An optical design is shown which provides simultaneous color correction over the visible spectrum and passive thermal compensation, for an f/4 doublet made of a glass and a polymer gradient index (GRIN) element. The design is enabled by a new optical model for the thermally varying GRIN element, which incorporates measured material properties from 20-40°C (limited only by the extent of the measured data set). The design is made possible because of the GRIN degrees of freedom available to the material. A color-corrected doublet is most efficient when there is a large ratio of the dispersion strength (Abbe number) between the two materials. To make that doublet athermal, however, there needs to be an equally high ratio between the thermal coefficients. The large ratio of polymer to glass thermal coefficients presents a unique advantage for GRIN: the effective GRIN dispersion coefficient can have just as large a ratio to the glass as the thermal coefficients, making for a powerful athermal achromat. To our knowledge, this is the first example of a polymer GRIN used for simultaneous chromatic and thermal correction.

Date Published: 17 May 2016
PDF: 7 pages
Proc. SPIE 9822, Advanced Optics for Defense Applications: UV through LWIR, 98220S (17 May 2016); doi: 10.1117/12.2224124

Published in SPIE Proceedings Vol. 9822:
Advanced Optics for Defense Applications: UV through LWIR
Jay N. Vizgaitis; Bjørn F. Andresen; Peter L. Marasco; Jasbinder S. Sanghera; Miguel P. Snyder, Editor(s)