Demodulation Method and Experiment Study of Orthogonal Polarized Laser Measurement

Orthogonally polarized laser interferometer signal demodulation is one of the prerequisites to achieve high-precision nano-scale laser interferometry , now and in the future will be the key topics of the entire laser interferometer field of signal demodulation . Advanced and reliable quadrature signal demodulation techniques can make the laser interferometer measurement accuracy has been greatly improved , the nanometer or even sub-nanometer Therefore, the quadrature signal demodulation techniques such as precision measurement , microelectronics , super finishing , space technology , materials science and other fields has broad application prospects . This paper focuses on the orthogonally polarized laser interferometer signal output characteristics of the the orthogonal interference signal phase demodulation technology to do in-depth research and exploration , focusing on the signal demodulation system hardware design , signal nonlinearity error calibration and thin stripes sub-technical design , the main research contents and the results obtained can be summarized as follows : First , the design of low noise gain adjustable photoelectric conversion circuit and anti-aliasing filter circuit as well as non - orthogonal signals orthogonal pre - processing hardware circuit to achieve a the low noise and high gain of the photoelectric conversion and the interference signal preprocessing functions . Secondly, the study of laser interference signal error characteristics discussed in depth for the first time based on the method of least squares ellipse fitting algorithm parameters error characteristics of calibration algorithm criterion and design experiments , the TMS320VC5416 Evaluation Board platform on its verified. Again, the design of the interference signal tangent look - up table stripe segmentation software solutions , segmentation error were carefully studied , and ultimately to achieve a cycle of 456 points stripes subdivision precision . Finally, orthogonal interference signal demodulation system simulation experiments , experimental results show that the signal demodulation system can achieve the 0.79nm measuring displacement resolution , and finally give the error analysis of experimental results .