Autocollimation form dual-frequency laser diffraction grating interferometer design and analysis

Propose a new measurement system of autocollimation form laser grating heterodyne interferometer. Take grating diffraction and polarization optics as theoretical foundation, combined with electronics knowledge to analyze the system. First, the interferometer measurement system take grating pitch as measuring datum, therefore, reduce the impact of environmental factors, measurement error is small; second, make use of autocollimation diffraction of grating, the structure is simple, stable, easy to install and debug; furthermore, measurement information obtained by dual-frequency laser belongs to ac signal, possess great gain and high signal-noise ratio, completely overcome the disadvantages of DC level drift caused by light intensity variation of single-frequency laser; system can achieve nanometer resolution.