SIST EN ISO 8980-3:2022

SLOVENSKI STANDARD
01-september-2022
Nadomešča:
SIST EN ISO 8980-3:2014
Očesna optika - Nebrušena zglajena stekla očal - 3. del: Specifikacije za
prepustnost in preskusne metode (ISO 8980-3:2022)
Ophthalmic optics - Uncut finished spectacle lenses - Part 3: Transmittance
specifications and test methods (ISO 8980-3:2022)
Augenoptik - Rohkantige fertige Brillengläser - Teil 3: Transmissionsanforderungen und
Prüfverfahren (ISO 8980-3:2022)
Optique ophtalmique - Verres de lunettes finis non détourés - Partie 3: Spécifications
relatives au facteur de transmission et méthodes d'essai (ISO 8980-3:2022)
Ta slovenski standard je istoveten z: EN ISO 8980-3:2022
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 8980-3
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2022
EUROPÄISCHE NORM
ICS 11.040.70 Supersedes EN ISO 8980-3:2013
English Version
Ophthalmic optics - Uncut finished spectacle lenses - Part
3: Transmittance specifications and test methods (ISO
8980-3:2022)
Optique ophtalmique - Verres de lunettes finis non Augenoptik - Rohkantige fertige Brillengläser - Teil 3:
détourés - Partie 3: Spécifications relatives au facteur Transmissionsanforderungen und Prüfverfahren (ISO
de transmission et méthodes d'essai (ISO 8980- 8980-3:2022)
3:2022)
This European Standard was approved by CEN on 1 July 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8980-3:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 8980-3:2022) has been prepared by Technical Committee ISO/TC 172 "Optics
and photonics" in collaboration with Technical Committee CEN/TC 170 “Ophthalmic optics” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2023, and conflicting national standards shall
be withdrawn at the latest by January 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 8980-3:2013.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 8980-3:2022 has been approved by CEN as EN ISO 8980-3:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 8980-3
Fourth edition
2022-06
Ophthalmic optics — Uncut finished
spectacle lenses —
Part 3:
Transmittance specifications and test
methods
Optique ophtalmique — Verres de lunettes finis non détourés —
Partie 3: Spécifications relatives au facteur de transmission et
méthodes d'essai
Reference number
ISO 8980-3:2022(E)
ISO 8980-3:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, 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 ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 8980-3:2022(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Classification . 2
6 Requirements . 2
6.1 General . 2
6.2 General transmittance requirements . 2
6.2.1 Tint descriptions, categories, and UV transmittance requirements . 2
6.2.2 Tolerances on luminous transmittance of tinted lenses . 3
6.3 Spectral transmittance requirements of spectacle lenses intended for driving and
road use . . 4
6.3.1 General . 4
6.3.2 Spectral transmittance . 4
6.3.3 Daylight use . 4
6.3.4 Driving in twilight or at night . 4
6.3.5 Relative visual attenuation coefficient (quotient) for incandescent traffic
signal light detection . 4
6.4 Additional transmittance requirements for special types of spectacle lenses. 4
6.4.1 Photochromic spectacle lenses . 4
6.4.2 Polarizing spectacle lenses . 5
6.4.3 Gradient-tinted spectacle lenses . 6
6.5 Resistance to ultraviolet radiation . 6
6.6 Claimed UV absorption/transmittance properties . 6
6.6.1 General . 6
6.6.2 Solar UV absorption . . 6
6.6.3 Solar UV transmittance . 6
7 Test methods . 7
7.1 General . 7
7.2 Spectral transmittance . 7
7.3 Luminous transmittance and relative visual attenuation coefficient (quotient). 7
7.4 Ultraviolet transmittance . 8
7.4.1 Principle . 8
7.4.2 Apparatus . 8
7.4.3 Calculation . 8
7.5 Transmittance properties of photochromic spectacle lenses and photochromic
specimens. 8
7.5.1 Test lenses . 8
7.5.2 Apparatus . 8
7.5.3 Determination of transmittance . 11
7.6 Test methods for polarizing spectacle lenses .12
7.6.1 Mean luminous transmittance .12
7.6.2 Polarizing efficiency .12
7.6.3 Plane of transmission .12
7.7 Determination of resistance to ultraviolet radiation . 13
7.7.1 Principle .13
7.7.2 Reference apparatus . 13
7.7.3 Procedure using reference apparatus . 14
8 Identification .14
iii
ISO 8980-3:2022(E)
