A novel algorithm of wave front time domain testing

Abstract

In order to achieve the surface testing of entire caliber large-aperture optical elements, the distance between the tested piece and the interferometer is often several meters to tens of meters. In such long optical path the impact of environment vibration and air turbulence are inevitable, which seriously affects the accuracy of the interferometry and also limits the possibility of processing and testing large optical system. This paper presents a novel algorithm of wave front time domain detection, which needn't equal interval phase shifting and precise calibration of the phase-shifting step, just by means of using the environment vibration and air turbulence as phase shifters. On basis of enough interfergrams light intensity vs time curves of each point can be achieved. Light intensity vs phase curves of each point can be figured out by proposed algorithm. Then, we can gain the phase value of each point in terms of the light intensity, and also the wave surfaces corresponding to each interfergram by the unwrapping calculation. As result, we can obtain the stable wave surface wiping off random vibration and air turbulence under taking of average on all wave surfaces. Compared to conventional phase shifting interferometry algorithms, this algorithm can effectively decrease the impact of vibration and air turbulence within the interferometric measurement, enhance its ability of anti-jamming, and improve the adaptability, particularly in real-time detection of 1arge-aperture mirror.