Silicon Pore Optics for Athena and beyond

Optics development for ESA’s L-class X-ray observatory Athena has resulted in a new mirror technology: Silicon Pore Optics (SPO). Light-weight optics modules are manufactured out of silicon mirror plates using technology from the semiconductor industry and custom robots. A large collecting area and a consistently high optical performance are achieved by combining a large number of modules. Moreover, SPO is a highly adaptable technology, as the design of the mirror plates and the modules can be optimized for new applications beyond the Athena mission. Several applications have already been put forward. Arcus is a candidate probe-class mission, which employs SPO modules in combination with transmission gratings in order to perform high resolution spectroscopy. The Off-plane Grating Rocket Experiment (OGRE) uses SPO’s direct bonding techniques to align its reflection gratings to high accuracy. The Cosmic Web Explorer was a concept for ESA’s long-term science program “Voyage 2050”, and it explored how SPO can deliver an unprecedented effective area of 10 m². Aside from mission concepts, different optical designs have been investigated as well, including Kirkpatrick–Baez optics and X-ray interferometry. Finally, Silicon Laue Components (SiLC) use Bragg diffraction to focus hard X-rays and soft gamma-rays in the energy range of 80 keV to about 500 keV, and are produced using the same technologies as SPO. In conclusion, SPO technology is mature and can be mass produced: it enables Athena, and can be efficiently adapted to other needs.