Determining secretion of sebum in skin - has fixed frequency light from LED shining onto ground glass screen contacting skin with reflected light measured and compared with standard

摘要

The secretion of sebum in the skin is determined by a light source shining onto a ground glass screen contacting the skin. The light reflected is measured and the result interpreted by comparison with a reference standard. The light source is an LED emiting a beam of fixed frequency light, this being the only frequency measured when reflected by a plane mirror onto a photo-transistor. Two co-axial optic fibres may alternatively be used. One end is connected to a transmitter-receiver and the other placed opposite the screen. The outer fibre transmits light and the centre fibre receives it.