Research On Key Technology Of Integrated Triple-beam Homodyne Laser Interferometer

With the development of the precision and ultra-precision machinery manufacturing and processing, microelectronics equipment, nanotechnology industrial equipment and other technical fields, the requirements of synchronous measurement of linear and angular displacement with high-precision are proposed. In the case of measurement requirements with high-precision and high-resolution, homodyne laser interferometer is widely used in nano-measurement system for that its system structure is relatively easy to integrate, signal processing is relatively simple and other advantages.The dissertation ‘Research on key technology of integrated triple-beam homodyne laser interferometer’ is mainly to the key technology of synchronous measurement of linear and angular displacement with high-precision. Including the system design of optical and mechanical structure, and the nonlinear errors correction based on light switch. The the main research works of the thesis are as follows:Aiming at the synchronous measurement of linear and angular displacement, the paper proposes a kind measurement of triple-beam homodyne laser interferometer, analyzes the principle of the optical design using Jones matrix, based on the linear displacement of the homodyne laser interferometer, the angular displacement principle is given. First, analysis the apatial characteristics of the laser in the triple-beam measurement and its influence on the measurement result, including the analysis and simulation on the parallelism between lasers, the design and analysis of the laser adjusting mechanism and the detection on the lasers’ parallelism and polarization state; finally complete the integrated system design, including the design of the laser splitting mechanism and integrated system design of optical and mechanical structure.Aiming at the correction model in the traditional nonlinear errors correction only can be established elliptic fitting by moving more than half wavelength, the paper research a new kind of correction method, by adding the light switches in both the measurement and reference arms, tne correction can be achieved without the request of the moving more than half wavelength. Before the measurement turn on the system and get all the initial DC offset states by controling the light switches, then using these initial signals to accomplish the correction in the measurement, basically realize the elimination of the DC offset and AC amplitude and the phase delay, establish the correction model, and realize the precise linear and angular measurement.Finally, design and develop integrated triple-beam homodyne laser interferometer based on the above methods and key technologies, then test its key technical indexes, give the resolution and measuring range for the linear displacement, pitch angular displacement and yaw angular displacement. The experimental results indicate that in the case of without pase subdivision acquisition, the resolution of the linear displacement can achieve 3nm, the measuring range can achieve 60 mm at the distance of 200mm; the resolution of the pitch angular displacement can achieve 0.01″, the measuring range can achieve ±51.8″at the distance of 100mm; the resolution of the yaw angular displacement can achieve 0.01″, the measuring range can achieve ±86.4″at the distance of 100 mm. It can receive more favorable measurement characteristics with better lasers’ parallelism and more stringent test environment.