Technical research on fabricating steep off-axis aspherical mirror based on infrared interferometric testing

Abstract

This article mainly take the research on the technique of fabricating a steep off-axis aspherical mirror based on infrared interferometric testing. In the stage of asphercal shape grinding ,we take use of an infrared interferometer to test the aspherical surface error rapidly, along with the arm-swinging polishing method and choose the appropriate processing parameters according to the testing results. After more than twenty times polishing and testing circles ,the off-axis mirror’s wavefront error converge to PV≤5 λ,RMS≤1 λ(λ=632.8nm),this surface map is suitable for the final sub-surface polishing. Through these research and experiments, we have verified the applied advantage of infrared interferometric technique in fabricating steep off-axis aspherical mirror. This technology is also very useful in the processing other types of large-scale aspherical mirrors.