High Resolution Moire Photography

Deformations of engineering structures are measured by applying a fine grid pattern to the surface and photographing this in white light with a specially modified 35 mm camera. The processed negatives are analyzed in a spatial filtering system to produce moire fringe maps which represent in detail the three-dimensional displacements that have occurred. Measurements have been obtained from brick built and concrete structures, from steel surfaces heated to 600°C, and from plastic and composite materials.