Research On Integration Design Of Double-frequency Laser Heterodyne Interference Scanning Detection System

With the constant progress of science and technology,the development of electronic product has a trend with higher integration and higher performance.Meanwhile,the size of the product is becoming smaller and smaller,so the detection technology is more and more important.Therefore,the research and exploration of the detection system optimization and instrumentation design has a good application and a development prospect.In this paper,based on the research status of optical surface detection methods at home and abroad,the integrated dual-frequency laser heterodyne interference scanning detection system is proposed.It includes an integrated two-frequency laser heterodyne interference module,three-dimensional scanning displacement table module and data processing module.In the integrated design of dual-frequency laser heterodyne interferometer module,the space occupied by optical devices can be reduced greatly,and the whole module can also be moved freely.And the alignment of the optical path can be well adjusted under the condition of reducing the degree of freedom.The integrated double-frequency laser heterodyne interference module has been designed.The adjustment of the lens angle must be ensured smoothly.The spring and screw are used to adjust the lens angle continuously,and the light path can be ensured in laymen.Based on the Jones matrix,the mixing error of the optical system is analyzed.The parameters of the integrated system are taken for the numerical simulation.The influence of reflection coefficient ratio r and transmission coefficient ratio t of PBS on the mixing error is analyzed.The influence of angle between fast axis and X axis of 1/4 wave plate on the mixing error is also analyzed.The results show that the maximum mixing error of the optical integrated system is 0.68 nm.A self-checking light path for testing the feasibility and stability of integrated parts is designed in this paper.The measurement stability experiments are carried out on the integrated system and the original system respectively.The results show that the measurement displacement drift is 1.47 nm and 1.51 nm at the same time respectively,and the results also show that the measurement stabilities of two systems have basically the same value.It indicates that the design of optical integrated system is feasible.At the same time,due to the integration of the whole module,the integration system has the advantages of the reducing the occupancy space and switching quickly when having several detection modules.Thus the integration of discrete components of the system can be realized.