Controlling propagation of spatial coherence for enhanced imaging through scattering media

TL;DR

This paper demonstrates how controlling the propagation of spatial coherence in light fields can significantly improve imaging contrast at various depths through scattering media, enabling clearer images at multiple planes.

Contribution

It introduces a method to control spatial coherence propagation, achieving enhanced and adjustable imaging contrast at different transverse planes in scattering environments.

Findings

Propagation-invariant spatial coherence improves image consistency across planes.

Tailored partial coherence sources maximize contrast at specific depths.

Experimental validation shows significant contrast enhancement in scattering media.

Abstract

It is known that a spatially partially coherent light field produces better imaging contrast compared to a spatially coherent field and that the contrast increases as the spatial coherence length of the field becomes smaller. The transverse spatial coherence length of most spatially partially coherent fields increases upon propagation. As a result, the field produces progressively decreasing image quality at subsequent transverse planes. By controlling the propagation of spatial coherence, we demonstrate enhanced image quality at different transverse planes along the propagation direction through a scattering medium. Using a source with propagation-invariant spatial coherence function, we report experimental observations of imaging different transverse planes with equal contrast over a significant distance. Furthermore, we generate a spatially partially coherent source that can be tailored to have minimum-possible transverse coherence area at the plane of the object to be imaged, and using this source, we demonstrate imaging spatially separated transverse planes with maximum possible image contrast.