1、BRITISH STANDARD BS ISO 15795:2002 Incorporating corrigendum no. 1 Optics and photonics Quality evaluation of optical systems Assessing the image quality degradation due to chromatic aberrations ICS 37.020 BS ISO 15795:2002 This British Standard was published under the authority of the Standards Pol
2、icy and Strategy Committee on 30 May 2002 BSI 2008 ISBN 978 0 580 60483 6 National foreword This British Standard is the UK implementation of ISO 15795:2002, incorporating corrigendum September 2007. The start and finish of text introduced or altered by corrigendum is indicated in the text by tags.
3、Text altered by ISO corrigendum September 2007 is indicated in the text by . The UK participation in its preparation was entrusted to Technical Committee CPW/172, Optics and optical instruments. A list of organizations represented on this committee can be obtained on request to its secretary. This p
4、ublication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments/corrigenda issued since publication Date Comments 31 January 2008 Impleme
5、ntation of ISO corrigendum September 2007 Reference number ISO 15795:2002(E)INTERNATIONAL STANDARD ISO 15795 First edition 2002-04-15 Optics and photonics Quality evaluation of optical systems Assessing the image quality degradation due to chromatic aberrations Optique et instrument doptique valuati
6、on de la qualit des systmes optiques Estimation de la dgradation de la qualit de limage due des aberrations chromatiques ISO 15795:2002(E) ii ISO 15795:2002(E) iiiContents Page Foreword.iv Introduction.v 1 Scope 1 2 Normative references1 3 Symbols and units.1 4 Terms and definitions, principle and m
7、athematical relationships .2 5 Classes of applications.8 6 Measurement procedures.8 7 Presentation of the results .11 8 Test report 12 Annex A (informative) Examples of the presentation of results 13 Bibliography16 ISO 15795:2002(E) iv Foreword ISO (the International Organization for Standardization
8、) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be repr
9、esented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards ar
10、e drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Internation
11、al Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO
12、 15795 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 1, Fundamental standards. Annex A of this International Standard is for information only. ISO 15795:2002(E) vIntroduction Aberrations due to the variation of the refractive index with wavelength (dispersion)
13、 are usually termed “chromatic aberrations”. Originally, this wording was based on the fact that, in the presence of these aberrations, the image of objects such as points, lines and edges, exhibit coloured fringes in addition to the variation of luminance. From this point of view, the concept of th
14、e point spread function (PSF) and the related optical transfer function (OTF), see ISO 9334, is basically a luminous (or more general radiative) transfer of optical information. There is only one signal regarding wavelength which is the result of the spectral transmission and sensitivity of the tran
15、smission chain, even if the latter is not identical to the relative luminous sensitivity of the human eye. Nowadays, the terms “colour” and, more specifically, “chroma” in the domain of physical science are well defined by colorimetry according to CIE Publication Nr. 15.2 (see reference 1 in the Bib
16、liography) and are restricted to that region of the electromagnetic spectrum, which is accessible to the normal (trichromatic) human observer. However, when concerned with aberrations due to the dispersive behaviour of electromagnetic waves, it is necessary to take into account that the spectral reg
17、ion of the optical waveband is by far wider than the limits of sensitivity of the human eye. This region may extend from the UV to the medium IR. In such applications, the human visual process is not involved or, if so, only by means of certain translations of the information into the visual waveban
18、d. Nevertheless, the fact of variation of the form and position of the point or line spread function with wavelength or with some spectrally weighted wavebands is still given. To characterize this dispersive behaviour, one has not to deal with colorimetry, but should describe the position and extent
19、 of the spread function relative to that of a certain reference wavelength or reference spectral weighting. In this sense, the present International Standard will not deal with colour sensations, but the term “chromatic aberrations” is used in a purely physical manner to describe the wavelength depe
20、ndent properties of such aberrations. The variation of the spread function with wavelength in a given image plane of an optical system may be characterized by a lateral translation and additionally by a variation in form and width. The lateral translation of a typical coordinate point of the spread
21、function will be called lateral chromatic aberration, whereas the form and extent can be characterized by two numbers derived from a weighting procedure over the spread function (edge width). The longitudinal chromatic aberration indicates the axial position of the best image plane for a certain wav
22、elength or waveband with respect to a reference plane and for a defined focusing (or image quality) criterion. INTERNATIONAL STANDARD ISO 15795:2002(E)1Optics and optical instruments Quality evaluation of optical systems Assessing the image quality degradation due to chromatic aberrations 1 Scope Th
23、is 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 s
24、ymmetric imaging geometry. It is also valid for optoelectronic imaging systems. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or
25、revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the n
26、ormative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 9334:1995, Optics and optical instruments Optical transfer function Definitions and mathematical relationships ISO 9335:1995, Optics and optical instruments Optical transf
27、er function Principles and procedures of measurement ISO 9039:1994, Optics and optical instruments Quality evaluation of optical systems Determination of distortion ISO 11421:1997, Optics and optical instruments Accuracy of optical transfer function (OTF) measurement 3 Symbols and units Symbol Meani
28、ng Unit Specified in Measurement wavelength nm, m 4.2.1 rReference wavelength nm, m 4.3 W() Weighted spectral distribution dimensionless 4.2.2 W R () Weighted spectral reference distribution dimensionless 4.3 u() Local image field coordinate for measurement wavelength m 4.5 u( r ) Local image field
