Traceable reference full metrology chain for innovative aspheric and freeform optical surfaces accurate at the nanometer level

Abstract

The design of innovative reference aspheric and freeform optical elements was investi-gated with the aim of calibration and verification of ultra-high accurate measurement systems. The verification is dedicated to form error analysis of aspherical and freeform optical surfaces based on minimum zone fitting. Two thermo-invariant material measures were designed, manufactured using a magnetorheological finishing process and selected for the evaluation of a number of ultra-high-precision measurement machines. All collected data sets were analysed using the implemented robust reference minimum zone (Hybrid Trust Region) fitting algorithm to extract the val-ues of form error. Agreement among the results of several partners was observed, which demon-strates the establishment of a traceable reference full metrology chain for aspherical and freeform optical surfaces with small amplitudes.