BS 3062-1985 Specification for Ophthalmic lens materials.pdf

1、BRITISH STANDARD CONFIRMED JUNE 1990 BS 3062:1985 Incorporating Amendment No. 1 Specification for Ophthalmic lens materials UDC 617.7-76:681.732.066.03 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproduction or networking pe

2、rmitted without license from IHS - - -BS3062:1985 This British Standard, having been prepared under the directionof the Optical EquipmentStandards Committee,was published underthe authority of the Board ofBSI and comes into effect on 28February 1985 BSI 08-1999 First published April 1959 First revis

3、ion November 1970 Second revision February 1985 The following BSI references relate to the work on this standard: Committee reference OES/3 Draft for comment 84/65629 DC ISBN 0 580 14491 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the

4、Optical Equipment Standards Committee (OES/-) to Technical Committee OES/3 upon which the following bodies were represented: Association of Dispensing Opticians Department of Health and Social Security Federation of Manufacturing Opticians Flat Glass Manufacturers Association Institute of Physics Mi

5、nistry of Defence Amendments issued since publication Amd. No. Date of issue Comments 5467 September 1986 Indicated by a sideline in the margin Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproduction or networking permitted

6、without license from IHS - - -BS3062:1985 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Designation 1 3 Category of material 1 4 Refractive index and constringence 1 5 Other properties of ophthalmic materials 1 6 Freedom from visible defects 2 7 Flamma

7、bility 2 8 Information to be provided by the supplier 2 Appendix A Method for determination of refractive index and constringence 3 Appendix B Method for determination of yellowness index and absorptivity of white materials 3 Appendix C Method for determination of luminous transmittance of all ophth

8、almic materials and fatigue of photochromic materials 3 Appendix D Method for determination of solar infra-red transmittance 5 Appendix E Method for determination of internal quality 7 Appendix F Method for assessment of flammability 7 Appendix G Bibliography 7 Figure 1 Spectral transmittance of hea

9、t-absorbing filter 4 Table 1 Refractive property tolerances 1 Table 2 Spectral irradiance E 2for the infra-red spectral range 6 Publications referred to Inside back cover Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproducti

10、on or networking permitted without license from IHS - - -BS3062:1985 ii BSI 08-1999 Foreword This revision of this British Standard was prepared under the direction of the Optical Equipment Standards Committee and supersedes the second edition published in1970, which is withdrawn. There are three ma

11、in changes from the previous edition. First, this British Standard takes into account the international proposal to standardize the derivation of constringence. Secondly, the method for conditioning glass specimens before determination of their refractive properties has changed slightly. Thirdly, th

12、e scope has been expanded to cover a greater variety of ophthalmic materials. A British Standard does not purport to 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 con

13、fer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to8, 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

14、 the amendment table on the inside front cover. Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproduction or networking permitted without license from IHS - - -BS3062:1985 BSI 08-1999 1 1 Scope This British Standard specifies

15、requirements for three categories of white or tinted materials used for the manufacture of ophthalmic spectacle lenses. This standard does not specify requirements for contact lens materials. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Desig

16、nation The material shall be designated according to the following: a) category; b) refractive index and constringence (all materials); c) absorptivity (for white materials) or luminous transmittance (for tinted non-photochromic materials); d) heat-absorbing properties (for tinted materials); e) lum

17、inous transmittance in both the clear and dark states (for photochromic materials). 3 Category of material A material shall be described as being of one of the following three categories. 4 Refractive index and constringence The refractive index and constringence of all materials shall not differ fr

18、om the nominal values declared by the supplier see clause8 a) by more than the appropriate tolerances given inTable 1. The refractive index and constringence shall be determined by the method described inAppendix A using the conditioning method that is appropriate for the material. 5 Other propertie

19、s of ophthalmic materials 5.1 White materials 5.1.1 When white ophthalmic materials are tested by the method described inB.1, B.2 andB.3.1, the yellowness index shall be between0 and1.5. 5.1.2 When white ophthalmic materials are tested by the method described inB.1, B.2 andB.3.2 at wavelengths betwe

