Inverse Hartmann surface form measurement system based on spherical coordinates

A new method named inverse Hartmann surface form measurement based on spherical coordinates is presented. The method reduces the measured ray slope efficiently, increases the measurement dynamic range and spatial resolution simultaneously. A large asphericity surface with diameter 340 mm is tested by the new method. The simulation result shows its accuracy of form error can be assured within λ/10, and is better than that in rectangular coordinates. It can be applied in on-line optic product evaluation rapidly and accurately with low cost.