Design Process ExampleRichard JuergensAdjunct Fellow in Optical Designrcjuergens@msn.comOpti 517Goal of OptimizationThe goal of optimization is to achieve a design which meets the systemperformance requirements and all the optical and mechanical constraintsConstraints include things like focal length,overall lengths,clearances,distortion,etc.Optimization requires:An error function (sometimes called a merit function)This is a measure of the "non-goodness"of the lensA process for reducing the error functionThe way to get from the current state to better performanceA method for controlling the boundary conditions(constraints)Acceptable performance which violates the constraints is not useful2What is an Error Function?A single positive number that represents the current state of the optical systemThe error function is usually related toaberrations or image errors but can includeother components as wellError functions are always structured such thatsmaller values are better than larger values0 is the best error function (zero errors)The "Single Number'The Mona Lisarepresentation ofthe Mona LisaIn CODE V,the default error function represents the mean square spot radius,suitably averaged over wavelengths and over the field of view,times 106An error function of 16 means the RMS spot radius averaged over the FOVis 0.004 inches(dimensions in inches)or 4 microns(dimensions in mm)Thus,it is possible to relate the default error function value to the size of thegeometrical blur needed to achieve the desired perfommanceIt is also possible in CODE V to optimize on other error functions,such as RMSwavefront error,MTF,or a user-defined error function3