High-efficiency laser interference transceiving dichroic plate with good spatial environment tolerance

Abstract

This invention discloses a high-efficiency laser interferometric transceiver dichroic film with good space environment tolerance, belonging to the field of optical thin film technology. The dichroic film has a multifunctional beam-splitting film deposited on the front side of a fused silica substrate, and a thermal stress-free antireflection film deposited on the back side. The front film system uses TiO2 and SiO2 as high and low refractive index materials, and is designed with a main film system based on a back-cutoff filter superimposed with a multi-layer energy control structure to achieve efficient reflection of 1550±10nm laser light; and eliminates half-wave apertures by matching asymmetric equivalent layers to ensure neutral beam splitting in the 750-900nm band. The back film system is composed of Ta2O5 and SiO2, which not only efficiently eliminates residual reflections (ghost images) but also compensates for surface distortion caused by the front film layer. This laser interferometric transceiver dichroic film exhibits good spectral stability and can withstand the harsh environment of direct exposure to geostationary orbit. It can also be used for spectral and energy control of other laser rangefinders.

Description

Technical Field

[0001] This invention relates to the field of optical thin film technology, and specifically to a high-efficiency laser interferometric transceiver color separator with good space environment tolerance. Background Technology

[0002] In space laser observation systems, the laser interferometric transceiver dichroic filter is a core optical component for integrating precise deformation measurement and visual monitoring of the system's primary mirror. Its specific application scenario is as follows: when the system simultaneously emits 1550nm and 850nm lasers to the primary mirror of the laser observation system to detect mirror surface shape, vibration, or attitude and perform precise FMCW ranging, the dichroic filter efficiently guides the 1550nm signal reflected back from the primary mirror into the receiving optical fiber, while simultaneously achieving neutral beam splitting of the 850nm near-infrared light (considering bandwidth limitations, the actual coating is based on 750~900nm), enabling the camera to simultaneously perform high-definition imaging of the primary mirror and its surrounding reference targets. The advantages of this dichroic filter lie in its physical static stability and extremely high spectral selectivity, ensuring that the laser ranging and optical observation channels do not interfere with each other and can operate in parallel without conflict under a shared aperture. Its core advantages for the entire observation system are maximized functional density and precise data source registration: a compact design with no moving parts replaces the traditional two independent optical path systems, significantly improving the system's reliability and integration. This mechanism enables operators to obtain precise visual feedback and spatial coordinates when calculating mirror displacement data with millimeter-level or even higher precision. Its potential applications can be extended to active optical correction of primary mirrors of large radio telescopes, deformation monitoring of primary mirrors of on-orbit satellites, and high-precision spacecraft rendezvous and docking observation systems. Summary of the Invention

[0003] The purpose of this invention is to provide a high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance. The main film system is constructed by superimposing a multi-layer energy modulation structure on a back cutoff filter, and the half-wave aperture is eliminated by matching an asymmetric equivalent layer to achieve efficient reflection of 1550±10nm laser while neutral dispersion of the 750~900nm spectral band. With a compact design without moving parts, it replaces the traditional two independent optical path systems, which mainly improves the reliability and integration of the camera system.

[0004] The technical solution of the present invention is as follows:

[0005] A high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance includes:

[0006] Color separation film base;

[0007] A multifunctional controllable dichroic film layer is located on one surface of the dichroic filter substrate. The multifunctional controllable dichroic film layer is composed of alternating deposition of low refractive index material SiO2 and high refractive index material TiO2. Its film structure is a multi-layer energy control structure superimposed on a back cutoff filter, and matched with an asymmetric equivalent layer to eliminate half-wave aperture, thereby achieving: reflectivity ≥95% in the 1550±10nm band, and neutral beam splitting function with reflectivity R and transmittance T both close to 50%±5% in the 750~900nm band.

[0008] The stress compensation and control film layer located on the other surface of the color separation substrate is composed of a SiO2 film layer with a thickness of 1000~1500nm;

[0009] The high-efficiency broadband antireflection film located on the stress compensation and control film layer is composed of alternating deposition of low refractive index material SiO2 and high refractive index material Ta2O5;

[0010] The color separation film is able to withstand the space environment of geostationary orbit.

