SIST EN ISO 8980-4:2026

• Abstract:

  This document specifies optical and non-optical requirements and the test methods for anti-reflective and hydrophobic properties of coatings on spectacle lenses.; This document does not apply to the following topics:; requirements and test methods incorporated in other ISO 8980 series standards;; the colour of the reflected light.

• Status: Published
• Public Enquiry End Date: 29-Jun-2025
• Publication Date: 20-Jul-2026
• ICS: 11.040.70 - Ophthalmic equipment
• Technical Committee: VAZ - Healthcare
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 17-Jul-2026
• Due Date: 21-Sep-2026
• Completion Date: 21-Jul-2026
• Ref Project: EN ISO 8980-4:2026 - Ophthalmic optics - Uncut finished spectacle lenses - Part 4: Specifications and test methods for the properties of anti-reflective coatings and hydrophobic coating (ISO 8980-4:2026)

• Replaces: SIST EN ISO 8980-4:2006 - Ophthalmic optics - Uncut finished spectacle lenses - Part 4: Specifications and test methods for anti-reflective coatings (ISO 8980-4:2006)
• Effective Date: 01-Sep-2026

SIST EN ISO 8980-4:2026 is the Slovenian adoption of EN ISO 8980-4:2026, published from ISO 8980-4:2026. It specifies optical and non-optical requirements, plus test methods, for anti-reflective and hydrophobic coatings on uncut finished spectacle lenses. The document is for lens manufacturers, coating suppliers, test laboratories, and others who need to verify coated spectacle lenses.

What does SIST EN ISO 8980-4:2026 specify?

SIST EN ISO 8980-4:2026 covers the properties of anti-reflective and hydrophobic coatings on spectacle lenses, and it sets both requirements and the corresponding test methods. It applies to lenses with anti-reflective coating, hydrophobic coating, or both, while excluding topics already covered in other ISO 8980 series standards and the colour of the reflected light.

The document is organized into six clauses and eight annexes. The main clauses move from scope and references to definitions, requirements, testing, and how to state compliance on the product or in product documentation.

Annex	What it covers
Annex A	Meaning of luminous reflectance ρV and mean reflectance ρM for anti-reflective coated lenses
Annex B	Normative environmental sequence for durability testing
Annex C	Normative rubbing sequence procedure
Annex D	Normative evaluation of surface quality
Annex E	Informative examples of lenses passing and failing visual evaluation
Annex F	Informative examples of environmental sequence setups
Annex G	Informative examples of a rubbing tool and components
Annex H	Informative example of a contact angle test apparatus

What are the key requirements of SIST EN ISO 8980-4:2026?

SIST EN ISO 8980-4:2026 ties coated-lens performance to both optical behavior and practical durability. The most important points are the coated-area size, reflectance limits, water repellency, and resistance to adhesion loss after environmental and rubbing exposure.

General applicability and coated area

Clause 4.1 says anti-reflective coated and hydrophobic coated lenses shall also comply with the general finished-lens requirements in ISO 8980-1, ISO 8980-3 and ISO 14889. In practice, that means a coating does not replace the base lens requirements - the lens still has to meet the wider optical and fundamental rules for finished spectacle lenses.

Clause 4.2 sets the usable diameter of the coated area for uncut finished spectacle lenses at at least the nominal lens diameter minus 4 mm. This matters because coating performance is only meaningful over the usable coated zone, not just at the very edge of the lens.

Anti-reflective coating performance

Clause 4.3 requires luminous reflectance ρV and mean reflectance ρM to be determined by the specified method, and any manufacturer-declared values may be exceeded by no more than 20% in the measured result. It also requires any anti-reflective coated lens surface, when tested by the stated method, to have luminous reflectance below 2.5%.

Clause 5.2 gives the reflectance test setup. It uses a spectrophotometer over 380 nm to 780 nm, with an incident angle not larger than 17°, wavelength steps no greater than 5 nm, and an uncertainty below 0.1%. In practice, this gives laboratories a defined way to compare coatings, and it explains why calibration specimen curvature and back-surface reflection control matter.

