Volume 24, Issue 1 (January 1979)
Reconstruction of Fractured Glass by Laser Beam Interferometry
The matching of fractured glass fragments has been extended by von Bremen  to include the intrinsic heterogeneities referred to in the glass industry as “ream” . Von Bremen used a fiber optics source to project a shadowgraph of fractured glass onto a photographic film that was then developed. Although this is a powerful method for comparing ream marking, the technique suffers a disadvantage in that the ream cannot readily be seen with the naked eye in all samples. It is readily apparent in container glass, lamp bulb glass, and drawn window glass. In other types of glass including float glass, the photographic film must be developed before it is known whether an image of the heterogeneities of the glass has been adequately recorded.