EN 61341:2011

Method of measurement of centre beam intensity and beam angle(s) of reflector lamps

IEC/TR 61341:2010 describes the method of measuring and specifying the centre beam intensity and the associated beam angle(s) of reflector lamps. It applies to: - incandescent, - tungsten halogen, - gas-discharge and LED based reflector lamps for general lighting purposes. It does not apply to lamps for special purposes such as projection lamps. This second edition cancels and replaces the first edition published in 1994 and constitutes a technical revision. Due to the increasing use of reflector equipped LED lamps, the scope has been broadened and measurement conditions been included in order to take account of these lamps. Further, for easier understanding of the relation between the different axis and different intensities, two figures have been added. The luminous intensity distribution shall be reported instead of the centre beam intensity, if the latter is very low ("butterfly" distributions).

Verfahren zur Messung der Lichtstärke in Hauptausstrahlungsrichtung und des (der) Ausstrahlwinkel(s) von Reflektorlampen

Méthode de mesure de l'intensité dans l'axe du faisceau et de l'angle (ou des angles) d'ouverture des lampes à réflecteur

La CEI/TR 61341:2010 décrit la méthode de mesure et de spécification de l'intensité dans l'axe du faisceau des lampes à réflecteur et de l'angle (ou des angles) d'ouverture dudit faisceau. Il s'applique aux lampes à réflecteur pour éclairage général des types suivants: - à filament de tungstène, - tungstène-halogène, - à décharge et à LED. Il ne s'applique pas aux lampes spéciales, telles que les lampes de projection. Cette déuxième édition annule et remplace la première édition publiée en 1994 et constitue une révision technique. Suite à l'utilisation de plus en plus répandue des réflecteurs équipés de lampes à DEL, le domaine d'application a été élargi et des conditions de mesure ont été introduites pour tenir compte de ces lampes. En outre, deux figures ont été ajoutées pour une meilleure compréhension de la relation entre les différents axes et les différentes intensités. La répartition de l'intensité lumineuse doit être utilisée à la place de l'intensité dans l'axe du faisceau, si cette dernière est très faible (répartitions de type "butterfly").

Merilne metode za intenzivnost osrednjega snopa in kot(i) snopa reflektorskih sijalk (IEC/TR 61341:2010)

To tehnično poročilo opisuje merilno metodo in določa intenzivnost osrednjega snopa in z njim povezanih kotov snopa reflektorskih sijalk. Velja za reflektorske sijalke z žarnicami z žarilno nitko, z volframsko halogenskimi in obločno plinskimi žarnicami ter žarnicami, zasnovanimi na tehnologiji LED, za splošne razsvetljave. Ne velja za sijalke za posebne namene, kot so projekcijske sijalke. Ta priporočila se nanašajo samo na preskušanje zasnove sijalk.

General Information

• Status: Published
• Publication Date: 07-Jul-2011
• Withdrawal Date: 03-Jul-2014
• ICS: 29.140.20 - Incandescent lamps
• Technical Committee: CLC/TC 34 - 'Lamps and related equipment
• Drafting Committee: IEC/SC 34A - IEC_SC_34A
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 08-Jul-2011
• Completion Date: 08-Jul-2011
• Ref Project: SIST EN 61341:2011 - Method of measurement of centre beam intensity and beam angle(s) of reflector lamps (IEC/TR 61341:2010)

Overview

EN 61341:2011, titled "Method of measurement of centre beam intensity and beam angle(s) of reflector lamps," is a European Standard adopted from IEC/TR 61341:2010. It outlines standardized procedures for accurately measuring and specifying the centre beam intensity and beam angle(s) for various types of reflector lamps. This standard applies to incandescent, tungsten halogen, gas-discharge, and LED-based reflector lamps used for general lighting purposes. It does not cover lamps designed for special uses such as projection lamps.

The second edition of this standard, published in 2011, replaces the 1994 edition and incorporates technical updates, particularly reflecting the growing prevalence of LED reflector lamps. It includes expanded scope, updated measurement conditions, and additional illustrative figures to clarify measurement relationships. The standard is essential for ensuring consistent, comparable photometric data for reflector lamps, supporting manufacturers, testers, and regulatory bodies.

Key Topics

• Scope and Lamp Types

  • Applies to incandescent, tungsten halogen, gas-discharge, and LED-based reflector lamps.
  • Excludes lamps for special purposes like projection lamps.
  • Focus on lamps for general lighting only.

• Measurement Principles

  • Defines centre beam intensity as the luminous intensity measured along the optical beam axis.
  • Peak intensity is the highest luminous intensity observed anywhere in the beam pattern.
  • Beam angle is the angular width where intensity falls to 50% of the centre beam intensity.

• Beam Pattern Classification

  • Symmetrical (circular) beams: measured in two perpendicular planes.
  • Asymmetrical (oval or elliptical) beams: measured along major and minor axes.
  • Irregular beams with multiple intensity peaks require measurements in multiple planes and different methods.

• Measurement Conditions

  • Lamps must be aged under specified conditions before testing.
  • Voltage, current, and ambient temperature stabilization required to ensure accurate and reproducible results, especially for LED lamps.
  • Lamp positioning and photodetector alignment follow goniometer-based methods, enabling precise intensity distribution mapping.

