A simple one-dimensional wave calculation was implemented for designing a micro-focusing protein crystallography beamline. Wave propagation was successively traced, starting from a Gauss beam as a simple approximation of the undulator light source, to slit as a secondary light source, focusing device replaced with a simple phase shifter, and a focal point. Each source/optics element was divided into the fine segments. Fraunhofer diffraction amplitudes from the segments were summed up at the point on the next element. Source position and emission direction were changed based on the electron beam size and divergence of the storage ring. Intensity distributions at the focal position were finally obtained.

Beam sizes, beam profiles, and photon flux of focused x-rays were calculated by changing the slit size, resulting in the focused beam sizes between 1x1 and 50x50 μm² at the sample position with photon flux of 10¹⁰~10¹³ photons/s with proper photon density of 10¹⁰ photon/s/μm². It satisfies the experimental requirements for the micro-focusing protein crystallography.

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Shunji Goto, "Optics design of a micro-focusing protein crystallography beamline using a wave calculation," Proc. SPIE 10760, Advances in X-Ray/EUV Optics and Components XIII, 107600D (Presented at SPIE Optical Engineering + Applications: August 20, 2018; Published: 17 September 2018); https://doi.org/10.1117/12.2323295.