Spatial coherence measurement and partially coherent diffractive imaging

TL;DR

This paper introduces a versatile method for measuring the complete spatial coherence of light without prior knowledge, enabling improved imaging of nanoscale structures in various wavelengths.

Contribution

It presents a novel, scalable technique for fully characterizing mutual coherence functions and retrieving objects under unknown partial coherence conditions.

Findings

Successfully measures complete mutual coherence functions.

Retrieves objects illuminated by partially coherent beams.

Applicable across any wavelength without prior assumptions.

Abstract

The complete characterization of spatial coherence is difficult because the mutual coherence function is a complex-valued function of four independent variables. This difficulty limits the ability of controlling and optimizing spatial coherence in a broad range of key applications. Here we propose a method for measuring the complete mutual coherence function, which does not require any prior knowledge and can be scaled to measure arbitrary coherence properties for any wavelength. Our method can also be used to retrieve objects illuminated by partially coherent beam with unknown coherence properties. This study is particularly useful for coherent diffractive imaging of nanoscale structures in the X-ray or electron regime. Our method is not limited by any assumption about the illumination and hence lays the foundation for a branch of new diffractive imaging algorithms.