Ex vivo optical coherence tomography imaging of larynx tissues using a forward-viewing resonant fiber-optic scanning endoscope

A miniature endoscope probe for forward viewing in a 50 kHz swept source optical coherence tomography (SS-OCT) configuration was developed. The work presented here is an intermediate step in our research towards in vivo endoscopic laryngeal cancer screening. The endoscope probe consists of a miniature tubular lead zirconate titanate (PZT) actuator, a single mode fiber (SMF) cantilever and a GRIN lens, with a diameter of 2.4 mm. The outer surface of the PZT actuator is divided into four quadrants that form two pairs of orthogonal electrodes (X and Y). When sinusoidal waves of opposite polarities are applied to one electrode pair, the PZT tube bends transversally with respect to the two corresponding quadrants, and the fiber optic cantilever is displaced perpendicular to the PZT tube. The cantilever's resonant frequency was found experimentally as 47.03 Hz. With the GRIN lens used, a lateral resolution of ∼ 13 μm is expected. 2D en face spiral scanning pattern is achieved by adjusting the phase between the pairs of X and Y electrodes drive close to 90 degrees. Furthermore, we demonstrate the imaging capability of the probe by obtaining B-scan images of diseased larynx tissue and compare them with those obtained in a 1310 nm SS-OCT classical non-endoscopic system.