Digital Optical and Scanning Probe Microscopy for Inspection and Manipulation of Biocells - Bioanalysis Advanced Materials Methods and Devices - page 96

proportional to the velocity of the erythrocytes creating this speckle pattern. This
relationship is widely used for velocity measurements on rough surfaces employing
dynamic speckle methods [ 8 ]. Both experimental and theoretical investigations
show that a similar equation can be used for double and triple scattering from the
moving erythrocytes [ 12 ]. Numerical investigation of Okamoto and Asakura [ 11 ]
shows that the value of t c increases almost linearly with the increase of the averaged
scatterers velocity in the case of multiple scattering as well. Thus, the value of 1/ e is
seen to be proportional to the velocity of scatterers even in more complicated cases,
including multiple scattering. However, the relation, similar to ( 7.5 ) for such cases,
must include many factors like the density of scatterers, and diameters of
capillaries. Hence the measurement of the absolute value of the scatterers velocities
for such cases needs additional experimental calibration. Consequently, the evolu-
tion of the dynamic biospeckle pattern has a more complicated character than in the
Speckle Photography technique, where the speckle displacement is always directly
proportional to the scatterers displacement in the flow studied. In addition to
biospeckle displacement as described above there is the so-called boiling of
speckles, i.e., temporal variation of the speckle intensity independent of speckle
movement. In the context of addressing such behavior, three methods are now
described for the analysis of variations in dynamic speckle patterns.

7.7 Speckle Pattern Analysis

The experimental arrangement at the Belarus State Medical University (BSMU)
used for human biotissues monitoring in vivo is shown in Fig. 7.5 . A low power
He-Ne laser is used as a light source. The laser radiation is transported by

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Fig. 7.5 In vivo human tissues monitoring at Belarus State Medical University: 1 —He-Ne laser
with power supply; 2 —waveguides for laser beam transportation; 3 —Digital CCD camera of
high resolution; 4 —patient table; 5 , 6 —mechanical supports; 7 —PC; 8 , 9 —mechanical
supports. On the right , example of intensity of subskin blood microcirculation within a tested
area in arbitrary units