Research On Hyperspectral Polarization Imaging Method Based On Ferroelectric Liquid Crystal Modulation And Birefringence Interference

The Spectropolarimetric Imager is capable of acquiring two-dimensional spatial information of the scene,spectral information of each point,and polarization information in each spectral band.It is a novel optical detecting instrument,which improves the ability to detect and recognize the target.Research on hyperspectral polarization imaging technology is of great significance in the fields of biomedicine,precision agriculture,environmental monitoring,military reconnaissance and astronomical detection.The measurement of high-dimensional information takes a long time.So improves the measurement efficiency is very important for the promotion of hyperspectral polarization imaging technology under the premise of ensuring resolution and measurement accuracy.In order to realize fast,high precision,high optical resolution and high signal to noise ratio spectral polarization imaging detection,a new hyperspectral polarization imaging system based on ferroelectric liquid crystals and birefringence interference is proposed.The main research includes the following sections:This paper first describes the optical path structure of the hyperspectral polarization imaging system,and introduces the principle of spectral and polarization imaging of the system,including: Fourier transform spectroscopy and time-sharing polarization modulation.Then the modulation and demodulation process of spectral and polarization information is studied,and on this basis,the system equation is derived.At the same time,the simulation verified the feasibility of quadruple rate sampling.The design problems of FLC polarization analyzer and Savart birefringent shear are studied.The synchronous control signals of FLCs and the detector are designed.The polarization response matrix of FLC polarization analyzer is optimized by genetic algorithm according to the condition number evaluation criterion,therefore noise immunity for polarization measurements is improved.The transverse shear principle of Savart plate is studied,and the improved Savart birefringent shear is designed to solve the problem of spectral line position drift during spectral recovery.To study the calibration method of spectral polarization imager,a feasible calibration method is proposed.Aiming at the flat field problem in the relative radiation calibration process,a frequency domain filtering method based on symmetric extension is proposed to extract the background information,which effectively corrects the non-uniformity of the vertical stripe direction.The method of adjusting the key components is studied and the system prototype is built.A fast and high-precision image registration algorithm is proposed for the motion registration of the system in the spectral restoration process.The experimental results are used to verify the effect of the algorithm.The scene is measured by a system prototype.The experimental results show that the proposed high-spectral polarization imaging system based on ferroelectric liquid crystal and birefringence interference can effectively measure the spectral polarization information.