I would like to describe some of our programs at NASA, Langley Research Center, Hampton, VA, on the development and use of a new type of phase insensitive transducer we call an Acoustoelectric Converter, or an AEC. In the very short time I have here, I shall indicate why the AEC is significant and show some ultrasonic transmission results obtained from modified isometric attentuation scans of c...

The recent development of laser light probes for stress wave measurements has aided our understanding of acoustic emission and ultrasonic signals by allowing quantitative measurements of stress waveforms. This paper reports on applications of the laser interferometer probe for surface detection of stress waves and the laser transmission probe for sensing of stress waves inside transparent mater...

Underwater acoustic signals need transducers to generate and detect signals with high power, linearity, dynamic-range and beamwidth. Among a variety of transducer designs, a Tonpilz transducer stands out for power and long-range applications. A Tonpilz transducer for underwater acoustic signaling is developed to scale and analyzed using FEM tools with Comsol. The underlying pressure-acoustics a...

This paper investigates low cost matching network for high impedance ultrasonic transducers. Matching the output transmitter impedance to high impedance transducer is important to maximize the transfer of power and improve the transmitting efficiency of the transducer, and so achieve better signal-to-noise ratio. In NDT ultrasonic applications based on piezoelectric transducers it is usual to i...

A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for a single rectangular transducer and required approximation considerations or nonlinear...

A broad overview of laser-ultrasonics, which is a technique for non-contact generation and detection of ultrasound is presented. The principles of generation and detection are outlined, stressing a few key characteristics of laser-ultrasonics: the material is actually the emitting transducer and transduction is made by light, thus allowing generation and detection at a distance. These features ...

In this article application of direct and indirect ultrasonic methods for evaluating and measuring porous materials are reviewed. Ultrasonic waves, due to their physical properties and wide frequency range can successfully be applied when evaluating the porosity of materials. Ultrasonic methods have many advantages when comparing them with other, non-acoustic measurement methods, which are also...

The application of intense ultrasound to a liquid-gas interface results in the formation of an ultrasonic fountain and generates both mist and vapor from the liquid. Here, the composition of the vapor and aerosol above an ultrasonic fountain is determined as a function of irradiation time and compared with the results of sparging for five different solutions. The experimental apparatus for dete...

In turbid media such as biological tissue, multiple scattering hinders direct light focusing at depths beyond one transport mean free path. As a solution to this problem, time-reversed ultrasonically encoded (TRUE) optical focusing is proposed based on ultrasonic encoding of diffused laser light and optical time reversal. In TRUE focusing, a laser beam of long coherence length illuminates a tur...