1、BRITISH STANDARD BS3668:1963 Specification for Red and green filters used in ophthalmic dichromatic and dissociation testsBS3668:1963 This BritishStandard, having been approved by the OphthalmicStandards Committee, was published underthe authority of the GeneralCouncil on 9 October1963 BSI02-2000 Th
2、e following BSI references relate to the work on this standard: Committee reference M/48/3 Draft for comment D62/11524 ISBN 0 580 343596 Co-operating organizations The Ophthalmic Standards Committee, under whose supervision this BritishStandard was prepared, consists of representatives from the foll
3、owing Government departments and professional and industrial organizations: Admiralty Association of Dispensing Opticians* British Medical Association* Faculty of Ophthalmologists* Federation of Manufacturing Opticians* Guild of British Dispensing Opticians* Joint Committee of Ophthalmic Opticians*
4、Ministry of Education Ministry of Health* National Physical Laboratory (D.S.I.R.) The Government department and professional and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the Committee entrusted with the preparation
5、of this standard: Scottish National Committee of Ophthalmic Opticians Amendments issued since publication Amd. No. Date CommentsBS 3668:1963 BSI 02-2000 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 Section 1. Filters for use in dichromatic tests
6、 3 Weighted spectral transmission 1 4 Luminous transmission factor 1 Section 2. Filters for use in dissociation tests 5 Spectral transmission 1 6 Luminous transmission factor 1 7 Quality of viewing goggles 2BS 3668:1963 ii BSI 02-2000 Foreword This BritishStandard defines some necessary characterist
7、ics of the complementary colour filters which are used in certain tests in an examination of the eyes. Complementary filters are used in two main classes of ophthalmic tests, one of which (dichromatic test) is applicable to either eye separately; the other (dissociation test) is not thus applicable
8、because its purpose is to distinguish one eye from the other while both are in use at the same time. Filters transmitting mainly in the red and the green respectively are alone considered in this BritishStandard, but this should not be taken as either rejection or disapprobation of tests employing f
9、ilters of other colours and based on different theoretical considerations. Requirements for red and green filters for use in dichromatic tests have been specified on the following assumptions: a) that the charts or panels projected or viewed through the filters will be illuminated with lamps approxi
10、mating to C.I.E. Standard Illuminant A, b) that the zero point for the axial chromatic aberration of the eye should be taken as570m, the wavelength for which the relative luminous efficiency of the light-adapted eye is assumed to be the maximum when the relative energy values of Standard Illuminant
11、A are taken into account, and c) that, in terms of generally accepted values of the eyes axial chromatic aberration, the wavelengths at which the two filters have their maximum weighted transmission factor should be equally spaced about the zero point and separated by a total interval corresponding
12、to0.25 to0.50 dioptres. BritishStandards relating to ophthalmic subjects include the following: BS2738, Spectacle lenses. BS3062, Spectacle lens materials. BS3162, Ophthalmic trial case lenses. BS3172, Screw threads of Unified form for spectacle frames including screwing taps and gauges. BS3186, Cel
13、lulose acetate sheet for spectacle frames. BS3199, Measurement of spectacles: method and glossary. BS3352, Spectacle frames made of cellulose acetate. BS3462, Metal spectacle frames. BS3521, Glossary of terms relating to ophthalmic lenses and spectacle frames. A British Standard does not purport to
14、include 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, p
15、agesi andii, pages1 and 2, an inside back cover 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.BS 3668:1963 BSI 02-2000 1 1 Scope This BritishStandard specifies re
16、quirements for red and green filters of glass or plastics materials used in ophthalmic tests as follows: a) dichromatic tests for ametropia, and b) dissociating the eyes in various tests of binocular co-operation. 2 Definitions For the purposes of this BritishStandard the following definitions apply
17、: 2.1 radiant flux power emitted, transferred or received in the form of radiation 2.2 luminous flux that quantity characteristic of radiant flux which expresses its capacity to produce visual sensation, evaluated according to the figures of relative luminous efficiency adopted by C.I.E. for the lig
18、ht-adapted eye 2.3 filter a device, normally a sheet of tinted material of substantially uniform thickness, designed to modify the spectral distribution of energy of the light passing through it 2.4 spectral transmission factor for a specified wavelength, the ratio of the radiant flux transmitted by
19、 a filter to the incident radiant flux 2.5 weighted spectral transmission factor the spectral transmission factor multiplied by thedistribution coefficient of the C.I.E. system weighted by the relative energy values for Standard Illuminant A 1) 2.6 weighted spectral transmission curve a graph in whi
20、ch the weighted spectral transmission factor is plotted against wavelength 2.7 luminous transmission factor the ratio of the luminous flux transmitted by a filter to the incident flux, found by calculation or integration from the weighted spectral transmission curve Section 1. Filters for use in dic
21、hromatic tests 3 Weighted spectral transmission The weighted spectral transmission curves shall have the following characteristics: a) for the green filter, a peak within the waveband530 to550m, b) for the red filter, a peak within the waveband600 to620m, c) for each filter, a maximum separation of6
22、0m between the two wave lengths for which the weighted spectral transmission factor is0.5 of themaximum. 4 Luminous transmission factor The luminous transmission factors of the two filters shall not differ from each other by more than15 per cent of the higher value. Section 2. Filters for use in dis
23、sociation tests 5 Spectral transmission The following requirements apply to filters both for presenting and for viewing the test objects: a) For the green filter the spectral transmission factor shall not exceed0.02 for all wavelengths from595 to605m and0.001 for all wavelengths from605 to700m. b) F
24、or the red filter the spectral transmission factor shall not exceed0.02 for all wavelengths from595 to605m and0.001 for all wavelengths from400 to595m. 6 Luminous transmission factor The luminous transmission factor for the pair of filters of one colour taken together (one before the light source an
25、d one in the goggles) shall not differ significantly from the corresponding factor for the pair of filters of the other colour. 1) See Commission Internationale de LEclairage, Compte Rendu des Sances,1931, page19; also W. D. Wright(1958), “TheMeasurement of Colour”, Hilger & Watts Limited, London.yB
26、S 3668:1963 2 BSI 02-2000 NOTEThis condition may not be satisfied if goggles of one manufacture are used with dissociation apparatus of different manufacture. 7 Quality of viewing goggles Goggles for dissociation tests shall be so made as not to introduce significant distortion or doubling of the im
27、ages under normal conditions of use. They shall not introduce a significant prismatic error between the two eyes in any direction of gaze within the field of binocular fixation.BS 3668:1963 BSI 02-2000 British Standards The following are available on application: YEARBOOK Including subject index and
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