Grazing incidence telescopes for x-ray astronomy

With grazing incidence telescopes, x-ray astronomy became a major branch of astrophysics. They are an indispensable tool in the study of >10 6 K thermal and non-thermal high energy phenomena occurring in objects from the solar system to the most distant sites in the universe. They have shed light upon dark matter and dark energy. Four cosmic mis- sions with focusing grazing incidence x-ray telescopes based upon the Wolter 1 geometry are currently in space. They include two observatory class facilities launched in 1999, NASA's high resolution x-ray and ESA's high throughput XMM-Newton. Two others are Japan's Suzaku, perform- ing a variety of studies, and the Swift XRT, which finds precise positions for the x-ray afterglows of gamma-ray bursts. Four new cosmic missions with Wolter-like focusing telescopes are scheduled for launch. They will pro- vide much broader bandwidth (NuSTAR and Astro-H), perform a new sky survey with more exposure time and a broader energy range than previous surveys (eROSITA), have an imaging detector with much better energy resolution (Astro-H), and measure polarization (GEMS). The Kirkpatrick-Baez and the lobster-eye are two types of potentially useful grazing incidence telescopes that have not yet been in orbit. It may not be possible to improve upon Chandra's 0.5 arcsec resolution without new technology. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1.OE.51.1.011010)