IEC 60825-4:1997/AMD2:2003

INTERNATIONAL IEC
STANDARD
60825-4
AMENDMENT 2
2003-07
Amendment 2
Safety of laser products –
Part 4:
Laser guards
Amendement 2
Sécurité des appareils à laser –
Partie 4:
Barrières laser
 IEC 2003 Droits de reproduction réservés  Copyright - all rights reserved
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– 2 – 60825-4 Amend. 2  IEC:2003(E)

FOREWORD
This amendment has been prepared by IEC technical committee 76: Optical radiation safety

and laser equipment.
The text of this amendment is based on the following documents:

FDIS Report on voting
76/263/FDIS 76/273/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until 2005. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.

Page 2
CONTENTS
Add the following to the existing table of contents:
Annex E (informative) Guidelines on the arrangement and installation of laser guards
Bibliography
Page 22
Add, after Annex D, the new Annex E as follows:

60825-4 Amend. 2  IEC:2003(E) – 3 –

Annex E
(informative)
Guidelines on the arrangement and installation

of laser guards
E.1 Overview
This informative annex addresses the arrangement and installation of guards to protect

personnel against laser radiation hazards around the process zone of a laser materials
processing machine. These guidelines are for use by manufacturers and/or users. The object
of the annex is to encompass guarding for a stand-alone laser-processing machine (see
ISO 11553 ) and additional (often user-installed) guarding required to safely integrate a laser-
processing machine. Guarding issues relating to associated hazards of laser processing
(which include mechanical, electrical, fume and secondary radiation hazards) are not
considered in detail in this annex.
E.2 General
E.2.1 Introduction
Laser guarding is required to isolate the laser hazard in addition to the associated hazards of
laser processing. Some of the guards may form part of a laser-processing machine, additional
guarding may be used to facilitate safe loading and unloading of workpieces, and for
servicing.
E.2.2 Arrangement of guards
Key elements in assessing the arrangement and installation of guards around the process
zone include:
a) the degree of accessibility required for workpiece handling (especially the degree of
manual manipulation);
b) the method of fixing the workpiece (e.g. use of jigs and clamps);
c) the method of removal of the workpiece and any associated parts (e.g. scrap) after
processing.
E.2.3 Location of guards
Good practice in determining the location of laser guards includes:
– the laser guard should be located at least 3 focal lengths away from the focal point of a
focussing lens;
– laser guards with lower protective exposure limits (PELs), for example viewing windows,
should not be located where the direct beam or specular reflections are expected.
E.2.4 Complete enclosure
A complete enclosure is one which meets all the requirements for a protective housing as
specified in Clause 4.2.1 of IEC 60825-1 and encompasses the embedded laser and the
entire process zone, such that there is no human access to hazardous radiation.
___________
Also published by the European Committee for Standardization as EN 12626.

– 4 – 60825-4 Amend. 2  IEC:2003(E)

E.2.5 Incomplete enclosure
An incomplete enclosure is one which does not provide a complete protective housing

encompassing the embedded laser and the entire process zone, such that human access to

hazardous radiation is possible.

If the risk of exposure is not tolerable, (to those who may be on walkways or platforms which

raise them above the guards of an open topped machine) additional control measures are

required.
E.2.6 Hierarchy of control of laser hazard areas

The following hierarchy of measures is recommended for keeping persons out of an area
where there is an intolerable risk:
a) fit a fixed guard;
b) fit a removable guard;
c) fit an electronic protection device linked to the safety interlock chain of the machine,
around the perimeter of the area (e.g. a light beam sensor) or over the area (e.g. a
pressure mat);
d) provide a physical barrier plus information, instruction, training, supervision;
e) provide a means of allowing use with the operator some distance from the process zone
plus personal protective equipment (PPE).
NOTE Measures (c) and (d) provide no protection from laser radiation emerging from the laser machine and
should therefore only be considered where the distance of the controlled boundary from openings in the machine
exceeds the "Nominal Ocular Hazard Distance” (NOHD).
E.2.7 Personal protective equipment
Personal protective equipment should only be used as a last resort where a combination of
engineering and administrative controls cannot reasonably provide a sufficient level of
protection. Where personal protective equipment is employed it should be supported with an
adequate level of administrative control governing its use. It should only be used when a risk
assessment has shown that the use of other means of risk reduction has failed to produce a
sufficient degree of safety and when it is not reasonably practicable to ensure adequate
protection by other means. When working with UVB and UVC, protective clothing may be
required.
E.2.8 Human intervention
Where machine operations require a human access, then human intervention can be included

