Error Analysis of Frequency Mixing on Heterodyne InterferometryDetecting Device for Superfinish Surface Scratch

摘要

The precision measurement on surperfinish surface scratch has been currently paid much attention to on electronicproducts. To meet these demands, a novel method has been proposed which is based on heterodyne interferometry thatutilizes birefringent lens as beam splitter and cantilever tip as scanning probe to get the measurement values of sampletopography. But the optical nonlinear errors affect the measurement precision of the system. In this paper, we adopt theJones matrix to analyze the elliptic polarization caused by the three factors existing at the same time, which arepolarization ellipticity of laser source, installation orientation error and phase retardation of birefringent lens. Themeasurement errors of frequency mixing about these elliptic polarization beams arriving at the photodiode detecter arestudied by vector theory. The results show that the measurement errors are periodic errors, and they will change from1.24nm to 3.94 nm when the magnitude of orientation error of birefringent lens changes from 1°to 5°. Also, the methodsof reducing measurement errors according to the numerical results in the system are suggested. The measurementprecision will be improved by reducing the orientation error or choosing high performance laser source