Experimental research of noiseproof wavefront testing method in time- and spatial-domain

The noiseproof wavefront testing method in both time- and spatial-domain mentioned, which neither equal step-length phase-shifting nor accurate step-length calibration is necessary in this method. Active phase-shifting works associated with passive phase-shifting caused by the environmental vibration and air turbulences. Large amount of sequentially acquired interferograms are analyzed for the phase distributions corresponding to each interferogram, and then all the phase distributions are averaged to produce a wavefront free from various random noises in time- and spatial-domain. The problems in most available anti-vibration phase-shifting interferometry can be avoid. Large-aperture optical elements testing with high accuracy can be achieved with this method. In this paper an experimental system is set up comprising a minitype interferometer made by ourselves. Surface profile measurement of a standard plane is done with this method and the result is compared with that obtained with a Zygo interferometer. The two results coincide well with each other, which demonstrate further that this method is insensitive to the environmental vibration and air turbulence and it can help improve the noiseproof feature of the interferometer. High-accuracy testing of large-aperture optical elements and systems can be achieved with this method.