Two-dimensional measurement of the nonlinearity parameter B/A in excised biological samples.

The method previously developed for measuring the acoustic nonlinearity parameter B/A in a liquid sample with a volume as small as 0.1 ml [S. Saito, J.

Finite amplitude method for measuring the nonlinearity parameter BA in small-volume samples using focused ultrasound.

On the basis of finite amplitude and comparative methods, the acoustic nonlinearity parameter BA of a liquid sample of as small as 0.1 ml is measured using an 18.6-MHz focused Gaussian beam.

Multiple-frequency ultrasonic imaging by transmitting pulsed waves of two frequencies.

Purpose: The aim of this study was realization of a broadband measurement system that is capable of effectively carrying out a frequency compound method. In the present method, the secondary wave components of difference and sum frequencies are generated along with the higher harmonic components through the nonlinear interaction of two-frequency ultrasound. A multiple-frequency beam is generated together with the initially radiated frequency components.

Automatic measurement of the nonlinearity parameter B/A in liquid media.

Using a 19-MHz focused Gaussian beam generated by a LiNbO(3) plate with an inverted polarization layer coupled to an acoustic lens, a method to automatically measure the nonlinearity parameter B/A in liquid media is presented. A liquid sample is poured into a cylindrical cell set with a glass tube on the lens surface. The focusing source emits burst waves.

Development of an ultra-broadband ultrasonic imaging system: prototype mechanical sector device.

Purpose: We constructed an ultra-broadband ultrasonic transducer in a mechanical sector device, and prototyped a system to generate real-time images with higher harmonics. The potential of the system to reduce speckle was also studied.

Methods: To efficiently detect the higher harmonic components in echo signals, in addition to the transmitting transducer, another transducer only for broadband reception is necessary.

An ultrasonic transducer for second harmonic imaging using a LiNbO3 plate with a local ferroelectric inversion layer.

A new lithium niobate (LiNbO3) transducer of separated transmitter-receiver configuration is proposed for application to second harmonic imaging in a high-frequency range. In this transducer, a domain-inverted layer of half the plate thickness is formed selectively by Ti-diffusion and heat treatment in the central part of a LiNbO3 plate. The uniformly polarized surrounding region is used as the transmitter that will generate the fundamental wave component.

Broadband ultrasonic transducers using a LiNbO3 plate with a ferroelectric inversion layer.

Some heat treatment of a lithium niobate (LiNbO3) plate induces domain inversion, thereby yielding a ferroelectric inversion layer. In such a piezoelectric plate with an inversion layer, even-order thickness-extensional modes, as well as odd-order modes, can be excited piezoelectrically. Therefore, the ultrasonic transducer using such a piezoelectric plate is expected to operate over a wide frequency range.