[0011] In the above technical solution, the membrane structure of the multifunctional color-separating control film layer is represented as follows:

[0012] k1(0.5L h 0.5L)^2 ( a1H b1L) (a2H b2L) … (a n H b n L) k2(0.5L h 0.5L)^3;

[0013] Where L represents a SiO2 film with an optical thickness of λ0 / 4, H represents a TiO2 film with an optical thickness of λ0 / 4, λ0 is the center wavelength (unit: nm), and h represents a TiO2 film with an optical thickness of a specific ratio.

[0014] a n b n These are the scaling factor values ​​for λ0 / 4 optical thickness;

[0015] n is the number of stacked periods, 1≤n≤8;

[0016] ^2 and ^3 represent the number of membrane stack cycles;

[0017] k1 and k2 are optimization coefficients.

[0018] In the above technical solution, the film structure of the high-efficiency broadband antireflection film is represented as follows:

[0019] c1H c2L c3H c4L … c k-1 H c k L;

[0020] Where L represents a SiO2 film with an optical thickness of λ0 / 4; H represents a Ta2O5 film with an optical thickness of λ0 / 4;

[0021] c1, c2, c3, c4…c k-1 c k λ0 / 4 represents the proportionality coefficient of optical thickness for different stacking periods;

[0022] k is the number of stacked cycles, 3≤k≤10.

[0023] In the above technical solution, the thickness of the stress compensation control film layer is determined by software simulation optimization based on the difference between the residual stress of the color separation film system and the residual stress of the antireflection film.

[0024] In the above technical solution, the film layer of the color separation sheet is prepared by the following deposition process:

[0025] Deposition equipment: Box-type vacuum coating equipment with a diffusion pump system;

[0026] Deposition method: Electron beam evaporation deposition;

[0027] Assisted deposition: Ion beam assisted deposition;

[0028] Deposition vacuum degree: 1.0~1.5×10 -3 Pa;

[0029] Deposition temperature: 230℃;

[0030] TiO2 deposition rate: 0.3~0.5 nm / s;

[0031] Ta2O5 deposition rate: 0.15~0.3 nm / s;

[0032] SiO2 deposition rate: 0.8~1nm / s.

[0033] In the above technical solution, the color separator is applied to a space laser observation system to efficiently guide the 1550nm laser signal into the receiving optical fiber, while performing neutral beam splitting on the 750~900nm band to achieve synchronous high-definition imaging.

[0034] In the above technical solution, the color separation film is used to ensure that the laser ranging and optical observation channels do not interfere with each other under the shared aperture.

[0035] In the above technical solution, the dichroic film is suitable for active optical correction of the primary mirror of a large radio telescope, deformation monitoring of the primary mirror of an on-orbit satellite, and high-precision spacecraft rendezvous and docking observation system.

[0036] In the above technical solution, the material of the color separation substrate is JGS-1.

[0037] In the above technical solution, the asymmetric equivalent layer is obtained by combining materials with different proportions of high and low refractive indices to achieve different optical admittances and match the admittance of the main film system, thereby eliminating the half-wave aperture.

[0038] The beneficial effects of this invention are as follows:

[0039] 1. This invention provides a design and fabrication method for a high-efficiency laser interferometric transceiver dichroic plate with good space environment tolerance, which achieves efficient reflection of 1550±10nm laser while neutral dispersion of the 750~900nm spectral band. This is of great significance for simplifying the optical system of space laser observation camera and ensuring that the laser ranging and optical observation channels do not interfere with each other and can run in parallel under the shared aperture.

[0040] 2. The present invention employs a method of eliminating near-half-wave aperture by using asymmetric equivalent layers composed of high and low refractive index materials and matching them with the main film system. This achieves the required spectral and energy modulation with fewer film layers, reducing the reflection wavefront distortion caused by film thickness.

