mwang_pay (11/08/82)
DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF WATERLOO SEMINAR ACTIVITIES NUMERICAL ANALYSIS SEMINAR - Friday, November 12, 1982. Prof. C. Crawford of York University will speak on "The Design of a Photographic Lens as an Optimization Problem". TIME: 3:30 PM ROOM: M&C 5158 ABSTRACT The design of photographic lenses using a computer is a simulation/optimization problem. The paths of selected light rays are traced through the system and the results used to simulate the image of a point source of light. Objective functions - called merit functions - are defined and then repeatedly minimized and redefined in an effort to improve the quality of the simulated image. The minimization of the merit function can usually be posed as a constrained non- linear least-squares problem - a small residual prob- lem but usually highly non-linear. Most of the software packages available for optical design are interactive. Lens design is still con- sidered an art, and the solution of the problem must be closely monitored by the designer. The most popu- lar approach to the solution of the minimization problem is the Levenberg damped least-squares method modified for constrained problems. The talk will describe the merit functions, some of the numerical problems involved in computing them as well as the methods used by designers to monitor and guide the optimization problem. November 8, 1982