High-optical-subdivision grating interferometer based on plane mirrors

A high-optical-subdivision grating interferometer based on plane mirrors comprises a double-frequency orthogonal linear polarization laser light source, a polarization beam splitter, the first mirror, the second mirror, the third mirror, the fourth mirror, a first quarter wave plate, a second quarter wave plate, a scale grating, a data collection, processing and control unit and a double-frequency heterodyne interference photoelectric detection unit which is composed of a non-polarization beam splitter, a first analyzer placed on the orthogonal double-frequency linearly polarized light by 45 degrees, a first detector corresponding to the first analyzer, a second analyzer placed on the orthogonal double-frequency linearly polarized light by 45 degrees and a second detector corresponding to the second analyzer. The scale grating is designed into a high-density -1-level sub-high diffraction efficiency reflection type grating, measurement light beams are diffracted multiple times through the scale grating through the combination with the plane mirrors, and therefore the high optical subdivision fold can be obtained, and important application value in the field of increasing the grating interferometer resolution ratio and accuracy is achieved.