IEC 60825-12:2004

INTERNATIONAL IEC
STANDARD
60825-12
First edition
2004-02
Safety of laser products –
Part 12:
Safety of free space optical communication
systems used for transmission of information

Reference number
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the

base publication incorporating amendment 1 and the base publication incorporating

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INTERNATIONAL IEC
STANDARD
60825-12
First edition
2004-02
Safety of laser products –
Part 12:
Safety of free space optical communication
systems used for transmission of information

 IEC 2004  Copyright - all rights reserved
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mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
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International Electrotechnical Commission
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For price, see current catalogue

– 2 – 60825-12  IEC:2004(E)
CONTENTS
FOREWORD.3

1 Scope.5

2 Normative references .6

3 Terms and definitions .6

4 Requirements .9

4.1 General remarks.9
4.2 Access level and classification requirements by location type.11
4.3 Classification.17
4.4 Determination of access level.19
4.5 Installation protection systems (IPS) .19
4.6 Specular reflections.19
4.7 Organisational requirements.19
Annex A (informative) Examples of applications and calculations.23
Annex B (informative) Methods of hazard/safety analysis.30
Annex C (informative) Guidance for installing, servicing and operating organisations.31
Bibliography.33
Figure 1 – Commercial structures .11
Figure 2 – Residential areas .11
Figure 3 – Examples of external location types .12
Figure 4 – Class 1M or 2M transmitter near edge of unrestricted rooftop.13
Figure 5 – Class 1M transmitter in unrestricted location .14
Figure 6 – Class 3R transmitter in restricted location .16
Table 1 – Restrictions for product classes and access levels .10
Table 2 – Requirements for warning signs .22

60825-12  IEC:2004(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
SAFETY OF LASER PRODUCTS –
Part 12: Safety of free space optical communication systems

used for transmission of information

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60825-12 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
76/281/FDIS 76/285/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 60825-12  IEC:2004(E)
IEC consists of the following parts, under the general title: Safety of laser products:

Part 1: Part 1: Equipment classification, requirements and user's guide

Part 2: Safety of optical fibre communication systems

Part 3: Guidance for laser displays and shows

Part 4: Laser guards
Part 5: Manufacturer's checklist for IEC 60825-1

Part 6: Safety of products with optical sources, exclusively used for visible information

transmission to the human eye
Part 7: Safety of products emitting infrared optical radiation, exclusively used for wireless
'free air' data transmission and surveillance
Part 8: Guidelines for the safe use of medical laser equipment
Part 9: Compilation of maximum permissible exposure to incoherent optical radiation
Part 10: Application guidelines and explanatory notes to IEC 60825-1
Part 12: Safety of free space optical communication systems used for transmission of
information
The committee has decided that the contents of this publication will remain unchanged until
2008. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
60825-12  IEC:2004(E) – 5 –
SAFETY OF LASER PRODUCTS –
Part 12: Safety of free space optical communication systems

used for transmission of information

1 Scope
This part of IEC 60825 provides requirements and specific guidance for the manufacture and
safe use of laser products and systems used for point-to-point or point-to-multipoint free
space optical data transmission. This standard only addresses the open beam portion of the
system. If portions of the equipment or system incorporate optical fibre that extends from the
confinements of the enclosure(s), the manufacturing and safety requirements under IEC
60825-1 apply to those portions only. This standard does not apply to systems designed for
purposes of transmitting optical power for applications such as material processing or medical
treatment. This standard also does not apply to the use of systems in explosive atmospheres.
Throughout this part of IEC 60825, light-emitting diodes (LEDs) are included whenever the
word “laser” is used.
The objective of this part of IEC 60825 is to:
• provide information to protect people from potentially hazardous optical radiation produced
by free space optical communication systems (FSOCS) by specifying engineering controls
and requirements, administrative controls and work practices according to the degree of
the hazard;
• specify requirements for manufacturing, installation, service and operating organisations in
order to establish procedures and provide written information so that proper precautions
can be adopted.
Because of the nature of FSOCS, also known as optical wireless or free-air information
transmission systems, care must be taken in their manufacture as well as their installation,
operation, maintenance and service to assure the safe deployment and use of these systems.
This standard places the responsibility for certain product safety requirements, as well as
requirements for providing appropriate information on how to use these systems safely, on the
manufacturer of the system and/or transmitters. It places the responsibility for the safe
deployment and use of these systems on the installer and/or operating organisation. It places
the responsibility for adherence to safety instructions during installation and service

operations on the installation and service organisations as appropriate, and during operation
and maintenance functions on the operating organisation. It is recognised that the user of this
standard may fall into one or more of the categories of manufacturer, installer, service
organisation and/or operating organisation as mentioned above.
Any laser product is exempt from all further requirements of this part of IEC 60825 if
• classification by the manufacturer according to IEC 60825-1 shows that the emission level
does not exceed the accessible emission limit (AEL) of Class 1 under all conditions of
operation, maintenance, service and failure, and
• it does not contain an embedded laser product.

