3D shape measurement of convex aspheric surface using reverse Hartmann test

Abstract

Based on the reflection of sinusoidal fringes and their distortions due to surface deviations from the ideal geometry, a method, called the reverse Hartmann test method, for the three-dimensional shape measurement of convex aspheric surfaces was developed. This method has an accuracy comparable to that of interferometry, in addition to its simple structure, low cost, and robustness against environmental turbulence and vibration. The developed method, which is based on the relative geometric position, is free from high-precision physical benchmarks. Furthermore, accurate surface data can be obtained through iterative fitting of Zernike slope polynomials without the need of complex calibration. Implementation of this measurement method will enable solving the problems associated with the measurement of convex aspheric surfaces with high dynamic range, high resolution, and high precision.