A systematic approach to global optical design

The optical design space of some simple lenses is investigated systematically. Typical space topographies are visualized with computer generated perspective views, where the complete set of available solutions is clearly identified. The space characteristics are then studied and compared through the use of several merit functions with differing degrees of complexity. A two phase search algorithm, based on global optimization techniques, is proposed here. In a first phase, using a coarse sampling approach, the program finds the favorable regions that correspond to potentially promising configurations. In a second phase, conventional optimization routines are used to find the best solutions in each region. Then an optimum solution is determined according to the application at hand. The proposed algorithm is analyzed and compared to more conventional design approaches. A further refinement of the algorithm excludes from the systematic search some unfavorable configuration regions, through the use of a simple expert system. Search times are further reduced through parallel-processing methods. The algorithm provides overall information about a given design space and offers a selection of "best" solutions to choose from. It is particularly efficient when used to search for the best glass combination in lens design. Some lens systems such as the air spaced doublet, the triplet objective and the double Gauss were used to test and study the proposed algorithm, which proved to be a promising new approach to optical design.