| The demodulation technique of orthogonal polarized laser interferometer is one of the crucial preconditions that, for the moment and future, it will be priority project in laser interferometer signal demodulation domain. The advanced and credible signal demodulation technique may improve the measurement precision of laser interferometer greatly; make the resolution to 1nm or 0.1nm level. Therefore, orthogonal signal demodulation technique will be very useful in precision measurement, ultra-precision manufacturing, space technology, material science, etc,In this dissertation, the output signal's characteristic of orthogonal polarized laser interferometer was analyzed. It studied the interference signal demodulation technique deeply, and mainly designed signal demodulation hardware, signal nonlinearity error correction and fringe subdivision. The main works and contributions achieved in this dissertation were concluded as follows:Firstly, it designed photo-electronic conversion circuit with low noise and adjustable gain, anti-aliasing filter circuit and nonlinearity error pretreatment hardware. It realized low noise and high gain photo-electronic conversion and interference signal pretreatment function.Secondly, it studied interference signal's characteristic, originally discusses ellipse fitting method's parameter error characteristic, which is based on least square method. Then, it gave correction criterion. In addition, it designed an experiment which is based on the TMS320VC5416 evaluation board to validate this arithmetic.Thirdly, it designed tangent table-checking fringe subdivision scheme. It discussed subdivision error carefully, and finally realizes 456 points subdivision in one period.Lastly, it implemented orthogonal interference signal demodulation system's experiment study. The experiment result indicated that, this signal demodulation system can achieve 0.79nm displacement measurement resolution. It gave out experiment result error analysis in the end.
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