Archives of Acoustics, 26, 2, pp. , 2001

Verification of measurement possibilities of quasi-continuous acoustic wave packets for technical and medical applications

M. Szustakowski
Institute of Optoelectronics

L. Jodłowski
Institute of Optoelectronics

M. Piszczek
Institute of Fundamental of Electronics

Quasi-continuous acoustic wave packets are used for
investigations of real objects due to determination of their material parameters
such as, for example, propagation velocity of an acoustic wave, or localisation
of their inner structures. Application of low sampling frequencies (500kHz) in
comparison with the strict harmonic probing signals [ampersand]sim;1.5MHz offers very
promising measuring possibilities (detection of the transit time changes of
acoustic signal [ampersand]asymp;5ns). This paper shows the test measurement results for a
glass vessel (300mm probing path in distilled water) and patients with
pathological changes (ischemia and internal haemorrhage in the brain tissue)
using the phase and time methods. High sensitivity of measurements ensures
detection of differences in density of the order of [ampersand]sim;3[ampersand]middot;10-3kg/m3,
propagation velocity of acoustic wave [ampersand]sim;4[ampersand]middot;10-2m/s, temperature
[ampersand]sim;1.5[ampersand]middot;10-2K and change of the acoustic path [ampersand]sim;4[ampersand]mu;µm. Sensibility
and simplicity of the measuring system makes the proposed solution a very
attractive tool for investigations. It can be applied for measurement of
different changes of the material properties in the automatic systems and
medicine.
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