Abstract: The functional and perceived quality of an optical component depend on both the global and localized nature of its surfaces. While small departures in specification of surface form, roughness, and waviness occur as global errors, extending over the whole surface and being difficult to see, digs and scratches accumulated during manufacture and subsequent handling are highly localized. It is this characteristic that results in such flaws, which are usually extremely small in width and depth, being readily visible and therefore rated as an indicator of poor quality. Due to expansion in the use of electronic imaging and laser systems and heightened international competition, more effort has been devoted in the last few years to drafting new standards and the development of improved methods of measurement of all surface-related parameters. This paper concentrates on recent progress in the characterization, measurement, and standardization of localized surface defects. Particular attention is paid to both deterministic methods, needed for diagnostics and research, and the parametric approach more appropriate to control of quality in component production. The need for international collaboration in setting acceptance thresholds for localized surface quality, relating to different applications, is stressed to ensure the full benefit of increased yields is attained. !8
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