Use of normal and electronic interferometric holography for defect localization and characterization of artifacts

摘要

Deterioration of natural stone, man-made building materials such as mortar, bricks and concrete, and other materials such as wood, paint, glass, metal, etc. has been of increasing concern in recent decades. More specifically, problems of lifetime and durability of reinforced concrete structures on the one hand and museum objects diagnostic on the other became more important due to different factors. Since the late seventies, all this had led to intensified research about the causes and the nature of degradation processes and to the development of general strategies for handling such situations. Environmental factors are often cited as major parameters, but the concept, design, and manufacture of the elements are also very important. Both from the civil engineering point of view, and from the restoration aspects, early detection of damage can save a lot of trouble, labor, and thus money. Holographic interferometry is in principle a method very well suited for this purpose, as it combines whole-field measurement and high sensitivity with non-contact and non-preparation of the materials studied. This paper describes some results obtained on real-size, real-life objects. Up to now, tests were conducted in the lab using continuous and pulsed lasers combined with silver-halide and electronic recording schemes. It is hoped that in a later phase, in-situ experiments will be effectuated; some preliminary concepts of that are discussed.