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中国物理学会期刊

角锥棱镜的斜入射远场衍射图样

CSTR: 32037.14.aps.70.20210261

Far-field diffraction pattern of cube corner retroreflector at oblique incidence

CSTR: 32037.14.aps.70.20210261
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  • 角锥棱镜是激光反射器的主要光学组件, 在合作目标卫星激光测距中发挥着关键作用. 精确计算角锥棱镜的远场衍射图样是估算激光测距回波能量的必要过程. 本文基于角锥棱镜的反射原理, 分析了不同激光入射方向对反射器有效反射面积的影响, 提出了一种适用范围更广的有效反射面积计算方法, 同时分析了激光入射方向对角锥棱镜光学反射率的影响. 在此基础上, 应用光学标量衍射理论建立了远场衍射图样算法, 分别对多种激光入射方向的镀金属(银)膜和无镀膜角锥棱镜进行了远场衍射图样仿真计算, 得到了两类角锥棱镜的远场衍射图样分布随入射方向变化的规律. 搭建了角锥棱镜远场衍射图样测试系统, 通过实测结果与仿真计算的对比分析, 验证了仿真计算的准确性.

     

    Corner cube retroreflector (CCR) as a main optical component of laser ranging retroreflector array plays a key role in satellite laser ranging (SLR) to cooperative targets. To accurately estimate the echo energy of SLR, it is necessary to precompute photons’ distribution in the distance of SLR station by calculating the Far field diffraction pattern (FFDP) of CCR under various conditions. In this paper, the analysis of the effective reflection area and optical reflectivity of CCR for arbitrary incidence angle are carried out, in which a method to calculate the CCR effective reflection area with a wider applicability is used, and the difference between optical reflectivity of metal-coated CCR and uncoated (total internal reflection) CCR is also discussed. On this basis, combined with optical diffraction theory, a simulation program for CCR FFDP calculation is established, thereby producing FFDPs of CCR for a variety of incidence angles under different coating conditions. The results show that the FFDP of metal-coated CCR is almost unrelated to the azimuth angle of incident light or polarization, but is determined only by elevation angle of incident light. The pattern is always like Airy spot or its tensile deformation. Relatively, uncoated CCR’s FFDP has a more complex figure, its reflected energy is divided into several lobes whose size, number and position are all influenced by elevation and azimuth angle of incidence, and also by the polarization. Generally, the incidence direction which has a large total intensity of far optical field is to an extent the same as that of large effective reflection area and optical reflectivity. Furthermore, simulation results with uncoated CCR presents a higher relevance of incidence direction and FFDP.
    To verify the reliability and correctness of these simulation results, a diffraction optical experimental system at a wavelength of 1550 nm is set up to conduct laboratory confirmation, including laser, camera, beam expander, rotating platform and other essential optics. A silver-coated CCR and an uncoated CCR (both made of fuse silica, each has different dihedral angle offset) are chosen to measure their FFDPs with random polarization directions at several random incidence angles. All the measurement results are in good agreement with the simulations of FFDPs.

     

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