Freeform Measurement with Stitching Talbot Interferometer

摘要

Freeform optics are being used in many fields to realize the outstanding performance due to their high degree of freedom. To realize sufficiently high performance, it is necessary to manufacture the freeform surface with high accuracy, which requires a high accurate measurement of the freeform surface. Several methods to measure the freeform surface have been suggested. However, they are time-consuming, expensive or their dynamic range is limited. Therefore, we propose a new system that realizes high dynamic range and rapid freeform measurements of freeform surfaces using a combination of the Talbot interferometer and the stitching technique. In this thesis, we introduced the theory and simulation of the Talbot interferometer, and verified that the large reflected wavefront from a freeform (50 micromPV) can be retrieved from the Talbot image. For the stitching, we introduce the algorithm and confirm by simulation that alignment errors of the surface under test can be estimated and reduced. In addition, we estimate the measurement error of both the Talbot interferometer and stitching. In the experiment, the Talbot interferometer was assembled using Fizeau interferometer and a displacement sensor. Furthermore, we suggest a way to assemble the optical system for freeform surface measurement.