Annex A (normative) Spectral data for calculating relative visual attenuation quotients for
incandescent signal lights . .16
Annex B (normative) Calculation of solar UV and blue-light transmittance values .21
Annex C (normative) Cut-on filter for UV filtering .23
Annex D (informative) Spectral radiation risks .27
Annex E (informative) Transmittance equations in summation form .28
Annex F (informative) Example of the calculation of luminous transmittance, τ .32
V
Bibliography .34
iv
ISO 8980-3:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing 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, in 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/IEC 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 possibility 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 patent 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 to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 172, Optics and photonics,
Subcommittee SC 7, Ophthalmic optics and instruments, in collaboration with the European Committee
for Standardization (CEN) Technical Committee CEN/TC 170, Ophthalmic optics, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 8980-3:2013), which has been technically
revised.
The main changes are as follows:
— terms and definitions, previously in Clause 3, have been referenced to ISO 13666;
— requirements regarding claimed transmittance properties have been added in 6.6;
— references have been updated as appropriate and needed;
— descriptions of requirements throughout the document have been updated and amended for
clarification.
A list of all parts in the ISO 8980 series can be found on the ISO website.
v
INTERNATIONAL STANDARD ISO 8980-3:2022(E)
Ophthalmic optics — Uncut finished spectacle lenses —
Part 3:
Transmittance specifications and test methods
1 Scope
This document specifies requirements for the transmittance properties of uncut and unmounted
finished spectacle lenses, including attenuation of solar radiation.
This document is not applicable to
— spectacle lenses having specific transmittance or absorption characteristics prescribed for medical
reasons,
— products to which specific personal protective equipment transmittance standards apply, and
— products intended for direct observation of the sun, such as for solar-eclipse viewing.
NOTE 1 By reference to ISO 21987 and ISO 14889, this document also applies to lenses mounted in spectacles.
NOTE 2 Optical and geometric requirements are given for uncut finished spectacle lenses in ISO 8980-1
and ISO 8980-2, and for mounted lenses, in ISO 21987.
2 Normative references
The following documents are referred to in the text in such 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 11664-1, Colorimetry — Part 1: CIE standard colorimetric observers
ISO 11664-2, Colorimetry — Part 2: CIE standard illuminants
ISO 13666:2019, Ophthalmic optics — Spectacle lenses — Vocabulary
ISO 14889, Ophthalmic optics — Spectacle lenses — Fundamental requirements for uncut finished lenses
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13666 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols
The symbols for the characteristic luminous transmittances of photochromic lenses are given in Table 1.
ISO 8980-3:2022(E)
Table 1 — Symbols for the characteristic luminous transmittances of photochromic lenses
Symbols Characteristic luminous transmittances
τ Luminous transmittance in the faded state as reached at (23 ± 2) °C after specified conditioning.
v 0
τ Luminous transmittance in the darkened state as reached at (23 ± 2) °C after specified irradi-
v 1
ation simulating mean outdoor conditions.
τ Luminous transmittance in the darkened state as reached at (5 ± 2) °C after specified irradi-
v W
ation simulating outdoor conditions at low temperatures.
τ Luminous transmittance in the darkened state as reached at (35 ± 2) °C after specified irradi-
v S
ation simulating outdoor conditions at high temperatures.
τ Luminous transmittance in the darkened state as reached at (23 ± 2) °C after specified irradi-
v R
ation simulating reduced light conditions.
NOTE 1 When describing a photochromic lens, the luminous transmittance refers to the faded state before exposure to
optical radiation, and the darkened state after exposure to optical radiation.
