基于频域分析的抗振移相干涉测量

Vibration-insensitive phase-shifting interferometry based on frequency domain analysis

针对移相干涉测量中振动引起的移相误差和对比度变化,提出了一种从空间载波干涉图频谱中提取移相和对比度信息的方法。该方法通过分析载波干涉图频谱,从基带和边带中提取移相和对比度信息,运用最小二乘法补偿对比度变化并复原波前位相。最后采用构造平滑孔径函数对带有孔径的干涉图进行处理。数值仿真证明:提出的方法可以高精度检测移相量和对比度变化,能够有效补偿因对比度变化引起的位相复原误差。在频率为9Hz、幅度为0.5μm的简谐振动条件下实验验证了本文方法的实用性。结果显示:从受振动干扰的干涉图中复原平晶表面时,其复原误差PV值小于0.015波长。该方法无需硬件改动,有望为移相干涉测量应用于现场测量提供一种低成本的解决方法。

An algorithm was proposed to deal with the phase-shifting error and contrast variation in a Phase-shifting Interferometry （PSI） under vibration.The algorithm detected phase shifts and contrast variation by analyzing the spectra of spatial-carrier interferograms firstly.Then the phase shifts were used as priori information to retrieve the wavefront phase from least-square equation with contrast compensation.To deal with interferograms with non-rectangular aperture,a mask with soft border was constructed and data extrapolation was avoided.The effectiveness of the proposed algorithm was validated by simulations and experiments.The simulation results show the proposed method can detect the phase shifts and contrast variation in high accuracy and can compensate effectively phase retrieval errors caused by contrast variation.The practicability of the algorithm was verified under a simple harmonic vibration with a frequency of 9 Hz and an amplitude of 0.5 μm.The measurement under vibration demonstrates that the retrieval error of a flat surface is less than 0.015 waves （PV value）.The algorithm provides a low-cost approach to application of PSI to field measurement under vibration without modification of the hardware of interferometers.