A novel approach for measuring linear X-ray polarization over a broad-band using conventional imaging optics and cameras is described. A new type of high efficiency grating, called the critical angle transmission grating is used to disperse soft X-rays radially from the telescope axis. A set of multilayer-coated paraboloids re-image the dispersed X-rays to rings in the focal plane. The intensity variation around these rings is measured to determine three Stokes parameters: I, Q, and U. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors over 50% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be used with the Constellation-X optics.

Date Published: 20 September 2007
PDF: 11 pages
Proc. SPIE 6688, Optics for EUV, X-Ray, and Gamma-Ray Astronomy III, 66880Z (20 September 2007); doi: 10.1117/12.746957

Published in SPIE Proceedings Vol. 6688:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy III
Stephen L. O'Dell; Giovanni Pareschi, Editor(s)