RAP FIGURING SLUMPED MIRRORS TO REMOVE MID-SPATIAL FREQUENCY ERRORS FUTURE X-RAY TELESCOPES REQUIRE SIGNIFI…

Public award description

RAP FIGURING SLUMPED MIRRORS TO REMOVE MID-SPATIAL FREQUENCY ERRORS FUTURE X-RAY TELESCOPES REQUIRE SIGNIFICANT AMOUNTS OF OPTICAL AREA. TO ACCOMMODATE THIS IN A GRAZING INCIDENCE DESIGN, EXTREMELY THIN MIRRORS ARE FORMED IN CONCENTRIC SHELL CONFIGURATIONS. A SLUMPING TECHNIQUE HAS BEEN DEMONSTRATED WITH SUCH THIN, LIGHTWEIGHT SHELLS. HOWEVER, THE OPTICAL SURFACE IS FOUND TO CONTAIN A SIGNIFICANT AMOUNT OF MID-SPATIAL FREQUENCY ERRORS. IT IS PROPOSED TO DEMONSTRATE A SUB-APERTURE FIGURING TECHNIQUE THAT DOES NOT IMPART MID-SPATIAL FREQUENCIES TO THE OPTICAL SUBSTRATE GEOMETRIES PLANNED FOR INTEGRATION INTO NEXT-GENERATION X-RAY TELESCOPES. REACTIVE ATOM PLASMA (RAP) IS A SUB-APERTURE, ATMOSPHERIC PRESSURE, NON-CONTACT FIGURING TECHNOLOGY THAT RELIES ON A DETERMINISTIC GAS-PHASE ETCHING OF THE OPTICAL SURFACE WITH HIGH MATERIAL REMOVAL RATES. RAP HAS ALREADY BEEN DEMONSTRATED AS A VERY CREDIBLE APPROACH FOR FABRICATING THE LIGHTWEIGHT WEDGES REQUIRED FOR THE ASSEMBLY OF SUCH MIRRORS. RAP IS ESPECIALLY SUITABLE FOR DAMAGE-FREE PROCESSING OF EXTREMELY LIGHTWEIGHT MIRRORS GIVEN THE NON-CONTACT OPERATION, AND ITS ABILITY TO AMELIORATE SUB-SURFACE DAMAGE. THE TOOL FOOTPRINT IS A GAUSSIAN AND HENCE HAS A LIMITED CAPABILITY TO BOTH IMPART MID-SPATIAL ERRORS, AS WELL AS TO FIX THEM. IN PHASE 1, WE PLAN ON DEMONSTRATING THE ABILITY OF THE RAP PROCESS TO IMPART MINIMAL MID-SPATIAL ERRORS INTO THE OPTICAL SURFACE WHILE A FIGURING DEMONSTRATION USING ADJUSTABLE FOOTPRINTS IS PLANNED FOR PHASE 2.