On the optical design of a large X-ray mirror based on silicon pore optics

Silicon Pore Optics (SPO) have been chosen as the X-ray optics technology for the European Space Agency's Athena mission. Although in principle SPO can be used to realize classical Wolter-I or Wolter-Schwarzschild systems, technological and manufacturing considerations introduce constraints that lead to a system where some of the parameters of the optics are altered with respect to the classical description. In this paper we describe some of the constraints and how they affect the way one goes about designing optics based on SPO. Further we present ray-tracing results that show how these constraints do not impact the performance goals of a large mission like Athena.