or equal to 0.02mm, and a blackened surface.

4. The optical antenna structure of claim 1, wherein, The axial thermal expansion coefficient of the graphene gasket is 8x10 -6 / K, the radial thermal expansion coefficient is 25x10 -6 / K, and the temperature resistance range is -180℃ to 650℃.

5. A method of assembling an optical antenna structure with a wide temperature adaptation range, characterized in that The application comprises the following steps: S1, matching the ambient temperature of the optical antenna structure assembly with the thermal control reference of the satellite in-orbit operation; S2, cleaning and activating the outer surface of the lens barrel, then uniformly spraying a polyimide thermal insulation coating on the surface and performing gradient temperature curing treatment; S3, placing a gasket on the contact surface of the optical lens and the lens barrel; S4, sequentially installing H-ZF12 optical glass, H-ZLAF53B optical glass, H-ZF73 optical glass and H-FK61 optical glass in the lens barrel, and installing a stainless steel spacer ring between each optical glass; S5, installing the solar filter at the front end of the lens barrel at an inclination of 2 degrees; S6, performing final inspection.

6. A method of assembling an optical antenna structure with a wide temperature range of adaptation according to claim 5, characterized in that, In step S3, a torque feedback wrench is used to exert a pre-tightening force of 1.8N.m on the compression ring for fixing the H-FK61 optical glass, a pre-tightening force of 1.5N.m on the compression ring for fixing the H-ZF73 optical glass and the H-ZLAF53B optical glass, and a pre-tightening force of 1.2N.m on the compression ring for fixing the H-ZF12 optical glass.

7. A method of assembling an optical antenna structure with a wide temperature range of adaptation according to claim 5, characterized in that, The ambient temperature in step S1 is 23 DEG C + / - 5.

8. A method of assembling an optical antenna structure with a wide temperature range of adaptation according to claim 5, characterized in that, In step S4, a laser interferometer is used to detect the wavefront error of the optical glass during installation, and the wavefront error is less than lambda / 10 (@ 632.8nm).

9. A method of assembling an optical antenna structure with a wide temperature range of adaptation according to claim 5, characterized in that, The activation treatment in step S2 is etching the surface of the lens barrel with an acidic solution to remove the oxidation film, grease and other impurities on the surface.

10. A method of assembling an optical antenna structure with a wide temperature range of adaptation according to claim 5, characterized in that, The thickness of the thermal insulation coating is 0.1mm.

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