Sound-velocity distribution measurement apparatus, sound velocity distribution measuring method and program

摘要

PROBLEM TO BE SOLVED: To measure an optional inner sound velocity distribution, without assuming the form of an inner sound velocity distribution of an object to be measured.;SOLUTION: A sound velocity distribution measuring device according to the present invention comprises: a resonance frequency measuring section that radiates ultrasonic waves in teh thickness direction of an object to be measured and that measures N resonance frequencies up to the Nth resonance frequency of the thickness direction of the object to be measured; an inverse-analysis section that assumes a mass-spring system model made up of N pieces of mass bodies and (N-1) pieces of springs connecting the mass bodies mutually adjacent to each other, and that calculates a mass of each of the N pieces of mass bodies and a spring constant of each of the (N-1) pieces of springs, utilizing the measured N resonance frequencies; and a sound velocity distribution calculating section that calculates acoustic impedance and the thickness of each layer divided into (N-1) layers having a thickness corresponding to each length of the (N-1) pieces of springs in the thickness direction of the object to be measured, by using a known density of the object to be measured and using the mass and the spring constant calculated on the presumption that the sound velocity distribution of the ultrasonic waves in the thickness direction of the object to be measured is symmetrical with the center of the thickness of the object to be measured.;COPYRIGHT: (C)2012,JPO&INPIT