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1、BRITISH STANDARD AUTOMOBILE SERIES CONFIRMED DECEMBER 1987 BS AU 170:1979 Methods for Measurement of reflectance of rear view mirrors UDC 629.113.0181:535.346.1 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI B
2、S AU 170:1979 This British Standard, having been prepared under the direction of the Automobile Standards Committee, was published under the authority of the Executive Board on 28 February 1979 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference AUE/- Dr
3、aft for comment 77/73276 DC ISBN 0 580 10695 0 Foreword This British Standard, which has been prepared under the direction of the Automobile Standards Committee, is based on ISO 5740 “Road vehicles Rearview mirrors Test method for determining reflectivity”. A British Standard does not purport to inc
4、lude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, page
5、s i and ii, pages 1 to 6 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: London So
6、uth Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 170:1979 BSI 03-2000i Contents Page ForewordInside front cover 1Scope and field of application1 2References1 3Definitions1 4Apparatus1 5Procedures2 Appendix A Spectral tristimulus
7、values for CIE 1931 standard colorimetric observer4 Figure 1 Generalized reflectometer showing geometries for the two calibration methods5 Figure 2 Generalized reflectometer incorporating an integrating sphere6 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:
8、52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 170:1979 BSI 03-20001 1 Scope and field of application This British Standard specifies a test meth
9、od for determining the reflectance of rear-view mirrors for road vehicles. It applies to flat and convex surface mirrors intended for internal and external mounting. 2 References The following publications are referred to in this standard. BS 354, Recommendations for photometric integrators. BS 667,
10、 Portable photoelectric photometers. BS 4727, Glossary of electrotechnical, power, telecommunications, electronics, lighting and colour terms Part 4: Terms particular to lighting and colour Group 01: Radiation and photometry Group 02: Vision and colour terminology. 3 Definitions For the purposes of
11、this British Standard, the following definitions apply. 3.1 CIE standard illuminant A (as defined in term number 402 2031 of BS 4727-4:Group 02:1971) colorimetric illuminant, representing the full radiator at T68= 2 855.5 K 3.2 CIE standard source A (as defined in term number 402 2032 of BS 4727-4:G
12、roup 02:1971) gas-filled tungsten filament lamp operating at a correlated colour temperature of T68= 2 855.5 K 3.3 CIE 1931 standard colorimetric observer (as defined in term number 402 2011 of BS 4727-4:Group 02:1971) receptor of radiation whose colorimetric characteristics correspond to the spectr
13、al tristimulus values , , adopted by the International Commission on Illumination in 1931 (See 3.4 and Appendix A.) 3.4 CIE spectral tristimulus values (as defined in term number 402 2008 of BS 4727-4: Group 02:1971) tristimulus values of the spectral components of an equienergy spectrum in the CIE
14、(XYZ) system NOTE 1Formerly CIE-distribution coefficients. NOTE 2In the CIE 1931 standard colorimetric system, applicable to observing fields of angular subtense between 1 and 4 (0.017 and 0.07 rad), these tristimulus values, , are so chosen that the values of are identical with the spectral luminou
15、s efficiencies V (2). (See Appendix A.) 3.5 photopic vision (as defined in term number 402 1111 of BS 4727-4:Group 02:1971) vision by the normal eye when it is adapted to levels of luminance of at least several candelas per square metre NOTEThe cone receptors of the retina are considered to be the p
16、rincipal active elements under these conditions and the spectrum appears coloured. 3.6 reflectance (as defined in term number 401 3008 of BS 4727-4:Group 01:1971) the ratio of reflected luminous flux to the incident luminous flux () NOTEWhere mixed reflection occurs, the total reflectance may be div
17、ided into two parts, specular reflectance (r) and diffuse reflectance (d). Total reflectance may be expressed by the following equation: = r+ d 4 Apparatus 4.1 General. The apparatus shall consist of a light source, a holder for the test sample, a reflectometer with a photodetector and an indicating
