Absorption imaging of quantum gases near surfaces using incoherent light

TL;DR

This paper presents a new absorption imaging method for ultracold gases near surfaces that reduces coherence artifacts by controlling light coherence, enabling clearer imaging close to complex surfaces.

Contribution

The authors develop a modular incoherent illumination technique that suppresses interference artifacts in absorption imaging of quantum gases near surfaces.

Findings

Effective suppression of interference fringes and artifacts.

Reliable imaging of ultracold gases within microns of complex surfaces.

Adjustable coherence without altering existing imaging setups.

Abstract

We introduce an absorption imaging technique for ultracold gases that suppresses interference fringes and coherence-induced artifacts by reducing the transverse spatial coherence of the imaging light. The method preserves the narrow spectral bandwidth required for resonant absorption imaging and is implemented as a modular extension to standard imaging setups using a rotating diffuser. We demonstrate tunability of the illumination light's coherence without modifying the imaging optics. Using this approach, we achieve reliable imaging of ultracold atomic clouds in micron-scale proximity to complex surfaces, where standing waves, edge diffraction, and speckle severely limit conventional absorption imaging.