Miniature ultrahigh-resolution visible-light OCT endoscopy

Endoscopic optical coherence tomography (OCT) offers near histologic quality visualization of tissue microanatomy in vivo, circumventing the challenges of traditional biopsy by enabling volumetric sampling without tissue removal. Miniaturized probes have been designed to overcome the limited imaging depth of conventional OCT, thereby facilitating minimally invasive imaging. Visible light OCT (vis-OCT) endoscopy has the potential to achieve ultrahigh resolution of less than 2μm with enhanced image contrast. However, current vis-OCT endoscopes, which rely on achromatic lenses and distal motors, are cumbersome and pose safety concerns in clinical environments, underscoring the need for ultracompact, current-free alternatives. Additionally, conventional fabrication methods for high-performance, ultrathin vis-OCT endoscopes have limitations. In this study, we introduce a submillimeter monolithic vis-OCT endoscope, created by directly coupling microlens to the fiber tip using a liquid shaping technique. Our ultrathin vis-OCT endoscope of 0.4mm in outer diameter enables ultrahigh-resolution (1.4μm × 4.5μm in axial and transversal directions) interstitial imaging in vivo.