Optimization for as-built performance

Traditionally optical design via computer optimization uses a numerical merit function to represent the optical performance of the simulated system. The conventional design approach is to maximize the nominal performance of the design, and then as a separate step, add fabrication tolerances to the nominal parameters so that upon manufacturing the resulting system still performs to specification. This paper will demonstrate an alternate approach. Because the angle rays make with respect to the normal on each surface are the primary drivers of optical aberrations and tolerance sensitivity, the method uses these ray angle as a fast, numerical approximation for the sensitivity to tolerance defects. This hybrid merit function thus includes the fabrication errors as part of the design process. The resulting design is effectively optimized for as-built, rather than nominal performance. Design examples will be provided which show that optimization using the hybrid merit function yields designs of different forms, which may have inferior nominal performance but superior as-built performance. The resulting alternate designs will be compared to conventional post-design tolerance analysis to demonstrate the reduction in tolerance sensitivity and superior resulting performance.