Triplets

doi:10.1117/3.397107.ch10

Triplets

Book: Fundamental Optical Design

Author(s): Michael J. Kidger

Published: 2001

https://doi.org/10.1117/3.397107.ch10

Author Affiliations +

Abstract

The simplest design that is capable of correcting all of the seven Seidel aberrations over a wide field of view is the Cooke triplet. H. Dennis Taylor invented this in 1893, using the advances of Seidel's theory. It is named after the optical company in York, England, for which Taylor worked at the time, Cooke and Sons (later to become Cooke, Troughton and Sims). The lens is described in two very interesting United States patents, Nos. 540,132 (1895) and 568,053 (1896). Taylor's designs, despite their antiquity, are close to optimum for the aperture and field he intended, given the glass types available in his day. The triplet uses two of the principles of a good design. First, the Petzval sum is corrected by the use of spaced positive and negative lenses, as described in Chapter 9 on telephoto lenses. Secondly, it has approximate front-back symmetry about a central stop, to control the odd-order aberrations, coma, distortion, and transverse color.