Measuring technique for off-axis aspherical mirror in fine grinding process using coordinate measurement machine

A method was proposed to measure off-axis aspherical mirrors by a coordinate measurement machine (CMM). The 3D coordinates of the actual points on the off-axis mirrors were obtained with this method, and were compared with the data by the theoretical model, through which the profile errors and root-mean-square values of the actual mirrors were obtained. All the fine grinding processes were guided according to the measurement results. Thus the problem that off-axis mirrors are difficult to measure and manufacture is resolved. As the off-axis mirror came into the polishing process successfully, the measurement of off-axis aspherical mirrors in the grinding process was successfully followed by that in the polishing process.