Measurement of an off-axis parabolic mirror using coordinates measurement machine and swing arm profilometer during the grinding process

摘要

We present the measurement methods for off-axis parabolic mirrors using Coordinates Measurement Machine and Swing Arm Profilometer during the grinding process. An off-axis parabolic mirror with 1200mm in parent focal length, 360mm in off-axis displacement and 410mm in diameter is measured using the methods introduced in this paper. The convergence curves of the surface error are reported, which is reduced from 204.7μm in PV, 55.3μm in rms to 1.1μm in PV, 0.3μm in rms after 39 iterations of grinding. Besides, the measurement methods are able to control the parent focal length and off-axis displacement to less than 0.1mm tolerance. An interferometric result is presented, which validates the measurement methods.