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

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 S0 (the sum of light intensity between 0° and 90°), S1(the difference of light intensity between 0° and 90°) and S2 (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 as λ=500 nm, λ=550 nm and λ=600 nm.