A Study Of High-presion Phase Extraction For Heterodyne Interferometer Of Infrared Laser

With the development of aerospace and other important national science and technology projects, along with the uniformity of large aperture optical material, needs for high-precision measurement are more urgent. But some of the infrared optical material like Ge, Si, PbS can not be projected visible light by the conventional laser interferometers.These precision infrared optoelectronic materials and equipment’s applicatied in infrared camera, large laser windows,infrared semiconductor wafers and other sophisticated equipment application.For these reasons, this paper does deep reaserch in the key issues in the accuracy of MEMS scanning infrared laser heterodyne interferometer by simulation methods. Algorithms are used to extract the phase information. After further processing, the discrete thickness information of the sample can be obtained.First,it gives a brief introduction to the structure of each module of the infrared laser heterodyne interferometer and MEMS scanning system structure principle and the principle of collecting data acquisition card. In addition,it analysis of the research progress of the algorithm on external difference signal extraction. As used herein, it eventually establish three kind of the phase extraction algorithms and develops the overall program of the experiment. three algorithms for mathematical (Least Squares, IQ quadrature demodulation method,FFT)and logical principles are elaborate theoretical analysised.Second, three algorithms were compared by MATLAB software simulation studies. The main research projects Include the computing speed and accuracy of three algorithms and the comparative analysis of the sampling frequency, the frequency of the signal to noise ratio on the accuracy of the calculation of the size of the three algorithms.After the results’ analysis，then the semi-simulation applications optimized optimal algorithm is choosed.It aso use the simulation method for MEMS scanning study.The use of MEMS scanning principle simulation program are described at last. GUI emulation interface is displayed.Third, I use a signal generator, data acquisition cards do a same research like the full simulation before. I do a deep research on computing speed and accuracy of research on FFT algorithm.The phase transition of the principle of compensation algorithms is described. The effects of the experiment of adding compensation algorithm on the experimental results is descriped.Fourth, FFT algorithm for computing the results in both simulation methods were compared.The same with the previous content, it is a operation of the algorithm speed and accuracy comparative study. Finally, the error sources were analyzed and summarized.