Method and apparatus for measuring LSAW propagation characteristics
AssigneeJun-ichi Kushibiki
InventorsJun-ichi Kushibiki, Yuu Ono
Life of this patent
Estimating the term…
Abstract
The temperature distribution in water is measured by two thermocouples to obtain a temperature compensating parameter. Under measurement conditions where the temperature distribution in water varies, a measured V(z) curve is used to monitor a change in the wave number of a longitudinal wave in an ultrasonic wave propagation region in water to thereby detect variations in the water temperature and the longitudinal wave velocity with high accuracy.
Claims27
An LSAW propagation characteristics measuring method in which:
- a specimen under examination is irradiated with a focused ultrasonic beam by an acoustic lens through water used as an acoustic coupler;
- variations in an interference signal, which is a reflected signal from said specimen, with the relative distance z between an ultrasonic device and said specimen is obtained as a V(z) curve that is a function of said z;
- and said V(z) curve is analyzed to obtain the phase velocity and propagation attenuation that are propagation characteristics of a leaky surface acoustic wave (LSAW), said method comprising the steps of:
- (a) pre-measuring, for said specimen, the water temperature TAM in a region directly below the surface of said acoustic lens and the water temperature TBM in a region near said acoustic lens to detect the temperature difference ΔTM;
- (b) measuring said V(z) curve at the same time as the measurement of said water temperature TBM and obtaining an interference interval Δz with respect to said z;
- (c) estimating, for said specimen, the water temperature TAM in said region directly below the surface of said acoustic lens, and determining the longitudinal wave velocity VW in said water at said estimated temperature TAM based on a known data table;
- and
- (d) calculating the velocity VLSAW of said leaky surface acoustic wave from said determined longitudinal wave velocity VW, said interference interval Δz, and an ultrasonic frequency f.
An LSAW propagation characteristics measuring apparatus which:
- applies a ultrasonic beam generated by a transducer to a specimen under examination by an acoustic lens through water used as an acoustic coupler;
- obtains variations in a reflected signal from said specimen with the relative distance z between an ultrasonic device and said specimen, as a V(z) curve that is a function of said z;
- and analyzes said V(z) curve to obtain the phase velocity and propagation attenuation that are propagation characteristics of a leaky surface acoustic wave (LSAW), said apparatus comprising:
- receiving means for receiving a signal from said transducer to derive therefrom an interference signal V(z);
- analysis means for analyzing said interference signal V(z) from said receiving means to obtain said LSAW propagation characteristics;
- and
- temperature measuring means for measuring the water temperature in the vicinity of said acoustic lens and in a region directly below the surface of said acoustic lens;
- wherein said analysis means comprises means for calculating a temperature difference ΔTM between the water temperature TBM in the vicinity of said acoustic lens and the water temperature TAM in said region directly below the surface of said acoustic lens pre-measured for said specimen under examination, and for estimating a water temperature TAM in said region directly below the surface of said acoustic lens by TAM=TBM+ΔTM during measurement of said interference signal V(z) of said specimen under examination to remove a measurement error by said temperature difference ΔTM.
The apparatus of 19, wherein said means for maintaining the quantity of water is means for maintaining the quantity of water by periodically supplying said water into between said acoustic lens and said specimen.
Dependencies are inferred from the claim text.