In-line digital video holography for the study of erosion processes in sediments

The use of in-line digital video holography was demonstrated for observation of the incipient erosion processes in a laboratory experiment using non-cohesive estuarine sediments. Erosion was caused by the impingement of a vertical water jet on the surface of the test bed. Holographic video reconstructions were obtained using an angular spectrum algorithm. The transverse resolution of approximately 25 µm was limited mainly by resolution of the recording camera and image acquisition chain. This procedure is substantially simpler and more convenient than the previously reported use of in-line holography with pulsed laser illumination and photographic recording. Comparisons between photographic and digital holography are discussed.