NOTE 2 The symbol for the luminous transmittance in reduced light conditions, τ , has been changed from τ which is
v R v A
in ISO 13666. This is to avoid possible confusion with the luminous transmittance measured in CIE standard illuminant A,
which is also frequently given the symbol τ .
v A
5 Classification
Spectacle lenses are classified with respect to transmittance as follows:
a) clear lenses, with no intended colour/tint in transmission;
b) uniformly tinted lenses;
c) gradient-tinted lenses;
d) photochromic lenses;
e) polarizing lenses.
NOTE b) or c) can be combined with d) and/or e).
6 Requirements
6.1 General
The fundamental requirements for uncut finished lenses, including reference to 6.3, are in ISO 14889.
For other than photochromic lenses, the requirements shall apply at a temperature of (23 ± 5) °C, and
shall apply at the design reference point unless specified otherwise. For photochromic lenses, the
applicable temperatures are given in Table 1.
The results of all calculations of values to be assessed against the requirements of this document shall
be rounded to the same precision as the statement of requirement.
NOTE For example, luminous transmittance is stated as an integer, UV transmittance to one decimal place,
consistent with Table 1.
6.2 General transmittance requirements
6.2.1 Tint descriptions, categories, and UV transmittance requirements
Spectacle lenses shall be nominated to one of five tint descriptions or luminous transmittance categories
as specified in Table 2. Lenses shall be tested as described in Clause 7.
ISO 8980-3:2022(E)
A spectacle lens nominated by the manufacturer as having a luminous transmittance, τ , that is in
v
category 0, 1, 2 or 3 shall have a luminous transmittance at its design reference point that shall not lie
outside the limits of the stated category by more than 2 % absolute.
A spectacle lens nominated by the manufacturer as having a luminous transmittance, τ , that is in
v
category 4 shall have a luminous transmittance, τ , at its design reference point that shall not lie outside
v
the limits of that category by more than 20 % relative to the stated luminous transmittance.
For gradient-tinted lenses, the overlap in luminous transmittance allowed between categories shall be
double that for uniformly tinted lenses.
A lens nominated by the manufacturer as having a luminous transmittance, τ , that is in a particular
v
category shall comply with the ultraviolet (UV) transmittance requirements of that category, regardless
of the actual luminous transmittance. For example, a lens nominated to have a luminous transmittance
in category 2 but actually having a luminous transmittance of 45 % (category 1, or category 2 allowing
for the 2 % tolerance) shall comply with the UV transmittance requirements of a category 2 lens.
Any lens that does not meet the UV transmittance requirements in Table 2 shall include the warning
indicated in 8 g).
6.2.2 Tolerances on luminous transmittance of tinted lenses
A tint should be ordered by reference to a manufacturer's sample. Such a tint should not be visibly
different from the tint of the sample and its assessment is not restricted to its luminous transmittance,
τ , measured by spectrophotometer.
v
A lens ordered by a specific luminous transmittance, τ , shall have a measured, τ , at the design reference
v v
point within ±8 % absolute of that ordered.
The tint of the two lenses of a pair should not be visibly different.
Table 2 — Categories for luminous transmittance and the related permissible transmittance in
the ultraviolet solar spectral range
Visible spectral range Ultraviolet spectral range
380 nm to 780 nm 315 nm to 380 nm 280 nm to 315 nm
UV-A UV-B
Range of luminous Maximum value of solar Maximum value of solar
Luminous
Tint descrip-
transmittance UV-A transmittance UV-B transmittance
transmittance
tion
category
τ τ τ
v SUVA SUVB
Clear or very
0 τ > 80 % τ 0,05 τ
v v v
light tint
Light tint 1 80 % ≥ τ > 43 % τ 0,05 τ
v v v
1,0 % absolute or 0,05 τ ,
v
Medium tint 2 43 % ≥ τ > 18 % 0,5 τ
v v
whichever is greater
Dark tint 3 18 % ≥ τ > 8 % 0,5 τ 1,0 % absolute
v v
1,0 % absolute or 0,25 τ ,
v
Very dark tint 4 8 % ≥ τ > 3 % 1,0 % absolute
v
whichever is greater
NOTE For the convenience of the reader, formulae are presented in Annex F in summation form.
