Study of the optical properties of human hair.

Synopsis The optical properties of human hair were studied by photogoniometry. Starting from an optical model of hair, we developed a computerized method of decomposition of the goniophotometric curve. From our analysis we obtained structural parameters of the hair surface, average scale angle and cosmetic parameters like lustre and pigmentation. This method gave us new results in the following areas: - the effects of bleaching on scale and internally reflected light; - the study, from root to tip, of surface damage and hair pigmentation; - the effects of stretching the hair on scale angle and lustre; - the effects of sebum and dust on hair lustre.