Research On Interference Signal Processing Technology Based On Sinusoidal Phase Modulation

Interference signal processing is a technology of processing interference signal gotby interferometry. There are different interference signal processing method forinterference signal got by different interferometry. Phase shifting interferometry can bedivided into hardware phase shifting and wavelength phase shifting two kinds by thedifferent methods of phase shifting. Hardware phase shifting generally use piezoelectricceramics to shift reference lens, but it is more difficult to make the large diameterinterferometer.The new technology of wavelength phase shifting is rapidly developed inrecent years, and has a broad prospect in the production of large diameter interferometer.This method don’t need to move the reference lens, laser is both the light source and themodulator, and the structure of interferometer is simple. Sinusoidal phasemodulation(SPM) interferometry is a simple phase shifting method, which have higheraccuracy of measurement. This thesis mainly adopted filtering processing method forSPM interference signal, extracted the phase principal value and processed phaseunwrapping. Specific research work were as follows:1. This thesis introduced SPM interferometry based on filtering technology, simulatedand analyzed the effect of filter, multiplicative and additive noise on the measurementsin order to provide scientific basis for the selection of parameters for filter.2. This thesis advanced a self-adaptive SPM interferometry, and processed thesimulation research for object vibration and displacement with the measurement error ofthe angstrom level. Then this thesis simulated object surface topography at theimproved interferometry.The error analysis showed that the method had higher accuracyof measurement than traditional measuring method of object surface topography.3. This thesis proposed a interval sampling method based on SPM interferencesignal,which reduced heavily the strict requirement that the SPM interferometry needvery high CCD frame frequency (reduce CCD frame frequency by ten times). Throughthe simulation, the method was proved to be feasible and could improve theanti-interference ability of the interferometer. 4. This thesis proposed a mid-balanced branch blocking algorithm based on the branchblocking algorithm. The algorithm improved Branch cut algorithm——the setting of thebranch was optimized. It could effectively reduce the possibility of the branches to formclosed area and make sure to balance all the residual points when there were moreresidual points, so it could be used to process phase unwrapping for relatively complexphase mapping.5. This thesis put forward a rotating phase unwrapping algorithm, introducing medianfilter technology at the course of phase unwrapping, which could inhibit the noise to agreat degree. The simulation research showed that this algorithm did not identify theresidual points, but had several times higher reliability and speed than traditional branchblocking algorithm.