Exceptional imaging performance optic coherence tomography miniature probe based on sizable fiber axicon

Clinical diagnosis increasingly relies on obtaining visualization images through optical coherence tomography (OCT) endoscopes with small-volume, large focusing depth, and high-resolution performance without damaging fragile tissues and organs. However, the mutual constraints of the depth of focus (DOF) and the lateral resolution currently limit the comprehensive imaging performance and widespread application of optical endoscopic probes. To overcome the inherent DOF-resolution tradeoff, a low-cost, ultra-thin fiber-optic endoscopic OCT probe with extended Bessel-like focus has been proposed and demonstrated. The waist diameter of the illumination beam is expanded by a large-diameter no core fiber (∼250 μm) and a fiber microsphere (∼600 μm). The sizable fiber axicon ground on the microsphere provides an opportunity to generate quasi-Bessel beam with a full width at half maxima (FWHM) diameter of the quasi-invariant focused spot-size of about 1.67 μm over the DOF range of 534 μm. The imaging performance and the vast potential for diverse applications of the fiber axicon-based OCT probe were validated by imaging of multiple samples. The low-cost, miniaturization, and ultrahigh imaging performance fiber-optic axicon probe are very attractive for OCT imaging in biomedical, clinical diagnosis, and intervention applications.