Clause 5.2.5 says luminous reflectance, mean reflectance, and the spectral reflectance curve shall be made available on request for a typical surface with radius of curvature of at least 80 mm. That helps buyers and quality teams ask for comparable evidence, not just marketing claims.

Hydrophobic coating performance

Clause 4.4 uses static contact angle as the measure of water repellency. For lenses where the hydrophobic property is claimed, the mean static contact angle of water on the front surface shall be at least 90°. In practical terms, this is the document’s pass/fail indicator for whether the surface behaves as hydrophobic rather than only feeling easier to wipe.

Clause 5.3 defines the contact-angle test conditions. The sample lens has to be large enough for a valid test area, the front surface radius has to be at least 80 mm, and the lens has to be cleaned, handled with clean gloves, and protected from contamination before testing. The procedure uses small water droplets, measures at least three positions, and reports the mean value for the front surface.

Durability and adhesion

Clause 4.5 requires five consecutively tested lenses to remain free of significant loss of adhesion after the durability test. Significant loss of adhesion means more than a total of 3 mm of coating delaminated from either surface, with the two surfaces assessed separately.

Clause 5.4 combines environmental cycling and rubbing sequences, using the equipment and methods in Annexes B, C and D. The test uses five lenses, checks the surface quality before and after exposure, and repeats rubbing and environmental cycling in a defined sequence. This is the part that matters most for service life, because it challenges coating adhesion under heat, light, moisture, and mechanical wear.

Test timing and compliance marking

Clause 5.1 says these are type test methods, and at least 24 h shall elapse after coating before testing begins, with lenses stored at 20 °C to 26 °C. This avoids testing a coating before it has stabilized.

Clause 6 says that if the manufacturer or supplier claims compliance, the reference to this document shall appear on the package or in product documentation. That gives procurement and inspection teams a clear traceability point.

What terms does SIST EN ISO 8980-4:2026 define?

SIST EN ISO 8980-4:2026 defines several terms that are central to judging coating performance.

• Durability - for an anti-reflective coating, this is the ability to resist deterioration of reflectance characteristics over time in intended use.
• Static contact angle - the angle between the lens surface and the tangent to a resting water droplet; a larger angle indicates stronger water repellency.
• Hydrophobic coating - a coating on the top lens surface, or surface coating layers, with water-repellent properties.
• Luminous reflectance, ρV - the reflected light ratio weighted to visible sensitivity, so it reflects how bright the surface reflection appears to the eye.
• Mean reflectance, ρM - a reflectance measure that is not weighted by V(λ), so it shows the coating’s overall spectral balance.
• Usable diameter of coated area - the part of the coated lens that counts for compliance and practical use.

Who uses SIST EN ISO 8980-4:2026?

SIST EN ISO 8980-4:2026 is used by spectacle-lens manufacturers, coating applicators, and optical test laboratories that need to specify, measure, or verify anti-reflective and hydrophobic performance. Quality managers use it to define acceptance checks, and buyers use it to state what evidence they expect when a supplier claims coating performance.

It is also relevant to conformity assessment bodies and technical staff who inspect finished lenses, because it sets the test conditions, reporting points, and durability sequence used to judge coated products.

What changed in SIST EN ISO 8980-4:2026 from the previous edition?

SIST EN ISO 8980-4:2026 replaces SIST EN ISO 8980-4:2006. The document states these main changes:

• the title was updated;
• the scope was expanded to include hydrophobic coatings;
• the scope now excludes requirements and test methods covered in other ISO 8980 series standards;
• normative references and terms linked to hydrophobic properties were added;
• hydrophobic test methods were added in Clause 5 and in Annexes C, D and E.

Which standards are used with SIST EN ISO 8980-4:2026?

SIST EN ISO 8980-4:2026 uses several companion standards in its requirements and methods:

• ISO 48-2 - gives the hardness reference for the eraser used in the rubbing sequence.
• ISO 8980-1 - supplies the general finished-lens specifications for single-vision and multifocal lenses.
• ISO 8980-2 - supplies the general finished-lens specifications for power-variation lenses.
• ISO 8980-3 - supplies transmittance specifications and test methods for finished spectacle lenses.
• ISO 13666:2019 - provides vocabulary and the equations used for luminous reflectance and mean reflectance.
• ISO 14889 - gives fundamental requirements for uncut finished lenses.

