ISO/TC 172/SC 1/WG 1 - General optical test methods

This document provides rules for the measurement of the spectral reflectance of plane surfaces and the spectral transmittance of plane parallel elements using spectrophotometers. This document only applies to measurements of the regular transmittance and the regular reflectance; it does not apply to those of the diffuse transmittance and the diffuse reflectance. This document is applicable to test samples, which are coated or uncoated optical components without optical power.

This document gives fundamental explanations to interferometric measurement objects, describes hardware aspects of interferometers and evaluation methods, and gives recommendations for test reports and calibration certificates.

This document specifies general optical test methods for the measurement of the relative irradiance in the image field. This document is applicable to optical imaging systems in the optical spectral region from λ = 100 nm to λ = 1 μm. Theoretical reflections and the comparison with the calculation apply only to optical systems. This document is applicable to rotationally invariant and rotationally variant systems; anamorphic systems, for example, are included. Telescopic systems are also included. The title of this document refers to the relative irradiance in the image field, but this document is also applicable to determination of the relative radiant power. NOTE For telescopic systems, it is suitable to state only the radiant power; for most imaging systems, the conversion from radiant power to irradiance is easy. As far as measurements are concerned, this document is also applicable to electro-optical systems. The two methods described differ particularly in the influence of veiling glare.

This document specifies procedures for determining the spectroscopic forward scattering characteristics of coated and uncoated optical surfaces over a specified wavelength range between 350 nm and 850 nm using a double-beam spectrophotometer with an integrating sphere. This document is also applicable to the forward scattering properties at a single wavelength. This document is applicable to spectroscopic forward scattering measurements with collection angles larger than 2,7 degrees. ISO 13696 provides a measurement method for smaller collection angles.

ISO 8478:2017 specifies a method for measuring the spectral transmittance of camera lenses. It describes particular conditions for measuring the axial spectral transmittance, over a wavelength range from 350 nm to 700 nm, of camera lenses which are intended to be used mainly for taking pictures of very distant objects. If the spectral transmittance values are used exclusively for the calculation of the ISO colour contribution index (see ISO 6728) throughout ISO 8478:2017, the wavelength range reads 370 nm to 680 nm. ISO 8478:2017 is also applicable to mirror lenses (see Annex A).

ISO/TR 21477:2017 intends to guide the user to understand the origins, meanings and differences between the two systems of specifying and evaluating surface imperfections in ISO 10110-7 and ISO 14997, specifically the dimensional method and the visibility method, and to provide information on how to use them. Tables are provided to show specifications of roughly equivalent yield loss for imperfections in the two systems.

ISO 14997:2017 specifies the physical principles and practical means for the implementation of methods for evaluating surface imperfections. For imperfections specified using the visibility method, two inspection methods are described. The first is visual evaluation of the surface without any comparison standard (IVV). The second is a visibility assessment of a surface imperfection when compared to an artefact of known brightness (ISV). For imperfections specified using the dimensional method, three methods are described. The first is visual evaluation of the surface without any comparison standard (IVD). The second is a dimensional assessment of a surface imperfection when compared to an artefact of known size (ISD). The third is the dimensional measurement of a surface imperfection using magnification and either a comparison artefact of known size or a reticle or ruler (IMD). Instruments exist that allow objective measurement of brightness (digital scatterometry) or size (digital microscopy). While these instruments can be used for evaluation of surface imperfections, they are beyond the scope of this document. ISO 14997:2017 applies to optical surfaces of components or assemblies such as doublets or triplets. ISO 14997:2017 can be applied to optical plastic components; however, attention is drawn to the fact that impact damage to plastic materials often looks very different from that on harder materials as it does not always result in the removal of material but instead can displace material, causing ripples in the surface. Consequently, visual comparisons of scratch and dig damage to plastic with those on glass or crystalline materials can give very different results.

ISO 14999-4:2015 applies to the interpretation of interferometric data relating to the measurement of optical elements. ISO 14999-4:2015 gives definitions of the optical functions and values specified in the preparation of drawings for optical elements and systems, made in accordance with ISO 10110‑5 and/or ISO 10110‑14 for which the corresponding nomenclature, functions, and values are listed in ISO 10110‑5, Annex B. It also provides guidance for their interferometric evaluation by visual analysis.

ISO 9335:2012 gives general guidance for the construction and use of equipment for measurement of the optical transfer function (OTF) of imaging systems. It specifies important factors that can influence the measurement of the OTF, and gives general rules for equipment performance requirements and environmental controls. It specifies important precautions that should be taken to ensure accurate measurements and correction factors to be applied to the collected data.

ISO 15529:2010 specifies the principal MTFs associated with a sampled imaging system, together with related terms, and outlines a number of suitable techniques for measuring these MTFs. It also defines a measure for the “aliasing” related to imaging with such systems. ISO 15529:2010 is particularly relevant to electronic imaging devices such as digital still and video cameras and the detector arrays they embody.

ISO 9336‑1:2010 specifies a method of testing interchangeable lenses for 35 mm still cameras with a picture format of 24 mm x 36 mm in terms of imaging states aimed at making valid optical transfer function measurements.

