Four‑state polarized multispectral imaging system to evaluate the morphological diversity and biophysical basis of the skin

Polarized multispectral imaging (PMSI) is a non-invasive imaging technique that enhances depth and contrast resolution of skin architecture with minimal glare. We present a novel, robust low-cost optical system that integrates spectral imaging with a high-speed polarized monochrome camera for skin morphology assessment and physiological monitoring of bruising. Our PMSI system integrates a linearly polarized Xenon light source with a camera equipped with sensor-level polarizing filters (0°, 45°, 90°, 135°), enabling simultaneous acquisition of nine discrete wavelengths (420–980nm) across four dual polarization orientations with minimal calibration effort. Chromophore quantification of superficial melanin, deep melanin, oxyhemoglobin, and deoxyhemoglobin were visualized as content maps, and were based on inverse theory model applications on pixel-based reflectance spectra. Preliminary evaluations of melanoma lesions reveal that early-stage lesions exhibit elevated hemoglobin signals, while more advanced stages show significantly increased melanin presence and diminished hemoglobin signals within the superficial and deeper layer of the skin. Additionally, using a pulse dye laser-induced bruising model, hemoglobin mapping over two weeks shows a dynamic shift from deoxyhemoglobin dominance during vessel damage to oxyhemoglobin restoration as healing occurs. We demonstrate our PMSI system’s high speed image acquisition and versatile clinical applications in assessing skin morphological and physiological changes in a non-invasive manner.