Eddie Judd
Leaving SIRA in 1971, Eddie then spent a couple of years at MEL Watson designing optics for military systems and then at Crosfield Electronics designing optics for pre-press systems. In 1975 Eddie had the opportunity to join the newly formed Davin Optics Ltd with the task of bring optical system design and manufacture to what was then an optical components manufacturing company. And he has been there ever since, occasionally as Marketing Director, but mostly as Technical Director.
In the 30 years Eddie has worked in lens design and optical engineering he has designed literally hundreds of lens systems for a great diversity of industries; night vision, missile optics, simulation systems, pre-press industry, machine vision, medical systems, laser beam delivery and so on. This considerable experience has given him insight into the problems of producing economic, manufacturable lenses.
Articles by this Author
Take Care With 'Exact Equivalent' Glasses
- By Eddie Judd
- Published 13 February 2007
- User Articles , Glass and Refractive Index
-
Rating:




A few years ago the manufacturers of optical glasses started the process of reformulating their glasses to remove arsenic and lead. At first glance, most of these glasses appear to be the exact equivalents of the original glasses. However, examining the indices in the near UV and the NIR shows that the indices can differ in the 3rd decimal place.
Further more, many other properties of the glasses differ significantly: the new formula glasses absorb earlier at each end of the spectrum, and there can be massive differences in the thermal properties between the old and new formulations.
This article discusses these topics, and shows some traps it is easy to fall into with 'Exact Equivalent' glasses.
This article is also available in Japanese.