ISO 8980-3:2022(E)
6.3 Spectral transmittance requirements of spectacle lenses intended for driving and
road use
6.3.1 General
Spectacle lenses having a luminous transmittance, τ , less than or equal to 8 % are not intended for
v
driving and road use. Therefore, there are no requirements for such lenses in this clause.
6.3.2 Spectral transmittance
The spectral transmittance, τ(λ), at any wavelength in the range 475 nm to 650 nm shall be not less
than 0,20 τ .
v
6.3.3 Daylight use
The luminous transmittance, τ , of spectacle lenses for driving and road use during daylight shall be
v
greater than 8 % at the design reference point.
6.3.4 Driving in twilight or at night
Spectacle lenses with a luminous transmittance, τ , less than 75 % shall not be used for driving and
v
road use in twilight or at night. In the case of photochromic spectacle lenses, this requirement applies
when tested in accordance with 7.5.3.5.
6.3.5 Relative visual attenuation coefficient (quotient) for incandescent traffic signal light
detection
Spectacle lenses for driving and road use shall have a relative visual attenuation coefficient
(quotient), Q , not less than:
signal
a) 0,80 for Q ;
red
b) 0,60 for Q ;
yellow
c) 0,60 for Q ;
green
d) 0,40 for Q .
blue
The relative visual attenuation coefficients (quotients), Q , shall be calculated according
signal
to ISO 13666:2019, 3.17.8, with the spectral data as specified in Annex A. An alternative calculation can
be made in summation form according to E.6 with the spectral data as specified in Annex A.
6.4 Additional transmittance requirements for special types of spectacle lenses
6.4.1 Photochromic spectacle lenses
6.4.1.1 General
Two categories are typically used to characterize photochromic spectacle lenses, corresponding
to the faded state and to the darkened state. Additional lens states may be specified under various
temperatures (see 6.4.1.3) and moderate light levels (see 6.4.1.4). Transmittances shall be determined
according to the method in 7.5. The UV transmittance in any state shall conform to the values specified
for that category in Table 2.
ISO 8980-3:2022(E)
6.4.1.2 Photochromic response
When tested by the methods described in 7.5.3.1 to 7.5.3.3, the ratio of the luminous transmittance
of a photochromic lens (see 7.5.1) in its faded state, τ , to that in its darkened state, τ , after 15 min
v 0 v 1
irradiation, shall be at least 1,25, as given by Formula (1):
τ
v 0
≥ 12, 5 (1)
τ
v 1
6.4.1.3 Photochromic response at various temperatures
If the influence of temperature on photochromic response is stated, it shall be determined by measuring
the luminous transmittance of the lens (see 7.5.1) in the darkened state using the procedure described
in 7.5.3.6 at 5 °C (τ ), 23 °C (τ ) and 35 °C (τ ).
v W v 1 v S
The manufacturer can use additional temperatures, provided this information is made available.
6.4.1.4 Photochromic response at moderate light levels
If the photochromic response at moderate light levels is stated, it shall be determined by measuring the
luminous transmittance of the lens (see 7.5.1) in the darkened state, τ , using the procedure described
v R
in 7.5.3.4.
6.4.2 Polarizing spectacle lenses
6.4.2.1 Polarizing efficiency
When tested according to the method in 7.6, the polarizing efficiency shall be >78 % for luminous
transmittance categories 2, 3, 4 and >60 % for luminous transmittance category 1.
6.4.2.2 Orientation
When tested according to the method in 7.6, the actual plane of transmittance shall be at (90 ± 5)° from
the horizontal reference.