29、coordinate for reference wavelength m 4.5 u(W) Local image field coordinate for weighted spectral measurement distribution m 4.5 ISO 15795:2002(E) 2 Symbol Meaning Unit Specified in u(W R ) Local image field coordinate for weighted spectral reference distribution m 4.5 h( r ), h(W R ) Image height f
30、or reference wavelength or distribution mm 4.5 T() Lateral chromatic aberration m 4.6 T(W) Weighted lateral chromatic aberration m 4.7 L() Longitudinal chromatic aberration m 4.9 L(W) Weighted longitudinal chromatic aberration m 4.9 LE Left edge width m 4.8.2 RE Right edge width m 4.8.2 EW Edge widt
31、h m 4.8.2 z(), z( r ) Position of best focus for wavelengths and rmm 4.9 z(W), z(R) Position of best focus for spectral weightings W() and W R () mm 4.9 pImage pupil field angle degree 3.8 of ISO 9039:1994 pObject pupil field angle degree 3.7 of ISO 9039:1994 OTF(r) One-dimensional optical transfer
32、function dimensionless 3.11 of ISO 9334:1995 MTF(r) One-dimensional modulation transfer function dimensionless 3.9 of ISO 9334:1995 PTF Phase transfer function degree, rad 3.10 of ISO 9334:1995 PSF Point spread function mm 23.5 of ISO 9334:1995 LSF Line spread function mm 13.13 of ISO 9334:1995 ESF
33、Edge spread function dimensionless 3.14 of ISO 9334:1995 Azimuth degree 4.21 of ISO 9334:1995 Reference angle degree 4.12 of ISO 9334:1995 Integration variable dimensionless 4.5 4 Terms and definitions, principle and mathematical relationships 4.1 General For the purposes of this International Stand
34、ard, the terms and definitions given in ISO 9334 and ISO 9335 apply. 4.2 Wavelengths and spectral distributions For the determination of chromatic aberrations, several wavelengths or spectral distributions shall be given for which the aberrations are to be determined. 4.2.1 Quasi-monochromatic measu
35、rement In this case, the spectral bandwidth of the measurement radiation is small compared to the distance between neighbouring measurement wavelengths. The measurement wavelength under consideration is the mean wavelength of that quasi-monochromatic radiation for which the chromatic aberrations are
36、 to be determined. ISO 15795:2002(E) 34.2.2 Measurement with finite spectral bandwidth The spectral bandwidth is specified by a spectral weighting function, W(). For the purpose of analytical calculations, this shall be approximated by spectral area weighting with different discrete wavelengths. The
37、 measurements of chromatic aberrations shall always be carried out in the same manner, regardless of whether they are determined for discrete wavelengths or for certain wavebands. 4.3 Reference wavelength and weighted spectral reference distribution In the case of quasi-monochromatic radiation (see
38、4.2.1), the reference wavelength, r , is the wavelength to which the determination of the chromatic aberrations is related. In the case of finite spectral bandwidth (see 4.2.2), the reference spectral distribution is the spectral weighting function, W R (), to which the determination of the chromati
39、c aberrations is related. 4.4 Measurement plane The measurement plane is a plane perpendicular to the optical axis in which the measurement is carried out. It may be defined by geometric means, or with the help of a suitably defined focusing criterion, which can be applied by measurement and shall b
40、e accessible for analytical calculations. 4.5 Image heights and local image field coordinates The image heights are defined by means of the line spread function (LSF). Figure 1 shows an example of (measured) line spread functions. For the definition of line spread function, see 3.13 of ISO 9334:1995
41、. This definition is also valid for weighted spectral distribution, W(). Figure 1 Examples for quasi-monochromatic line spread functions The image height, h, is the position within the line spread function where the area fractions of the line spread function are equal. ISO 15795:2002(E) 4 Thus: 1 LS
42、F ( ) d LSF ( ) d 2 h + = (1) where is an integration variable. Local image field coordinates, u, are introduced by choosing the origin u = 0 at the reference image height, h( r ), for the reference wavelength, r , or h( W R ) for the weighted spectral reference distribution, W R (). 4.6 Lateral chr
43、omatic aberration The lateral chromatic aberration, T(), is defined as the radial variation in image height for the wavelength, , relative to the image height for the reference wavelength, r . This definition requires a numerical evaluation of the line spread function, as it is also necessary for th
44、e determination of the optical transfer function. For given magnification ratio and relative aperture, the lateral chromatic aberration is a function of wavelength and image height. For finite image distance, the lateral chromatic aberration, T(), in the measurement plane is given by: T() = u() u( r
45、 ) (2) where u( r ) = 0. 4.7 Weighted lateral chromatic aberration The weighted lateral chromatic aberration, T(W), is defined as the radial variation in image height, u(W), for the weighted spectral distribution, W(), relative to the image height, u(W R ), for the weighted spectral reference distri
46、bution, W R (). For given magnification ratio and relative aperture, the weighted lateral chromatic aberration in the measurement plane is a function of image height. For finite image distance: T(W) = u(W) u(W R ) (3) where u(W R ) = 0. As in 4.6, this requires a numerical evaluation of the line spr
47、ead function, here with weighted spectral distribution, W(). 4.8 Form and extent of the edge spread function (ESF) 4.8.1 General In addition to the lateral chromatic aberration as a displacement between the median values of the edge spread functions for the reference and measurement wavelength or sp
48、ectral weighting, one shall judge the degradation in image quality with the help of the form of the line or edge spread function for the different wavelengths or spectral weightings. This will give information in the space domain alternatively to the optical transfer function in the spatial frequenc
49、y domain. The edge spread function will be used, because, in general, its structure is relatively, simple. See Figure 2. ISO 15795:2002(E) 5For the definition of edge spread function, see 3.14 of ISO 9334:1995. This definition is also valid for weighted spectral distribution, W(). The edge spread function may be derived from the line spread f
