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The present paper deals with new results on the development of a holographic nonspatial filter to be used for laser beam clean up. This is the problem which any user of laser radiation necessarily meets. At the present time it is usually solved by means of spatial filters (pinholes or single mode optical fibers) which are placed on the beam way. Such filters exhibit, however, some important drawbacks, namely, they are rather expensive, require a long time for their alignment, can not be used with powerful lasers. Recently [1,2,3] we reported theory and ffitt experiments on the development of a holographic optical element to be used for filtration of spatial frequencies in laser beams, which is a principally new solution of this task. Such elements have several advantages as compared with traditional elements, namely, they operate directly in laser beam, without its focussing, they are aligned considerably easier, may be used with high power lasers, and are cheaper in manufacturing. However, our previous investigations were devoted mainly to the development of a holographic filter which allows to select spatial frequencies only in one direction. In the current paper we present results on 2D selection of laser beams. The theoretical estimations and first experimental results [2] show the possibility to obtain a holographic filter with angular selectivity of 10-104 rad, that is close to the magnitude of the initial divergence of laser beam.
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