DIN ISO 10110-5:2016-04

DIN ISO 10110 specifies the presentation of design and functional requirements for optical elements and systems in technical drawings used for manufacturing and inspection. This part of ISO 10110 specifies rules for indicating the tolerance for surface form deviation. It applies to both spherical and non-spherical surfaces. This part of ISO 10110 refers to deviations in the form (shape) of an optical surface and provides a means of specifying tolerances for certain types of surface form deviation in terms of nanometres. As it is common practice to measure the surface form deviation interferometrically as the wavefront deformation caused by a single reflection from the optical surface at normal (90° to surface) incidence, it is possible to describe a single definition of interferometric data reduction that can be used in both cases; that is, in surface form deviation as well as wavefront deformation. As the analysis of most measurements is software based, the deviations are expressed in nanometres. Interferometrical measurements, however, use the unit "fringe spacings". One "fringe spacing" is equal to a surface form deviation that causes a deformation of the reflected wavefront of one wavelength. A value expressed in nanometres is an indication of the actual height deviation of the surface itself (and not that of the reflected wavefront). The surface under test, together with the test glass is, for example, such an interferometer. The surface form deviation is represented by the wavefront deformation which is the difference between the wavefront reflected by the actual surface and that reflected by the test glass surface.