5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
371
their comparison is a rather difficult task. Various methods are offered for estimation
of information about fluctuation [75].
A simpler parameter, which characterizes blood flow, is the value of time integral
of the module of fluctuating signal. The value of the integral will be greater where
the fluctuation frequency is higher if fluctuation amplitude is the same during the
same time. Because of its simplicity, this integral characteristic suits well where a
great value of information is processed in real time.
The authors of the works [69, 86] used it while constructing spatial maps of
the blood flow. Skin surface with scattered coherent radiation was projected onto
one-dimensional CCD matrix. Each of its pixels measured time fluctuations in its
point. A computer added fluctuations, and a color-encoded pattern was displayed
on the screen. A scanned image due to another coordinate was used for obtaining
a two-dimensional pattern. Selection of informative parameters of intensity fluctuation spectra of the scattered radiation is also a rather difficult problem, because
the task is multiparameter. It is due to the change of registration conditions as well
as of the object of the study itself during changes. Skin suffers constant microvibrations caused by the contraction of separate fibers and a group of underlying
skeletal muscles, tremor, etc. [41, 44]. Blood cells move not only with capillaries
inside skin, but also they have their own velocity relative to them. Thus, the average
velocity of erythrocytes appears to be much higher than velocity of shifts of cutaneous
tissues [74].
The possibility of measurements in many points is a characteristic of speckleinterferometry. The works [37, 88–101] investigated maps of deformation distribution of isolated tissues as well as of living organisms using the method of twodimensional speckle-photography. The question of speckle-photography method
application in biological experiments was almost not considered, though it was
successfully applied in nondestructive testing of solid bodies and testing of materials for construction of deformation fields. First of all, the following fact remained
unclear, whether speckle-fields experience shifts at a value, which is greater than
the speckle size preserving correlation, or deformation of living tissue, which is
inevitably accompanied by microstructure changes, causes only speckle “boiling.”
That is why a number of experiments were conducted to determine the deformation field of living tissue using the method of double-pulse speckle-photography.
According to the works [93–95], it is necessary to register two images covered with
speckle-structure in the initial and excited states for determination of transversal
shifts. The shift was conducted either artificially [95] or during real muscle contraction [37] in the plane of movement perpendicular to the optical axis. The obtained
photography is enough to determine the shift field where two speckle systems were
registered. Interference fringes were observed as a result of optical Fourier transformation of small areas. Their direction was perpendicular to the direction of shifts,
and their period was inversely proportional to the shift [96, 97]. It is worth taking
into consideration that broken speckles shift homogeneity of illuminated area of
the specklogram leading to diminishing the contrast of interference fringes down to
371
their comparison is a rather difficult task. Various methods are offered for estimation
of information about fluctuation [75].
A simpler parameter, which characterizes blood flow, is the value of time integral
of the module of fluctuating signal. The value of the integral will be greater where
the fluctuation frequency is higher if fluctuation amplitude is the same during the
same time. Because of its simplicity, this integral characteristic suits well where a
great value of information is processed in real time.
The authors of the works [69, 86] used it while constructing spatial maps of
the blood flow. Skin surface with scattered coherent radiation was projected onto
one-dimensional CCD matrix. Each of its pixels measured time fluctuations in its
point. A computer added fluctuations, and a color-encoded pattern was displayed
on the screen. A scanned image due to another coordinate was used for obtaining
a two-dimensional pattern. Selection of informative parameters of intensity fluctuation spectra of the scattered radiation is also a rather difficult problem, because
the task is multiparameter. It is due to the change of registration conditions as well
as of the object of the study itself during changes. Skin suffers constant microvibrations caused by the contraction of separate fibers and a group of underlying
skeletal muscles, tremor, etc. [41, 44]. Blood cells move not only with capillaries
inside skin, but also they have their own velocity relative to them. Thus, the average
velocity of erythrocytes appears to be much higher than velocity of shifts of cutaneous
tissues [74].
The possibility of measurements in many points is a characteristic of speckleinterferometry. The works [37, 88–101] investigated maps of deformation distribution of isolated tissues as well as of living organisms using the method of twodimensional speckle-photography. The question of speckle-photography method
application in biological experiments was almost not considered, though it was
successfully applied in nondestructive testing of solid bodies and testing of materials for construction of deformation fields. First of all, the following fact remained
unclear, whether speckle-fields experience shifts at a value, which is greater than
the speckle size preserving correlation, or deformation of living tissue, which is
inevitably accompanied by microstructure changes, causes only speckle “boiling.”
That is why a number of experiments were conducted to determine the deformation field of living tissue using the method of double-pulse speckle-photography.
According to the works [93–95], it is necessary to register two images covered with
speckle-structure in the initial and excited states for determination of transversal
shifts. The shift was conducted either artificially [95] or during real muscle contraction [37] in the plane of movement perpendicular to the optical axis. The obtained
photography is enough to determine the shift field where two speckle systems were
registered. Interference fringes were observed as a result of optical Fourier transformation of small areas. Their direction was perpendicular to the direction of shifts,
and their period was inversely proportional to the shift [96, 97]. It is worth taking
into consideration that broken speckles shift homogeneity of illuminated area of
the specklogram leading to diminishing the contrast of interference fringes down to