Apparatus for Generating a Focusable and Scannable Ultrasonic Beam for Non-Destructive Examination.
Patent, Filed 1 Sep 83, patented 23 Apr 85,
DEPARTMENT OF THE NAVY WASHINGTON DC
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This invention relates to an apparatus for generating a focusable and scannable ultrasonic beam for use in nondestructive internal examination of an object. In one embodiment an optical mask modifies a pulsed light beam to form an optical zone pattern. The zone pattern is imaged on the surface of an optically absorbing thermoelastic layer in contact with a propagation medium. An ultrasonic beam is thereby generated which focuses at a point in an object submerged in the propagation medium. An optical lens and a mirror respectively focus and scan the modified light beam, whereby the ultrasonic beam is also focused and scanned. A second embodiment utilizes an acoustooptic modulator to modify the light beam and cause scanning and focusing of the ultrasonic beam. Suitable detectors and instrumentation may be provided to analyze the ultrasonic beam after it has traversed the object under examination. An important application of ultrasonics is examining opaque materials and tissue for internal flaws and abnormalities. The examination of materials for flaw detection as well as the examination of tissue for medical diagnostic purposes are improved by the use of small acoustic beams which can be scanned and focused. Such small acoustic beams are desirable in order to detect small defects.
- Acoustic Detection and Detectors