Research On The 1.55 Micron Laser MEMS Scanning Heterodyne Interferomer

As technology develops, people'requirements on the processing and measurement accuracy are getting higher and higher, sub-micron to nanometer accuracy measurement has becoming the urgent problem to be solved in the industrial development and scientific development nowdays. Laser heterodyne interferometer has such advantages as follows: non-contact damage,little noise, fast response, large measuring range, high signal to noise ratio,overcomming direction fuzzy and changes in light intensity,so it has been widely studied and applied.Derived the mathematical model of balanced heterodyne receiver,specially studied the relationship between the balanced heterodyne receiver signal to noise ratio and fiber optic beam splitter splitting ratio,by means of MATLAB numerical simulation,theoretical verified the balanced heterodyne receiver can suppress local oscillator noise.Analysised the basic theory of optical scanning system and it's requirements on heterodyne interferomete.Established the theoretical model of heterodyne interferometer nonlinearity error,by means of analysis and deduce,finally got the expression of nonlinearity error caused by the acoustic-optic modulator frequency aliasing, laser beam ellipsometry, disclosure and rotation error of polarization beam splitter, non-ideal characteristics of polarizers and so on. By using MATLAB simulation the nonlinear error curve under various conditions, analysis, discussion and finally got size and forms of various factors on the heterodyne interferometer nonlinearity error: non-ideal optical components are mainly showing the first or second harmonic of the practical phase.Finally, a semi-free space,semi-1.55-micron optical fiber channel scanning heterodyne interferometer system has been designed and built,using the component and apparatus in our laboratory.Obtained single point and scanning results.