Spatial coherence characterization of light: an experimental study using digital micromirror devices

TL;DR

This study experimentally investigates the spatial coherence of partially coherent light from incoherent sources using a digital micromirror device, aiming to inform solar coherence measurement instruments.

Contribution

It introduces an experimental setup combining a telescope, DMD-based interferometer, and imaging system to measure spatial coherence in the far-field of incoherent sources.

Findings

Spectral degree of coherence matches theoretical predictions

Demonstrates feasibility of using DMD-based interferometry for coherence measurements

Provides data relevant for solar coherence measurement instruments

Abstract

We present spatial coherence measurements of partially coherent light in the far-field of incoherent sources with an experimental setup based on the Thompson-Wolf and Partanen-Turunen-Tervo experiments, to be performed in the context of a possible solar coherence measurement space instrument. The optical setup consists of a telescope to collimate light from a source, to diffract it by a digital micromirror device implementing a Young double-aperture interferometer in retroreflection mode, and finally to image the source into a two-dimensional sensor. Two multimode optical fibers with different diameters were used as incoherent sources and the results obtained for the spectral degree of coherence are compared to those expected from the van Cittert-Zernike theorem.