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S.J. Connell, A.A. Abusafieh, G.V. Mehle, D.A. Sheikh, D.C. Giles (Composite Optics, Inc.)
In recent years, Composite Optics, Inc. (COI) has made significant advances in the use of graphite fiber reinforced composite (GFRC) materials for astronomical instrument applications. The inherent low density, high stiffness, and thermal stability makes GFRC a natural candidate for many astronomy applications. In order to reap these inherent benefits in astronomical applications, basic research has focused on material and process improvement. This has been accompanied by the design, fabrication, and test of several prototype reflectors that cover a broad wavelength spectrum of astronomical interests. The results of, and applications for, these efforts are summarized in the following list.
X-Ray Carrier Shell: Innovative composite process yields accuracy and moisture stability. Demonstrated by vacuum optical test of 6" Wolter-I shell. Applicable to Con-X, etc.
Lightweight Mirror Substrate for Visible Astronomy: Composite/glass hybrid design. Areal density < 15 kg/m2. Demonstrated by cryo-optical test (to 35K) of 1.6m NMSD mirror. Applicable to NGST, etc.
Polishable Composite Facesheet: Glass-like coating applied to composite. Polishable by conventional methods. Multiple six-inch substrates polished to 20 angstroms. Technology will enable future 5 kg/m2 visible to UV optics.
10 kg/m2 Submillimeter Reflector: Apertures to 5m possible with economical, all-composite mirror design, diffraction limited at 80 microns. Demonstrated with cryo-optical test (to 70K) of FIRST 2-meter prototype mirror. Applicable to FIRST and other IR astronomy.
Large, Ultra-Stable Optical Support Structure: Uniform and near-zero CTE over broad dimensions. Demonstrated with cryo-optical test of 2-meter FIRST prototype. Applicable to NGST, SIM, LISSA.
Ground Based Radio Telescope Reflector: Low-cost, accurate, stable, durable all-composite design for support structure & reflective surface. Demonstrated via fab & test of 3m adjustable and 5m static prototypes. Applicable to LMT, ALMA, etc.
These recent accomplishments represent new enabling technologies to meet the needs of numerous astronomical instrument concepts. COI will soon transition two of these technologies to production (FIRST and LMT), while continuing to further the capability of composites with on-going research.
COI gratefully acknowledges the financial and technical support of NASA and the NSF for these projects.