1、 Reference numberISO 14997:2011(E)ISO 2011INTERNATIONAL STANDARD ISO14997Second edition2011-04-15Optics and photonics Test methods for surface imperfections of optical elements Optique et photonique Mthodes dessai applicables aux imperfections de surface des lments optiques ISO 14997:2011(E) COPYRIG
2、HT PROTECTED DOCUMENT ISO 2011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
3、 ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedISO 14997:2011(E) ISO 2011 All rights reserved iiiCon
4、tents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Physical principles 2 5 Measurement of obscured or affected area2 5.1 General .2 5.2 Requirements.4 5.3 Calibration4 5.4 Procedure.4 5.5 Test report4 Annex A (informative) Component inspection.6 Annex
5、 B (informative) Recommended dimensions of artefacts on a scale comparison plate.7 Annex C (informative) Description of the instrument used for measuring imperfections below 0,01 mm: microscope image comparator .8 Annex D (informative) Imperfection quality control 11 Annex E (normative) Preferred va
6、lues of grade numbers and subdivision factors 13 Bibliography14 ISO 14997:2011(E) iv ISO 2011 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards
7、 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, in liaison with ISO, also take p
8、art in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to
9、 prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility t
10、hat 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. ISO 14997 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 1, Fundamental standards. This second editio
11、n cancels and replaces the first edition (ISO 14997:2003), which has undergone minor revision to adapt ISO 14997:2011 to ISO 10110-7:2008; the main changes are the deletion of one of the two test methods and the addition of a new Annex E. ISO 14997:2011(E) ISO 2011 All rights reserved vIntroduction
12、This International Standard was developed in response to worldwide demand for test methods for surface imperfections that are objective and permit fast assessment of component quality. Existing standards have been assessed (see Reference 9) and found to be too variable in use to satisfy the current
13、requirements of industry. Surface imperfections, such as digs and scratches, arise from localized damage during or after manufacture. They can be visible as a result of the light they scatter, giving rise to a false impression of poor quality. Alternatively, this light can appear as unwanted veiling
14、 glare (stray radiation) in an image plane, or it can lead to a degradation in signal quality at an image sensor. Imperfections can also provide centres of stress, eventually leading to failure of components exposed to high laser radiation power/energy densities. Since modern methods of surface exam
15、ination are capable of atomic resolution, no surface is likely to be found totally free of localized imperfections. Most surfaces produced are satisfactory for their intended purpose, but a small proportion can have suffered obvious damage and will be reworked or regarded as unacceptable. This can l
16、eave some components which, although slightly damaged, may still be found acceptable, when tested, depending on the level of acceptability of surface imperfections requested by the customer and specified on drawings in ISO 10110-7. This International Standard describes how these methods are implemen
17、ted. The obscuration of imperfections larger than 10 m can be judged visually by comparison of areas with artefacts of known size on a comparison plate. The obscuration caused by imperfections equal to or less than 10 m across and yet still visible under dark-field illumination either is too small f
18、or accurate area measurement or may transmit as well as scatter radiation. These need to be quantified by comparison of their radiometric obscuration with totally absorbing artefacts of known size. Every imperfection detected is measured and considered for summation to produce a level of grade for e
19、ach surface. It should be noted that other light scattering defects, which also need to be measured, can arise as digs distributed over the surface of an incompletely polished surface, and as bubbles and as striae within an optical material. The measurement of laser damage thresholds also requires s
20、ensitive means for quantifying the level of radiation scattered by damage in its early stages. INTERNATIONAL STANDARD ISO 14997:2011(E) ISO 2011 All rights reserved 1Optics and photonics Test methods for surface imperfections of optical elements 1 Scope This International Standard establishes the ph
21、ysical 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. The method is suitable for prototype, small-scale or large-scale production of a wide variety of optical comp
22、onents. Imperfection appearance or functional tolerances related to a particular component can be determined by agreement between supplier and customer. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the ed
23、ition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 10110-7, Optics and photonics Preparation of drawings for optical elements and systems Part 7: Surface imperfection tolerances ISO 11145, Optics and photonics Lasers and
24、 laser-related equipment Vocabulary and symbols 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 10110-7 and ISO 11145 and the following apply. 3.1 fully-developed imperfection imperfection which scatters all radiation incident upon it 3.2 partially-d
25、eveloped imperfection imperfection which transmits as well as scatters radiation incident upon it 3.3 line-equivalent width LEW width of a fully-developed scratch or absorbing line which obscures the same amount of radiation as a partially-developed scratch NOTE The LEW of a fully-developed scratch
26、equals its geometrical width. ISO 14997:2011(E) 2 ISO 2011 All rights reserved3.4 spot-equivalent diameter SED diameter of a fully-developed dig or absorbing spot which obscures the same amount of radiation as a partially-developed dig NOTE The SED of a fully-developed dig equals its geometrical dia
27、meter, but its grade number is the square root of its area. 3.5 imperfection threshold total magnitude of imperfections on a surface quoted as a numerical term above which the component may be rejected for a particular application 3.6 bright-field imperfection contrast ratio of the difference betwee
28、n the background maximum and minimum intensities across an imperfection image to the sum of these values NOTE This value depends on whether the imperfection is viewed in transmission or reflection and on whether it is viewed directly or through the component. 3.7 obscuration comparison process of me
