Optical surfaces feature a wide range of length scales from “figure” down to “finish”, but the mid-spatial frequency structure (MSF) holds growing significance. Cost-effective production of systems demands answers to multiple layers of related questions, such as how best to quantify MSF, assess its optical impact, and employ existing production tools to meet MSF requirements. These answers evolve as new production technologies are introduced. I present general observations about a few of the associated challenges and attempt to clarify some essential aspects related to quantifying MSF as well as estimating its impact.
G. W. Forbes, G. W. Forbes,
"Never-ending struggles with mid-spatial frequencies", Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 95251B (22 June 2015); doi: 10.1117/12.2191135; https://doi.org/10.1117/12.2191135