基于双AOTF的新型成像光谱偏振探测系统

The Research of Spectral Polarization Imaging Detection System Based Dual-AOTFs

声光可调谐滤波器(AOTF)具有体积小、波长稳定性好、扫描范围宽、调制速度快等优点,在光谱成像中被广泛应用,但单独采用AOTF的成像光谱偏振探测还较少。为此提出只采用两个AOTF的成像光谱偏振探测新方法。该方法首先通过分束镜将入射光分成两束,两束光分别通过两个AOTF,而两个AOTF的正一级衍射光的偏振方向互成45°,由于AOTF的正一级衍射光的偏振方向互相垂直,因此两个AOTF的正负一级分别可得到0°,45°,90°和135°的光强,在测量中需保持两个AOTF的滤光所对应的波长完全相等。最后通过对两个AOTF的正负一级衍射成像,最终得到Stokes偏振信息中S0(0°和90°光强和)、S_1(0°和90°光强差)和S_2(45°和135°光强差),结合相应的理论公式对被测目标的线偏振度(DoLP)和线偏振角(AoLP)实现成像。再通过对AOTF的射频驱动进行扫频,实现对被测目标不同波长偏振成像,最终实现成像光谱偏振探测。并通过对500,550和600nm偏振成像进行实验验证。该方法具有无运动部件、无需转动、一次测量同时获得成像光谱偏振信息的优点。

Acousto-optic tunable filter（AOTF）has the advantages of small size,good stability,wide range of wavelength scanning,quick modulation speed and so on.So AOTF is widely used in spectral imaging.But the detection of spectral polarization imaging is seldom found by using AOTF individually.,Anew method of spectral polarization imaging based on dual-AOTFs is proposed.This method shows that the incident light is firstly divided into two beams by splitting mirror,and then two beams of light are through two AOTFs respectively,and the polarization direction of ＋1 diffraction order formed by AOTF is at a 45° against the other.The intensity of 0°,45°,90°and 135°can be obtained by ±1 diffraction orders of dual-AOTFs.Finally,the Stokes parameters are obtained by ±1 diffraction orders imaging of dual-AOTFs.They are S_0（the sum of light intensity between 0°and 90°）,S_1（the difference of light intensity between 0°and 90°）and S_2（the difference of light intensity between 45° and 135°）.The target degree of linear polarization（DoLP）and angle of linear polarization（AoLP）is realized by corresponding theoretical formula.Furthermore,the polarization imaging of different wavelengths is realized with frequency sweep of dual-AOTFs so as to ultimately detect the spectral polarization imaging.The experiment has been verified through polarization imaging of three different lights,such asλ=500nm,λ=550nm and λ=600nm.