Use of the Modulation-Transfer Function (MTF) as an Aberration-Balancing Merit Function in Automatic Lens Design

A new aberration-balancing merit function for automatic lens design is described in which the MTF squared, with suitable weightings, serves directly as image-quality criterion. Details concerning the optimization procedure are given and a new set of normal equations is described. The basic assumption is that the design-parameter changes should be kept small, which is a valid approximation for the optimization technique employed. The evaluation of the coefficients in the normal equations requires extensive numerical integration; a method based on the modified Hopkins algorithm is suggested.