Quantitative phase and polarisation endoscopy applied to detection of early oesophageal tumourigenesis

• Main Authors: Gordon, George S. D, Joseph, James, Alcolea, Maria P, Sawyer, Travis, Macfaden, Alexander J, Williams, Calum, Fitzpatrick, Catherine R. M, Jones, Philip H, di Pietro, Massimiliano, Fitzgerald, Rebecca C, Wilkinson, Timothy D, Bohndiek, Sarah E
• Format: Journal Article
• Language: English
• Published: 09-11-2018
• Subjects: Physics - Medical Physics; Physics - Optics
• DOI: 10.48550/arxiv.1811.03977

Phase and polarisation of coherent light are highly perturbed by interaction
with microstructural changes in pre-malignant tissue, holding promise for
label-free early cancer detection in endoscopically accessible tissues such as
the gastrointestinal tract. Flexible optical fibres used in conventional
diagnostic endoscopy scramble phase and polarisation, restricting clinicians
instead to low-contrast amplitude-only imaging. Here, we unscramble phase and
polarisation images by exploiting the near-diagonal multi-core fibre (MCF)
transmission matrix to create a novel parallelised fibre characterisation
architecture, scalable to arbitrary MCFs without additional experimental
overhead. Our flexible MCF holographic endoscope produces full-field en-face
images of amplitude, quantitative phase and resolved polarimetric properties
using a low-cost laser diode and camera. We demonstrate that recovered phase
enables computational re-focusing at working distances up to 1mm over a
field-of-view up to 750$\times$750 $\mu m^2$. Furthermore, we demonstrate that
the spatial distribution of phase and polarisation information enables
label-free visualisation of early tumours in oesophageal mouse issue that are
not identifiable using conventional amplitude-only information, a milestone
towards future application for early cancer detection in endoscopy.