Equivalent thin-plate method for stressed mirror polishing of an off-axis aspheric silicon carbide lightweight mirror

Abstract

No physical model of stressed mirror polishing, based on the small deflection and deformation of elastic thin plates, has been applied in processing lightweight mirrors. We propose an equivalent thin-plate method for the stressed loading of lightweight mirrors for the first time. Stressed loading and polishing of an aspheric lightweight mirror are simulated using the small-deflection deformation theory of an elastic thin plate. We simulate off-axis aspheric silicon carbide (SiC) lightweight mirrors with three different structures, determining the corresponding equivalent thickness plate in a lightweight structure with a nearly uniform surface density distribution and isotropic bending properties. We then establish a residual removal model of a stressed polishing surface, design the stressed loading equipment, and propose an iterative method for stressed polishing of an off-axis aspheric SiC lightweight mirror. The results demonstrate that it is feasible to choose a lightweight structure that performs full-aperture stressed polishing on off-axis aspheric lightweight mirrors consisting of SiC or other materials.

Measurement of Aspheric Surfaces Using an Arcuate Region Scanning Method by 2D Laser Displacement Sensor

“…In the processing process of large-diameter aspheric surface, the installation and adjustment of elements are complex, and the off-line measurement is easy to introduce new errors. Therefore, in-situ measurement technology is proposed and applied to the actual machining process according to the contour scanning method [4][5]. At present, in-situ measurement error compensation technology includes contact and non-contact sampling methods, which are most widely used in compensation processing stage [6][7].…”