Holography underwater inspection

In this work, the under-water inspection processes are focused. The difficulties during the process and the quality of the image generated are the main concern for bodies in the ocean deep water. The holography is proposed as an under-water inspection process and its advantages and disadvantages are compared to the other more common used processes. The fundamental theoretical aspects of holography are discussed and the relevant influence of the water over physical behavior laser beam are theoretically considered in the analysis. The experimental analysis is done by recording holograms of a steel plate submerged into water. In order to create a fixed standard image hologram, the steel plate was submitted to a load generating interference bands, when the double exposure technique was used. In order to investigate the effect of the water over the resolution of the interferogram, it was used distilled water, sea water, drinking water and tap water, and also compared to the interferogram taken in the air, under the same loading condition. The values of the displacements obtained in air and underwater are compared. The images were processed by using the Global Lab. Software. The software, analyzing the interference bands, gives information about band resolution per 'mm', average resolution for the full amplitude, the distribution of the bands along the interferogram, the separation between bands, a graphical recording of the bands intensity, the width of bands and the fringe pattern recording.