Lens Design (WP) - Dr Dr Bills Page透镜的设计（WP）-比尔博士的页面.pdfVIP

OPT ICA L DES IGN of OPHT HA LMIC LENS ES OPT ICA L DES IGN of OPHT HA LMIC LENS ES Introduction We tend to prescribe ophthalmic lenses as though any lens with the right back vertex power will do. Lens curves are not, however, chosen haphazardly. Just like a telescope, photographic objective, or any other optical device, ophthalmic lenses are designed to maximize performance. General Principles of Optical Design set up first system evaluate the systems performance yes is it good enough? end no change system The process of optical design follows the flow chart above. ophthalmic lens design, page 1 © W. F. Long, 1992 Here are the parameters a lens designer may vary to improve performance: ☞ surface curvatures ☞ optical indices ☞ number of elements ☞ spacing of elements. These are the degrees of freedom. In addition to degrees of freedom there are constraints, for example, ☞ focal lengths ☞ magnification ☞ physical constraints like weight, lens to screen distance, etc. Here are the tools of the optical designer: ☞ ray tracing ☞ knowledge of aberrations ☞ computation short cuts such as Seidel 3rd order formulas, the Abbe sine condition, Petzval sum ☞