LAUSR

Abstract. The purpose of this study was to compare the optical properties of different astigmatic optical surfaces by direct physical measurement of their surface shapes. The back-surface heights of different astigmatic optical lenses were measured with a freeform measuring machine (FMM). In order to calculate the function of the part point cloud fitting surface for the dispersed data points of the astigmatic lenses, the measured shape data were modeled through surface fitting of a bicubic spline. The principal curvatures of each point on the surface were calculated, and the optical properties of each surface and their combinations were generated as contour plots using custom MATLAB routines. The fitting surface of the actual measurement points was compared with the design surface to determine the surface error. Analyses showed that this nonoptical method using an FMM can be used to effectively evaluate a cylindrical lens by surface height measurements alone. Compared to the optical measurement method, the optical properties derived directly from the surface shape can provide information not accessible by other methods. Therefore, this approach is potentially useful to clinicians who want to better understand the design of astigmatic optical lenses for making better recommendations to their clients.