[0041] 3. The method of using back-side stress compensation control film layer superposition of high-efficiency antireflection film system for color separation surface correction has reference value for the development of optical components with high surface accuracy requirements.

[0042] 4. The technical solution of the present invention is reasonable and feasible, and the product has stable performance. It can be widely used in various laser observation instruments, laser rangefinders, deformation monitoring of on-orbit satellite primary mirrors, and high-precision spacecraft rendezvous and docking observation systems. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the film structure of a laser interferometer transceiver dichroic filter;

[0044] Figure 2 These are the measured transmittance and reflectance curves of the laser interferometer transceiver dichroic filter.

[0045] Among them, 1 is the color separation film substrate; 2 is the multifunctional control color separation film layer; 3 is the stress compensation control film layer; and 4 is the high-efficiency broadband antireflection film. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0047] Example:

[0048] like Figure 1As shown, a high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance includes:

[0049] Color separation film base 1;

[0050] A multifunctional controllable dichroic film layer 2 is located on one surface of the dichroic filter substrate 1. The multifunctional controllable dichroic film layer 2 is composed of alternating deposition of low refractive index material SiO2 and high refractive index material TiO2. Its film structure is a multi-layer energy control structure superimposed on a back cutoff filter, and matched with an asymmetric equivalent layer to eliminate half-wave aperture, thereby achieving: reflectivity ≥95% in the 1550±10nm band, and neutral beam splitting function with reflectivity R and transmittance T both close to 50%±5% in the 750~900nm band.

[0051] The stress compensation and control film layer 3 located on the other surface of the color separation substrate 1 is composed of a SiO2 film layer with a thickness of 1000~1500nm.

[0052] The high-efficiency broadband antireflection film 4, located on the stress compensation and control film layer 3, is composed of alternating deposition of low-refractive-index material SiO2 and high-refractive-index material Ta2O5.

[0053] The specific technical specifications of this embodiment are: 1550±10nm, R≥0.95; 750~900nm, R≈T=0.5±0.05; the substrate material is JGS-1.

[0054] According to technical requirements, a technical solution was adopted to fabricate a multifunctional dichroic film with spectral selection and energy regulation on the incident surface of the JGS-1 substrate, and a stress-compensated high-efficiency broadband antireflection film on the back side of the substrate. The design of the multifunctional dichroic film with spectral selection and energy regulation had to consider both the high reflectivity of the 1550nm laser and the balanced spectral dispersion in the 750-900nm band. Therefore, the main film system was constructed by superimposing a back-cutoff filter with a multi-layer energy regulation structure. An asymmetric equivalent layer with different optical admittances was obtained by matching high and low refractive index materials, and a design scheme to eliminate half-apertures was implemented. Finally, the film system was optimized using film system design software, especially for the optimization and control of a few key layers, to obtain a usable film system that achieves accurate spectral selection and energy regulation. The high-efficiency antireflection film on the back side, in addition to reducing residual reflectivity and eliminating "ghosting," also bears the important responsibility of stress regulation to reduce the distortion of the dichroic film surface. Therefore, the residual stress was calculated through thickness and stress simulation of the dichroic film and antireflection film, and stress regulation was achieved by depositing a SiO2 film of a certain thickness between the antireflection film and the substrate. The final film system is as follows:

[0055] n0 / 0.5337L 1.0049H 1.3707L 1.1657H 1.1009L 1.3136H 1.4139L 0.8466H0.7679L 0.1523H 0.7890L 0.8052H 1.6046L 1.0786H / n s / 5.4087L 0.1203N 0.3005L0.4535N 0.2217L 0.3180N 1.8437L 0.2036N 0.2236L 0.9481N 0.6404L / n0.

[0056] N, H, and L represent Ta₂O₅, TiO₂, and SiO₂, respectively. s The substrate is n0, the air is n0, and the center wavelength is 1400nm.

[0057] In this embodiment, the film system of the laser interferometer transceiver is prepared by electron beam evaporation deposition of coating material at a deposition temperature of 230°C, with ion beam assisted deposition throughout the process.