This reference is constituted by
— the permanent alignment reference markings for power-variation lenses and position-specific
single-vision lenses,
— the dividing line for straight-top and E-line multifocal lenses, and to the tangent to the mid-point of
the dividing line of curved-top multifocal lenses in their intended orientation,
— the marking according to 6.4.2.3 for single-vision and multifocal lenses with no other geometric
orientation properties, and
— for finished lenses, the horizontal line joining the boxed centres of the lenses when fitted to the
intended frame.
6.4.2.3 Marking
Polarizing finished single-vision and multifocal lenses with no other geometric orientation properties
shall include permanent or non-permanent marking on the horizontal meridian to identify clearly the
intended horizontal orientation.
Alternatively, if manufacturers or suppliers choose to include marking on the vertical meridian of the
finished lenses to indicate the plane of transmission, this alternative method of marking shall be clearly
identified. In this case, the same tolerance as stated in 6.4.2.2 (±5°) applies for the difference between
the marking and the actual plane of transmittance.
ISO 8980-3:2022(E)
6.4.3 Gradient-tinted spectacle lenses
The requirements for gradient-tinted spectacle lenses shall be determined at the design reference point
of the spectacle lens. It is recommended that gradient tints be ordered by reference to a manufacturer’s
sample lens, identification code, name or reference number.
6.5 Resistance to ultraviolet radiation
Following irradiation as specified in 7.7, the absolute change in the luminous transmittance (τ ' – τ )
v v
of the lenses shall be less than or equal to 5 % absolute, where τ ' is the luminous transmittance after
v
irradiation. This tolerance shall also apply to photochromic lenses in the faded state when measured
after conditioning according to 7.5.3.1, following testing according to 7.7.
In addition, the following shall be met:
τ
v 0
a) for photochromic filters shall be ≥1,25;
τ
v 1
b) the UV requirements for the initial τ shall continue to be satisfied;
v
c) if originally intended for driving and road use, the requirements of 6.3 shall continue to be satisfied.
6.6 Claimed UV absorption/transmittance properties
6.6.1 General
In cases where it is claimed that a lens reaches a certain percentage of UV absorption or UV
transmittance better than the requirement in Table 2, the relevant requirement(s) below shall apply.
For reference, Annex B shall be used.
6.6.2 Solar UV absorption
In the case where it is claimed that a lens has x % solar UV absorption, the solar UV transmittance of the
lens, τ , shall not exceed (100,5 - x) %.
SUV
6.6.3 Solar UV transmittance
In the case where it is claimed that a lens has less than x % solar UV transmittance, the solar UV
transmittance of the lens, τ , shall not exceed (x + 0,5) %.
SUV
6.6.4 Solar UV-A absorption
In the case where it is claimed that a lens has x % solar UV-A absorption, the solar UV-A transmittance
of the lens, τ , shall not exceed (100,5 - x) %.
SUVA
6.6.5 Solar UV-A transmittance
In the case where it is claimed that a lens has less than x % solar UV-A transmittance, the solar UV-A
transmittance of the lens, τ , shall not exceed (x + 0,5) %.
SUVA
6.6.6 Solar UV-B absorption
In the case where it is claimed that a lens has x % solar UV-B absorption, the solar UV-B transmittance
of the lens, τ , shall not exceed (100,5 - x) %.
SUVB
ISO 8980-3:2022(E)
6.6.7 Solar UV-B transmittance
In the case where it is claimed that a lens has less than x % solar UV-B transmittance, the solar UV-B
transmittance of the lens, τ , shall not exceed (x + 0,5) %.
SUVB
7 Test methods
7.1 General
This clause specifies reference methods for transmittance properties of spectacle lenses.
For purposes of quality control, etc., alternative test methods can be used provided they have been
shown to be equivalent and include uncertainties of measurement no greater than those required of the
reference method.
7.2 Spectral transmittance
The uncertainties of the test methods determining transmittance values shall be not greater than:
— 2 % absolute, for transmittance >20 %;
— 1 % absolute, for luminous transmittance ≤20 %;
— 10 % relative, for UV transmittance of lenses with luminous transmittance ≤20 %.
