Two-degree-of-freedom heterodyne grating interferometry measurement system

A two-degree-of-freedom heterodyne grating interferometry measurement system, comprising:

• a single-frequency laser device for emitting a single-frequency laser, the single-frequency laser split into a beam of reference light and a beam of measurement light;
• an interferometer mirror group and a measurement grating for forming a reference interference signal and a measurement interference signal from the beam of reference light and the beam of measurement light,
• a plurality of receiving optical fibers for receiving the reference interference signal and the measurement interference signal, wherein a core diameter of each of the receiving optical fibers is smaller than widths of interference fringes of the reference interference signal and the measurement interference signal, so that the plurality of receiving optical fibers receive parts of the reference interference signal and the measurement interference signal, and wherein the interferometer mirror group, in sequence from one side to an opposing side, comprises:
• a reflecting mirror, a refractive element, a quarter wave plate, a beam splitting prism, and a polarization splitting prism, wherein the beam splitting prism is positioned on the polarization splitting prism.