[0058] like Figure 2 As shown in the figure, R, T, and R' represent the transmittance, reflectance, and average reflectance of the balanced beam splitter, respectively. Under wavelength conditions of 750–900 nm, the transmittance and reflectance are T = 48.3% and R = 51.7%, respectively; at 1550 ± 10 nm, the average reflectance R' = 97.6%. The optical performance of the laser interferometric transceiver dichroic filter meets the requirements of the laser observation camera and can satisfy the system's spectral selection and energy control needs. The sample films from the example were tested according to the requirements of the optical thin film space reliability test specifications, and all passed the relevant tests, meeting the space reliability requirements.

[0059] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance, characterized in that, include: Color separation film substrate (1); A multifunctional controllable color separation film layer (2) is located on one surface of the color separation substrate (1). The multifunctional controllable color separation film layer (2) is composed of alternating deposition of low refractive index material SiO2 and high refractive index material TiO2. Its film structure is a post-cutoff filter film system superimposed with a multi-layer energy control structure, and matched with an asymmetric equivalent layer to eliminate half-wave aperture, achieving: reflectivity ≥95% in the 1550±10nm band, and transmittance and reflectivity T=48.3% and R=51.7% in the 750~900nm band, respectively. The stress compensation control film layer (3) located on the other surface of the color separation substrate (1) is composed of a SiO2 film layer with a thickness of 1000~1500nm; the thickness of the stress compensation control film layer (3) is determined by software simulation optimization based on the difference between the residual stress of the multifunctional control color separation film layer (2) and the residual stress of the high-efficiency broadband antireflection film (4). The high-efficiency broadband antireflection film (4) located on the stress compensation control film layer (3) is composed of alternating deposition of low refractive index material SiO2 and high refractive index material Ta2O5; The color separation film can withstand the space environment of geostationary orbit. The membrane structure of the multifunctional color-separating membrane layer (2) is as follows: n0 / 0.5337L 1.0049H 1.3707L 1.1657H 1.1009L 1.3136H 1.4139L 0.8466H0.7679L 0.1523H 0.7890L 0.8052H 1.6046L 1.0786H / n s / 5.4087L 0.1203N 0.3005L0.4535N 0.2217L 0.3180N 1.8437L 0.2036N 0.2236L 0.9481N 0.6404L / n0; N, H, and L represent Ta₂O₅, TiO₂, and SiO₂, respectively. s The substrate is n0, the air is n0, and the center wavelength is 1400nm.

2. The high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance according to claim 1, characterized in that, The film layer of the color separation sheet is prepared by the following deposition process: Deposition equipment: Box-type vacuum coating equipment with a diffusion pump system; Deposition method: Electron beam evaporation deposition; Assisted deposition: Ion beam assisted deposition; Deposition vacuum degree: 1.0~1.5×10 -3 Pa; Deposition temperature: 230°C; TiO2 deposition rate: 0.3~0.5 nm / s; Ta2O5 deposition rate: 0.15~0.3 nm / s; SiO2 deposition rate: 0.8~1nm / s.

3. The high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance according to claim 1, characterized in that, The dichroic filter is used in a space laser observation system to efficiently guide 1550nm laser signals into the receiving optical fiber, while simultaneously performing neutral beam splitting in the 750~900nm band to achieve synchronous high-definition imaging.

4. The high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance according to claim 1, characterized in that, The color separation is used to ensure that the laser ranging and optical observation channels do not interfere with each other when sharing the aperture.

5. The high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance according to claim 1, characterized in that, The dichroic film is suitable for active optical correction of primary mirrors of large radio telescopes, deformation monitoring of primary mirrors of on-orbit satellites, and high-precision spacecraft rendezvous and docking observation systems.

6. The high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance according to claim 1, characterized in that, The material of the color separation film substrate is JGS-1.

7. The high-efficiency laser interferometric transceiver dichroic filter with good space environment tolerance according to claim 1, characterized in that, The asymmetric equivalent layer eliminates half-wave apertures by combining materials with different proportions of high and low refractive indices to achieve different optical admittances that match the admittance of the main film system.

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