Dynamic focal spots registration algorithm for freeform surface measurement
Date of Issue2013
International Conference on Optics in Precision Engineering and Nanotechnology (2013 : Singapore)
School of Mechanical and Aerospace Engineering
In a wavefront sensing system, the raw data for surface reconstruction, either the slope matrix or curvature matrix, is obtained through centroiding on the focal spot images. Centroiding is to calculate the first moment within a certain area of interest, which encloses the focal spot. As the distribution of focal spots is correlated to the surface sampling condition, while a uniform rectangular grid is good enough to register all the focal spots of a uniformly sampled near flat surface, the focal spots of aspherical or freeform surfaces have varying shapes and sizes depending on the surface geometry. In this case, the normal registration method is not applicable. This paper proposed a dynamic focal spots registration algorithm to automatically analyze the image, identify and register every focal spot for centroiding at one go. Through experiment on a freeform surface with polynomial coefficients up to 10th order, the feasibility and effectiveness of the proposed algorithm is proved.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE). This paper was published in International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013) and is made available as an electronic reprint (preprint) with permission of SPIE. The paper can be found at the following official DOI: [http://dx.doi.org/10.1117/12.2021107]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.