Modulation of intensity in defocused beams

Josep Nicolas; Gastón García

doi:10.1117/12.2024528

27 September 2013 Modulation of intensity in defocused beams

Josep Nicolas, Gastón García

Proceedings Volume 8848, Advances in X-Ray/EUV Optics and Components VIII; 884810 (2013) https://doi.org/10.1117/12.2024528
Event: SPIE Optical Engineering + Applications, 2013, San Diego, California, United States

Abstract

Many synchrotron experimental techniques require a variable size x-ray photon beam on the sample or on the detector. The easiest way to achieve this, with the minimum set of optical elements, is to defocus the beam, typically by changing the bending radius of the focusing mirrors. Nevertheless, to defocus the beam from sample has the problem that the beam profile is heavily modulated by striations caused by the surface error of the focusing optics. To our knowledge, a relationship between these modulations of the beam and the surface errors that originates them has not been properly established. In this work we show that beam modulation of a defocused beam has a nonlinear dependence on the slope profile of the mirror. From the derived relationships it follows that the relative contributions to beam striations of slope error lower and higher spatial frequencies vary depending on how far away the measurement plane is from the image plane. We explore the relationship between the amplitude of the striations and the power spectral density of the slope errors.

Citation Download Citation

Josep Nicolas and Gastón García "Modulation of intensity in defocused beams", Proc. SPIE 8848, Advances in X-Ray/EUV Optics and Components VIII, 884810 (27 September 2013); https://doi.org/10.1117/12.2024528

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