A model has been developed which predicts the chromatic properties of gradient-index materials based on the composition of the glass. It yields a gradient Abbe number and a gradient partial dispersion which can be used by the lens designer in the design of achromatic gradient-index lens systems. Over 100 glasses with various ion exchange pairs have been investigated. The result is a gradient Abbe number ranging from -2000 to+5000 and a gradient partial dispersion ranging from -5 to+7. This wide range of gradient Abbe numbers and gradient partial dispersions can be further extended by using a glass which has two exchange ions with one diffusing ion or a glass which has one exchange ion with two diffusing ions. In addition to an extended range, the designer is afforded the luxury of a continuously varying Abbe number rather than the discrete Abbe number of conventional materials.
© 1985 Optical Society of America
Danette P. Ryan-Howard and Duncan T. Moore, "Model for the chromatic properties of gradient-index glass," Appl. Opt. 24, 4356-4366 (1985)