Holographic Detection of Microcracks

This paper describes the application of optical holographic interferometry to the detection of microcracks in metals. In particular, detection of radial cracks extending from bolt holes in high strength aircraft steel was studied. The method was found to hvve several advantages over currently used detection methods. The results of the holographic study compared favorably with independent results obtained by magnaflux, eddy current, and X-ray inspection. Some evidence of a possible ability to detect untempered martensite deposits was also noted.