Laser interferometers are generally divided into single frequency and dual frequency. China Library Laser Interferometer products adopt high-frequency stable He-Ne laser imported from the United States, laser double longitudinal mode thermal frequency stabilization technology, high-precision environmental compensation module, geometric parameter interference optical path design, high-precision laser interference signal processing system and high-performance computer control system technology to achieve high-precision measurement of various parameters. Laser thermal frequency stabilization control technology can realize laser frequency output with high speed (about 6 minutes), high precision (0.05ppm), strong anti-interference ability and good long-term stability. Geometric quantities such as straightness, angle, straightness, flatness and verticality can be measured by different optical lens groups, and dynamic analysis can be carried out.