Dark field coaxial ultrasonic transducer
US4760304A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 24, 1986 |
| Grant date | Jul 26, 1988 |
| Priority date | — |
| Expiry date | Nov 24, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/056
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A dark field ultrasonic transducer is constructed with an outer annular spherical or conical transducer element and an inner spherical element. The outer annular element is excited and insonifies a small portion of a part surface near a discontinuity or crack with longitudinal waves or with surface waves. The inner dark field element is not focused to be sensitive to either reflected sound or waves reradiated from the surface waves, but detects sound scattered from surface discontinuities such as a crack edge. When surface waves strike a crack edge and restrike it after reflection from the bottom of the crack, two pulses are received and the time delay between them is a measure of crack depth. The crack shape and crack depth profile are determined as the part is scanned.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.