29、asuring the severity of an imperfection by comparing its peak contrast under bright-field conditions with that of an obscuring artefact of known size 3.8 visual contrast threshold smallest ratio of the brightness of an object to its background which can be seen by a particular observer 4 Physical pr
30、inciples Precise metrology of small surface imperfections, which may be clearly visible under dark-field illumination, has proved to be very difficult (see Reference 9) under workshop conditions. The parametric method described in Clause 5 overcomes this problem by equating imperfection severity wit
31、h the obscuration of the incident beam in comparison with an absorbing artefact of known size. The obscuration of each imperfection of doubtful severity identified during inspection is measured separately. A dig is usually fully developed and is quantified by measuring its encircled diameter and the
32、n calculating its area and grade number in accordance with ISO 10110-7. Preferred values for grade numbers are given in Annex E. The length and width of a scratch with dimensions greater than 10 m are measured with the aid of a comparison plate or low power measuring microscope. Scratches equal to o
33、r less than 10 m in width are measured from their LEW values. If different values are found for actual width and LEW or the actual diameter of a dig and its SED, for these two approaches the smaller number which allows for transmission of a partially-developed imperfection shall be used when calcula
34、ting the grade number. NOTE Choice of the smaller value is likely to reduce over-specification and lead to increased yields and lower costs. 5 Measurement of obscured or affected area 5.1 General Optical components shall first be cleaned and inspected, preferably in low angle scattered light by stro
35、ng side-illumination under dark-field conditions, to select the usually small proportion of doubtful components with imperfections which require measurement. A typical arrangement for the routine inspection of optical elements for imperfections seen in transmission is shown in Annex A. A mirror can
36、be inspected by placing it close to the back wall of the box and tilted so as to avoid reflected light entering the eye. ISO 14997:2011(E) ISO 2011 All rights reserved 3The affected areas of imperfections with dimensions greater than 10 m on transmitting or reflecting substrates can be determined wi
37、th the aid of a scale comparison plate, such as that described in Annex B. A simple magnifier or low power microscope may be used for this purpose. For imperfections equal to or smaller than 10 m, Figure 1 a) shows a schematic arrangement illustrating the simplest configuration required for the meas
38、urement of LEW and SED when viewing in transmission. Light from a distant source on the left illuminates the component. A comparison plate is placed close to the component so that the eye can form a match between the contrast of the imperfection under bright-field conditions and that of a line of kn
39、own width on the plate or a spot of known diameter when quantifying a dig. In the event that there is no specification for long imperfections, all scratches are measured and accumulated by area with general imperfections. Imperfections on a reflecting substrate shall be viewed through a beam splitte
40、r to provide normally incident illumination of the mirror. The same comparison plate operating again in transmission is used as shown schematically in Figure 1 b). a) Viewing in transmission b) Viewing in reflection Key 1 source 2 comparison plate 3 test component 4 test mirror 5 beam splitter Figur
41、e 1 Schematic arrangement for measurement ISO 14997:2011(E) 4 ISO 2011 All rights reserved5.2 Requirements The requirements for the measurement of LEW and SED for imperfections of size equal to or less than 10 m are summarized below. a) The imperfection on the component under test and the comparator
42、 plate shall be illuminated and imaged under the same conditions. b) The illumination shall be substantially parallel and avoid speckle in the image plane. c) The imaging system shall have a low numerical aperture, typically 0,01, chosen to remove fine structure from the imperfection image, but to l
43、eave sufficient radiation to enable comparison of the peak contrasts of the imperfection and artefact images. d) The image may be viewed directly, but remote viewing by television is preferred. A variety of different designs of image comparator may be used to fulfil the above requirements, but the p
44、referred arrangement with a precision and sensitivity which exceeds that possible with unaided vision is a microscope image comparator described in Annex C. If the LEW of a scratch varies along its length, its peak value shall be taken when calculating its grade number. The length of scratches requi
45、red to calculate their grade number and the extent of edge chips from the physical edge of the surface should be measured with the aid of the comparison plate or by low power microscope. 5.3 Calibration The measurement of LEW and SED requires the use of a reference dig and scratch calibration plate
46、which may be of the form of that described in Annex B, extended to sub-micrometre values, if required. When testing in transmission, this shall have opaque lines and spots on a transparent substrate. Testing in reflection, when using the microscope image comparator, requires the negative of this pla
47、te with transparent slits and spots of the same size on a reflecting substrate. The uncertainty of measurement of these artefacts shall be 5 % of the measured dimension. 5.4 Procedure The precise procedure for optical component inspection and measurement will vary between companies, depending on pas
48、t experience and customer needs. The approach described in Annex D is based largely on existing practice. 5.5 Test report If a test report is requested on the drawing, the following information shall be provided for each face of component tested. a) General information: 1) name and address of worksh
49、op; 2) name of the inspector; 3) date of the measurement; 4) International Standard and/or test specification numbers. ISO 14997:2011(E) ISO 2011 All rights reserved 5b) Sample information: 1) component drawing number; 2) specifications relating to storage, cleaning and production date; 3) transmitting/reflecting component; 4) component diameter; 5) description of orientation and face marking; 6) operational mode: conformity/quality grade. c) Test specification: 1) description of test equipment; 2) f/ratio of imaging l
