Optical system design of four-channel low light level polarization imaging

In order to improve the quality of low-light-level(LLL) imaging and achieve the requirement for real-time imaging for dynamic targets or changing scenes, a LLL polarization real-time imaging optical system was designed based on the polarization imaging principle and the division of aperture technique. To achieve simultaneously polarization imaging, the optical system uses an array of common-caliber four-channel configuration. This structure divides four polarization states to be measured into four independent imaging channels, and four-quadrant segmentation imaging is performed on the target surface of the detector through a sub-aperture imaging group set. Each polarized channel obtains an intensity image with different polarization states by placing polarizing plates with different polarization states. The focal length of the optical system is 100 mm, the system whole F number is 1.2, the operating wavelength is 0.4 μm~0.85 μm, the minimum working illumination is 1×10^-3 lx, and the 1 080 pixel full high-definition (HD image) can be outputted. The total optical length of the system is 167.5 mm, and the modulation transfer function (MTF) value of the single-channel is higher than 0.57 at 40 lp/mm in full field of view.