THE SPREAD FUNCTION OF A POLYCAPILLARY LENS AND A CONFOCAL X-RAY MICROSCOPE IN RETUNING ITS CONFOCAL VOLUME
D. S. Sorokoletov, Y. V. Rakshun, F. A. Dar’in
Budker’s Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent’eva 11, Novosibirsk, 630090 Russia
Keywords: микро-РФА, рентгеновская оптика, поликапиллярные линзы, конфокальный рентгеновский микроскоп, КРМ, аппаратная функция, обратная задача, micro-XRF, X-ray optics, polycapillary lenses, confocal X-ray microscope, CXRF, spread function, inverse problem
Abstract
A confocal experimental scheme with two polycapillary lenses is used to analyze the nearsurface layers of samples by X-ray fluorescent microanalysis with an accuracy of up to 10 μm. To increase the spatial resolution, it is required to account for the influence of the spread function of the confocal X-ray optical node. It is interesting to experiment with a tunable aperture of the confocal volume. In this case, the contribution of tuning inaccuracies in the spread function can increase. A method for describing the spread function of a confocal X-ray microscope that allows for its retuning and accounts for the effect of the angular tuning errors is proposed and experimentally proved. The method is based on the use of an approximating expression of the type of asymmetric approximation of the “Gaussian beam caustic”.
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