Five-degree-of-freedom measurement system and method based on two-dimensional absolute grating

The invention discloses a five-degree-of-freedom measurement system based on a two-dimensional absolute grating. The five-degree-of-freedom measurement system comprises a CCD camera, a coaxial light telecentric lens, a laser, a beam splitter, a field-of-view separation device, a two-dimensional absolute grating coding disc, a plane mirror and an image processing module, the two-dimensional absolute grating coding disc is fixed on the precise workbench; coaxial light emitted by the coaxial light telecentric lens is irradiated on the two-dimensional absolute grating coding disc through the view field separation device to form two independent view fields; the CCD camera obtains an image in the field of view and transmits the image to the image processing module, and X-Y-theta position information is obtained after processing; light emitted by the laser is irradiated to the plane mirror pasted on the two-dimensional absolute grating coding disc through the beam splitter, and the light is projected to the CCD came