Measurement and Characterization of Position and Posture of Conjunctive Multifreeform Surfaces Using Multisensors

Abstract

Conjunctive multi-freeform surfaces play an important role in many advanced optical systems. The position and posture accuracy of freeform surfaces are the key to system performance. However, there is no effective method of measuring the positions and postures of multiple freeform surfaces. In this study, a conjunctive multi-freeform surface measurement system based on multi-sensors is developed, and a trust region registration based on the least squares method is proposed, with the aim of registering multiple freeform surfaces at different positions and postures. The performance of the proposed system was analyzed and the errors were calibrated. The calculation accuracy of the registration method was within 20 nm at Φ50 mm in terms of root-mean-of-squares (RMS) values. The positioning accuracy of the freeform surface measurement system proved to be 1.2 μm within the area of 120 mm × 120 mm; the related uncertainty was also analyzed. The proposed measurement approach provides a comprehensive solution to optical conjunctive multi-freeform surfaces.