A Shack-Hartmann wavefront sensor (SHWFS) which consists of a microlens array and an image sensor has been used to measure the wavefront aberrations in various fields owing to its advantages such as simple configuration. However, a conventional SHWFS has the finite dynamic range. The dynamic range cannot be expanded without sacrificing the spatial resolution and the sensitivity in a conventional SHWFS. In this study, the SHWFS using a dual microlens array to solve the problem is proposed. In the proposed method, an astigmatic microlens is arranged at the center of a group of 2 x 2 spherical microlenses. A pattern image including spots and linear patterns is obtained at the focal plane by the dual microlens array. The pattern image can be separated into two images as if two microlens array with different diameter were used by discriminating spots from linear patterns with the pattern matching technique. The proposed method enables to expand the dynamic range of an SHWFS by using the separated two images. The performance of the proposed method is confirmed by the numerical simulation for measuring a spherical wave.

Date Published: 9 December 2015
PDF: 4 pages
Proc. SPIE 9792, Biophotonics Japan 2015, 97921B (9 December 2015); doi: 10.1117/12.2204889

Published in SPIE Proceedings Vol. 9792:
Biophotonics Japan 2015
Takashige Omatsu; Yoshio Hayasaki; Yusuke Ogura; Yasuyuki Ozeki; Seigo Ohno, Editor(s)