United States of America As Represented by the Secretary of the Air Force

University of Dayton

John T Welter

Shamachary Sathish

Richard Reibel

Kumar V Jata

Philip Gregory Brodrick

Daniel Christensen

Charles Buynak

Jason D Heebl

Matthew R Cherry

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.

Air coupled acoustic aperiodic flat lens

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. The non-contact near field high resolution acoustic imaging system further includes a surface displacement detector for detecting the longitudinal wave displacements or surface acoustic wave displacements, the detector including a tip and a tip diameter; and a computer for digitizing and storing the longitudinal wave displacements or surface acoustic wave displacements. The longitudinal displacements or surface acoustic wave displacements are analyzed to create an image of at least a portion of the sample, the image alternatively having a resolution about equal to the surface displacement detector tip diameter.

Non-contact high resolution near field acoustic imaging system

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.

Non-contact thermo-elastic property measurement and imaging system for quantitative nondestructive evaluation of materials

Growing community of inventors

Fairborn, OH, United States of America

John T Welter