– 6 – 60825-12  IEC:2004(E)
2 Normative references
The following referenced documents are indispensable for the application 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.

IEC 60825-1:1993, Safety of laser products – Part 1: Equipment classification, requirements

and user’s guide
Amendment 1 (1997)
Amendment 2 (2001)
IEC 60825-2, Safety of laser products – Part 2: Safety of optical fibre communication systems
3 Terms and definitions
3.1
access level
potential hazard at any accessible position associated with a free space optical
communication system (FSOCS) installation
NOTE 1 The access level is based on the level of optical radiation which could become accessible in reasonably
foreseeable circumstances, e.g. walking into an open beam path. It is closely related to the laser classification
procedure in IEC 60825-1.
NOTE 2 Practically speaking, it takes two or more seconds to fully align an optical aid with a beam, (which might
occur in an unrestricted location), and this delay is incorporated into the method for determining access level.
3.2
access level 1
level for which, under reasonably foreseeable circumstances, human access to laser radiation
in excess of the accessible emission limits (AEL) of Class 1 for the applicable wavelengths
and emission duration will not occur
3.3
access level 1M
level for which, under reasonably foreseeable circumstances, human access to laser radiation
in excess of the accessible emission limits (AEL) of Class 1M for the applicable wavelengths
and emission duration will not occur
NOTE If the applicable limit of access level 1M is larger than the limit of 3R and less than the limit of 3B, access
level 1M is allocated.
3.4
access level 2
level for which, under reasonably foreseeable circumstances, human access to laser radiation
in excess of the accessible emission limits of Class 2 for the applicable wavelengths and
emission duration will not occur
3.5
access level 2M
level for which, under reasonably foreseeable circumstances, human access to laser radiation
in excess of the accessible emission limits of Class 2M for the applicable wavelengths and
emission duration will not occur
NOTE If the applicable limit of access level 2M is larger than the limit of 3R and less than the limit of 3B, access
level 2M is allocated.
___________
1)
A consolidated edition (1.2) exists comprising IEC 60825-1 (1993) and its Amendments 1 (1997) and 2 (2001).

60825-12  IEC:2004(E) – 7 –
3.6
access level 3R
level for which, under reasonably foreseeable circumstances, human access to laser radiation

in excess of the accessible emission limits of Class 3R for the applicable wavelengths and

emission duration will not occur

NOTE If the applicable limit of access level 1M or 2M is larger than the limit of 3R and less than the limit of 3B,

access level 1M or 2M is allocated.

3.7
access level 3B
level for which, under reasonably foreseeable circumstances, human access to laser radiation
in excess of the accessible emission limits of Class 3B for the applicable wavelengths and

emission duration will not occur
3.8
access level 4
level for which, under reasonably foreseeable circumstances, it is possible that human access
to laser radiation in excess of the accessible emission limits of Class 3B for the applicable
wavelengths and emission duration could occur
3.9
automatic power reduction (APR)
feature of a transmitter of a FSOCS, provided by the system equipment manufacturer, by
which the accessible power in the nominal hazard zone (NHZ) or NHZ-Aided is reduced to a
specified value within a specified time, whenever there is an event which could result in
human exposure to optical radiation above the maximum permissible exposure (MPE), e.g. by
a person entering the NHZ or NHZ-Aided as applicable. In FSOCS, this feature may be used
by the transmitter manufacturer to determine the classification
3.10
beacon
optical source whose function is to aid in pointing or alignment of an optical system
3.11
embedded laser product
See definition 3.29 in IEC 60825-1.
3.12
end-to-end system
FSOCS that is comprised of at least one transmitter, one receiver, and any peripheral
hardware necessary for the effective transfer of data along the transmission path from one
position in space to another
3.13
free space optical communication system (FSOCS)
installed, portable, or temporarily mounted, through-the-air system typically used, intended or
promoted for voice, data or multimedia communications and/or control purposes via the use of
modulated optical radiation produced by a laser or LED. “Free space” means indoor and
outdoor optical wireless applications with both non-directed and directed transmission.
Emitting and detecting assemblies may or may not be separated
NOTE Refer to the conditions within Clause 1 (Scope) by which Class 1 FSOCS products are exempt from all
requirements of this standard.
3.14
FSOCS transmitter; transmitter
optical transmitter emitting radiation through the air and used in FSOCS

