Standards For Optical Surface Quality Using Total Integrated Scattering

Standards for optical surface quality are suggested to address two distinct problems: (1) the cosmetic appearance of the optical component and (2) its functional performance in an optical system. For the first problem, a series of standard scratches with appropriately defined profiles is suggested, so that the visual appearance of the standard scratch matches the appearance of scratches produced by normal optical polishing. For the second problem, we suggest a measurement of total integrated scattering, which can be related quantitatively to the rms height of surface microirregularities. The scattering from scratches of differ-ent sizes can also be made quantitative. Angular scattering is too dependent on surface properties to permit it to be a useful standard. However, total integrated scattering is useful for approximately predicting the relative amounts of light scattered at a given angle by surfaces having different roughnesses.