Dual-Comb Hyperspectral Digital Holography

TL;DR

This paper introduces dual-comb hyperspectral digital holography, combining broad spectral bandwidth and high temporal coherence to enable advanced 3D imaging and precise optical diagnostics.

Contribution

It presents a novel dual-comb holography technique that captures spectral hypercubes of complex holograms, enhancing 3D imaging and metrology capabilities.

Findings

Enables hyperspectral 3D imaging with high spectral resolution

Allows precise dimensional metrology over large distances

Demonstrates molecule-selective imaging of absorbing gases

Abstract

Holography has always held special appeal, for it is able to record and display spatial information in three dimensions. Here, we show how to augment the capabilities of digital holography by using a large number of narrow laser lines at precisely-defined optical frequencies simultaneously. Using an interferometer based on two frequency combs of slightly different repetition frequencies and a lens-less camera sensor, we record time-varying spatial interference patterns that generate spectral hypercubes of complex holograms, revealing, for each comb line frequency, amplitudes and phases of scattered wave-fields. Unlike with previous multi-color holography and low-coherence holography (including with a frequency comb), the unique synergy of broad spectral bandwidth and high temporal coherence in dual-comb holography opens up novel optical diagnostics, such as precise dimensional metrology over large distances without interferometric phase ambiguity, or hyperspectral 3-dimensional imaging with high spectral resolving power, as we illustrate by molecule-selective imaging of an absorbing gas.