Single-shot hybrid photoacoustic-fluorescent microendoscopy through a multi-mode fiber with wavefront shaping

TL;DR

This paper introduces a minimally-invasive, hybrid photoacoustic-fluorescent microendoscope using a multimode fiber and wavefront shaping, enabling fast, high-resolution imaging with a single laser shot per pixel.

Contribution

It presents a novel endoscopic system combining photoacoustic and fluorescence imaging via wavefront shaping in a multimode fiber, with a calibration-free focusing method.

Findings

Achieved fast 2D hybrid imaging with a single laser shot per pixel.

Demonstrated high signal-to-noise ratio imaging of biological samples.

Developed a compact imaging tip less than 250 micrometers in size.

Abstract

We present a minimally-invasive endoscope based on a multimode fiber that combines photoacoustic and fluorescence sensing. From the measurement of a transmission matrix during a prior calibration step, a focused spot is produced and raster-scanned over a sample at the distal tip of the fiber by use of a fast spatial light modulator. An ultra-sensitive fiber-optic ultrasound sensor for photoacoustic detection placed next to the fiber is combined with a photodetector to obtain both fluorescence and photoacoustic images with a distal imaging tip no larger than 250um. The high signal-to-noise ratio provided by wavefront shaping based focusing and the ultra-sensitive ultrasound sensor enables imaging with a single laser shot per pixel, demonstrating fast two-dimensional hybrid imaging of red blood cells and fluorescent beads.