Laboratory progress in soft x-ray polarimetry

We present continued development of components for measuring linear X-ray polarization over the 0.2-0.8 keV (15-62 Angstrom) band. We present results from measurements of new laterally graded multilayer mirrors and critical angle transmission gratings essential to the approach. While the lab is designed to verify components to be used in a soft X-ray polarimeter, it is reconfigurable and has been used to verify grating efficiencies with our new CCD detector. Our development work is the basis for a sounding rocket mission (Rocket Experiment Demonstration of a Soft X-ray Polarimeter) and future orbital missions.