METHOD FOR DESIGNING A REFRACTIVE OR REFLECTIVE OPTICAL SYSTEM AND METHOD FOR DESIGNING A DIFFRACTION OPTICAL ELEMENT

摘要

In the design of a lens system, lens parameters are determined by minimizing a merit function which is a sum of squares of ray aberrations or wavefront errors at many sampling points. Prior methods often select the parameters which give very narrow tolerances to production errors. The small tolerance increases the difficulty of production. In order to increase the tolerance, states which allot errors ±&dgr; to some chosen parameters are considered. Merit functions corresponding the error-allotted states are made. An integrated merit function is produced by adding the error-allotted merit functions to the non-error allotted normal merit function. Parameters are determined by minimizing the integrated merit function. The optimized parameters will give wider tolerances for the error-allotted parameters. ;DOE (diffraction optical element) design includes the steps of considering error-allotted states S₁, S₂, . . . in addition to a non-error state S₀, making merit functions E₁, E₂, . . . for S₁, S₂, . . . besides E₀ for S₀, defining an integrated merit function E=&Sgr;W_kE_k by multiplying the merit function with weights and summing up, minimizing the integrated merit function and determining optimum variables for the DOE.