A full-wave approach to quantitative characterization of x-ray zone plate lenses is proposed. Distributed focusing efficiency η(<i>z</i>) of a multifocus optical element is defined as the energy flux through the Airy disk of a reference perfect lens with variable focal length <i>z</i>. Maxima of this function characterize diffraction efficiencies and spatial resolution of the zone plate foci. The parabolic wave equation is used to take into account diffraction effects inside the optical element. Rough and fuzzy interface models are introduced to describe realistic zone profiles. Numerical simulation reveals the limited capability of zone width reduction to improve the zone plate imaging performance. The possibilities of second-order focus enhancement by optimization of the zone plate thickness, line-to-space ratio, and zone tilt are studied numerically.
© 2002 Optical Society of America
(000.4430) General : Numerical approximation and analysis
(050.1960) Diffraction and gratings : Diffraction theory
(050.1970) Diffraction and gratings : Diffractive optics
(340.7460) X-ray optics : X-ray microscopy
Alexei N. Kurokhtin and Alexei V. Popov, "Simulation of high-resolution x-ray zone plates," J. Opt. Soc. Am. A 19, 315-324 (2002)