A Brief  History of Lens Design ~o8$/%Oeb/  
Since about 1960, the way lenses are designed has changed profoundly  as a result of  the introduction of  electronic digital computers and numerical optimiz-ing methods. Nevertheless, many of  the older techniques remain valid. The lens designer still encounters terminology and methods that were developed even in previous centuries. Furthermore, the new methods often  have a strong classical heritage. Thus, it is appropriate to examine, at least briefly,  a history of  how the techniques of  lens design have evolved. 3*'!,gK~[  
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