Experimental and theoretical investigation of common path optical coherence tomography using conical tip lens fiber

Abstract

We proposed Common Path Optical Coherence Tomography (CPOCT) using gold coated conical tip lens fiber with a central wavelength of 1310 nm SLD to improve lateral resolution under the water. We already verified that conical tip lens fiber was good to improve the lateral resolution in CPOCT in air. However, CPOCT using conical tip lens fiber could not be functioning under the water solution because the value of back-reflected light field from the conical tip was too low. For this reason, we had to set reference intensity at a high level by coating the tip with a thin layer of gold. Then, we could have the right balance of reference intensity and sample intensity with gold coated conical tip lens fiber. Furthermore, the results of beam diameter, SNR, lateral resolution show that gold coated conical tip lens fiber is better than cleaved fiber. Then, we could observe two dimensional cross sectional scan of samples, for example, fresh leaves under the water by CPOCT using gold coated conical tip lens fiber.