Automated control of manufacturing sensitivity during optimization

Immediately following an optimization sequence, many designers typically implement sensitivity analysis prior to more intensive tolerance analysis and system error budgeting. This paper proposes a method of automating optical design optimization into a two stage process which incorporates design sensitivity into the optimization process. The first stage consists of the standard optimization approach where the error function is a user defined combination of system performance as well as optical and physical parameter constraints. The second stage amends the error function to include the minimization of incident ray angles on each optical surface as part of the error function. The amendment to the error function in the second stage targets the root mean square of incident angles of sample rays. These rays may typically consist of the marginal ray to the image center, as well as the upper and lower rim rays to the image corner. A priority is placed on reducing large angles as the result of a least squares method. This paper will address the detailed implementation of the proposed approach inside of the optical design program. Practical examples will be presented where the proposed optimization has reduced the system sensitivity to manufacturing errors without substantially effecting image quality. The results of incorporating the amended error function into an automated global optimization approach will be described.