温度变化对金属Ag膜反射镜偏振特性的影响研究

空间遥感应用中的光学有效载荷对系统偏振控制提出了越来越高的要求,作为常用的宽光谱反射镜,金属银(Ag)膜反射镜的偏振特性随着环境温度的改变而变化。本文设计并制备了低偏振灵敏度的Ag膜反射镜,研究了反射镜在45°和60°入射角下,从室温25℃升温到150℃时的偏振特性变化和反射光谱变化情况。随着温度的升高,Ag膜的折射率在350~1 200 nm波长范围内有所增加;Ag膜反射镜的反射光中s和p光的相位差Δ在350~600 nm波长范围内减小,在600~650 nm波长范围内基本稳定,在650~1 200 nm波长范围内增大。温度上升到125℃时,Ag膜和反射镜表面形貌发生改变,增加了表面散射和吸收,导致350~900 nm波段反射率降低,在波长350 nm附近的降低约25%。

Influence of temperature variation on polarization characteristics of silver thin film mirror

Optical payloads in space remote sensing applications impose increasingly high requirements on system polarization control. As a wide spectral reflector, the polarization characteristics of silver thin film mirror usually changes with the ambient temperature. In this paper, silver thin film mirrors with low polarization sensitivity are designed and fabricated. The changes of polarization characteristics and reflection spectrum of the mirrors with room temperature from 25℃ to 150℃ are investigated at 45° and 60° incident angles. The refractive index of silver thin film increases in spectral range of 350 nm to 1 200 nm with the increase of temperature. The phase difference Δ between the s and p light in the reflected light of the silver film mirror is reduced in the wavelength range of 350 to 600 nm, keep stable in 600-650 nm, and increases in the wavelength range of 650 to 1 200 nm. The surface morphology of the silver film and mirror changes, and the surface scattering and absorption increases when temperature reaches 125℃, resulting in a decrease in reflectivity in the 350-900 nm band and even a decrease of about 25% in the wavelength of 350 nm.