26 December 1984 Novel Zero-Expansion Materials For Precision Optical Substrates
Author Affiliations +
Abstract
A novel family of "germania-modified cordierite" ceramics has been developed for fabrication of precision optical components. Compositions in this family possess zero average coefficient of thermal expansion (CTE) over selected temperature regions. Moreover, the zero CTE can be "tailored" to a desired temperature range of operation by varying the relative proportions of Ge02 and Si02 in the modified cordierite structure. Thermal diffusivity of these ceramics is more than twice that of ULETM glass, a current state-of-the-art material for precision mirror substrates. In addition, germanium-cordierites possess high specific stiffness and low thermal moment/rigidity ratio. Controllable fine-grained structure enables good polishability and offers the potential for an optical quality surface. These thermal and mechanical properties make Ge-cordierite an excellent material for optical and structural applications. The theoretical basis for germania substitution for silica in the pure cordierite struc-ture has been examined. Material characteristics including solid solubility and sinterability have been considered. All the germanium-cordierite compositions presented in this study are morphologically single phase and microstructurally homogeneous materials. These properties along with "tailorable" zero CTE characteristics offer the potential of employing cordierites for high precision optics.
© (1984) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yogesh Mehrotra, Yogesh Mehrotra, Dinesh K. Agrawal, Dinesh K. Agrawal, V. S. Stubican, V. S. Stubican, } "Novel Zero-Expansion Materials For Precision Optical Substrates", Proc. SPIE 0505, Advances in Optical Materials, (26 December 1984); doi: 10.1117/12.964646; https://doi.org/10.1117/12.964646
PROCEEDINGS
10 PAGES


SHARE
RELATED CONTENT

Cooled ISOFLOW laser mirrors
Proceedings of SPIE (February 25 1993)
Precision Finishing Of Ceramics
Proceedings of SPIE (January 11 1987)

Back to Top