Abstract: A broadband acoustic lens and method of designing same is provided for focusing an incident acoustic wave. The broadband lens includes a plurality of concentric rings, where each concentric ring of the plurality of concentric rings has a ring width, and a plurality of gaps, where each gap of the plurality of gaps has a spacing. The concentric rings are separated by a spacing corresponding to a gap of the plurality of gaps. The widths of the plurality of concentric rings and the spacings of the plurality of gaps are arranged such that the incident acoustic wave is focused to a spot within a sub-wavelength of the incident acoustic wave in air. The arrangement of the widths of the plurality of concentric rings and spacings of the plurality of gaps is aperiodic.

Abstract: A non-contact near field high resolution acoustic imaging system of a sample, the system including an acoustic wave generator generating a plurality of acoustic waves a ultrasonic horn amplifying the waves to an amplitude of between about 20 microns and about 300 microns, and a frequency between about 20 kHz and about 40 khz. The ultrasonic horn further directs the amplified waves to impinge upon the sample. On contact between the waves and the sample, a plurality of transmitted energy is transmitted to the sample, a plurality of longitudinal displacements and surface acoustic wave displacements in the sample are created. An adjustable separation distance lies between the sample and the ultrasonic horn, the distance adjusted to maximize the transmitted energy. The distance is preferably greater than the maximum displacement of the ultrasonic horn, or approximately 0.1 mm.

Abstract: A non-contact thermo-elastic property measurement and imaging system and method thereof are described. Acoustic energy is incident on a first surface of a specimen under test. The acoustic energy is converted partially into heat by the specimen, causing a slight increase in the temperature in a region of interaction. The temperature increase is imaged using a high sensitivity infrared camera. Presence of defects (surface and subsurface) in the material modifies the distribution of temperature. An image of temperature distribution can be used for nondestructive testing and evaluation of materials. The temperature change in the specimen caused by acoustic excitation is related to thermal and elastic properties of the material. A measurement of the change in the temperature as a function of the amplitude of incident excitation can be used for direct measurement of thermo-elastic property of the specimen.

Abstract: A non-contact acousto-thermal method and apparatus are provided for detection of incipient damage in materials. The apparatus utilizes an ultrasonic horn which receives an acoustic wave generated by an ultrasonic transducer energized by an RF pulse. The ultrasonic horn is placed at a distance from the sample to be tested with sufficient gap so that when excited, the face of the ultrasonic horn does not come into contact with the sample. An IR camera is placed at a distance from the opposite side of the sample. The acoustic wave is amplified by the ultrasonic horn, and the interaction between the sample and the acoustic wave produces changes in the temperature of the sample in the region of interaction during acoustic excitation such that the temperature of the material rapidly increases. The temperature-time profile is captured by the IR camera and may be analyzed by a data acquisition unit.

Abstract: A non-contact thermo-elastic property measurement and imaging system and method thereof are described. Acoustic energy is incident on a first surface of a specimen under test. The acoustic energy is converted partially into heat by the specimen, causing a slight increase in the temperature in a region of interaction. The temperature increase is imaged using a high sensitivity infrared camera. Presence of defects (surface and subsurface) in the material modifies the distribution of temperature. An image of temperature distribution can be used for nondestructive testing and evaluation of materials. The temperature change in the specimen caused by acoustic excitation is related to thermal and elastic properties of the material. A measurement of the change in the temperature as a function of the amplitude of incident excitation can be used for direct measurement of thermo-elastic property of the specimen.