1、BS ISO 14490-7:2016Optics and photonics Test methods for telescopic systemsPart 7: Test methods for limit of resolutionBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 14490-7:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation
2、of ISO 14490-7:2016. It supersedes BS ISO 14490-7:2005 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CPW/172, Optics and Photonics.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does
3、 not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 90382 3 ICS 37.020 Compliance with a British Standard cannot confer immunity from legal
4、obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 14490-7:2016 ISO 2016Optics and photonics Test methods for telescopic systems Part 7
5、: Test methods for limit of resolutionOptique et photonique Mthodes dessai pour systmes tlescopiques Partie 7: Mthodes dessai pour limite de rsolutionINTERNATIONAL STANDARDISO14490-7Second edition2016-11-15Reference numberISO 14490-7:2016(E)BS ISO 14490-7:2016ISO 14490-7:2016(E)ii ISO 2016 All right
6、s reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or a
7、n intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.o
8、rgwww.iso.orgBS ISO 14490-7:2016ISO 14490-7:2016(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Method of determination of the limit of resolution . 14.1 General . 14.2 Test equipment . 14.3 Preparation and carrying out of measurements 34.4 Determination o
9、f results . 35 Test report . 4Annex A (informative) Dimensions of a bar-type test target for determination of the limit of resolution of telescopic systems 5Bibliography .10 ISO 2016 All rights reserved iiiContents PageBS ISO 14490-7:2016ISO 14490-7:2016(E)ForewordISO (the International Organization
10、 for Standardization) 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
11、the right to be represented 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.The pro
12、cedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editor
13、ial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights
14、 identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explana
15、tion on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.The committee respons
16、ible for this document is ISO/TC 172, Optics and photonics, Subcommittee SC 4, Telescopic systems.This second edition cancels and replaces the first edition (ISO 14490-7:2005), which has been technically revised with the following changes: addition of a new sentence in A.4 “Alternatively, a test pat
17、tern down to 2-1/3= 0,79 is acceptable.”; corrected Table A.2, last row: 302 replaced by 320.A list of parts in the ISO 14490 series can be found on the ISO website.iv ISO 2016 All rights reservedBS ISO 14490-7:2016ISO 14490-7:2016(E)IntroductionThere are various characteristics which are relevant f
18、or overall image quality of telescopic systems and observational telescopic instruments. Two important characteristics are the limit of resolution and the optical transfer function.This document specifies the test method for the determination of the limit of resolution of telescopic systems and obse
19、rvational telescopic instruments. Optical transfer function measurement as applied to telescopic systems is specified in ISO 9336-3.Besides the limit of resolution and the optical transfer function, further characteristics are relevant for an assessment of the image quality; the most important of th
20、em are the following: secondary spectrum (dispersive aberrations); distortion; vignetting; colour matching.The secondary spectrum of the test specimen can produce colour fringes surrounding observed objects (especially at high contrast edges) which can look like coloured neon tube light.The perceive
21、d image might have barrel or pincushion distortion. Pincushion distortion is considered to give a more natural impression of the observed object when swivelling the test specimen.Vignetting can lead to a perceivable intensity degradation from the centre to the edge of the field of view.Colour matchi
22、ng is the accuracy of the colour rendition of an object observed with the test specimen. Any colour deviation might be due to the lens material or to coatings. ISO 2016 All rights reserved vBS ISO 14490-7:2016BS ISO 14490-7:2016Optics and photonics Test methods for telescopic systems Part 7: Test me
23、thods for limit of resolution1 ScopeThis document specifies the test methods for the determination of the limit of resolution of telescopic systems and observational telescopic instruments.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of the
24、ir content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 14490-1:2005, Optics and optical instruments Test methods for telescopic systems Pa
25、rt 1: Test methods for basic characteristics3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 14132-1 apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.ele
26、ctropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp4 Method of determination of the limit of resolution4.1 GeneralThe limit of resolution of a telescopic system is the minimum angular distance between centrelines of two adjacent bright (or dark) bars of the bar-type resol
27、ution test target whose direction can be detected when viewing through the test specimen.4.2 Test equipmentThe limit of resolution of telescopic systems shall be determined with the test arrangement shown in Figure 1.INTERNATIONAL STANDARD ISO 14490-7:2016(E) ISO 2016 All rights reserved 1BS ISO 144
28、90-7:2016ISO 14490-7:2016(E)The bar-type resolution test target has contrast, as given by Formula (1):K =+tr optr op09, (1)wheretris the transmittance of a translucent part of the resolution test target;opis the transmittance of an opaque part of the resolution test target.The resolution test target
29、 shall be placed at the focal plane of the collimator lens.For systems that require the limit of resolution to be measured with a focus setting other than infinity, the position of the resolution test target with respect to the collimator lens shall be adjusted in order to obtain its image at the sp
