Video-rate dual-modal photoacoustic and fluorescence imaging through a multimode fibre towards forward-viewing endomicroscopy

Multimode fibres (MMFs) are becoming increasingly attractive in optical endoscopy as they promise to enable unparallelled miniaturisation, spatial resolution and cost. However, high-speed imaging with wavefront shaping has been challenging. Here, we report the development of a video-rate dual-modal photoacoustic (PA) and fluorescence microscopy probe with a high-speed digital micromirror device (DMD) towards forward-viewing endomicroscopy. Optimal DMD patterns were obtained using a real-valued intensity transmission matrix algorithm to raster-scan a 1.5 mu m-diameter focused beam at the distal fibre tip for imaging. The PA imaging speed and spatial resolution were varied from similar to 2 to 57 frames per second and from 1.7 to 3 mu m, respectively. Further, high-fidelity PA images of carbon fibres and mouse red blood cells were acquired at unprecedented speed. The capability of dual-modal imaging was demonstrated with phantoms. We anticipate that with further miniaturisation of the ultrasound detector, this probe could be integrated into medical needles to guide minimally invasive procedures.

Automated summary

Multimode fibres (MMFs) are gaining attention in optical endoscopy due to their potential for miniaturization, improved spatial resolution, and cost-effectiveness. Researchers have developed a video-rate dual-modal photoacoustic (PA) and fluorescence microscopy probe using a high-speed digital micromirror device (DMD) for forward-viewing endomicroscopy. The probe achieved high-speed imaging with adjustable PA imaging speed and spatial resolution, and demonstrated the capability of dual-modal imaging.