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Abstract

Double Exposure Holographic Interferometry (DEHI) technique has wide applications in the field of science and engineering. DEHI can be used to determine very small surface changes in an object at very small interval of time. Holographic Interferometry has been widely accepted as viable tool for nondestructive testing of materials. It permits the qualitative and quantitative analysis study of minute changes in the body contours by comparing each point on its surface with itself before and after a change takes place. The success of nondestructive testing of materials, however, depends upon stressing technique adopted. In DEHI interference takes place between the wave fronts reconstructed by two holograms of object recorded on the same photographic plate. Continuous comparison of surface displacements relative to initial state may in certain cases supply more information. It is sufficient to a permanent record of relative surface displacement occurring after a fixed interval of time. The attempt is made to study the rate of chemical corrosion of aluminium and iron strips placed in hydrochloric acid for certain interval of time.