Qualitative Investigation of Fresh Human Scalp Hair with Full-Field Optical Coherence Tomography

The study used ultrahigh-resolution full-field optical coherence tomography (FF-OCT) to investigate the depth-resolved cellular structures of fresh human scalp hairs. The Linnik-type white light interference microscope allowed observation of the micro-internal layers of hair shafts, revealing the cuticle and cortex layers with keratin filaments and melanin granules. The main difference between black and white hair was the absence of melanin granules in white hair, indicating that melanin density affects hair color. Additionally, three-dimensional anatomical descriptions of plucked hair bulbs were obtained. This method was expected to be useful for cosmetic assessments and diagnosing hair diseases.