High-accuracy displacement detection device and method

The invention discloses a high-accuracy displacement detection device and a high-accuracy displacement detection method, which belong to the field of optical detection. The device comprises a short coherent light source, a collimating lens, a polarizer, an optical splitter, a focusing lens, a reflecting mirror, an analyzer, an image sensing device and two 1/4 wave plates, wherein the short coherent light source, the collimating lens, the polarizer, the optical splitter, the first 1/4 wave plate and the reflecting mirror are arranged in sequence in one row to form a first light path; the focusing lens, the second 1/4 wave plate, the optical splitter, the polarizer and the image sensing device are arranged in sequence in one row to form a second light path; the first light path and the second light path intersect with each other through the optical splitter, and are vertical to each other; the light output end of the short coherent light source faces the collimating lens; and the reflecting mirror is arranged o