X-ray Reflection Gratings: Limitations and Improvements

RECENT DEVELOPMENTS IN OFF-PLANE DIFFRACTION GRATINGS HAVE PLACED THEM IN THE CONTEXT OF FUTURE NASA X-RAY MISSIONS INCLUDING EXPLORERS PROBES AND THE LARGE STRATEGIC MISSION LYNX. OUR PREVIOUS NASA-SUPPORTED EFFORTS HAVE SHOWN IMPROVEMENTS IN DIFFRACTION EFFICIENCY SPECTRAL RESOLVING POWER AND GRATING ALIGNMENT TECHNIQUES. WE RECENTLY DEMONSTRATED IMPRESSIVE DIFFRACTION EFFICIENCIES USING BLAZED LARGE FORMAT PROTOTYPE GRATINGS. WE HAVE ALSO DEMONSTRATED EXTREMELY HIGH SPECTRAL RESOLVING POWER USING AN UNBLAZED LARGE FORMAT RADIAL PROFILE PROTOTYPE GRATING. HOWEVER WE HAVE NOT DEMONSTRATED HIGH-PERFORMANCE IN BOTH EFFICIENCY AND RESOLVING POWER IN A SINGLE GRATING. OUR FABRICATION STUDIES HAVE IDENTIFIED METHODS FOR ACHIEVING THE DESIRED CUSTOM PROFILE IN A SINGLE GRATING. WE INTEND TO IMPLEMENT THESE METHODS DURING THIS PROJECT TO FABRICATE NOVEL REFLECTION GRATINGS. THESE GRATINGS WILL BE TESTED FOR DIFFRACTION EFFICIENCY AND SPECTRAL RESOLVING POWER TO VERIFY PERFORMANCE. IN ADDITION WE HAVE ALSO DEMONSTRATED PROMISE FOR AN OPTICAL ALIGNMENT METHODOLOGY. USING RESULTS FROM RECENT TESTS KEY IMPROVEMENTS HAVE BEEN IDENTIFIED THAT WILL ENABLE ACHIEVEMENT OF GRATING ALIGNMENT TOLERANCE REQUIREMENTS. DURING THIS PROJECT WE INTEND TO ALIGN THE NEWLY FABRICATED GRATINGS USING AN ADVANCED OPTICAL ALIGNMENT SETUP. THE ALIGNMENT WILL BE VERIFIED USING X-RAY PERFORMANCE TESTING BEFORE AND AFTER ENVIRONMENTAL TESTING.