Integrating optical fabrication and metrology into the optical design process

The recent validation of a generalized linear systems formulation of surface scatter theory and an analysis of image degradation due to surface scatter in the presence of aberrations has provided credence to the development of a systems engineering analysis of image quality as degraded not only by diffraction effects and geometrical aberrations, but to scattering effects due to residual optical fabrication errors as well. This generalized surface scatter theory provides insight and understanding by characterizing surface scatter behavior with a surface transfer function closely related to the modulation transfer function of classical image formation theory. Incorporating the inherently band-limited relevant surface roughness into the surface scatter theory provides mathematical rigor into surface scatter analysis, and implementing a fast Fourier transform algorithm with logarithmically spaced data points facilitates the practical calculation of scatter behavior from surfaces with a large dynamic range of relevant spatial frequencies. These advances, combined with the continuing increase in computer speed, leave the optical design community in a position to routinely derive the optical fabrication tolerances necessary to satisfy specific image quality requirements during the design phase of a project; i.e., to integrate optical metrology and fabrication into the optical design process.