Ultrathin forward-imaging short multimode fiber probe for full-field optical coherence microscopy

Abstract

To extend the applications of optical coherence tomography (OCT) to the fields of physiology and clinical medicine, less invasive, robust, and reliable optical probes are required. Thus, we demonstrate an ultrathin forward-imaging short multimode fiber (SMMF) optical coherence microscopy (OCM) probe with a 50 μm core diameter, 125μm total diameter, and 5.12mm length. Imaging conditions and magnification were analyzed, and they correspond closely to the measured results. The dispersion of the SMMF was investigated, and the modal dispersion coefficient was found to be 2.3% of the material dispersion coefficient. The axial resolution was minimized at 2.15μm using a 0.885-mm-thick dispersion compensator. The lateral resolution was evaluated to be 4.38μm using a test pattern. The contrast of the OCM images was 5.7 times higher than that of the signal images owing to the coherence gate. The depth of focus and diameter of the field of view were measured to be 60μm and 40–50 μm, respectively. OCM images of the dried fins of small fish (Medaka) were measured and internal structures could be recognized.