Annex B also names ASTM D4329 and ISO 9022-9 as options for the environmental sequence equipment, and Annex 5.3.2 notes ISO 3696 Grade 2 water as a possible test-water source.

What does the SIST EN ISO 8980-4:2026 document contain?

SIST EN ISO 8980-4:2026 contains formulas for calculating calibration-surface reflectance and lens reflectance, and it defines how to derive luminous reflectance and mean reflectance from spectral data. It also gives a contact-angle test procedure for hydrophobic coatings, including droplet handling, timing, and repeat measurements.

For durability, the document contains the environmental cycling sequence, the rubbing sequence, and the visual inspection method used to judge adhesion loss. The annexes add example apparatus layouts, example sequences, and pass/fail photographs, which are useful for setting up laboratory procedures and for comparing inspection practice between suppliers and customers.

SLOVENSKI STANDARD
01-september-2026
Nadomešča:
SIST EN ISO 8980-4:2006
Očesna optika - Nebrušena zglajena stekla očal - 4. del: Specifikacije in preskusne
metode za lastnosti antirefleksnih prevlek in hidrofobno prevleko (ISO 8980-
4:2026)
Ophthalmic optics - Uncut finished spectacle lenses - Part 4: Specifications and test
methods for the properties of anti-reflective coatings and hydrophobic coating (ISO 8980-
4:2026)
Augenoptik - Rohkantige fertige Brillengläser - Teil 4: Anforderungen und Prüfverfahren
für die Eigenschaften von reflexmindernde und hydrophobe Vergütungen (ISO 8980-
4:2026)
Optique ophtalmique - Verres de lunettes finis non détourés - Partie 4: Spécifications et
méthodes d'essai relatives aux propriétés des traitements antireflet et hydrophobe (ISO
8980-4:2026)
Ta slovenski standard je istoveten z: EN ISO 8980-4:2026
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 8980-4
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2026
EUROPÄISCHE NORM
ICS 11.040.70 Supersedes EN ISO 8980-4:2006
English Version
Ophthalmic optics - Uncut finished spectacle lenses - Part
4: Specifications and test methods for the properties of
anti-reflective coatings and hydrophobic coating (ISO
8980-4:2026)
Optique ophtalmique - Verres de lunettes finis non Augenoptik - Rohkantige fertige Brillengläser - Teil 4:
détourés - Partie 4: Spécifications et méthodes d'essai Anforderungen und Prüfverfahren für die
relatives aux propriétés des traitements antireflet et Eigenschaften von reflexmindernde und hydrophobe
hydrophobe (ISO 8980-4:2026) Vergütungen (ISO 8980-4:2026)
This European Standard was approved by CEN on 3 July 2026.

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, Türkiye 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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8980-4:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 8980-4:2026) 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 2027, and conflicting national standards shall
be withdrawn at the latest by January 2027.
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 8980-4:2006.
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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 8980-4:2026 has been approved by CEN as EN ISO 8980-4:2026 without any
modification.
International
Standard
ISO 8980-4
Third edition
Ophthalmic optics — Uncut finished
2026-06
spectacle lenses —
Part 4:
Specifications and test methods
for the properties of anti-reflective
coatings and hydrophobic coatings
Optique ophtalmique — Verres de lunettes finis non détourés —
Partie 4: Spécifications et méthodes d'essai relatives aux
propriétés des traitements antireflet et hydrophobes
Reference number
ISO 8980-4:2026(en) © ISO 2026

