Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Optic Express. 2013;21(15):18255-60.
Liang CW, Chang HS, Lin PC, Lee CC, Chen YC.
Department of Optics and Photonics, National Central University, 300 Chungda Rd., Chungli 32001, Taiwan.
Abstract
A novel subaperture stitching interferometry is developed to measure the surface deformation of the lens by utilizing the mechanical vibration induced from a motorized stage. The interferograms of different subapertures are acquired on the fly while the tested optics is rotating against its symmetrical axis. The measurement throughput and the subaperture positioning accuracy are improved simultaneously by adopting both the synchronous rotational scanning mechanism and the non-uniform phase shifting algorithm. The experimental measurement shows the stitched phase RMS error of 0.0037 waves proving the feasibility of the proposed phase acquisition method.
© 2013 OSA
Additional Information
The subaperture stitching interferometry is a high dynamic range method to measure the optical surfaces. It acquires the local resolvable interferograms to be the phase maps at portions of the tested lens and stitches them together to form the complete surface deformation map.
Unlike the normal interferometry that needs a stable environment with no vibrations, the vibration modulated subaperture stitching interferometry cannot work without any vibrations during the measurement. This innovative interferometric system includes 4-axis motorized stages, a dynamic interferometer, and a robust subaperture stitching algorithm. The phase shifting of the interferometer is induced by the vibration of the rotational stage. When the interferograms are acquired on the fly, the vibrated stage acts as the random phase modulator. Different from most of the commercial systems, the proposed interferometer uses a non-stop acquisition process. This data acquisition method can avoid the position uncertainty and significantly increase the number of subapertures that can be acquired in a short time. Therefore, it is easy to have a large amount of subapertures to form the tested surface and average out the measuring errors. Important advantages of this high density subaperture stitching process are to increase the stability of the subaperture stitching algorithm and get a more accurate result of the tested surface.
In this study, the vibration modulated high density subaperture stitching interferometry has the capability to increase the measurement throughput of aspherical surfaces. We are looking forward to the realization of a cost effective and versatile asphere measurement system soon.
