Abstract

The well-known Cooke triplet design has been around for a long time. It has just enough degrees of freedom to correct all five third-order aberrations, as well as longitudinal and lateral color. In practice, third-order residuals are introduced to balance fifth-order aberrations, which are quite bad. In a system this simple, one would not expect there to be multiple solutions. This paper is about a very large number of discrete new triplet types, most of which do not look anything like the traditional Cooke design. This is achieved by giving up color correlation and using at least one thick element, ususlly a strongly curved shell.

© 1988 Optical Society of America