A METHOD OF PRODUCING ULTRASMOOTH PRESISION VISIBLE AND X-RAY MIRROR BLANKS WITH ULTRASTRUCTURED MATERIALS

THE APPROACH IN THIS PROJECT HAS THE POTENTIAL OF PRODUCING ASPHERIC MIRRORS WITH ORDER-OF-MAGNITUDE IMPROVEMENTS IN TWO KEY AREAS: FIRST, IN SURFACE FINISH, FIGURE, AND LIGHTNESS FOR SMALL- AND MEDIUM-SIZED (OR MOSAIC) MIRROR BLANKS; AND SECOND, IN THE TIME AND COST REQUIRED TO PRODUCEQUALITY ASPHERIC MIRROR BLANKS FOR LARGE PROJECTS. THE TRADITIONAL SEQUENCE OF GRINDING AND POLISHING IS REVERSED BY THE USE OF ULTRASTRUCTURE PROCESSING TO REPLACE MECHANICAL METHODS OF MATERIAL REMOVAL. THE METHOD STARTS WITH A CHEMICAL-MECHANICAL POLISHED, FLAT SILICON WAFER OF THE TYPE USED IN THE SEMICONDUCTOR INDUSTRY. THE WAFER IS BENT TO THE DESIRED SHAPE BY THE FORMATION OF STRESSED LAYERS OF SILICON DIOXODE, SILICON NITRIDE, BOROPHOSPHATESILICATER GLASS, AND SO FORTH. THE BENDING CANBE MODULATED TO COMPLEX SHAPES BY THINNING THE WAFER IN SELECTED REGIONS THROUGH ANISOTROPIC ETCHING OF THE BACK OF THE WAFER. THE STRESSED LAYERS, TOGETHER WITH THE ETCHED PATTERN, PRECISELY CONTROL THE TOPOLOGY OF THE SMOOTHSURFACE. THIS METHOD COULD BE CAPABLE OF CONTROLLING FIGUREAND SMOOTHNESS ON ATOMIC DIMENSIONS. PHASE I WILL SHOW FEASIBILITY BY MEASUREMENT OF THE MECHANICAL PROPERTIES OF THE STRESSING LAYERS, COMPUTER SIMULATION OF THE STRONGLY INTERACTING FORCES THAT CONTROL THE SURFACE TOPOLOGY, AND PRECISE MEASUREMENT OF SURFACE TOPOLOGY. THE APPROACH IN THIS PROJECT HAS THE POTENTIAL OF PRODUCING ASPHERIC MIRRORS WITH ORDER-OF-MAGNITUDE IMPROVEMENTS IN TWO KEY AREAS: FIRST, IN SURFACE FINISH, FIGURE, AND LIGHTNESS FOR SMALL- AND MEDIUM-SIZED (OR MOSAIC) MIRROR BLANKS; AND SECOND, IN THE TIME AND COST REQUIRED TO PRODUCEQUALITY ASPHERIC MIRROR BLANKS FOR LARGE PROJECTS. THE TRADITIONAL SEQUENCE OF GRINDING AND POLISHING IS REVERSED BY THE USE OF ULTRASTRUCTURE PROCESSING TO REPLACE MECHANICAL METHODS OF MATERIAL REMOVAL. THE METHOD STARTS WITH A CHEMICAL-MECHANICAL POLISHED, FLAT SILICON WAFER OF THE TYPE USED IN THE SEMICONDUCTOR INDUSTRY. THE WAFER IS BENT TO THE DESIRED SHAPE BY THE FORMATION OF STRESSED LAYERS OF SILICON DIOXODE, SILICON NITRIDE, BOROPHOSPHATESILICATER GLASS, AND SO FORTH. THE BENDING CANBE MODULATED TO COMPLEX SHAPES BY THINNING THE WAFER IN SELECTED REGIONS THROUGH ANISOTROPIC ETCHING OF THE BACK OF THE WAFER. THE STRESSED LAYERS, TOGETHER WITH THE ETCHED PATTERN, PRECISELY CONTROL THE TOPOLOGY OF THE SMOOTHSURFACE. THIS METHOD COULD BE CAPABLE OF CONTROLLING FIGUREAND SMOOTHNESS ON ATOMIC DIMENSIONS. PHASE I WILL SHOW FEASIBILITY BY MEASUREMENT OF THE MECHANICAL PROPERTIES OF THE STRESSING LAYERS, COMPUTER SIMULATION OF THE STRONGLY INTERACTING FORCES THAT CONTROL THE SURFACE TOPOLOGY, AND PRECISE MEASUREMENT OF SURFACE TOPOLOGY.