Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

Radial Shearing Interferometer for Reconstruction of Wavefront by Fringe Modeling

Huy Vu1, Seunghoo Lee1, Tien Dung Vu2 and Joohyung Lee1,a

1Department of Mechanical System Design Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 01811, Korea

2 School of Mechanical Engineering, Hanoi University of Science and Technology, 01 Dai Co Viet Road, Ha Noi, Viet Nam


A perfect aspherical lens design significantly enhances the performance of an imaging system. However, the trend of device miniaturization makes this surface measurement becomes a challenge. In this study, a novel waviness profile metrology method for an aspheric surface is proposed by fringe modeling of a radial shearing interferometer (RSI) to reconstruct a wavefront. An RSI experiment is conducted with a small shearing amount to minimize the asphericity and a dynamic interferometer using a polarizing camera is combined to obtain the wavefront by the phase-shifting technique. Fringe modeling of the interferometer is realized by Ray-tracing software and the wavefront is extracted to compare with the respective wavefront in the experiment. The parameters of modeling are optimized iteratively with a good wavefront agreement between modeling and experiment to obtain a testing surface. The waviness surface profile expects to achieve the nanometer scale and this potential method is powerful for applying to surface metrology as a new measurement standard.

Keywords: Radial shearing interferometer, Fringe modeling, Waviness surface profile

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