Measurement of mid-frequency wavefront error for large optical components with ptychography.

Abstract

In a high power laser system, the wavefront quality of large optical components in the mid spatial frequency band plays a critical role in system performance and safe operation. A simple and efficient method based on ptychography is used to measure mid-frequency wavefront error, which has the advantages of simple structure, strong anti-interference ability, flexible frequency-range selection, and low cost. It has excellent frequency response in the entire mid-frequency region. The transfer function is demonstrated to be greater than 0.7 at 1/2 Nyquist frequencies (8.33 mm-1) for 60mm field-of-view experimentally. The method has been successfully applied to the wedged focused lens (WFL) to achieve high-fidelity measurement. Without any auxiliary lens, the power spectrum of the WFL at the frequency of interest is obtained through large-aperture measurement. This technique is especially suitable for optical components difficult to be measured using interferometers and opens up a new perspective for measuring mid-frequency wavefronts.