Sun Ruoduan, Qiu Lirong, Yang Jiamiao, Zhao Weiqian
Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Opto-Electronic College, Beijing Institute of Technology, China.
Appl Opt. 2012 Sep 10;51(26):6275-81. doi: 10.1364/AO.51.006275.
A laser differential confocal radius measurement system with high measurement accuracy is developed for optical manufacturing and metrology. The system uses the zero-crossing point of the differential confocal intensity curve to precisely identify the cat's-eye and confocal positions and uses an interferometer to measure the distance between these two positions, thereby achieving a high-precision measurement for the radius of curvature. The coaxial measuring optical path reduces the Abbe error, and the air-bearing slider reduces the motion error. The error analysis indicates the theoretical accuracy of the system is up to 2 ppm, and the experiment shows that the system has high focusing sensitivity and is little affected by environmental fluctuations; the measuring repeatability is between 4 and 12 ppm.