in the risk assessment and the consideration of implications for the duration of the fault
condition. Under these conditions access should be controlled and accessible only to
authorised persons who have received adequate training in laser safety and servicing of the
laser system involved. The area should also be restricted and not open to the public and
where observers or other untrained personnel are kept from being exposed to the hazards by
barriers or administrative controls.
E.3 Risk assessment
E.3.1 Introduction
Human exposure to a laser beam of the type typically used in laser materials processing can
produce a moderate to severe injury, depending on laser wavelength, tissue exposed and the
response of the victim. The probability of such an exposure occurring becomes the key
variable element in assessing the risk of injury. The reduction of risk to tolerable levels is an
iterative process. There is no standard approach to procedure and documentation for this
process. Nevertheless, the steps involved are universal and are described in EN 1050.

60825-4 Amend. 2  IEC:2003(E) – 5 –

E.3.2 General considerations
A risk assessment should be performed to identify hazardous situations and to assess the

foreseeable exposure level on intended positions of a laser guard. This assessment should

take into account a number of factors, including the following.

E.3.2.1 Features of the laser process zone

Relevant features include the laser power and wavelength, the focal length of optics, the

degrees of freedom of the beam delivery (e.g. number of axes of movement).

E.3.2.2 Process
The nature of the process, such as cutting, drilling, welding, marking. The machine may be
dedicated or offer several processes.
NOTE Reflected laser powers differ appreciably with process and material being processed.
E.3.2.3 Process control
This factor addresses in particular the time during which laser guards may be exposed under
fault conditions, including those upon which the foreseeable exposure limit (FEL) is
determined (e.g. the process cycle time), the inspection process (e.g. per item or per time
period/ number of items), and the means and effectiveness of automatic process control
intervention in the event of a fault condition becoming evident.
E.3.2.4 Manual operations
Operator intervention considerations include the need and provision for manual control, the
means and effectiveness of process observation (including the location of viewing windows or
cameras) and the accessibility and effectiveness of intervention in the event of a fault
condition becoming evident.
E.3.2.5 Robot operations
The full range of robot movements, impact protection for the robot head and general
protection of service lines and the beam delivery to the robot, and the means of limiting robot
head movement and direction (e.g. software limits, hardware limits and physical limits), in
particular the closest approach of the exposed laser beam to laser guards.
E.3.2.6 Workpiece
The geometry, composition and surface finish of the workpiece, and how it can affect the

direction and strength of reflections during laser processing.
E.3.2.7 Clamping and fixturing
The holding and positioning of the workpiece and the related issues of reflections from
surfaces and collisions of the focussing head.
E.3.2.8 Loading and unloading
The method by which the workpiece is introduced and removed, in particular whether it is
manual or automatic, single piece or continuous, and the method (e.g. sliding, rolling or lifting
door) and control of access to the process zone.

– 6 – 60825-4 Amend. 2  IEC:2003(E)

E.3.2.9 Beam delivery
Beam delivery considerations include the optical method (mirror or fibre) and means of

inspection, positioning and movement of optical components. Considerations include the

structural integrity of the mounting of beam path components, means of maintaining the

condition of optical components (e.g. clean dry gas purge plus cooling supply), means of

maintenance of beam alignment, provision of on-line errant and non-errant beam monitoring,

and means of construction of the beam delivery enclosure.

NOTE Particular attention should be given to the use of novel (unproven) design of laser beam delivery, the

exposure of the beam delivery structure to external mechanical forces (e.g. vibration) which may give rise to optical

misalignment. Attention should also be given to tampering with optics or anomalous performance of lasers,
especially in regard t
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