These measurement uncertainties shall be based on a confidence level of 95 %.
NOTE Guidelines for evaluating uncertainty can be found in ISO/IEC Guide 98-3. Advice on the specific
issues in evaluating uncertainty of measurement in lenses can be found in ISO 18526-2:2020, Annex B. The user
can refer to operating manuals and other information provided by manufacturers of specific instruments for
additional information.
7.3 Luminous transmittance and relative visual attenuation coefficient (quotient)
7.3.1 The spectral distribution of standard illuminant D65 as specified in ISO 11664-2 and
the luminous efficiency of the average human eye for photopic vision (2° observer) as specified
in ISO 11664-1 shall be used to determine the luminous transmittance, τ . When calculating the
v
luminous transmittance, τ , from the spectral transmittance τ(λ), the step width (wavelength interval)
v
shall not exceed 10 nm.
7.3.2 When calculating the relative visual attenuation coefficient (quotient), Q , for incandescent
signal
signal lights from the spectral transmittance τ(λ), the step width shall not exceed 5 nm. The relevant
formula, from ISO 13666, is as given by Formula (2):
τ
signal
Q = (2)
signal
τ
v
where
τ is given in E.5;
v
τ is given in E.6;.
signal
NOTE Calculations are currently based on the measured values of E (λ) for traffic signal lights using
signal
incandescent quartz-halogen lamps given in Table A.1. Calculations using values for LED signals will give
different results than those using the values for quartz-halogen lamps.
ISO 8980-3:2022(E)
7.4 Ultraviolet transmittance
7.4.1 Principle
The ultraviolet transmittance in the spectral range from 280 nm to 380 nm of the finished spectacle
lens shall be determined using a spectrophotometer.
7.4.2 Apparatus
The spectrophotometer shall
a) operate over the wavelength range from 280 nm to 380 nm,
b) have a spectral bandwidth (full width at half maximum, FWHM) not exceeding 5 nm, and
c) be capable of measuring spectral data at wavelength intervals of 5 nm or less.
7.4.3 Calculation
In the calculation of solar UV-B transmittance, τ , solar UV-A transmittance, τ , and total
SUVB SUVA
solar UV transmittance, τ , the wavelength interval shall be no greater than 5 nm. The wavelength
SUV
interval should be nominally equal to the spectral bandwidth. For data recorded with varying spectral
bandwidth or for bandwidths that do not equal the wavelength interval, the effects of this mismatch
shall be accounted for in the reported values of spectral transmittance.
The relevant formulae for the solar ultraviolet transmittance values, τ , τ , and τ , are defined
SUV SUVA SUVB
in ISO 13666:2019, 3.17.4 and 3.17.5, and given, in summation form, in E.2 to E.4. The weighting data are
given in ISO 13666:2019, Table A.1 and Table B.1. Linear interpolation of these values for wavelength
intervals smaller than 5 nm is permitted.
7.5 Transmittance properties of photochromic spectacle lenses and photochromic
specimens
7.5.1 Test lenses
Lenses used for testing shall be plano power, normally with a reference thickness of (2,0 ± 0,1) mm.
If a thickness outside this range is used, the thickness shall be stated. After having undergone careful
cleaning, each lens shall be conditioned as described in 7.5.3.1.
The base curve is not specified but should be recorded.
7.5.2 Apparatus
7.5.2.1 Irradiation source, used to darken photochromic spectacle lens
The irradiation source (solar simulator) shall approximate as closely as practical the spectral power
distribution of solar radiation defined as air mass (AM) m = 2 (see Reference [7] or Reference [15]) at
an illuminance of (50 000 ± 5 000) lx, or, when the luminous transmittance for night driving shall be
measured, at the illuminance specified in 7.5.3.4.
Testing shall be done with a source (e.g. a high pressure xenon arc lamp with filters) that provides an
illuminance of (50 000 ± 5 000) lx and the irradiance values at the position of the lens given in Table 3.
The irradiation source should be monitored to correct for drifts in its output.
