Description
Optical microscopy is a powerful tool for observing fine structural details and dynamics in biological samples. However, absorption and scattering limit its reach to shallow regions, motivating the use of endoscopic approaches for minimally invasive access to deeper environments. Among these, multimode fibres (MMFs) offer a high information capacity imaging platform within a hair-thin footprint.
Light propagation through MMFs mixes spatial, phase, and polarisation degrees of freedom, making controlled light delivery and signal recovery a calibration-intensive problem. Wavefront-shaping approaches have successfully addressed the forward problem, enabling deterministic focusing and spot-scanning through MMFs. In combination with confocal, two-photon fluorescence microscopy, and coherent anti-Stokes Raman scattering (CARS), these methods provide high molecular specificity and contrast [1].
Label-free modalities, including quantitative phase imaging, polarimetry, and coherence-gated sectioning, remain essential for probing native tissue, particularly when exogenous labelling is invasive, disruptive, or impractical in heterogeneous samples. Accessing this information through MMFs remains challenging: scanning approaches inherently discard phase and polarisation by detecting intesnity only, while speckle-based methods either average out field information or rely on machine learning to reconstruct intensity-only images [2–3].
Here, we present an MMF imaging framework that reconstructs the full vectorial complex optical field at the distal fibre facet in a single-shot measurement. The same fibre is used for phase and polarisation-controlled illumination as well as phase and polarisation-sensitive detection. Our approach jointly utilises calibrated transmission and reflection matrices, using the transmission matrix for wavefront shaping to generate a desired illumination field, and reflection matrix for the sample field reconstruction. This framework opens the door to high-speed coherent imaging modalities through ultra-thin MMF probes that were previously inaccessible.
[1] Cao H et al. Adv. Opt. Photon. 15, 524–612 (2023).
[2] Choi Y et al., Phys. Rev. Lett. 109, 203901 (2012).
[3] Liu Y et al., Appl. Phys. Lett. 122, 063701 (2023).
| I am the presenting author | Yes |
|---|