Multi-scenario photoacoustic endoscopy for functional imaging.

Optical endoscopy has been extensively used in clinical screening and diagnosis of internal diseased organs. Photoacoustic endoscopy, one of the rapidest evolving optical endoscopies, combines rich optical contrasts with high spatial acoustic resolving capability at a considerable penetration depth. However, implementing high-speed, large field-of-view photoacoustic endoscopy in arbitrarily shaped biological tracts and cavities remains a challenge. Here, we develop a miniaturized, multi-view photoacoustic endoscope (Multi-PAE) that integrates a micro-optical scanner and a folded optical path within a capsule-sized probe. The probe features multiple interchangeable imaging interfaces in different orientations to image diverse tracts and cavities. We propose a compound double spiral resonant scanning (CDSRS) mechanism to enable the optical scanner to perform stable and uniform resonant scanning over a large field-of-view. We demonstrate the multi-scenario functional imaging applicability of Multi-PAE in rat rectums, rabbit cervices, and entire human oral cavities.