Where testing at (15 000 ± 1 500) lx is specified, the irradiances and tolerances in Table 3 shall be
multiplied by 0,30.
See Annex D for details of risks associated with solar radiation and solar simulators.
ISO 8980-3:2022(E)
Care should be taken to ensure that irradiation from the source does not interfere with the transmittance
measurements.
NOTE To attenuate the intensity of the irradiation source (solar simulator) for the measurement of the
transmittance properties of a photochromic lens at moderate light levels (see 6.4.1.4), a neutral density filter can
be used, suitably positioned in the irradiation beam.
Table 3 — Irradiance for testing photochromic lenses
Wavelength range Irradiance Irradiance tolerance
2 2
nm W/m W/m
300 to 340 <2,5 —
340 to 380 5,6 ±1,5
380 to 420 12 ±3,0
420 to 460 20 ±3,0
460 to 500 26 ±2,6
7.5.2.1.1 Radiation source using one lamp
Use a high-pressure xenon arc lamp, a filter or filter combination (e.g. heat absorbing filter and cut-on
filter) with a nominal spectral transmittance as specified in Figure 1.
If the lamp is not an ozone free type (OFR), it can be vented to prevent exposure of the operator to
ozone generated by the lamp.
NOTE Figure 1 is an idealized plot. Spectral irradiances according to Table 3 can be achieved, for example, by
1)
combination of a KG2 filter with a nominal thickness of 3 mm and an appropriate cut-on filter.
1)  Schott KG2 is the trade name of a product supplied by SCHOTT AG. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products
may be used if they can be shown to lead to the same results.
ISO 8980-3:2022(E)
Key
X wavelength (nm)
Y transmittance (decimal value)
Figure 1 — Spectral transmittance of the combination of the heat absorbing filter and the cut-
on filter for the irradiation of photochromic lenses
7.5.2.1.2 Radiation source using two lamps
The solar spectrum can be approximated more closely than with one lamp by using two high-pressure
xenon arc lamps with different filtering in front of them. The radiation from the two lamps is then
combined by means of a semi-transparent mirror.
The principle may be expanded by the use of more than two lamps in order to approximate better the
solar spectrum in the relevant spectral ranges.
If any lamp is not an ozone free type (OFR), it should be vented to prevent exposure of the operator to
ozone generated by the lamp.
7.5.2.2 Specimen chamber, to maintain the lens at the required temperature, 5 °C, 23 °C or 35 °C, to
within ±2 °C during exposure to the solar simulator.
NOTE A water bath can be used to achieve temperature control. Since immersion of the lens(es) in water
reduces the reflectivity of the surfaces, the transmittance values determined using water immersion will require
correction to yield the equivalent “air” values. In order to avoid modifying the photochromic performance due
to water absorption into the lens, do not immerse lenses longer than necessary. Calibration of the equipment
can be checked using a non-photochromic lens with refractive index within ±0,01 of the refractive index of the
photochromic lens.
ISO 8980-3:2022(E)
7.5.2.3 Spectrophotometer, capable of recording spectral transmittance data from 280 nm
to 780 nm within a time span that does not affect the results. Alternatively, the 280 nm to 380 nm range
may be measured immediately after removal from the irradiation source to ensure the performance
measurement is not affected by the measuring beam.
For determining transmittance properties in the darkened state, the spectrophotometer shall
a) have a spectral bandwidth not greater than 5 nm, and
b) be capable of measuring spectral data at wavelength intervals of 5 nm or less.
7.5.3 Determination of transmittance
7.5.3.1 Conditioning
Unless the manufacturer specifies a different procedure to reach the faded state in the information
supplied with the product, photochromic lenses shall be conditioned by the following procedure:
a) store lenses in the dark at (65 ± 5) °C for (2,0 ± 0,2) h, then,
b) store lenses in the dark at (23 ± 5) °C for at least 12 h.
7.5.3.2 Luminous and UV transmittance in the faded state
After conditioning and before exposing the lens to any irradiation source, determine the luminous
tran
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