1、 ISO 2017 Optics and photonics Test methods for telescopic systems Part 5: Test methods for transmittance Optique et photonique Mthodes dessai pour systmes tlescopiques Partie 5: Mthodes dessai du facteur de transmission INTERNATIONAL STANDARD ISO 14490-5 Second edition 2017-08 Reference number ISO
2、14490-5:2017(E) ISO 14490-5:2017(E)ii ISO 2017 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in Switzerland All 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 mechanica
3、l, including photocopying, or posting on the internet or an 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 office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switz
4、erland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 14490-5:2017(E)Foreword iv 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Principle 1 5 Test arrangement . 2 5.1 General . 2 5.2 Source of radiation and condenser 3 5.3 Monochromator or set of fil
5、ters . 3 5.4 Collimator 3 5.5 Aperture stop . 3 5.6 Specimen mounting 3 5.7 Veiling glare stop . 3 5.8 Integrating sphere 4 5.9 Radiation detector . 4 6 Procedure. 4 6.1 Preparation of the test assembly . 4 6.2 Determination of the measurement values 4 6.3 Further test methods . 5 7 Precision of the
6、 measurement . 5 8 Presentation of the results . 5 9 Analysis 5 9.1 Effective transmittance for photopic vision . 5 9.2 Effective transmittance for scotopic vision 6 10 Test report . 6 Annex A (informative) Calibration procedure for the photoreceiver/measuring instrument 7 Annex B (informative) T ri
7、chr omatic c oefficients and c olour c ontribution inde x10 Bibliography .14 ISO 2017 All rights reserved iii Contents Page ISO 14490-5:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of pr
8、eparing 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 represented on that committee. International organizations, governmental and non-governmental, i
9、n 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 procedures used to develop this document and those intended for its further maintenance are described in the ISO/I
10、EC 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 editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives). Attention is drawn to the possibil
11、ity 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 identified during the development of the document will be in the Introduction and/or on the ISO list of pa
12、tent 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 explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related t
13、o 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: w w w . i s o .org/ iso/ foreword .html. This document was prepared by Technical Committee ISO/TC 172, Optics and phot
14、onics, Subcommittee SC 4 Telescopic systems. This second edition cancels and replaces the first edition (ISO 14490-5:2005), which has been technically revised. It also incorporates the ISO 14490-5:2005/Amd 1:2015. The main changes are as follows: the normative references has been updated; In 5.8, th
15、e wording has been changed to “maximum diameter of the aperture stop”; Formulae (3) and (4) have been corrected. A list of all parts in the ISO 14490 series can be found on the ISO website.iv ISO 2017 All rights reserved INTERNATIONAL ST ANDARD ISO 14490-5:2017(E) Optics and photonics Test methods f
16、or telescopic systems Part 5: Test methods for transmittance 1 Scope This document specifies the test methods for the determination of the transmittance of telescopic systems and observational telescopic instruments. 2 Normative references The following documents are referred to in the text in such
17、a way that some or all of their 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 11664-2, Colorimetry Part 2: CIE standard illuminants
18、 ISO 14132-1, Optics and photonics Vocabulary for telescopic systems Part 1: General terms and alphabetical indexes of terms in ISO 14132 ISO 14490-1:2005, Optics and optical instruments Test methods for telescopic systems Part 1: Test methods for basic characteristics 3 T erms a nd definiti ons For
19、 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 h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t
20、t p :/ www .iso .org/ obp 4 Principle To determine the spectral transmittance , the flux of radiation in a limited bundle of rays will be measured before entering 0 and after passing p through the optical system. The transmittance results from Formula (1): (1) During the spectral measurement, the em
21、ergent light of the radiation source will be limited to a small wavelength band by means of a monochromator or a set of filters. ISO 2017 All rights reserved 1 ISO 14490-5:2017(E) 5 Test arrangement 5.1 General The measuring device consists of radiation source (optionally with a condenser), monochro
22、mator or set of filters, collimator lens, aperture stop, specimen mounting, veiling glare stop, integrating sphere, radiation detector and measuring and evaluation unit (signal processing). See Figure 1. Key 1 radiation source 6 aperture stop 2 condenser 7 integrating sphere 3 monochromator 8 detect
23、or 4 selectable diaphragm as field stop 9 baffle 5 collimator lens 10 measurement and evaluation unit Figure 1 Test arrangement without test specimen (schematic) Key 1 radiation source 7 test specimen 2 condenser 8 veiling glare stop 3 monochromator 9 integrating sphere 4 selectable diaphragm as fie
24、ld stop 10 detector 5 collimator lens 11 baffle 6 aperture stop 12 measurement and evaluation unit Figure 2 Test arrangement with test specimen (schematic)2 ISO 2017 All rights reserved ISO 14490-5:2017(E) 5.2 Source of radiation and condenser The radiation source shall emit a continuous flux of rad
25、iation in the specified wavelength range. The variation of flux during the measurement of a pair of values shall be less than 1 %. The condenser adapts the radiation source to the optical measurement path. 5.3 Monochr omat or or set of filt ers Grating or prism monochromators can be used to select t
26、he wavelength. The smallest adjustable wavelength distance shall be less than 2 % of the dominant wavelength of the respective measurement. The necessary spectral bandwidth depends on the sample. It shall be ensured that a steep alteration of the transmission curve is detected correctly. Thus, the b
27、andwidth shall be smaller than the distance in the wavelength, at which the transmittance is changed by 4 %. This condition cannot always be satisfied because of measuring and energy reasons or because the time/cost effort is not adequate. In these cases, a maximum bandwidth of 4 % of the wavelength
