Use of coordinate measuring machine to measure circular aperture complex optical surface

The measurement of complex surface with form accuracy up to micrometers is of critical importance in the field of precision manufacturing and measuring. In this paper, a systematical measuring method based on coordinate measuring machine (CMM) was proposed for the circular aperture complex optical surface. By proposed method, concentric-circles discretized by equally spaced angle were chosen to obtain the sampling points, and the spline interpolation method for probe radius compensation was considered, then the compensated data points were fitted to measured surface using Zernike polynomials. Furthermore, a simulation of toric surface was studied to analyze surface construction error. Under specific parameter condition of discretization angle of 15°, step length of 1 mm and fitting terms of Zernike polynomials 66, the PV form error was 0.1596 μm and RMS was 0.0292 μm. The simulation results show that the proposed fitting method can meet the requirement of inspection accuracy at the micron level. Finally, a progressive addition lens complex surface was measured by a MQ686 CMM to verify the feasibility of the proposed method.