The present invention discloses a large
radial displacement margin type
laser heterodyne interference angle
measurement device and a method thereof. According to the invention, two faraday rotators are adopted to realize the exact
orthogonal transformation of the
linearly polarized light in the polarization direction in a
laser heterodyne interference angle measurement light path. The device comprises a
laser heterodyne interference angle detection light path part and an angle measurement mirror. According to the invention, a light path structure is formed by faraday rotators, a
polarization beam splitter, a quarter-wave plate and a
plane mirror. Based on the light path structure, when a large
radial displacement error occurs in a measurement mirror, the effective return of a measurement
light beam is realized. According to the invention, the technical problem in the prior art that based on traditional
laser interference measurement mirror angle measurement techniques, the measurementlight beam deviates from an initial detection aperture on a
detector, caused by the large
radial displacement of the measurement mirror, so as to influence the normal generation of interference signals and even cause the interruption of interference measurement can be solved. The angle measurement of
high resolution and large measurement range can be realized. The device and the method are suitable for the angle measurement and calibration of precision operating platforms in the fields of precision
machining, manufacturing,
mechanical system adjustment, calibration and the like.