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5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
the velocity and intensity of the blood flow in each studied point of the surface with a
distribution of 2–5 mm. Through a rotary microprism, the speckle-field gets onto the
outlet face of the receiving single-mode light guide, the diameter of which matches
the size of a solitary spectrum and is ~ 5 μm. The receiving light guide is connected
with a sensitive photosensor by means of an input device. On the output window of
the photosensor, an interference filter is situated, which intercepts spurious radiation
(incandescent lamps, day light, etc.). An electric signal is formed on the output of
the photoelectric multiplier, which is connected with the amplifier. The analysis of
the signal gives the possibility to judge about biomechanical parameters of human
skeletal muscles (degree of contractility and tone) and about velocity alterations and
intensity of the skin blood flow.
Determination of signal speckles was conducted through analog processing with a
spectrum analyzer as well as through digital PC processing. Changes of the specklefield characteristics were analyzed in order to determine the informative parameters,
which reflect the functional state of muscles. Values such as power of fluctuation
spectrum, average frequency, frequency dispersion, half-breadth of a spectrum and
amplitude ratio on different frequencies were studied. Dependence of maximal value
of the spectral curve caused by a stressed state of muscles from the applied load is
shown in the work [132]. Common growth of spectral amplitudes is accompanied
by natural extension of the area under the spectral curve.
Most sensitive spectrum parameters, which have simple physical interpretation, are frequency characteristics, in particular, the average fluctuation frequency.
Frequency parameters are connected with movement characteristics in a most simple
way as frequency of intensity change is directly proportional to the velocity of the
diffuser.
The average frequency was estimated in the range between 0 and 150 Hz as on
higher frequencies the signal did not differ from noise during linear measurement.
Moreover, the program was to provide the possibility of recording a random process
into a file and organization of storing and activation of the recorded files, possibility
of PC input of 1024 or 4096 dots and conduction of a fast Fourier transformation
due to a full or partial realization.
Low-frequency spectra were usually recorded on a frequency band to 65.5 Hz
at time of realization accumulation of about 8 s. The main purpose of the abovementioned changes initially was to obtain reactive quantitative information about
muscle tone.
Besides, there is a possibility to broaden the boundaries of method application
and to use it for estimation of muscle relaxation time after removal of static load.
This mode gives the possibility to record up to 12 spectrograms with different muscle
loads and as a result to obtain graphic numerical dependencies of integral parameters
of spectrograms on the exposure factor.
Preliminary investigation and most vivid distinctions in low-frequency spectrograms on different levels of muscle activity appear when frequency f = 26–26.5 Hz
is chosen. As for the upper frequency f , its value is equal to the cutoff frequency of
a low-frequency filter (50 Hz). A signal of intensity fluctuations of the speckle-field
is recorded in a LF mode, which passes through the filter. The first two recorded
5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
the velocity and intensity of the blood flow in each studied point of the surface with a
distribution of 2–5 mm. Through a rotary microprism, the speckle-field gets onto the
outlet face of the receiving single-mode light guide, the diameter of which matches
the size of a solitary spectrum and is ~ 5 μm. The receiving light guide is connected
with a sensitive photosensor by means of an input device. On the output window of
the photosensor, an interference filter is situated, which intercepts spurious radiation
(incandescent lamps, day light, etc.). An electric signal is formed on the output of
the photoelectric multiplier, which is connected with the amplifier. The analysis of
the signal gives the possibility to judge about biomechanical parameters of human
skeletal muscles (degree of contractility and tone) and about velocity alterations and
intensity of the skin blood flow.
Determination of signal speckles was conducted through analog processing with a
spectrum analyzer as well as through digital PC processing. Changes of the specklefield characteristics were analyzed in order to determine the informative parameters,
which reflect the functional state of muscles. Values such as power of fluctuation
spectrum, average frequency, frequency dispersion, half-breadth of a spectrum and
amplitude ratio on different frequencies were studied. Dependence of maximal value
of the spectral curve caused by a stressed state of muscles from the applied load is
shown in the work [132]. Common growth of spectral amplitudes is accompanied
by natural extension of the area under the spectral curve.
Most sensitive spectrum parameters, which have simple physical interpretation, are frequency characteristics, in particular, the average fluctuation frequency.
Frequency parameters are connected with movement characteristics in a most simple
way as frequency of intensity change is directly proportional to the velocity of the
diffuser.
The average frequency was estimated in the range between 0 and 150 Hz as on
higher frequencies the signal did not differ from noise during linear measurement.
Moreover, the program was to provide the possibility of recording a random process
into a file and organization of storing and activation of the recorded files, possibility
of PC input of 1024 or 4096 dots and conduction of a fast Fourier transformation
due to a full or partial realization.
Low-frequency spectra were usually recorded on a frequency band to 65.5 Hz
at time of realization accumulation of about 8 s. The main purpose of the abovementioned changes initially was to obtain reactive quantitative information about
muscle tone.
Besides, there is a possibility to broaden the boundaries of method application
and to use it for estimation of muscle relaxation time after removal of static load.
This mode gives the possibility to record up to 12 spectrograms with different muscle
loads and as a result to obtain graphic numerical dependencies of integral parameters
of spectrograms on the exposure factor.
Preliminary investigation and most vivid distinctions in low-frequency spectrograms on different levels of muscle activity appear when frequency f = 26–26.5 Hz
is chosen. As for the upper frequency f , its value is equal to the cutoff frequency of
a low-frequency filter (50 Hz). A signal of intensity fluctuations of the speckle-field
is recorded in a LF mode, which passes through the filter. The first two recorded