18、 meter (see Figure 1), and a means of eliminating the effects of extraneous light. The reflectometer in Figure 1 measures the specular component of reflectance. The reflectometer may incorporate a light-integrating sphere to facilitate measuring the reflectance of non-flat (convex) mirrors (see Figu
19、re 2). In this case the reflectometer measures the total reflectance, i.e. the sum of the specular and diffuse components. The required characteristics of the components of the apparatus are described in BS 354 and in BS 667. 4.2 Spectral characteristics of light source and reflectometer. The light
20、source shall consist of a CIE standard source A and associated optics to provide a near-collimated light beam. A voltage stabilizer is recommended to maintain a fixed lamp voltage during instrument operation. x ( )y ( )z ( ) x ( )y ( )z ( )y ( ) Licensed Copy: London South Bank University, London So
21、uth Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 170:1979 2 BSI 03-2000 The reflectometer shall have a photodetector with a spectral response proportional to the photopic luminosity function of the CIE (1931) standard colorimetric observer (See Appendix A.) A
22、ny other combination of illuminant-filter-receptor giving the overall equivalent of CIE standard illuminant A and photopic vision may be used. When an integrating sphere is used in the reflectometer, the interior surface of the sphere shall be coated with a matt (diffusive) spectrally non-selective
23、white coating. 4.3 Geometric conditions. The angle of the incident beam (i) should preferably be 0.44 0.09 rad (25 5) from the perpendicular to the test surface and shall not exceed the upper limit of the tolerance (i.e. 0.53 rad or 30). The axis of the receptor shall make an angle (r) with this per
24、pendicular equal to that of the incident beam (see Figure 1). The incident beam upon arrival at the test surface shall have a diameter of not less than 19 mm (0.75 in). The reflected beam shall be narrower than the sensitive area of the photodetector, shall cover not less than 50 % of such area, and
25、 as nearly as possible shall cover the same area segment as used during instrument calibration. NOTEIf the beam width is the same as the sensitive area, problems with vignetting may occur. When an integrating sphere is used in the reflectometer, the sphere shall have a minimum diameter of 127 mm (5
26、in). The sample and incident beam apertures in the sphere wall shall be of such a size as to admit the entire incident and reflected light beams. The photodetector shall be located so as not to receive direct light from either the incident or the reflected beams, and should be screened from any scat
27、tered light which might pass directly from the sample (see Figure 2). 4.4 Electrical characteristics of the photodetector-indicator unit. The photodetector output as read on the indicating meter shall be a linear function of the light intensity on the photo-sensitive area. Means (electrical and/or o
28、ptical) shall be provided to facilitate zeroing and calibration adjustments. Such means shall not affect the linearity or the spectral characteristics of the instrument. The accuracy of the receptor-indicator unit shall be within 2 % of full scale, or 10 % of the magnitude of the reading, whichever
29、is the smaller. 4.5 Sample holder. The mechanism shall be capable of locating the test sample so that the axes of the source arm and receptor arm intersect at the principle reflecting surface. The reflecting surface may lie within or at either face of the mirror sample, depending on whether it is a
30、first-surface, second-surface, or prismatic “flip” type mirror. 5 Procedures 5.1 General. Four procedures, for use with different kinds of measuring instruments, are given below. (See 5.2 to 5.6.) 5.2 Direct calibration method. In the direct calibration method, the incident flux is used as the refer
31、ence standard. This method is applicable to those instruments which are so constructed as to permit calibration at the 100 % point by swinging the receiver to a position directly on the axis of the light source (see Figure 1). It may be desirable in some cases (such as when measuring low-reflectance
32、 surfaces) to use an intermediate calibration point (between 0 and 100 % on the scale) with this method. In these cases, a neutral density filter of known transmittance shall be inserted in the optical path, and the calibration control can then be adjusted until the meter reads the percentage transm
