Characterization of human scalp hairs by optical low-coherence reflectometry

Optical low-coherence reflectometry is used to investigate the internal structure and optical properties of human scalp hair. Regardless of hair color, the refractive index of the cortical region remains within the range of 1.56–1.59. The amplitude of the backscattered infrared light coupled into different-colored hair confirms the relative melanin content. Discontinuities in the refractive index permit identification of distinct structural layers within the hair shaft.