Flexible stitching interferometry for gull-wing asphere using variable-sign curvature compensation.

Aspheres have widespread applications in modern optical systems; however, the high-precision testing of the gull-wing asphere (GWA) is still challenging. In this Letter, flexible stitching interferometry (FSI) has been reported using variable-sign curvature compensation (VSCC) to realize accurate GWA testing. The method involves varying the sign and magnitude of the outgoing wavefront curvature by relative translation of VSCC to compensate for the curvatures of subapertures, and alternating optimization stitching is utilized to obtain the full-aperture absolute phase. The feasibility and performance of the proposed method are demonstrated experimentally. To our knowledge, such a stitching interferometry using VSCC is here proposed for the first time, and could contribute to general aspheric interferometry.