• Test Setup and Procedure

  • Photometric bench or directional photometer usage mandated.
  • The distance between lamp and photodetector follows the inverse square law principle.
  • Measurements taken by moving detector or lamp to assess intensity distribution and calculate beam angles visually or via instrumentation.

• Data Reporting

  • Centre beam intensity and associated beam angle(s) are formally reported.
  • For “butterfly” type distributions where centre beam intensity is very low, the luminous intensity distribution must be reported instead to represent the beam characteristics accurately.

Applications

EN 61341:2011 provides a robust framework for:

• Lighting Design and Classification
  Manufacturers can classify reflector lamps according to beam angle groups, aiding design optimization for residential, commercial, and industrial lighting.

• Quality Control and Compliance
  Measurement methodologies support product testing and certification processes, ensuring lamps meet design specifications and comply with regulatory requirements.

• Performance Benchmarking
  The standard facilitates consistent performance comparison across reflector lamp products, benefiting buyers, specifiers, and testing laboratories.

• Integration of LED Technology
  Updated provisions address LED-based reflector lamps, reflecting their increasing market share and ensuring measurement compatibility across lighting technologies.

• Photometric Testing Labs
  Laboratories adopt the standard for accurate measurement setups, enabling reliable testing results that align with international best practices.

Related Standards

• IEC 60081 – Specifications for tungsten halogen lamps.
• IEC 60969 – Methods of measurement for HID lamps.
• CIE Technical Report No. 43 – Photometric characteristics of floodlighting luminaires - complements EN 61341 for specialized lighting applications.
• IEC 61231 – Methods of measurement of performance of LED lamps, which may include parts relevant to LED reflector lamps.

Conclusion

EN 61341:2011 is a vital technical standard that ensures consistent and precise measurement of centre beam intensity and beam angles for various reflector lamps. It provides practical guidelines tailored to different lamp technologies, helping standardize testing procedures for manufacturers, testing institutes, and lighting designers worldwide. By adhering to this standard, stakeholders can achieve improved product comparability, higher measurement accuracy, and better lighting performance evaluation, thereby advancing quality in the lighting industry.

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2011
Merilne metode za intenzivnost osrednjega snopa in kot(i) snopa reflektorskih
sijalk (IEC/TR 61341:2010)
Method of measurement of centre beam intensity and beam angle(s) of reflector lamps
(IEC/TR 61341:2010)
Verfahren zur Messung der Axial-Lichtstärke und des (der) Ausstrahlungswinkel(s) von
Reflektorlampen (IEC/TR 61341:2010)
Méthode de mesure de l'intensité dans l'axe du faisceau et de l'angle (ou des angles)
d'ouverture des lampes à réflecteur (CEI/TR 61341:2010)
Ta slovenski standard je istoveten z: EN 61341:2011
ICS:
17.180.20 Barve in merjenje svetlobe Colours and measurement of
light
29.140.01 Žarnice na splošno Lamps in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61341
NORME EUROPÉENNE
July 2011
EUROPÄISCHE NORM
ICS 29.140.20
English version
Method of measurement of centre beam intensity and beam angle(s) of
reflector lamps
(IEC/TR 61341:2010)
Méthode de mesure de l'intensité dans Verfahren zur Messung der Lichtstärke in
l'axe du faisceau et de l'angle (ou des Hauptausstrahlungsrichtung und des (der)
angles) d'ouverture des lampes à Ausstrahlwinkel(s) von Reflektorlampen
réflecteur (IEC/TR 61341:2010)
(CEI/TR 61341:2010)
This European Standard was approved by CENELEC on 2011-07-04. CENELEC 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 Central Secretariat or to any CENELEC 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 CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61341:2011 E
Foreword
The text of the International Standard IEC/TR 61341:2010, prepared by SC 34A, Lamps, of IEC TC 34,
Lamps and related equipment, was submitted to the Unique Acceptance Procedure and was approved by
CENELEC as EN 61341 on 2011-07-04 without any modification.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2012-07-04
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2014-07-04
with the EN have to be withdrawn
__________
Endorsement notice
The text of the International Standard IEC/TR 61341:2010 was approved by CENELEC as a European
Standard without any modification.
__________
IEC/TR 61341 ®
Edition 2.0 2010-02
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Method of measurement of centre beam intensity and beam angle(s) of reflector
lamps
Méthode de mesure de l’intensité dans l’axe du faisceau et de l'angle (ou des
angles) d’ouverture des lampes à réflecteur

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
K
CODE PRIX
ICS 29.140.20 ISBN 978-2-88910-508-3
– 2 – TR 61341 © IEC:2010
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Terms and definitions .6
3 Basic beam patterns.7
4 General conditions for measurement .7
5 Test arrangement .7
6 Measuring procedure.8
7 Specification of centre beam intensity and beam angle(s).9
Bibliography.10

Figure 1 – Relation between optical beam axis, geometrical-mechanical axis, peak
intensity and centre beam intensity.6
Figure 2 – Measurement of luminous intensity distribution .9
Figure 3 – Case where the centre beam intensity is smaller than 50 % of the peak
intensity.9

TR 61341 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METHOD OF MEASUREMENT OF CENTRE BEAM INTENSITY
AND BEAM ANGLE(S) OF REFLECTOR LAMPS

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 61341, which is a technical report, has been prepared by subcommittee 34A: Lamps, of
IEC Technical Committee 34: Lamps and related equipment.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
34A/1340/DTR 34A/1371/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

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