ABSTRACT
A highly corrected lens is one of the most accurately made items that it is possible to buy at modest cost. But before an optical system can be made it must be designed, the job of a lens designer or possibly an optical engineer. The initial design task usually requires some 40 individual ray traces through each surface by repeated applications of Snell’s law and evaluation of their positions in the focal plane. Designs took years to perfect, but many have stood the test of time and can be little improved with reworking aided by digital computers. The Zeiss Biogon is one such lens. The work of the lens designer has been described by Kingslake et al. The evolution of digital computers and their availability as mainframe, desk-top, personal and programmable pocket versions removed much of the drudgery from optical design and permitted exciting new designs to be produced as well as suggesting different approaches.
