tutorial

tutorialENGINEERING ANOPTICAL SYSTEMChoosing the right starting point opens up a world of designs.ILLUSTRATION BY GEORGE ABEBy Warren Smith, Kaiser Electro-Opticsesigning the basic format for an optical almost always done using the thin-lens concept.system is a process very different from A thin lens has a thickness of zero, an obviousD lens design. It involves determining the impossibility but a very valuable simplificationcomponents of the system and their locations in of the process because a thin component of aorder to produce a system that will meet a set of system can be represented simply by a powerrequired characteristics. It is the layout of the sys- and a location. Both principal planes in a thintem up to, but not including, the lens-design lens are coincident with the lens. The thin lensstage (in which the lens designer determines the is a concept, not a reality. The lenses are laterdetailed component configurations that are expanded to match real components with physi-needed to do the job.) cal thickness.The initial layout of an optical system isjuly 2002 spie’s oemagazine 49|step by step as a checklist:The first step in the process should always be to establish the • The purpose of the system (obvious but often overlooked).requirements and specifications. One should try to collect all • Wavelength, bandwidth, spectral response, or distribution.of the specifications before beginning the design. The follow- • Aperture diameter.ing, which ...