ABSTRACT
Holography is an interferometric technique that has proved to be convenient to store and reconstruct the complete amplitude and phase information of a wave front. The popular interest in this technique is due to its unique property to obtain three-dimensional (3D) images of an object, but there are other less known but very useful applications that are concerned with microscopy, deformation measurement, aberration correction, beam shaping, optical testing, and data storage, just to mention a few. Since the technique was invented by Gabor [1], as an attempt to increase the resolution in electron microscopy, an extensive research has been done to overcome the original limitations and to develop many of its applications. Gabor demonstrated that if a suitable coherent reference wave is present simultaneously with the light scattered from an object, the information about both the amplitude and phase of the object wave could be recorded, although the recording media only registers the light intensity. He called this holography, from the Greek word “holos” (the whole), because it contained the whole information. The fi rst concept of holography developed in 1948 was as in-line arrangement using a mercury arc lamp as the light source; it allowed to record only holograms of transparent objects and contained an extraneous twin image. For the next 10 years, holographic techniques and applications did not develop further until the invention of the laser in 1960, whose coherent light was ideal for making holograms. By using a laser source, Leith and Upatnieks developed in 1962 the
off-axis reference beam method, which is most often used today [2]. It permitted the making of holograms of solid objects by refl ected light.
