{"id":10424,"date":"2022-09-19T01:59:00","date_gmt":"2022-09-19T01:59:00","guid":{"rendered":"https:\/\/www.szlaser.com\/?page_id=10424"},"modified":"2022-09-19T05:07:58","modified_gmt":"2022-09-19T05:07:58","slug":"calculating-visual-defects","status":"publish","type":"page","link":"https:\/\/www.szlaser.com\/index.php\/wiki\/calculating-visual-defects\/","title":{"rendered":"Measuring and Calculating Visual Defects"},"content":{"rendered":"

Measuring and Calculating Visual Defects<\/h1><\/h1><\/div>

There are seven main sources that address measuring, calculating, and\u00a0evaluating visual defects. These sources include three military specifications and two ISO standards, the latter of which are part of<\/p>\n

\u2022 ISO 10110,
\n\u201cOptics and photonics\u2014Preparation of drawings for optical elements and systems\u201d:<\/p>\n

\u2022 MIL-PRF-13830B:1997 (which replaced MIL-O-13830A:1963),
\n\u201cOptical Components for Fire Control Instruments; General Specification Governing the Manufacture, Assemble and Inspection of;\u201d<\/p>\n

\u2022 MIL-C-48497 (1980),
\n\u201cCoating, Single or Multilayer, Interference: Durability Requirements for;\u201d<\/p>\n

\u2022 MIL-F-48616 (1977),
\n\u201cFilter (coatings), Infrared Interference: General Specification for;\u201d<\/p>\n

\u2022 ISO 10110-3:1996,
\n\u201cMaterial imperfection\u2014Bubbles and Inclusions;\u201d<\/p>\n

\u2022 ISO 10110-7:2008,
\n\u201cSurface Imperfection Tolerances;\u201d<\/p>\n

\u2022 ISO 14997:2011,
\n\u201cOptics and photonics – Test methods for surface imperfections of optical elements;\u201d and<\/p>\n

\u2022 ANSI\/OEOSC OP1.002-2009, \u201cOptics and Electro-Optical Instruments\u2014
\nOptical Elements and Assemblies\u2014Appearance Imperfections.\u201d<\/p>\n

Customers may ask for a different and legal requirement for their needs.
\nThe result may also be a combination of special requirements with measuring and calculation according to the stated standards.<\/p>\n<\/div>

Scratches and digs<\/h3><\/h3><\/div>

The paragraphs in Figs. below, reprinted from MIL-PRF-13830B, are\u00a0relevant when dealing with scratches and digs.<\/p>\n

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Table below also from MIL-PRF-13830B, shows the scratch and dig\u00a0numbers for the central zone (half of the surface diameter) and the outer zone beam diameter (mm), respectively, referring to the focal planes and near-focal planes (the table represents general recommendations, and designers are free to determine different definitions that fit to the system\u2019s needs).<\/p>\n

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Surface defects on optical elements (scratches and digs) are designated by two numbers. The first number refers to scratch width, and the second number refers to dig diameter. For example, 80-50 means that the maximum allowable width of a scratch is 80 and the maximum allowable dig diameter is 50 by comparing both numbers to the quality standards, per drawing no. C7641866.
\nNote that the combined length of the maximum-size scratches located on each surface of a circular element should not exceed one-fourth of the surface diameter. Further notes:<\/p>\n