Measurement of multiple phase maps for wide-area aberration correction by switchable optical configuration

Abstract

We demonstrate a method of aberration correction for a wide field of view (FOV). To handle spatially varying aberrations, we divide the imaging FOV into multiple segments and determine the associated multiple phase maps (MPMs) that can compensate for the blurry focus. After applying the MPMs to the corresponding segment of the aberrated image, the entire field of view is recovered by recombining all of the image segments. The remaining spatial distortion is subsequently rectified using an inverse geometrical transformation (IGT) that can flatten the curved image space. To obtain information for aberration correction, our setup is designed to have a switchable configuration so that the MPMs and the IGT can be obtained by imaging the Fourier plane and the image plane, respectively. With these sequential processes, we can obtain an aberration-free image over an area of 937×937 µm2 at a microscopic resolution. In comparison, the degradation of the uniformity of the Strehl ratio over the entire FOV is 2.09 times lower than when using only a single PM. Because our method utilizes reflection geometry, it can potentially be used to mitigate the effect of aberrations in many existing imaging modalities.