Selective detection of second harmonic sound generated at the focal region in a finite amplitude focusing field

概要

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A method for selective detection of the second harmonic component generated at the focal region in a focused sound field due to the local nonlinear properties of medium is discussed. The phase shift of sound waves passing through the focus offers the principle of the present method. Assuming a source with a Gaussian profile excitation to avoid the edge diffraction, the effect of an inserted sample with a nonlinearity parameter different from that of surrounding liquid(water) is theoretically analyzed. The experiment employing a sample of benzyl alcohol shows the validity of the theory. The quadrature component of the second harmonic which differs in phase by pi/2 radians from that of non-diffraction case corresponds well to the second harmonic generation at the focus, i. e. the nonlinear property of the sample within the focal region.
社団法人日本音響学会の論文
1987-09-00