– 8 – 60825-12  IEC:2004(E)
3.15
installation organisation; installer

organisation or individual who is responsible for the installation of a FSOCS

3.16
installation protection system (IPS)

feature of an installation site, provided by the installer or operating organisation, that has two

functions: (1) it detects human entry into the accessible volume of either the NHZ for

restricted or controlled locations or the NHZ-Aided for an unrestricted location, and; (2) once

such entry is detected, causes reduction of the accessible power of the laser to a specified
level within a specified time
3.17
location
position or site occupied or available for occupancy
NOTE Other standards may use the same terms for location types (3.18 – 3.21) with somewhat different
definitions.
3.18
location of inaccessible space; inaccessible space
volume where a person cannot normally be located. All open space that is neither an
unrestricted, restricted nor controlled location, i.e. the space that has a horizontal spacing
more than 2,5 m from any unrestricted location and is both greater than 6 m above a surface
in any unrestricted location, and more than 3 m above a surface in any restricted location
NOTE Inaccessible space may be entered by, for example, aircraft.
3.19
location with controlled access; controlled location
location where an engineering or administrative control measure is present to make it
inaccessible except to authorized personnel with appropriate laser safety training
3.20
location with restricted access; restricted location
location that is normally inaccessible by the general public (including workers, visitors, and
residents in the immediate vicinity) by means of any administrative or engineering control
measure but that is accessible to authorized personnel (e.g. maintenance or service
personnel including window cleaners in exterior locations) that may not have laser safety
training
3.21
location with unrestricted access; unrestricted location
location where access to the transmission/receiver equipment and open beam is not limited

(accessible to the general public)
3.22
manufacturer
organisation or individual who makes or assembles optical devices and other components for
the construction or modification of an FSOCS
3.23
nominal hazard zone (NHZ) and NHZ-Aided
a) NHZ: the volume within which the level of the direct, reflected or scattered radiation
exceeds the applicable MPE (under measurement conditions indicated in IEC 60825-1).
Exposure levels outside the boundary of the NHZ are below the applicable MPE
b) NHZ-Aided: the volume within which, when optical aids are used, the level of the direct,
reflected or scattered radiation exceeds the applicable MPE. Exposure levels outside the
boundary of the NHZ-Aided are below the applicable MPE when optical aids are used

60825-12  IEC:2004(E) – 9 –
NOTE 1 These volumes are determined prior to activation of any IPS or APR systems unless the APR is used for

classification under the conditions of 4.3 of this standard.

NOTE 2 Examples of NHZ and NHZ-Aided are provided in A.2.

3.24
operating organisation; operator

organisation or individual who is responsible for the operation and maintenance of an FSOCS

3.25
optically-aided viewing
use of optical aids (for example binoculars or magnifiers) to view an emitting source from

within the emitted beam
NOTE 1 It is possible that telescopic optics, including binoculars, could increase the hazard to the eye by
intrabeam viewing of a collimated beam when viewed at a distance.
NOTE 2 It is possible that hand magnifiers or eye-loupes could increase the hazard to the eye from viewing a
close, but highly divergent, source.
3.26
primary beam
beam that transmits the modulated data signal
3.27
reasonably foreseeable event
event (or condition) when it is credible and its likelihood of occurrence (or existence) cannot
be disregarded
3.28
service organisation
organisation or individual who is responsible for the service of an FSOCS
3.29
special tool
tool that is not readily available at retail consumer hardware stores
NOTE Typical tools in this category are intended for use with tamper-resistant fasteners.
3.30
spillover
beam radiant energy that propagates past the receiving terminal
3.31
unaided viewing; without optical aids
viewing an emitting source from within the emitted beam without using magnifiers or other

optical aids, as with the naked eye (prescription eyeglasses and contact lenses are not
considered optical aids)
4 Requirements
4.1 General remarks
FSOCS have limitations imposed by this standard that are dependent on the location type(s)
in which they are installed. Product classification and access level restrictions by location type
are summarized in Table 1.
In each location where emission is transmitted, crosses or is received, respective exposure
conditions must be individually evaluated. Furthermore, potentially occupied locations along
the beam path, within the NHZ or NHZ-Aided, must also be evaluated for acceptable access
levels (Table 1) and appropriate controls applied. Locations traversed by partial reflections
from windows within the beam path must also be evaluated if the emission could exceed

