IEC 60825-4:1997

INTERNATIONAL
IEC
STANDARD
60825-4
First edition
1997-11
Safety of laser products –
Part 4:
Laser guards
Sécurité des appareils à laser –
Partie 4: Barrières laser
Reference number
IEC 60825-4: 1997 (E)
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INTERNATIONAL
IEC
STANDARD
60825-4
First edition
1997-11
Safety of laser products –
Part 4:
Laser guards
Sécurité des appareils à laser –
Partie 4: Barrières laser
 IEC 1997 Droits de reproduction réservés  Copyright - all rights reserved
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For price, see current catalogue

– 2 – 60825-4  IEC:1997 (E)
CONTENTS
Page
FOREWORD . 3

INTRODUCTION . 4

Clause
1 General. 5
1.1 Scope . 5
1.2 Normative references. 5
1.3 Definitions . 5
2 Laser processing machines . 7
2.1 Design requirements . 7
2.2 Performance requirements . 8
2.3 Validation. 8
2.4 User information . 9
3 Proprietary laser guards . 9
3.1 Design requirements . 9
3.2 Performance requirements . 9
3.3 Specification requirements . 9
3.4 Test requirements. 10
3.5 Labelling requirements. 10
3.6 User information . 11
Annexes
A General guidance on the design and selection of laser guards . 12

B Assessment of foreseeable exposure limits . 14
C Elaboration of defined terms. 21

60825-4  IEC:1997 (E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

___________
SAFETY OF LASER PRODUCTS –
Part 4: Laser guards
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60825-4 has been prepared by IEC technical committee 76: Optical
radiation safety and laser equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
76/159/FDIS 76/168/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
Annexes A, B and C are for information only.
The French version of this standard will be issued separately.

– 4 – 60825-4  IEC:1997 (E)
INTRODUCTION
At low levels of irradiance or radiant exposure, the selection of material and thickness for

shielding against laser radiation is determined primarily by a need to provide sufficient optical

attenuation. However, at higher levels, an additional consideration is the ability of the laser
radiation to remove guard material – typically by melting, oxidation or ablation; processes that

could lead to laser radiation penetrating a normally opaque material.

IEC 60825-1 deals with basic issues concerning laser guards, including human access,

interlocking and labelling, and gives general guidance on the design of protective housings and

enclosures for high-power lasers.
This part of IEC 60825 deals with protection against laser radiation only. Hazards from
secondary radiation that may arise during material processing are not addressed.
Laser guards may also comply with standards for laser protective eyewear, but such
compliance is not necessarily sufficient to satisfy the requirements of this standard.
Where the term “irradiance” is used, the expression “irradiance or radiant exposure, as
appropriate” is implied.
60825-4  IEC:1997 (E) – 5 –
SAFETY OF LASER PRODUCTS –
Part 4: Laser guards
1 General
1.1 Scope
This part of IEC 60825 specifies the requirements for laser guards, permanent and temporary
(for example for service), that enclose the process zone of a laser processing machine, and
specifications for proprietary laser guards.
This standard applies to all component parts of a guard including clear (visibly transmitting)
screens and viewing windows, panels, laser curtains and walls. Requirements for beam path
components, beam stops and those other parts of a protective housing of a laser product which
do not enclose the process zone are contained in IEC 60825-1.
In addition this part of IEC 60825 indicates:
a) how to assess and specify the protective properties of a laser guard; and
b) how to select a laser guard.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 60825. At the time of publication, the editions indicated
were valid. All normative documents are subject to revision, and parties to agreements based
on this part of IEC 60825 are encouraged to investigate the possibility of applying the most
recent editions of the normative documents indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60825-1: 1993, Safety of laser products – Part 1: Equipment classification, requirements
and user’s guide
ISO/TR12100-1: 1992, Safety of machinery – Basic concepts, general principles for design –
Part 1: Basic terminology, methodology
ISO/TR12100-2: 1992, Safety of machinery – Basic concepts, general principles for design –
Part 2: Technical principles and specifications

ISO 11553: 1996, Safety of machinery – Laser processing machines – Safety requirements
1.3 Definitions
For the purpose of this part of IEC 60825, the following definitions apply in addition to the
definitions given in IEC 60825-1.
1.3.1
active guard protection time
for a given laser exposure of the front surface of an active laser guard, the minimum time,
measured from the issue of an active guard termination signal, for which the active laser guard can
safely prevent laser radiation accessible at its rear surface from exceeding the class 1 AEL.

– 6 – 60825-4  IEC:1997 (E)
1.3.2
active guard termination signal

the signal issued by an active guard in response to an excess exposure of its front surface to

laser radiation and which is intended to lead to automatic termination of the laser radiation

NOTE – The action of a safety interlock becoming open circuit is considered a "signal" in this context.

1.3.3
active laser guard
a laser guard which is part of a safety-related control system. The control system generates an

active guard termination signal in response to the effect of laser radiation on the front surface

of the laser guard
1.3.4
foreseeable exposure limit (FEL)
the maximum laser exposure on the front surf
...