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Proceedings Paper

Cooke triplet design: what's the best crown glass, and is it worth it?
Author(s): Warren J. Smith
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Paper Abstract

The best glasses for use in the positive elements of an anastigmat lens are commonly understood to lie along the upper-left boundary of the glass map. That is, the best glasses have a high refractive index and/or a high v-value (low dispersion). These characteristics reduce the aberration contributions of the positive elements, and make possible lens designs which have smaller residual aberrations than designs which use glasses below the upper-left boundary. However this diagonal boundary line represents a trade-off between high index at one end and high v-value at the other. Thus the question becomes: "Which end of the boundary is best? Should one choose a glass with a high index at the expense of a low v-value, or vice-versa?" We discuss a controlled study of five triplet anastigmat configurations (of f-number and field angle), each using five glasses from along the boundary. The merit function (rms spot size), the MTF, and glass cost are presented as a function of the glass position along the boundary line.

Paper Details

Date Published: 25 September 1997
PDF: 9 pages
Proc. SPIE 3130, Lens Design, Illumination, and Optomechanical Modeling, (25 September 1997); doi: 10.1117/12.284055
Show Author Affiliations
Warren J. Smith, Kaiser Electro-Optics, Inc. (United States)

Published in SPIE Proceedings Vol. 3130:
Lens Design, Illumination, and Optomechanical Modeling
R. Barry Johnson; Robert E. Fischer; R. Barry Johnson; Richard C. Juergens; Richard C. Juergens; Paul R. Yoder Jr.; Warren J. Smith; Paul R. Yoder Jr., Editor(s)

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