Rapid calculation of paraxial wave propagation for cylindrically symmetric optics.

When calculating the focusing properties of cylindrically symmetric focusing optics, numerical wave propagation calculations can be carried out using the quasi-discrete Hankel transform (QDHT). We describe here an implementation of the QDHT where a partial transform matrix can be stored to speed up repeated wave propagations over specified distances, with reduced computational memory requirements. The accuracy of the approach is then verified by comparison with analytical results, over propagation distances with both small and large Fresnel numbers. We then demonstrate the utility of this approach for calculating the focusing properties of Fresnel zone plate optics that are commonly used for x-ray imaging applications and point to future applications of this approach.