A laser reflection confocal large-radius measurement

We propose a new laser reflection confocal large-radius measurement (RCLRM) method. By utilizing the precise correspondence relationship between the peak point of the confocal curve and the convergence point of the multi-reflected measuring beam, we identify the position of the test lens. With a distance interferometer, we obtain the position variation of the test lens with different reflection times. Therefore, a fast and precise large-radius measurement is achieved with a shorter measuring system. Additionally, the RCLRM significantly enhances the measurement accuracy by using conic fitting. The theoretical analyses and experiments indicate that the relative expanded uncertainty is better than 0.008% (k = 2).