ISO 517:2008 pertains to apertures and related properties of photographic lenses affecting the illuminance at the centre of the image. ISO 517:2008 specifies aperture markings for all types of lenses used in still cameras, and gives tolerances for the stop numbers. It also defines aperture stop, entrance pupil, focal length, relative aperture and stop numbers, and gives methods for their measurement or determination. ISO 517:2008 applies only to lenses focused on objects at infinity; that is, at least 50 times the focal length of the lens.

ISO 9039:2008 specifies methods of determining distortion in optical systems for the purposes of quality evaluation. It applies to optical imaging systems in the optical spectral range from 100 nm to 15 000 nm which, by their design, aim at a rotationally symmetric image geometry. It is applicable to electro-optical imaging systems provided that adequate rotational symmetry of the image is guaranteed. It does not, therefore, apply to anamorphic and fibre optic systems.

ISO/TR 14999-3:2005 discusses sources of error and the separation of errors into symmetric and non-symmetric parts. It also describes the reliance of measurements on the quality of a physical reference surface and the development of test procedures capable of achieving absolute calibration.

ISO/TR 14999-1:2005 gives terms, definitions and fundamental physical and technical relationships for interferometric measurements of optical wavefronts and surface form of optical elements. It explains, why some principles of the construction and use of interferometers are important due to the wave nature of the wavefronts to be measured. Since all wavefronts with the exception of very extended plane waves do alter their shape when propagating, ISO/TR 14999-1:2005 also includes some basic information about wave propagation. In practice, interferometric measurements can be done and are done by use of various configurations; ISO/TR 14999-1:2005 outlines the basic configurations for two-beam interference. The mathematical formulation of optical waves by the concept of the complex amplitude as well as the basic equations of two-beam interference are established to explain the principles of deriving the phase information out of the measured intensity distribution, either in time or in space. Both random and systematic errors may affect the results of interferometric measurements and error types to be clearly differentiated are therefore described in ISO/TR 14999-1:2005.

This International Standard defines terms relating to chromatic aberrations and indicates the mathematical relationships between those terms. It also gives general guidance for the measurement of chromatic aberrations and is valid for optical imaging systems which are constructed to be of rotational symmetric imaging geometry. It is also valid for optoelectronic imaging systems.

Adopts both the veiling glare index (VGI) and the glare spread function (GSF) as measures of the veiling glare characteristics of optical and electrooptical imaging systems. Laboratory measurement techniques are described in general terms and recommendations are made regarding the performance of the main subunits of the equipment. The measurement techniques described are chiefly valid for the visual spectral range. Also gives guidelines for the operation of measuring equipment such that accurate results can be achieved.

ISO 14997:2011 establishes the physical principles and practical means for the implementation of methods for measuring surface imperfections. This method evaluates the surface area obscured or affected by the imperfections.

ISO 15529:2007 specifies the principal MTFs associated with a sampled imaging system, together with related terms and outlines a number of suitable techniques for measuring these MTFs. It also defines a measure for the “aliasing” related to imaging with such systems. ISO 15529:2007 is particularly relevant to electronic imaging devices such as digital still and video cameras and the detector arrays they embody.

ISO 14999-4:2007 applies to the interpretation of interferometric data relating to the measurement of optical elements. ISO 14999-4:2007 gives definitions of the optical functions specified in the preparation of drawings for optical elements and systems as well as guidance for their interferometric evaluation with visual analysis.

ISO/TR 14999-2:2005 gives fundamental explanations to interferometric measurement objects, describes hardware aspects of interferometers and evaluation methods, and gives recommendations for test reports and calibration certificates.

ISO 14997:2003 establishes the physical principles and practical means for the implementation of two methods, specified in ISO 10110-7, for measuring surface imperfections. These methods are: Method l, the surface area obscured or affected by the defects, and, Method ll, the visibility of the imperfections. Both methods are suitable for prototype, small scale or large scale production of a wide variety of optical components. Imperfection appearance or functional tolerances related to a particular component can be determined by agreement between supplier and customer.

Pertains to apertures and related properties of photographic lenses affecting the illuminance at the centre of the image. Does apply only to lenses focused on objects at infinity; that is, at least 50 times the focal length of the lens.

Applies to optical imaging systems in the optical spectral region from 100 nm to 1 m. Telescopic systems are also included. The standard refers to the relative irradiance in the image field, but it is also applicable to determination of the relative radiant power.

Gives a method for measuring the spectral transmittance of camera lenses. Describes particular conditions for measuring the axial spectral transmittance over a wavelength range from 350 nm to 700 nm of camera lenses which are to be used mainly for taking pictures of very distant objects.

Gives general guidance for the construction and use of equipment for measurement of the optical transfer function of imaging systems and general rules for equipment performance requirements. Specifies important factors that can influence the measurements. Does not contain instruments for interferometric tests.

Specifies a method of testing interchangeable lenses for 35 mm still cameras with a picture format of 24 mm × 36 mm in terms of imaging states aimed at making valid optical transfer function measurements. Does not cover special lenses for macrophotography.

Specifies a method of testing lenses for office copiers in terms of imaging states aimed at making valid optical transfer function measurements.

Specifies methods of determining distortion in optical systems for the purposes of quality evaluation. Applies to optical imaging systems in the optical spectral range from 100 nm to 15 000 nm which, by their design, aim at a rotationally symmetric image geometry. Applicable to electrooptical imaging systems provided that adequate rotational symmetry of the image is guaranteed. Does not apply, therefore, to anamorphic and fibre optic systems.