Measurement improvement by high overlapping density subaperture stitching interferometry

Abstract

The vibration-modulated subaperture stitching interferometer acquires the interferogram on the fly dynamically. With its highly improved measurement throughput, we applied the device for high overlapping density subaperture stitching interferometry to acquire hundreds of overlapping subapertures in a single phase stitching measurement. The averaging effect of the high overlapping density stitching interferometer is discussed. In the experiment, the proposed high overlapping density stitching interferometer is also proved to reduce measurement uncertainty and improve measurement quality effectively.

Pentaprism Measurements of Large Flat Mirrors

“…The result of Equation 3is the same as that of Equation (2), indicating that the error ω has no impact on the angle difference. Six radial scans were carried out through the mirror centre ( Figure 3).…”

“…m The largest aperture of commercial interferometers is about 900mm, which is insufficient to cover the entire surface of a said large flat mirror. To overcome the problem, two methods have been developed, namely sub-aperture stitching interferometry [1,2] and Ritchey-Common test [3][4][5]. However, the accuracy and efficiency of the sub-aperture stitching interferometry are not high when the sub-apertures are far smaller than the test mirror.…”

Subaperture stitching interferometry based on digital holography

“…Some additional optical elements can be added to the testing optical path and complex algorithms can be used to process the phase or compensate the errors. In addition, Yichun Chen et al have proposed a vibration modulated subaperture stitching interferometry by adopting the random phase shifting caused by the stage mechanical vibrations [32,33]. It brings a large amount of data and computational problems.…”