title: Asymmetrical optical lenslet array realized by spatial light modulator for measuring toroidal surfaces.
abstract: The Shack-Hartmann wavefront sensor (SHWS) recently has been extensively researched for optical surface metrology due to its extendable dynamic range compared with interferometry technique. In this paper, we proposed to use a digital SHWS to measure toroidal surfaces, which are widely used in many optical systems due to their different symmetries and curvatures in the X and Y directions. For what is believed to be the first time, an asymmetrical optical lenslet array implemented by a spatial light modulator was presented to tackle the measurement challenge. This unconventional design approach has a great advantage to provide different optical powers in the X and Y directions so that focusing spots can be formed and captured on the detector plane for accurate centroid finding and precise wavefront evaluation for 3D shape reconstruction of the toroidal surface. A digital SHWS system with this extraordinary microlens array was built to verify the design concept, and the experimental results were presented and analyzed.
authors.affiliation: Precision Measurement Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075. lpzhao@simtech.a-star.edu.sg
authors.forename: L P
authors.initials: LP
authors.lastname: Zhao
authors.forename: N
authors.initials: N
authors.lastname: Bai
authors.forename: X
authors.initials: X
authors.lastname: Li