Study On Optical System Of Simultaneous And Complete Polarization Imaging

Polarization imagers are able to identify the target that may be difficult toconventional ones. They can reduce the influence of stray background and complexenvironment and enhance capability of target detection and recognition. Thedissertation researches a new type of simultaneous polarization imaging optical systemwith divided aperture, and its prototype is designed and manufactured, which isexpected to be used as airborne and spaceborne payload. The main contributions aresummarized as follows:The issue and significance of the dissertation is put forward in the first chapter.The application fields and research progress of polarization imaging systems arebriefly summarized. The main contents of dissertation are outlined.In second chapter, polarization characteristics of light and its quantitativecharacterization method is introduced. Modeling and imaging principle of generalpolarization imaging system are described. Existing polarization imaging methods arecompared and analyzed. According to requirements for practical usage, anaperture-divided simultaneous polarization imaging system without relay lens isproposed, which is consists of an aperture shared lens group and four aperture-dividedlens groups. It is capable of simultaneous complete Stokes vector imaging withcompact configuration.In third chapter, an optical transfer matrix (OTM) method is proposed to eveluatethe imaging quality in polarization imaging system and to analyze its polarizationmeasurement errors. The relationship of their OTM and polarization measurementerrors to their parameters is derived and analyzed with examples. OTM can describe not only imaging quality of each polarization channels but also the crosstalk betweendifferent channels.In fourth chapter, the basic parameters, including field angle of view, workingwavelength band, effective focal length, and relative aperture of the optical system tobe developed, are determined from its signal-to-noise ratio requirements and paraxialimaging theory. Two layouts of such aperture-divided imaging systems, consisting oftwo groups of lenses and three groups of lenses respectively, are suggested, and theirparaxial imaging properties are analyzed. Based on primary aberration of on-axis lensand transfer relations of skew rays, their primary aberration formula andcharacteristics and corresponding PW representation are derived and analyzed.In fifth chapter, method and result for determination of their initial structuralparameters is given based on the derived PW representations. Optimization design andimaging quality of both types of aperture-divided decenterd imaging systems arereported. It is shown that the designed lenses and their imaging quality meet therequired performance. Their tollerance is analyzed and its allocation optimized. Therelationship of polarization measurement tolerance to manufacture, assembly andalignment tolerances of polarization components is derived and analyzed from errortransfer formula and the derived polarization measurement error formulas.In sixth chapter, the manufacture process and result of aperture-dividedpolarization imaging optical system is reported. The optomechanical structure isdesigned. After alignment, the focal length and the OTF are measured. Thesimultaneous complete Stokes polarization imaging prototype is builted with thedeveloped lens and a CCD detector. Imaging experiments for unpolarized, linearlypolarized, elliptically polarized targets and natural objects is accomplished,respectively, in order to validate its polarization imaging performance. CompleteStokes vector, polarization degree and polarization angle images of these targets areachieved through processing the obtained four-channel images. Imaging experimentalresults are consistent with our design and theoretical expectations. In the last chapter, the main work and the innovative points of this dissertation aresummarized, and the further work is prospected.