| With the rapid development of science and technology,heterodyne interferometric measurement system has been widely used in ultra-precision machining and measurement.In practical application,the measurement result of the system is often affected by many factors.This paper analyzed the factors and proposed the corresponding suppression method to improve the accuracy of the system,especially for the optical nonlinear error and the environment error.The main research works done in this paper include:(1)The measuring principle was analyzed based on Doppler Effect and the theory of heterodyne interferometric.The error in the measurement system is measured and the data are analyzed with the results of total error 44.7388 nm.(2)Various factors in heterodyne interferometric measurement system,such as optical nonlinear error and environment error are studied and analyzed.The mathematical model for optical nonlinearity error with transmission coefficient of PBS was established and simulated,and so did the model for air refractive index with temperature,humidity and pressure was established and simulated,which provided a theoretical basis for the proposing of corresponding suppression method.(3)Two methods were proposed for the optical nonlinearity error of the system.According to frequency doubling method,a new four passage heterodyne interferometer was designed and verified in the experience system.It could reduce the error to 32.28 nm.Also,based on phase compensation method,a quarter-wave plate and a polarizer were added and the polarizer was rotated in the heterodyne interferometric measurement system,this method could reduce the error of the system to 22.45 nm.(4)To reduce the environment error of the system had been phase compensated,different errors of the system under different temperatures were measured to figure out the optimal operating temperature of the system.The index of air had been corrected and the error of the measurement system had been reduced. |
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