Optical endoscopy is widely used for visualising internal organs such as the gastrointestinal tract, the airways and the uterus. However, conventional optical endoscopy only provides morphological information of superficial tissue, and thus biopsies are still required to achieve definitive histopathological diagnosis. At PURL, we are developing the next generation endoscopy probes that combine the state-of-the-art optical imaging modalities including photoacoustic microscopy and fluorescence microcopy to provide structural, molecular and functional contrast of tissue at sub-celluar resolution in realtime for guiding surgical and interventional procedures such as tumour biopsy and fetal surgery.
MULTIMODE FIBRE-BASED ULTRA-THIN IMAGING PROBE
An ultra-thin endoscopy imaging probe is developed based on a multimode fibre for delivering and scanning a tightly focused pulsed laser beam. With a fibre-optic ultrasound sensor, excited ultrasound waves are detected for photoacoustic imaging. In the meanwhile, excited fluorescent light is collected by the same multimode fibre for additional label-based contrast.
FOCUSING LIGHT THROUGH MULTIMODE FIBRE VIA WAVEFRONT SHAPING
Coherent light transmission is scrambled through a multimode fibre due to mode dispersion. To use a multimode fibre for endoscopy imaging, we developed a method to calibrate the disordered light intensity change through the fibre, and shape the light out from the fibre into tightly focused light spots for microscopy imaging.
IMAGE TRANSMISSION THROUGH A MULTIMODE FIBRE
We developed an algorithm called real-valued intensity transmission matrix to characterise the disordered light transmission through multimode fibres. In addition to wavefront shaping for raster-scanning microscopy imaging, this matrix can also be used for single-shot image transmission through multimode fibres.