SILICON CARBIDE - A LOW-COST, ULTRA LIGHTWEIGHT REPLACEMENT FOR LARGE-APERTURE

SILICON CARBIDE (SIC) IS EMERGING AS A SERIOUS ALTERNATIVE FOR LIGHTWEIGHT, SPACEBORNE TELESCOPE APPLICATIONS AS A RESULT OF COMMERCIALLY AVAILABLE, REACTION-BONDED FABRICATION TECHNIQUES AND REPLICATION-PROCESSING ADVANCES. SIC OFFERS SIGNIFICANT ADVANTAGES: IT HAS THE LIGHTWEIGHT FEATURES OF BERYILLUM, THE CRYOGENIC AND OPTICAL PERFORMANCEAND STABILITY OF GLASS, AND THE LOW COST OF ALUMINUM. THIS PHASE I SBIR PROPOSES FABRICATING MIRRORS BY OVERCOATING SICSUBTRATES WITH SILICON (SI) TO FACILITATE POLISHING. THE SIMILARITY IN THERMAL EXPANSION BETWEEN SIC AND SI ENSURES AN INHERENTLY ATHERMAL DESIGN. THE SPECIFIC TASKS INCLUDE THE CONCEPTUAL DESIGN OF A 1-METER-CLASS SIC/SI OVERCOAT MIRROR AND SIC MOUNT ASSEMBLY FOR VISIBLE-TO-UV SPACEBORNE APPLICATIONS, AND THE DEMONSTRATION OF THIS TECHNOLOGY FEASIBILITY THROUGH THE FABRICATION AND TESTING OF AN 8-INCH-APERTURE, CONCAVE, SPHERICAL MIRROR AND MOUNT ASSEMBLY TO NEAR-DIFFRACTION-LIMITED, VISIBLE-TO-UV PERFORMANCE. PHASE II WOULD FABRICATE AND TEST A PROTOTYPE 1-METER-CLASS SIC/SI MIRROR AND MOUNT ASSEMBLY. SILICON CARBIDE (SIC) IS EMERGING AS A SERIOUS ALTERNATIVE FOR LIGHTWEIGHT, SPACEBORNE TELESCOPE APPLICATIONS AS A RESULT OF COMMERCIALLY AVAILABLE, REACTION-BONDED FABRICATION TECHNIQUES AND REPLICATION-PROCESSING ADVANCES. SIC OFFERS SIGNIFICANT ADVANTAGES: IT HAS THE LIGHTWEIGHT FEATURES OF BERYILLUM, THE CRYOGENIC AND OPTICAL PERFORMANCEAND STABILITY OF GLASS, AND THE LOW COST OF ALUMINUM. THIS PHASE I SBIR PROPOSES FABRICATING MIRRORS BY OVERCOATING SICSUBTRATES WITH SILICON (SI) TO FACILITATE POLISHING. THE SIMILARITY IN THERMAL EXPANSION BETWEEN SIC AND SI ENSURES AN INHERENTLY ATHERMAL DESIGN. THE SPECIFIC TASKS INCLUDE THE CONCEPTUAL DESIGN OF A 1-METER-CLASS SIC/SI OVERCOAT MIRROR AND SIC MOUNT ASSEMBLY FOR VISIBLE-TO-UV SPACEBORNE APPLICATIONS, AND THE DEMONSTRATION OF THIS TECHNOLOGY FEASIBILITY THROUGH THE FABRICATION AND TESTING OF AN 8-INCH-APERTURE, CONCAVE, SPHERICAL MIRROR AND MOUNT ASSEMBLY TO NEAR-DIFFRACTION-LIMITED, VISIBLE-TO-UV PERFORMANCE. PHASE II WOULD FABRICATE AND TEST A PROTOTYPE 1-METER-CLASS SIC/SI MIRROR AND MOUNT ASSEMBLY.