Application of pulsed reflection holography to material testing

A processing technique resulting in high quality reflection holograms is described. The pulse reflection holograms produced may be analyzed by microscope up to interference fringe densities of about 30 fringes/mm. An experimental study using the holographic technique for the detection of fatigue crack growth in a critical aircraft structure is discussed. Low-noise high-efficiency Denisyuk (1963) phase reflection holograms can be produced by the technique. Holograms of a quality sufficient for the convenient interferometric evaluation of low-diffuse reflectance objects are obtained. In addition, the technique provides a low emulsion shrinkage, making possible shrinkage manipulation and thus reconstructed-color manipulation. Rigid-body motion problems are readily solved if the plate holder is fixed to the object. Finally, sensitivity to in-plane as well as out-of-plane deformation is obtained through the observation of different angles of the objects.