Holography Based on the Weigert’s Effect
نویسنده
چکیده
Despite the numerous scientific and technological achievements in the field of holography, its main task still remains the registration and the reconstruction of the complete information of the wave scattered by the object. The wave of the light, scattered by an object, is characterized by four main parameters: Intensity, Phase, Wavelength and Polarization. The primary task of holography is solved, if all four parameters are recorded and reproduced adequately. The problem of holographic recording and reconstruction of the first three parameters was practically solved by using ordinary light-sensitive materials, which respond only to the Intensity of light (Gabor, 1948; Leith &Upatnieks, 1962; Denisiuk, 1974). As to the fourth parameter the polarization the problem of its adequate recording and reconstruction was not solved. It is natural that, in the case of the usual photosensitive material, all the characteristics of the wave, except polarization, are displayed as the distribution of isotropic optical properties. However, in the general case of holographic recording the light wave, scattered on the object, changes the polarization. Therefore the total interference pattern will have the modulation also with the polarization, the information about of which is lost during the holographic recording in the ordinary photographic materials. It should be noted that from the four basic parameters of the light the polarization can be regarded as the most complex. Particularly, to assess the polarization of the light, the measurement of four values is needed (so called Stokes parameters, So; S1; S2; S3)(Born&Wolf, 1974). However, it turned out that the question of the polarization is more difficult for the unpolarized light. For example, the light remains unpolarized during the passing of anisotropic and gyrotropic objects, but its statistical structure is altered, which radically changes the result of interference. The interference of unpolarized waves gives a usual pattern of light and dark bands, which are also unpolarized. But, if on the path of one of the interfering waves we put an anisotropic half-wave or gyrotropic half-wave (rotator at 900) phase plate, the interference pattern disappears and the field becomes evenly lighted. However, the polarization analysis shows, the interference pattern is polarized in this case (Langsdorf&Du Bridge, 1931; Vavilov, 1932). Therefore, the unpolarized light has a certain polarization parameter which can be detected and, accordingly, can be recorded in appropriate conditions. Thus, the problem of the holographic registration and the reconstruction of the polarization state of the wave can be considered as the most difficult problem in the holography. For registration of the polarization characteristics of light a photosensitive material, which
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