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