ISO 8980-4:2026(en)
© ISO 2026
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 8980-4:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 General requirements .2
4.2 Usable diameter of coated area .3
4.3 Luminous and mean reflectances . .3
4.4 Water repellency .3
4.5 Durability .3
5 Testing. 3
5.1 General .3
5.2 Anti-reflective coating .3
5.2.1 Method of determination of spectral reflectance .3
5.2.2 Determination of spectral reflectance values.4
5.2.3 Determination of luminous reflectance .4
5.2.4 Determination of mean reflectance .4
5.2.5 Information to be made available on request .4
5.3 Hydrophobic coating .5
5.3.1 Contact angle measurement apparatus .5
5.3.2 Water for testing . .5
5.3.3 Sample.5
5.3.4 Procedure .5
5.4 Determination of durability . .6
5.4.1 Equipment and consumables. .6
5.4.2 Test specimens .6
5.4.3 Test method: environmental cycling combined with rubbing sequences .6
5.4.4 Evaluation . .7
6 Reference to this document. 7
Annex A (informative) Significance of ρ and ρ in the description of anti-reflective coated
v M
lenses . 8
Annex B (normative) Environmental sequence . 9
Annex C (normative) Rubbing sequence procedure .11
Annex D (normative) Evaluation of surface quality .13
Annex E (informative) Examples of lenses passing and failing the visual evaluation .15
Annex F (informative) Examples of environmental sequence .16
Annex G (informative) Examples of a rubbing tool and components .18
Annex H (informative) Example of a contact angle test apparatus .20
Bibliography .22

iii
ISO 8980-4:2026(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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 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 third edition cancels and replaces the second edition (ISO 8980-4:2006), which has been technically
revised.
The main changes are as follows:
— the title has been updated;
— the scope has been expanded to include properties of hydrophobic coatings;
— the scope has been defined to exclude requirements and test methods found in other standards within
the ISO 8980 series;
— normative references, terms and definitions relating to hydrophobic properties have been added in
Clause 2 and 3;
— test methods for properties of hydrophobic coatings have been added in Clause 5 and informative and
normative Annexes C, D and E.
A list of all parts in the ISO 8980 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 8980-4:2026(en)
Ophthalmic optics — Uncut finished spectacle lenses —
Part 4:
Specifications and test methods for the properties of anti-
reflective coatings and hydrophobic coatings
1 Scope
This document specifies optical and non-optical requirements and the test methods for anti-reflective and
hydrophobic properties of coatings on spectacle lenses.
This document does not apply to the following topics:
— requirements and test methods incorporated in other ISO 8980 series standards;
— the colour of the reflected light.
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 48-2, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 2: Hardness between 10
IRHD and 100 IRHD
ISO 8980-1, Ophthalmic optics — Uncut finished spectacle lenses — Part 1: Specifications for single-vision and
multifocal lenses
ISO 8980-2, Ophthalmic optics — Uncut finished spectacle lenses — Part 2: Specifications for power-variation
lenses
ISO 8980-3, Ophthalmic optics — Uncut finished spectacle lenses — Part 3: Transmittance specifications and
test methods
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 following terms and definitions given in ISO 13666 and the following
apply.
ISO and IEC maintain terminology 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/

ISO 8980-4:2026(en)
3.1
durability
ability to resist deterioration of its reflectance characteristics, over time, in
intended use
Note 1 to entry: The major factors contributing to deterioration of an anti-reflective coating are rubbing, heat, UV
radiation and humidity.
Note 2 to entry: The main failure affecting the durability of anti-reflective properties is a loss of adhesion. Therefore,
requirements of this document are related to anti-reflective coating adhesion.
3.2
static contact angle
θ
angle in the vertical plane between the solid surface of the specimen and the tangent to the surface of a
droplet of liquid resting on the surface at the interface of air, liquid and the substrate under normal air
conditions
Note 1 to entry: The static contact angle is illustrated in Figure 1.
Key
1 surface of the droplet of liquid
2 surface of the lens
Figure 1 — Illustration of contact angle
3.3
hydrophobic coating
coating on the top of the lens surface or surface coating layers having water repellent properties
Note 1 to entry: A number of trade names, such as self-cleaning, hydrophobic, water repellent, waterproof are applied
to this type of coating.
Note 2 to entry: It is generally considered that a hydrophobic surface has a static water contact angle that is greater
than or equal to 90°.
Note 3 to entry: Hydrophobic coatings are frequently used to provide anti-fouling properties, i.e. ease of cleaning
4 Requirements
4.1 General requirements
Anti-reflective coated and hydrophobic coated lenses shall comply with the general requirements concerning
the finished spectacle lens specifications in ISO 8980-1, ISO 8980-3 and ISO 14889. This document applies to
lenses that are antireflective coated or hydrophobic coated, or a combination of both.
NOTE 1 For further information on the properties of anti-reflective coatings, see Annex A.

