DEPTH DISCRIMINATION IN LASER DOPPLER SKIN BLOOD-FLOW MEASUREMENT USING DIFFERENT LASERS

The principle of Doppler broadening of the optical spectrum, when laser light is scattered from moving red blood cells (RBC) in skin tissue, has been successfully employed in a number of laser Doppler skin blood flow meters. The technique is particularly suitable for noninvasive, continuous monitoring. There are many instances in routine dermatology where the superficial dermal plexus alone is most affected by the presence of disease (e. g. psoriasis and eczema). To discriminate between total and superficial skin blood flow it is necessary to select a suitable wavelength of laser light which will be preferentially absorbed and/or scattered in the upper dermis. The purpose of this study was to compare the Doppler shift frequency spectra obtained for three different laser wavelengths under the same conditions of flow through a simple physical model. 7 Refs.