33、ission of the neutral density filter. This filter shall be removed before making measurements on the sample. NOTETo expand the scale when dealing with low-reflectance samples, it may be desirable to set a full-scale reading with the calibrated filter and multiply the apparent measured reflectance by
34、 the transmittance of the filter. 5.3 Indirect calibration method. The indirect calibration method is applicable to those instruments with fixed source and receiver geometry. A properly calibrated and maintained reflectance standard is required. This reference standard should preferably be a flat mi
35、rror with a reflectance value as near as possible to that of the test samples. 5.4 Flat mirror measurement. The reflectance of flat mirror samples can be measured on instruments employing either the direct or indirect calibration method. The reflectance value is read directly from the indicating met
36、er. 5.5 Non-flat (convex) mirror measurement. The measurement of the reflectance of non-flat (convex) mirrors require requires the use of instruments which incorporate an integrating sphere (see Figure 2). If the instrument indicating meter indicates nE divisions with a reference standard mirror of
37、E % reflectance, then, with a mirror of unknown reflectance, nX divisions will correspond to a reflectance of X %, given by the formula where the symbols are as given above. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Co
38、py, (c) BSI BS AU 170:1979 BSI 03-20003 5.6 Measurement of diffuse component of reflectance. The reflectometer shown in Figure 2 may also be used to measure the diffuse components of reflectance separately. In this case a gloss trap shall be used which covers the geometrical optical cross section of
39、 the regularly reflected beam from the sample, allowing for any curvature of the sample. The gloss trap may consist of a blackened cap covering an additional port hole, or a blackened cavity held behind this additional port hole. When this additional port hole exists in the reflectometer, it should
40、be covered by a whitened cap whose coating is as similar to the sphere walls and coating as possible. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 170:1979 4 BSI 03-2000 Appendix A Spectral tristimulus
41、 values for the CIE 1931 standard colorimetric observer NOTEThis table, which is extracted from IEC Publication 50(45) (1970), has been abridged. The values of= V (2) are rounded to four decimal places. 2 mm 380 390 400 410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600
42、610 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760 770 780 0.001 4 0.004 2 0.014 3 0.043 5 0.134 4 0.283 9 0.348 3 0.336 2 0.290 8 0.195 4 0.095 6 0.032 0 0.004 9 0.009 3 0.063 3 0.165 5 0.290 4 0.433 4 0.594 5 0.762 1 0.916 3 1.026 3 1.062 2 1.002 6 0.854 4 0.642 4 0.447 9 0.283 5 0.16
43、4 9 0.087 4 0.046 8 0.022 7 0.011 4 0.005 8 0.002 9 0.001 4 0.000 7 0.000 3 0.000 2 0.000 1 0.000 0 0.000 0 0.000 1 0.000 4 0.001 2 0.004 0 0.011 6 0.023 0 0.038 0 0.060 0 0.091 0 0.139 0 0.208 0 0.323 0 0.503 0 0.710 0 0.862 0 0.954 0 0.995 0 0.995 0 0.952 0 0.870 0 0.757 0 0.631 0 0.503 0 0.381 0
44、0.265 0 0.175 0 0.107 0 0.061 0 0.032 0 0.017 0 0.008 2 0.004 1 0.002 1 0.001 0 0.000 5 0.000 2a 0.000 1 0.000 1 0.000 0 0.000 0 0.006 5 0.020 1 0.067 9 0.207 4 0.645 6 1.385 6 1.747 1 1.772 1 1.669 2 1.287 6 0.813 0 0.465 2 0.272 0 0.158 2 0.078 2 0.042 2 0.020 3 0.008 7 0.003 9 0.002 1 0.001 7 0.0
45、01 1 0.000 8 0.000 3 0.000 2 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 a In 1966 this value was altered from 0.0003 to 0.0002. y ( ) x ( )y ( )z ( ) Licensed Copy: London South Bank University, London South Bank Un
46、iversity, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 170:1979 BSI 03-20005 Figure 1 Generalized reflectometer showing geometries for the two calibration methods Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Un
47、controlled Copy, (c) BSI BS AU 170:1979 6 BSI 03-2000 Figure 2 Generalized reflectometer incorporating an integrating sphere Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: London South Ban
48、k University, London South Bank University, Sat Dec 09 01:52:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 170:1979 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK vi
49、ew on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which ca
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