ISO 8980-4:2026(en)
NOTE 2 The reflectance characteristics of an anti-reflective coating should not significantly change due to
deterioration of the coating in intended use.
4.2 Usable diameter of coated area
The usable diameter of the coated area for uncut finished spectacle lenses shall be ≥(d -4) mm, where d is
n n
the nominal diameter of the lens, in millimetres, indicated by the manufacturer.
4.3 Luminous and mean reflectances
The luminous reflectance, ρ , and the mean reflectance, ρ , of an anti-reflective coated lens shall be
V M
determined by the method specified in 5.2.2.
If the manufacturer specifies values for luminous and mean reflectances, the measured values shall not
exceed the specified values by more than 20 %.
When determined as described in 5.2.3, the luminous reflectance, ρ , of any anti-reflective coated lens
V
surface shall be less than 2,5 %.
4.4 Water repellency
The static contact angle of water for the front surface of a lens with hydrophobic coating shall be determined
by the method specified in 5.3.
For lenses for which the hydrophobic property is claimed, the mean static contact angle of water shall be
greater than or equal to 90°.
4.5 Durability
Under the conditions described in the test method given in 5.4, five consecutively tested lenses shall be free
of significant loss of adhesion as defined in 5.4.4.
A product meets the durability requirements of this document if all five lenses tested satisfy this criterion.
5 Testing
5.1 General
This clause specifies type test methods for anti-reflective and hydrophobic coatings on spectacle lenses. At
least 24 h shall elapse after coating before any type test is carried out. Lenses shall be stored at a temperature
of 20 °C to 26 °C.
5.2 Anti-reflective coating
5.2.1 Method of determination of spectral reflectance
5.2.1.1 Apparatus
Use any dual-beam or single-beam spectrophotometer with an incident angle not larger than 17° and
with a measurement accuracy sufficient to give the value of the spectral reflectance at all wavelengths, λ,
between 380 nm and 780 nm with an uncertainty of less than 0,1 % (for example an anti-reflective coating
quoted as having 0,5 % reflectance may be measured as having 0,4 % to 0,6 % reflectance). The wavelength
increment of measurement shall not be more than 5 nm. The spectral bandwidth (full width at half maximum,
FWHM) shall not exceed 5 nm.
The calibration specimen shall have a surface curvature within 0,50 D of that of the spectacle lens to be
tested. The back surface of this specimen shall be designed such that unwanted reflections will be minimized
(e.g. both frosted and painted matt black). The calibration specimen shall be of known refractive index n(λ)

ISO 8980-4:2026(en)
(uncertainty Δn < 0,001) and have no coating (which could affect its surface reflective properties). The
surface shall be cleaned.
5.2.1.2 Spectacle lens preparation
The surface of the spectacle lens under test shall have a radius of curvature greater than 80 mm. The back
surface of the lens shall be designed such that no reflection will interfere with the measurement (e.g. both
frosted and painted matt black). The surface shall be cleaned.
5.2.1.3 Measurement
Insert the calibration specimen and calibrate the spectrophotometer to give a value of 100 %. Then insert
the spectacle lens. The spectrophotometer will give the value of the spectacle lens to calibration specimen
spectral reflectance ratio R (λ), in %. By using this technique, any error due to surface curvature will be
T
minimized.
Measure the spectacle lens to calibration specimen spectral reflectance ratio over the range 380 nm
to 780 nm. The step width shall not exceed 5 nm.
5.2.2 Determination of spectral reflectance values
The value of the calibration specimen surface spectral reflectance value R (λ) is calculated theoretically
C
from the refractive index, as given by Formula (1):
n  1

R   (1)
  
C
n  1

 
 
where
R (λ) is the calibration specimen surface spectral reflectance;
C
n(λ) is refractive index
The value of the spectacle lens surface spectral reflectance is calculated by multiplying the calibration
specimen spectral reflectance value by the spectacle lens-to-calibration specimen spectral reflectance ratio,
as given by Formul
...