NEW-TYPE OF MANIFESTATION OF THE DOPPLER-EFFECT - AN APPLICATION TO BLOOD AND LYMPH-FLOW MEASUREMENTS

Based on theoretical and experimental analyses, it is shown that the s pectrum of intensity fluctuations contains a high-frequency peak in th e absence of a subsidiary reference wave at nonsmall angles of speckle observation. This phenomenon, interpreted as a new type of manifestat ion of the Doppler effect, is usual only for the case of strongly focu sed coherent beam scattering. The possibilities for using the observed effect in the measurements of blood and lymph flows in narrow native capillaries are discussed. The traditional Doppler method using strong ly focused Gaussian beam scattering is also considered, It is shown th at the frequency position of the Doppler peak in the spectrum of inten sity fluctuations is defined not only by the angle of speckle observat ion but also by the relation between the waist beam diameter and the a verage size of flow inhomogeneities. This result was experimentally ve rified, It is concluded that the Doppler method of blood flow measurem ent using strongly focused Gaussian beam diffraction should be revised .