20、en500nm and580nm, the average absorptivity shall not be greater than1% per10mm. Table 1 Refractive property tolerances 5.2 Tinted materials When tinted ophthalmic materials are tested by the method described inC.1, C.2.1 andC.3.1, the luminous transmittance shall be within 5% of the value declared b

21、y the supplier see clause8 b)2) for values over40%. For declared values under40%, the luminous transmittance shall be within 2. NOTEFor example, for declared values (X) over40, the luminous transmittance will be within X (X 5/100). For declared values of under40%, the luminous transmittance will be

22、within X 2%. 5.3 Heat-absorbing materials If tinted materials are designated as heat-absorbing see clause8 c), the solar infra-red transmittance of the material, determined by the method described inAppendix D, shall be not greater than the luminous transmittance, when determined by the method descr

23、ibed inC.1, C.2.1 andC.3.1. 5.4 Photochromic materials 5.4.1 When the luminous transmittance of a photochromic material in its clear state is determined by the method described inC.1, C.2 andC.3.2, it shall not differ from the value declared by the supplier see clause8 d)2) by more than5.0% of that

24、value. Category Description 1. Ophthalmic glass Material formed by the fusion of inorganic oxides and of which silica is normally a substantial part. 2. Ophthalmic hard resin Material consisting principally of organic thermosetting plastics. 3. Ophthalmic thermo-plastics Material consisting principa

25、lly of organic thermoplastics. Refractive index, n d Tolerance up to and including 1.59 0.001 from 1.59 up to and including1.69 + 0.001 0.0015 greater than 1.69 0.0015 Constringence, V d Tolerance up to and including 45 0.5 greater than 45 1.0 NOTE 1For the definition of n dseeA.2 and for the defini

26、tion of V dseeA.3. NOTE 2A closer tolerance is needed for the refractive index when two pieces of material are united to form a lens component without visible indication of the interface in normal use, for example, flat top fused glass bifocal lenses. In this case a tolerance of 0.0003 is recommende

27、d. Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproduction or networking permitted without license from IHS - - -BS3062:1985 2 BSI 08-1999 5.4.2 When the luminous transmittances for the clear state and the dark state are det

28、ermined by the method described inC.1, C.2, C.3.2 and C.3.3, the determined clear state value shall be not less than1.5 times the determined dark state value. 5.4.3 When subjected to the fatigue test described inC.1, C.2.2 and C.4, the relative change in luminous transmittance shall not exceed: a) 5

29、 % for the determined value for clear state from5.4.1; b) 20 % for the determined value for dark state from5.4.2. NOTEFor example, if the dark state transmittance before the test was15%, the limits of transmittance after the test are15 3%. 6 Freedom from visible defects When examined by the method d

30、escribed inAppendix E, the material shall be free from bubbles, veins and other visible irregularities. 7 Flammability When tested by the method described in Appendix F, the material shall not ignite or glow. 8 Information to be provided by the supplier The following items shall be included in the i

31、nformation provided by the supplier of the lens material. a) For all materials: 1) nominal refractive index (n d ); 2) nominal constringence (V d ). b) For white and tinted non-photochromic materials: 1) nominal spectral transmittance graphs over the wavelength range300nm to800nm for a2mm thickness

32、or for one other stated thickness; 2) nominal luminous transmittances for CIE illuminant C (seeG.1 andG.2) for a2mm thickness or for one other stated thickness. c) For tinted materials, the designation of the material as heat-absorbing (see5.3), where this is given. d) For photochromic materials: 1)

33、 nominal spectral transmittance graphs over the wavelength range300nm to800nm for a2mm thickness or for one other stated thickness of material both in the clear state and in the dark state; 2) nominal luminous transmittances for CIE illuminant C for a2mm thickness or for one other stated thickness o

34、f material both in the clear state and in the dark state. e) For plastics materials, the method of conditioning prior to determining the refractive properties (seeA.1.2). Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproducti

