星载成像光谱仪退偏器的设计及测试

Design and Test of Depolarizer for Space-Borne Imaging Spectrometer

为保证星载成像光谱仪测量结果的准确性,设计了双巴比涅退偏器。首先利用电磁波理论及光波传输理论分析了双巴比涅退偏器的工作原理,接着根据偏振光在双折射晶体中的传播公式设计出适当的该退偏器的楔角,最后搭建一套偏振测试装置,对研制完成的双巴比涅退偏器的退偏性能进行测试。测试结果表明:该双巴比涅退偏器在-15~15℃入射角范围内具有较好的退偏性能。退偏器楔角选择6°时,能在不影响成像质量的前提下较好地对探测波段退偏,且退偏度不受方位角及频率的影响,退偏度优于99%。该退偏器具有退偏度高、透射比高、性能稳定、体积小等优点。由于测量系统误差,测量不确定度为0.00290。

To guarantee the measurement accuracy of the space-borne imaging spectrometer, the dual Babinet compensator pseudo-depolarizer （DBCP） is designed. The principle of the DBCP is analyzed by utilizing the electromagnetic wave theory and light wave transmission theory, and a suitable wedge angle of the DBCP is schemed out based on the formula of polarized light propagation in birefringent crystal. The depolarization performance of the DBCP is worked out with a set-up polarization testing device. The results show that the DBCP has a better depolarization performance within the incidence angle range of -15-15 ℃. When the wedge angle is 6°, the depolarizer can realize depolarization at detection band with degree of depolarization better than 99%. Which is independent of the azimuth angle and frequency, and without affecting the imaging quality. Furthermore, the DBCP has many advantages, such as high degree of depolarization, high transmittance, stable performance and small volume. The uncertainty of measurement is 0.00290, because of the systems error.