Forward viewing OCT endomicroscopy

Abstract

A forward viewing fiber optic-based imaging probe device was designed and constructed for use with ultrahigh speed optical coherence tomography in the human gastrointestinal tract. The light source was a MEMS-VCSEL at 1300 nm wavelength running at 300 kHz sweep rate, giving an effective A-line rate of 600 kHz. Data was acquired with a 1.8 GS/s A/D card optically clocked by a maximum fringe frequency of 1 GHz. The optical beam from the probe was scanned by a freely deflecting optical fiber that was mounted proximally on a piezoelectric tubular actuator, which was electrically driven in two perpendicular dimensions to produce a spiral scan pattern. The probe has a 3.3 mm outer diameter and is intended for endoscopic imaging. Multiple optical systems were designed to enable microscopic imaging at variable fields. The probe could also be electrically zoomed by tuning the driving voltage to the piezoelectric actuator, reducing the deflection range of the scanning fiber and thus the scanned field. The optical and mechanical design of the probe was optimized for both axial and transverse compactness.