Nondestructive Testing Using TRW Acousto-Optical Imaging System
Semi-annual rept. 30 Jun-30 Dec 1970
TRW SYSTEMS GROUP REDONDO BEACH CA APPLIED MECHANICS LAB
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The technique of Acousto-Optical Imaging AOI enables one to see, on a real-time basis, within optically opaque materials and to detect internal or surface flaws andor other irregularities which might be present. The process uses an ultrasonic beam to probe the object under study. As it interacts with the object, the ultrasonic beam acquires an acoustical picture of the object. The acoustic waves then interact with a monochromatic light beam as from a laser. Optical sidebands are produced by the Bragg diffraction of light. The cumulative result of this process is that these sidebands produce a visual image of the interior of the object. This paper discusses the results of an experimental study to evaluate the applicability of acousto-optical imaging to nondestructive testing. In addition to the determination of the system resolution, the effects of specimen thickness, geometry, composition and surface roughness are under investigation. A new technique which utilizes the sound reflected from the specimen to obtain an acousto-optical image was also developed. Preliminary results utilizing this technique to detect surface flaws on a specimen are encouraging.
- Test Facilities, Equipment and Methods