Bond-Selective Full-Field Optical Coherence Tomography

TL;DR

This paper introduces a novel bond-selective full-field OCT technique that uses mid-infrared laser modulation to achieve label-free, chemical-specific 3D imaging of biological and material samples, expanding OCT capabilities.

Contribution

The work presents the first implementation of bond-selective full-field OCT using photothermal modulation for chemical contrast in 3D imaging.

Findings

Successfully imaged PMMA beads and polypropylene fibers with bond-specific contrast.

Achieved 3D hyperspectral imaging of surgical mask material.

Demonstrated biological imaging on cancer spheroids, C. elegans, and mouse brain slices.

Abstract

Optical coherence tomography (OCT) is a label-free, non-invasive 3D imaging tool widely used in both biological research and clinical diagnosis. Current OCT modalities can only visualize specimen tomography without chemical information. Here, we report a bondselective full-field OCT (BS-FF-OCT), in which a pulsed mid-infrared laser is used to modulate the OCT signal through the photothermal effect, achieving label-free bond-selective 3D sectioned imaging of highly scattering samples. We first demonstrate BS-FF-OCT imaging of 1 {\mu}m PMMA beads embedded in agarose gel. Next, we then show 3D hyperspectral imaging of polypropylene fiber mattress from a standard surgical mask. We then demonstrate BS-FFOCT imaging on biological samples, including cancer cell spheroids and C. elegans. Using an alternative pulse timing configuration, we finally demonstrate the capability of BS-FF-OCT on a bulky and highly scattering 150 {\mu}m thick mouse brain slice.