28、 is allowable. A bandwidth of less than 2 % of the wavelength is necessary if the colour rendition indices are to be calculated. Instead of a monochromator, a set of filters can be used. They are especially useful with flat-shaped transmittance curves. The number of measuring points shall allow for
29、a definite curve fitting. Measurement with spectral filters can be applied as well if only single measuring points are required. 5.4 Collimator The collimator may contain a refracting lens or mirror. The collimator has to be adjusted to the aligned components in such a way that full and uniform illu
30、mination of the following aperture stop is assured. The axial chromatic aberration of a refracting lens shall be less than or equal to 1 % of its focal length in the spectral range used. An off-axis parabolic mirror or an equivalent system is also suitable as a collimator. 5.5 Aperture stop The aper
31、ture stop should be circular and located close to objective lens of the test specimen if possible. The diameter should be 80 % (50 % recommended) of the maximum available aperture of the test specimen, as well as smaller than the opening of the integrating sphere. Auxiliary systems can be used for b
32、eam forming to realize these requirements. These systems shall stay in the ray path during measuring with and without test specimen. Generally, the smallest possible aperture stop should be used which is compatible with the signal-to- noise requirements of the detector. Special care should be taken
33、when measuring telescopic systems with variable magnification where at some magnification settings the entrance pupil can be considerably smaller than the free objective lens diameter. In this case, it is recommended to take the entrance pupil as the “maximum available aperture”. 5.6 Specimen mounti
34、ng The mounting of the test specimen shall be designed in a way that the test specimen can be adjusted and held stable. The test specimen should be oriented in a way such that no obstructions occur in the measurement beam (e.g. by reticle structures). 5.7 Veiling glare stop A veiling glare stop with
35、 a diameter that is 1,1 times the diameter of the image of the aperture stop is located in the image plane of the aperture stop, consequently in the exit pupil of the telescope. The veiling glare stop shall be dull black on both sides. It shall be designed in a way that the veiling glare ISO 2017 Al
36、l rights reserved 3 ISO 14490-5:2017(E) resulting from the test specimen and upsetting of the measurement result is reduced as far as possible. It shall further be designed in a way that the necessary radiation for the measurement passes through unobstructed. 5.8 Integrating sphere The integrating s
37、phere shall be located near the veiling glare stop to ensure that the light passing through the veiling glare stop will be completely collected by the integrating sphere. The integrating sphere has two openings, one for the input of the bundle of rays to be measured and one for the detector. Both op
38、enings shall not be located opposite each other. Direct radiation incident on the detector is prevented by baffles. The surfaces of the two openings together shall not occupy more than 5 % of the internal surface of the sphere. The diameter of the integrating sphere opening shall exceed the maximum
39、diameter of the aperture stop (6 in Figure 1) by 5 % to 7 %. The reflectance of the internal coating of the integrating sphere shall be as high as possible and diffuse across the whole spectral range. The reflectance across the whole spectral range from 380 nm to 780 nm shall be at least 85 %. 5.9 R
40、adiation detector The linearity of the radiation detector shall be better than 0,5 %, including the accompanying signal processing. 6 Procedure 6.1 Preparation of the test assembly Insert the test specimen in its mounting with the objective lens facing the radiation source (see Figure 1). Locate the
41、 veiling glare stop as required. Take care to avoid multiple reflections between aperture stop, test specimen, or other parts, which may upset the measurement result, by the use of additional protective screens. For systems with a reticle at an intermediate image plane, take care that parts of the t
42、est specimens reticle do not obscure any of the light passing through it. Ensure that the ambient light does not influence the measurement result. 6.2 Determination of the measurement values Carry out the measurements in the spectral range from 380 nm to 780 nm, if trichromatic coefficients shall no
43、t be calculated. First, determine a measuring value S 0 , which is proportional to the flux of radiation 0 through the aperture stop using the measuring instrument without the test specimen and without the veiling glare stop. Then, insert the test specimen into the ray path and determine the measuri
44、ng value S p which is proportional to the flux of radiation p . The ratio of both values with and without the test specimen gives the spectral transmittance in Formula (2): S S(2) Carry out the procedure at the required wavelengths to determine the spectral slope. The wavelengths shall be chosen in
45、a way that the shape of the transmittance curve can be surely recognized.4 ISO 2017 All rights reserved ISO 14490-5:2017(E) 6.3 Further test methods Integral and thus much less expensive testing methods are sufficient for many purposes such as comparison measuring or verification of the required tra
46、nsmission values for a standard illuminant. The transmittance can be measured directly by integral testing methods, utilizing the test assembly (see Figure 1), and additional suitable compensating filters, e.g. a conversion filter that modifies the spectral sensitivity of the integrating sphere and
47、the detector to be the same as that of the eye. A calibrated specimen shall be used to verify the accuracy of this simplified test method. If necessary, the measured values of an integral measurement are to be confirmed by a spectral measurement and calculated according to the document. If a measure
48、ment set-up without an integrating sphere is used, the photodetector shall be checked to ensure that the readout does not depend on the illuminated area of the photodetector using the procedure specified in Annex A. 7 Precision of the measurement The repeatability of the respective transmittance val
49、ue shall not exceed 0,02. The test assembly shall be designed and the parts chosen such that this requirement is fulfilled. 8 Presentation of the results The measuring results shall be presented in tabular and graphical form, as follows: a) for presentation in tabular form, the results shall be indicated in a table with three decimal digits; b) for graphical presentation, the values shall be plotted linear
