Spectrum analysis of low frequency vibration in interferometry
In order to reduce the influence of vibration on phase-shifting interferometry,the spectrum analysis of the vibration signal was carried out to separate the spectrum signal that contributed to the low-frequency vibration,which verified the fact that the phase-shifting interferometry(PSI)algorithm was more sensitive to vibration at 2 times the phase-shifting frequency.According to the standard PSI measurement steps and Newton's generalized binomial theorem,the multi-frequency vibration influence factor γ was derived.The phase error calculated by the standard PSI algorithm and the phase error after the multi-frequency vibration influence factor γ processing were simulated by Matlab software,and the experiment was carried out to verify it.The results show that the RMS value and phase error of the wavefront processed by the γ influence factor are lower than those of the PSI algorithm.The RMS value can be reduced by 22 times and the phase error can be reduced by 20 times.
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