Dynamic Holography Method for Nondestructive Testing of Optical Homogeneity of Transparent Media
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ICAL PROPERTIES OF CRYSTALS Dedicated to the memory of B.N. Grechushnikov
Dynamic Holography Method for Nondestructive Testing of Optical Homogeneity of Transparent Media N. V. Bogodaev, L. I. Ivleva, P. A. Lykov, V. V. Osiko, and A. A. Gordeev Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, 119991 Russia email: [email protected] Received June 25, 2010
Abstract—The potential of the dynamic holography method for testing the phase optical homogeneity of media transparent in visible light has been considered. This method is based on imaging samples in the scheme of twowave mixing of the secondharmonic radiation of a Nd:YAG laser and image amplification in a photorefractive barium–strontium niobate crystal. Examples of identifying phase inhomogeneities at a level of 10–5 cm–1 and less in crystals of different compositions are presented. DOI: 10.1134/S1063774510060167
INTRODUCTION The development of laser technology is determined in many respects by the possibilities of the laser mate rials and light control systems. Some urgent problems of materials science concern both the fundamental properties of active media (deviation from stoichiom etry, polymorphism, and phase equilibria) and applied problems (sources of characteristic optical and struc tural inhomogeneities, the optimization of crystal growth conditions, and the development of the tech nology of glasses and transparent ceramics). Along with some general regularities, the technologies of individual materials have a number of specific features which must be taken into account when optimizing the production of optically perfect active media. Easy toproduce materials with optimal characteristics (in particular, high optical quality and physicochemical stability under external effects) are advantageous for practical use. We propose a highspeed nondestructive method for testing the optical quality of materials which makes it possible to establish the dependence that the phase homogeneity of the medium has on the preparation conditions (initial composition, synthesis conditions, crystallization parameters, and regimes of thermal treatment) and efficiently optimize the crystal growth conditions, as well as to solve the materialsscience and technological problems in developing new optical media. One of the most important groups of active materi als includes dielectric crystals. Only a few of them find practical application because the growth of crystals of a quality satisfying the requirements for quantum optics is a very difficult problem. In this paper we used the dynamic holography method to study the real structure of nonlinear optical materials with quadratic
and cubic nonlinearities belonging to different sym metry classes and having different chemical composi tions and doping levels: scheelite crystals (calcium, strontium, and barium molybdates and tungstates) and solid solutions of barium–strontium niobate (BSN), both nominally pure and doped with transi tion and rare earth metals. The possibility for the high speed mo
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