Fabrication and Measurement of Precision Structures for External Occulter Optical Edges

This project proposes to develop an occulter optical edge and optical edge measurement verification system suitable for astrophysics missions including JWST and the Occulting Ozone Observatory (O3). The optical edge has tight cross-section requirements in order to produce the correct diffraction as light passes over the edge. It is also of importance is the optical edge profile tolerance. This requires precision machining and that the optical edge be thermally stable. Key technical challenges lie in manufacturing an optical edge with a cross-section appropriate for an occulter as well as in measuring that edge to the degree of precision required. Due to the thermal stability requirements, innovative materials or combinations of materials must be used. The focus of this research will be to produce an optical edge with the required cross-section and to measure that edge accurately. Advanced machining techniques will be investigated which may include milling, electrical discharge machining, grinding, and laser machining. Measurement techniques will include scanning laser displacement transducer and computerized measurement machine. This technology could be extended to a full scale optical edge with the correct profile in a Phase II program.