A new approach to surface shape and centration measurement on aspheres with the new V-SPOT technology

Abstract

Accurate measurement of centration of aspheric lenses or even freeforms is a challenge for most devices in optical manufacturing. We are providing a new attempt by combining an autocollimation device and a Vignetting Field Stop [1, 2, 3] device to measure lens centration and sagittal surface profile in a deflectometric approach. Both devices work independently at high accuracy. This presentation explains the technical setup, consisting of an autocollimation sensor (ELWIMAT-AKF) and a Vignetting Field Stop Sensor (ELWIMAT V-SPOT), which is mounted together with an air bearing rotary table in a vertical arrangement. Secondly, we provide the results of the centration measurement and the results from the surface reconstruction and slope error from the measured sagittal angle deviations. Finally, the results from a measured asphere (High Level Expert Meeting HLEM sample #3) is critically discussed to state the accuracy and applicability of the proposed measurement attempt.