Swing arm profilometer: High accuracy testing for large reaction-bonded silicon carbide optics with a capacitive probe

摘要

A feasible way to improve the manufacturing efficiency of large reaction-bonded silicon carbide optics is to increase the processing accuracy in the ground stage before polishing, which requires high accuracy metrology. A swing arm profilometer (SAP) has been used to measure large optics during the ground stage. A method has been developed for improving the measurement accuracy of SAP using a capacitive probe and implementing calibrations. The experimental result compared with the interferometer test shows the accuracy of 0.068μm in root-mean-square (RMS) and maps in 37 low-order Zernike terms show accuracy of 0.048μm RMS, which shows a powerful capability to provide a major input in high-precision grinding.