35、on or networking permitted without license from IHS - - -BS3062:1985 BSI 08-1999 3 Appendix A Method for determination of refractive index and constringence A.1 Conditioning A.1.1 Glass Anneal the glass by heating for15 1min at a temperature at which its dynamic viscosity is not less than0.1TPa s an

36、d not greater than1.0TPas. Cool the glass through a temperature range of130C at a rate of605 C per hour. Then cool the glass to room temperature at any rate that avoids breakage. A.1.2 Plastics Condition the test specimens prior to measurement according to the recommendations of the supplier see cla

37、use8 e). NOTEDue to the variety of possible materials, no one treatment condition can be universally applied. The treatment should represent as closely as possible the condition in which the material will be used as a spectacle lens. A.2 Refractive indices Using a method accurate to 0.0001 or better

38、, determine the refractive index in air at20C to25 C, using in turn the following light sources: A.3 Constringence Calculate the constringence (V d ) from the following equation 1) . where n C , n dand n Fare as defined inA.2. Appendix B Method for determination of yellowness index and absorptivity

39、of white materials B.1 Specimen preparation Prepare test specimens with flat polished surfaces and10 0.1mm thickness where possible. If other thicknesses are used then compute results for a10mm thickness. NOTEAttention is drawn to the precision of measurement required, especially if thicknesses are

40、appreciably less than10mm. B.2 Apparatus B.2.1 Spectrophotometer that operates over the wavelength range of380nm to770nm and is capable of determining spectral characteristics in excess of75% to within0.5% of a measured value and resolving wavelengths to within2nm of the selected value. B.3 Procedur

41、e B.3.1 Yellowness index Determine the yellowness index (YI) from the CIE tristimulus values, calculated from spectral transmittances obtained for a10mm thick sample over the wavelength range380nm to770nm at10nm intervals, from the following equation: YI = 100 (1.28 X 1.06 Z)/Y where X, Y and Z are

42、the 1931 CIE tristimulus values for illuminant C (see BS2782:Method530A). B.3.2 Absorptivity Calculate the mean absorptivity (a) from the arithmetical mean of spectral transmittances ( ), at10nm intervals from500nm to580nm inclusive, from the following equation: a = (1 r) 2 m where r is the surface

43、reflectance n dis as defined inA.2; mis the mean transmittance Appendix C Method for determination of luminous transmittance of all ophthalmic materials and fatigue of photochromic materials C.1 Specimen preparation Polish test specimens to achieve flat surfaces with a thickness of2.0 0.1mm or one o

44、ther stated thickness see clause8 b) and d). Line Source Wavelength Refractive index symbol nm C hydrogen 656.3 n C d helium 587.6 a n d F hydrogen 486.1 n F a This reference wavelength is one of the alternatives that comply with ISO7944:1984. 1) This equation for the calculation of constringence is

45、 one of the alternatives given in ISO7944:1984. Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Not for Resale No reproduction or networking permitted without license from IHS BS3062:1985 4 BSI 08-1999 C.2 Apparatus C.2.1 Spectrophotometer that op

46、erates over the wavelength range380nm to770nm and is capable of determining spectral transmittances to within0.5% of a measured value and resolving wavelengths to within2nm of the selected value. C.2.2 Light source for the illumination of photochromic materials that reproduces at the specimen positi

47、on the spectral energy distribution of solar radiation defined as air mass m = 2(seeG.3) with an intensity of60000lx. NOTEThis can be achieved in practice with a xenon high pressure arc lamp combined with a heat absorbing filter that has the spectral transmittance shown inFigure 1. C.3 Determination

48、 of luminous transmittance C.3.1 General Determine the spectral transmittance of the specimen using the spectrophotometer (C.2.1). Calculate the luminous transmittance from measured values of spectral transmittance (for CIE illuminant C) using the method described in “Colour Science” (seeG.4). C.3.2

49、 Photochromic materials in the clear state Store the specimens in the dark at a temperature of65 5 C for at least1h. Without exposing the specimen to the light source(C.2.2), determine the clear state spectral transmittance using the spectrophotometer (C.2.1). Determine the clear-state luminous transmittance by the method described inC.3.1. C.3.3 Photochromic