Symmetric and compact heterodyne interference grating displacement measuring system

A symmetric and compact heterodyne interference grating displacement measuring system comprises a dual-frequency laser device, a non-polarizing beam splitting prism, a Wollaston prism, a polarizing plate, a one-dimensional metering grating, a photoelectric detector and a signal processing unit, wherein orthogonal linearly polarized light emitted from the dual-frequency laser device is split into two beams after passing through the non-polarizing beam splitting prism; one beam passes through the polarizing plate and is received by means of the photoelectric detector to generate a reference signal; the other beam is divided into two paths of polarized light in different polarization directions by means of the Wollaston prism, the two paths of polarized light are incident on the surface of the metering grating in a symmetrical manner, return to the original paths after being diffracted by means of the metering grating satisfying a certain period conditions, and are received by means of the photoelectric detector