高光谱偏振成像全Stokes参量获取新方法（英文）

New Method for Obtaining Full-Stokes Parameters of High-Spectral Polarization Imaging System

考虑到现有Stokes参量获取方法测量速度慢、测量精度低、系统结构复杂等特点,提出了一种基于双液晶可调相位延迟器(liquid crystal variable retarder,LCVR)和声光可调滤波器(acousto-optic tunable filter,AOTF)的光谱偏振成像系统中全Stokes参量的新获取方法。从AOTF和LCVR的工作原理出发,介绍了系统的基本探测原理;根据偏振分析提出了快速获取全Stokes参量的新方法——该方法选取四个固定的LCVR控制电压,同时控制两个相同的LCVR对光波进行相位调制,得到四组(八个)两两相同的相位延迟量即可求得Stokes参量。此外,设计了能够稳定输出均方根为0^+8.72V连续可调方波的LCVR控制器,并对其进行定标,实现了不同波长下光波的精确调制。搭建实验样机,以偏振方向分别为0°,90°和45°的三个偏振片P_1,P_2,P_3作为偏振测量目标,测得了波长为632nm时的全Stokes参量图;以画有夹角为30°的红色、绿色、蓝色三色线条的实验板作为光谱测量目标,对400~750nm光谱范围的71个通道(光谱带宽为5nm)进行光谱成像,得到了与红色、绿色和蓝色的分析谱段范围相一致的光谱曲线。结果表明,该系统不仅可以快速准确地获取全部Stokes参量,而且系统结构简单、成像质量良好。

Taking into account of the slow measuring speed ,low measuring accuracy and complex system structure of the existing Stokes parameters acquisition method ,a new acquisition method of full-Stokes param-eters in double Liquid Crystal Variable Retarder （LCVR） and Acousto-Optical Tunable Filter （AOTF） combi-ning spectral polarization imaging system is established .Based on the working principle of AOTF and LCVR , this paper has explored the basic detection principles of the system before a new method for fast acquisition of full-Stokes parameters is proposed .According to polarization analysis ,fixed control voltage is selected as the basis ,in which four fixed voltages are selected as the control voltages of LCVR ,and two identical LCVR are controlled at the same time to complete phase modulation of optical waves .The Stokes parameters can be ob-tained with four groups of phase delay which are plunging the same .Besides ,a LCVR controller is designed to stabilize the output square wave whose root mean square is 0 to ＋8.72 V .Then ,its calibration is carried out in order to realize precise modulation of different optical waves .Finally ,an experimental prototype is set up to test the target ,with three polarizing plates P1 ,P2 and P3 whose polarization directions being 0 ,90 and 45 de-grees respectively as the targets of polarization measurement .The full-Stokes parameter figures with a wave-length of 632 nm is obtained;paper painted with red ,green and blue lines and the angle of 30 degrees are used as the target of spectral measurement ,spectral imaging on 71 channels of 400~750 nm spectral range （spectral bandwidth of 5 nm） ,the spectrum curves of red ,green ,blue are acquired which accordant with their theoreti-cal spectral graphs .The results show that not only all the Stokes parameters can be obtained quickly and accu-rately with the system ,but also the structure of system is simplified and the imaging quality is improved .