Laser Doppler flowmetry is a non-invasive technique that has been used to study the flow of cutaneous or peripheral blood flow. Tissue is illuminated with a low powered Helium-Neon laser. The resulting scattering of light is from static structures as well as moving red blood cells. A portion of the back scattered light from the skin is detected by a photodiode and the resulting spectrum can be analyzed. The spectrum is found to experience a broadening or shift due to the presence of the moving red blood cells causing a Doppler frequency shift. (Figure 28)
An absolute measure of blood flow is made complicated by the variation in skin properties. However, this technique can be used to estimate the flux of the red blood cells under illumination.
Figure 28 Photocurrent Amplitude Data using Laser Doppler Technique
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Support for the development of this module was provided by the National Science Foundation and The Cooper Union for the Advancement of Science and Art.
Please send questions or comments to Professor Ron Adrezin or Professor Daniel Raichel.