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Holographic interferometry provides certain advantages in the fabrication of interferograms for multidirectional observation of transparent media. This turns out to be useful, if inhomogeneous phase objects such as plasmas of technical interest are to be analyzed. The serious problem of a comparatively small fringe shift being caused by neutral or charged particles in a plasma can be reduced using the technique of spatial optical heterodyning. The corresponding highly resolved phase profiles are well suited for the application of sensitive tomographic reconstruction algorithms, as they are known from x-ray compute tomography in medicine. For the case of rotationally symmetric phase objects a new reconstruction technique is presented. The combination of resonant holographic interferometry with tomography allows the determination of the particle density of distinct atoms and ions and their spatial distribution in an inhomogeneous plasma. Finally, the consideration of saturation effects in the use of resonant holographic interferometry, the degree of ray-bending because of refractive index gradients due to inhomogeneities, and ways of suppression of the troubling strong self radiation of a plasma are discussed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
