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The contents of this volume reflect to a large extent the efforts made by a group of Institutes at the ETH Zürich to develop new techniques for measurements of flows in fluids in the last decade. The motivation came from the study of tr~sport and mixing processes in natural and industrial systems. One of the characteristic properties of turbulence is its high mixing efficiency. The techniques developed are therefore suitable, although not exclusively, for turbulence measurements. They can be subdivided into point-measurements and field-measurements. The aim of the point-measurements developed is to determine the three components of the velocity and all their first derivatives with good temporal resolution and accuracy in turbulent flows. The old and weIl established method of hot-wire anemometry was used for this purpose. One of the main achievements in this context is the construction of miniature multi-wire probes. This technique was introduced to the Institute of Hydromechanics and Water Resources Management of ETH Zürich by Profs. A. Tsinober and E. Kit from Tel-Aviv University. This was made possible by the generous financial support by ETH, for which I would like to express my gratitude on this occasion. In addition, Dr. F.E. Joergensen from DANTEC contributed an example of recent developments in the hardware ofConstant Temperature Anemometry (CTA), for which I am very thankful.

This monograph deals with diverse applications of holographic interferome­ try in experimental solid mechanics. Holographic interferometry has experienced a development of twenty years. It has enjoyed success and suffered some disappointments mainly due to early overestimation of its potential. At present, development of holo­ graphic interferometry is progressing primarily as a technique for quantita­ tive measurements. This is what motivated us to write this book - to ana­ lyze the quantitative methods of holographic interferometry. The fringe patterns obtained in holographic interferometry are graphi­ cally descriptive. In the general case, however, because they contain infor­ mation on the total vectors of displacement for points on the surface of a stressed body, the interpretation of these interferograms is much more complicated than in typical conventional interferometry. In addition, the high sensitivity of the method imposes new requirements on the loading of the objects understudy. New approaches to designing loading fixtures are needed in many cases to ensure the desired loading conditions. The wealth of information obtained in holographic interferometry necessitates the use of modern computational mathematics. Therefore, practical implementation of the various methods of holographic interferometry must overcome sub­ stantial difficulties requiring adequate knowledge in diverse areas of science such as coherent optics, laser technology, mechanics, and applied mathe­ matics. Experimental methods play a significant role in solid mechanics.