基于线偏振片和液晶可调滤光片的斯托克斯参量测量系统

Stokes Parameter Measurement System Based on Linear Polarizer and Liquid Crystal Tunable Filter

为了快速获得无抖动偏振图像,本文提出了一种实时测量斯托克斯参量的新方法,即在固定不动的液晶可调滤光片(LCTF)前加一块可旋转的偏振片,使入射光依次经过线偏振片和LCTF到达CCD,然后通过计算接收到的光强得出斯托克斯参量,确定光束的偏振态,得到偏振图像。通过计算发现,当LCTF透光轴与系统X轴的夹角为π/8,偏振片透光轴与系统X轴夹角分别为0、π/4、π/2和3π/4时,偏振参数的获得就比较简单。偏振片的旋转代替了LCTF的旋转,测量的偏振图像无抖动,偏振度和偏振角图像精确。该系统可以获得较高的帧频,在目标识别和反伪装领域具有重要的应用价值。

To obtain a vibrationless polarization image rapidly, a new real-time Stokes parameter measurement method is proposed. First, a rotatable linear polarizer is mounted in front of a fixed Liquid Crystal Tunable Filter （LCTF） so that the incident light can pass through the linear polarizer and the LCTF in turn and fall on a CCD. Then, through the calculation of the intensity of the received light, the stokes parameters are derived, the polarization state of the light beam is determined and a polarization image is obtained. The calculation result shows that when the angle between the optical axis of the LCTF and the X-axis of the system is π/8 and the angle btween the optical axis of the linear polarizer and the X-axis of the system is 0, π/4, π/2 and 3π/4, it is easier to obtain the polarization parameters. Since the polarizer is rotated other than the LCTF, the measured polarization image is vibrationless and its polarization degree and angle are rigorous. This system can obtain images at a high frame frequency and is of significance to object identification and anti-camouflage.