Functional dermoscopy integrated by cellular-resolution Mirau-based optical coherence microscopy

A Mirau-based optical coherence microscopy (OCM) with dual-modality is proposed to image cellular-level three-dimensional (3-D) skin morphology by OCM mode and to observe the blood circulation beneath the basal layer with an in-built orthogonal polarization spectral imaging (OPSI) mode. With the property of OCM, this system has sub-micron (0.9 μm in axis, 0.8 μm in transverse) spatial resolution in the volumetric dimension of 285 (length) × 215 (width) × 100 (depth) μm³ collected in 2 minutes from in-vivo skin tissue. By switching the optical component of an achromatic quarter-wave plate, a video-rate OPSI system is performed to count the red blood cells (RBCs) and to measure the projected capillary flow speed (CFS) of RBCs. Combining phase-shifted en-face frame OCM morphology and color-coding OPSI circulation, the analyses of CFS and count of RBCs were demonstrated. In addition, the size of a single RBC was determined via en-face and tomographic images. A dermoscope combining OCM and OPSI modes was achieved via a common high-brightness visible light source using a diode-pumped Ce³⁺:YAG single-clad crystal fiber.