Research On Interferometric Hyperspectral Polarization Imaging Technology Based On Liquid Crystal Modulation

Fourier transform imaging spectropolarimeters can measure spatial,spectral,and polarized four-dimensional data cubes and provide much information regarding various target features.These instruments have been explored for their potential to improve target recognition capacity in various applications,such as biomedical science,remote sensing,and military surveillance.A time-division Fourier transform imaging spectropolarimeter for acquiring spatial,spectral,and polarized information is presented.The proposed Fourier transform imaging spectropolarimeter employs two ferroelectric liquid crystals(FLCs)and a Wollaston interferometer.To the best of our knowledge,this is the first time FLCs have been used for rapid polarization modulation in the Fourier transform imaging spectrometer to obtain the spectropolarimetric information.The fast axes of the FLCs are controlled to switch quickly without mechanical movement,enabling the polarization state analyzer(PSA)to modulate the full set of Stokes parameters rapidly.The interferometer combines a Wollaston prism with a retroreflector,enabling high interference modulation and facilitating optical alignment.The remainder of this report is organized as follows.First,the principle of the proposed Fourier transform imaging spectropolarimeters is briefly introduced.The modulation and demodulation mechanism of the spectral and polarized information in the Fourier transform imaging spectropolarimeters is studied.This proposed Fourier transform imaging spectropolarimeter implementation is based on the principle of quadruple-sampling proposed in this work.Second,an optimization design of the broadband polarization state analyzer of ferroelectric liquid crystal is proposed.The Stokes measurement matrix of the PSA is deduced in terms of the principle of broadband polarization imaging.The synchronous electronic control signal about the data acquisition is designed.The genetic algorithm is selected to manage the global search.The combination mode and angles of the polarization components are optimized by genetic algorithm with evaluation criteria of Condition Number(CN)and Equally Weighted Variance(EWV).In the FLC-PSA configuration,the ordering of the components is determined by using CN as evaluation criterion.The accuracy of the algorithm is verified by comparing the optimization results of CN and EWV.Third,the design of the lateral shearing beam splitter using a Wollaston prism and a retroreflector is analyzed.The structural parameters of each optical device,and the simulation of the nonlinear distribution of the optical path difference are included.The method of recovering spectral and polarized information are discussed in detail.Finally,an alignment method based on the maximum light intensity is proposed for calibrating the fast axis azimuths of the phase retarders,and the sampling interval of wave number is calibrated.To verify the proposed scheme,a set of experimental device is set up,both laboratory and outdoor experiments were performed by the experimental device.Furthermore,the error source and SNR analysis of the proposed system are analyzed.The experimental results demonstrate that the proposed Fourier transform imaging spectropolarimeter offers much promise for spectropolarimetric measurement with the advantages of fast speed,high spectral resolution,and high signal-to-noise ratio.