30、ecified distance from the test specimen.The bar-type resolution test target is a glass plate bearing a picture that consists of bright bars having different widths on a dark background, the directions of which are vertical, horizontal and diagonal in 45 angular degrees.The dimensions of one acceptab
31、le design of bar-type resolution test target are given in Annex A.The resolution test target shall be illuminated uniformly (mean illuminance 5 % Peak to Valley) by means of a light source with a correlated colour temperature of 5 000 K to 6 000 K, condenser and diffuser for non-dazzling observation
32、 conditions. The luminance of the resolution test target shall be optimum for observation of its image.The diameter of the collimator lens shall at least exceed 1,2 times the diameter of the entrance pupil of the test specimen. The focal length of the collimator lens shall be at least five times tha
33、t of the objective of the test specimen.The magnification of the auxiliary telescope shall not reduce the diameter of the exit pupil of the whole system below 0,8 mm.Key1 light source2 condenser3 diffuser4 bar-type resolution test target5 collimator lens6 test specimen7 auxiliary telescopeThe auxili
34、ary telescope should not be used if the angular limit of resolution behind the eyepiece of the test specimen is worse than 2 to 3 and the diameter of the exit pupil is below 1 mm.Figure 1 Test arrangement for measurement of the limit of resolution (schematic)2 ISO 2016 All rights reservedBS ISO 1449
35、0-7:2016ISO 14490-7:2016(E)4.3 Preparation and carrying out of measurementsStray light and vibration shall be minimized (and if possible eliminated) from the test set up.Check the cleanliness of the optical surfaces of the lenses of the test specimen, the collimator lens, the condenser, and the auxi
36、liary telescope. No traces of lubricants, fingerprints, moisture, or dust are allowed.Select the size number of the resolution test target according to the focal length of the collimator lens and the limit of resolution of the test specimen (for instance, see Table A.2 or use the formula given for t
37、he angular resolution defined in ISO 14132).If an auxiliary telescope is used, adjust its eyepiece according to the observers eye to allow sharp viewing of the telescope reticle. The auxiliary telescope and the eye of the observer shall not limit the assessment of the resolution. After that, focus t
38、he auxiliary telescope on the image of the resolution test target which is located in the focal plane of the collimator lens.Focus the test specimen on the image of the resolution test target; then position the test specimen and the auxiliary telescope coaxially with the collimator lens.Set the eyep
39、iece of the test specimen in a position which enables sharp viewing of the reticle of the test specimen through the auxiliary telescope. If no reticle is provided, adjust the eyepiece to zero dioptres.Determine the limit of resolution of the test specimen in the centre of the field of view.During ob
40、servation through the eyepiece of the auxiliary telescope, the maximum sharpness of bars of a pattern at lowest sharpness in one group of the resolution test target shall be obtained by means of refocusing the test specimen. If no focusing is available in the test specimen, the maximum sharpness of
41、bars of a pattern at lowest sharpness in one group of the resolution test target shall be obtained by refocusing the auxiliary telescope.During successive viewing of images of certain groups of the resolution test target having different spatial frequencies, a group of the resolution test target sha
42、ll be found which enables easy detection of all four bar directions. This shall be achieved without refocusing for the different bar directions. This group shall be located in the centre of the field of view of the test specimen.4.4 Determination of resultsFrom the size number of the resolution test
43、 target group that enables the detection of all four pattern directions, determine the bar width, b.Calculate the angular distance, , in seconds of angle, between the centrelines of adjacent bright (or dark) bars of each resolution test target group according to Formula (2): =2206265bfk(2)whereb is
44、the bar width, in mm;fkis the focal length of the collimator lens, in mm;206 265 is the number of arc seconds/radian. ISO 2016 All rights reserved 3BS ISO 14490-7:2016ISO 14490-7:2016(E)5 Test reportA test report shall be presented and shall include the general information specified in ISO 14490-1:2
45、005, Clause 13, the result of the test as specified in 4.4 above and information on the test target used for the test.4 ISO 2016 All rights reservedBS ISO 14490-7:2016ISO 14490-7:2016(E)Annex A (informative) Dimensions of a bar-type test target for determination of the limit of resolution of telesco
46、pic systemsA.1 Resolution test target layoutThe resolution test target consists of 25 groups, as shown in Figure A.1, and two pairs of parallel, equally spaced marks. The distance between the centres of the marks that defines the size of the test target is called the test target base.NOTE Dimensions
47、 of resolution test targets are given in Table A.1.Figure A.1 Resolution test target layoutA.2 Layout of groups of resolution test targetEach group of the resolution test target consists of four patterns formed by five bars each. The bars have equal lengths and widths and are arranged as shown in Fi
48、gure A.2. The intervals between adjacent bars are equal to the bar width. ISO 2016 All rights reserved 5BS ISO 14490-7:2016ISO 14490-7:2016(E)A.3 DimensionsNOTE Dimensions of resolution test targets are given in Table A.1.Figure A.2 Group of the resolution test targetA.4 Bar widthThe bar width, b, i
49、n the resolution test target shall decrease from the group no. 1 to the group no. 25 in accordance with the geometric progression having the base 2-1/12= 0,94. Alternatively, a test pattern down to 2-1/3= 0,79 is acceptable.NOTE See Table A.1 for dimensions.A.5 Number of barsThe number, N, of bars per millimetre for any test target group number should be determined by division of 1 000 m by the distance between the centrelines of adjacent bright (or dark) bars (2b) in m.Table A.1 Dimensions of