– 10 – 60825-12  IEC:2004(E)
access level 1 or 2. At a given location, the installation and operational constraints applied

from 4.2 shall be determined by whichever is the more hazardous; the transmitted or the

received optical radiation.
Example 1: In the case of a location that receives access level 1 or 2 radiation but uses a

Class 1M transmitter in the opposite direction, these combined conditions are
acceptable for restricted locations but not for an unrestricted location unless the

transmission equipment is installed as described in 4.2.1.1 to reduce the

transmit access level to 1 or 2.

Example 2: For links with spillover beyond the receiver, but within the NHZ-Aided that is of
access level 1M or 2M, the spillover (and any accessible radiation otherwise
outside of the receiver path, e.g. in front of it) must be contained within a

restricted or controlled location, an unrestricted location compliant with 4.2.1.1,
or inaccessible space.
For Class 3B and Class 4 transmitters in controlled locations, the entire beam path that
potentially passes through other location types, including inaccessible space, must comply
with the access level restrictions of Table 1. This may be satisfied in some applications by
continually monitoring the entire NHZ to ensure rapid automatic power reduction in the event
of human interception of the beam path. Any spillover beyond the receiver, (and any
accessible radiation otherwise outside of the receiver path – e.g. in front of it), within the
NHZ, must also be contained in a controlled location or inaccessible space. Any additional
spillover within the NHZ-Aided must be contained within a restricted or controlled location, an
unrestricted location compliant with 4.2.1.1, or inaccessible space.
The following ranking of the access levels (in increasing order of hazard) shall apply in this
part of IEC 60825: 1, 2, 1M, 2M, 3R, 3B, 4.
NOTE Because of the application, this is not the same as the ranking used in IEC 60825-1.
Table 1 – Restrictions for product classes and access levels
Location type Permissible product classes Permissible access
and installation conditions levels
Class 1 or 2 – No conditions
Unrestricted Class 1M or 2M – See 4.2.1.1
1 or 2
Class 3R – See 4.2.1.2
Class 1, 2, 1M or 2M – No conditions
Restricted 1, 2, 1M or 2M
Class 3R – See 4.2.2.1
Class 1, 2, 1M, 2M, or 3R – No conditions 1, 2, 1M, 2M, or 3R
Controlled
Class 3B or 4 – See 4.2.3.1 3B or 4 – See 4.2.3.1

Inaccessible space Not applicable 1, 2, 1M, 2M or 3R
The operating organisation has the ultimate responsibility for the installation, service,
maintenance and safe use of the end-to-end system. This includes, especially
– identification of the location type at all portions of the entire transmission path, including
beam spillover outside the receiver collection area and partial reflections from
intermediate windows, where people may have access;
– ensuring that the product classification, access level requirements, and installation
conditions from Table 1 are satisfied for those location types;
– ensuring that installation, maintenance and service are performed only by organisations
with the capability of satisfying the requirements of 4.2.
Requirements for transmitter manufacturers, installers and service organisations are also
included in this standard.
60825-12  IEC:2004(E) – 11 –
4.2 Access level and classification requirements by location type

The location of the FSOCS shall determine the permissible access levels of emissions and

the classification of equipment to be used and subsequent types of controls. Table 1 shows

the acceptable product classes, and access levels for the different types of locations.

Figures 1 and 2 illustrate some of the location types described in this section for commercial
and residential areas.
2,5 m
3 m
3 m
IEC  090/04
Figure 1 – Commercial structures

3 m
IEC  091/04
Figure 2 – Residential areas
4.2.1 Requirements for unrestricted locations
Unrestricted locations are those areas that are normally accessible to the public (e.g.,
unrestricted areas of rooftops, public areas at ground level, open areas of offices and
industrial premises, etc). For windows that can be opened or unenclosed balconies, the
unrestricted region extends 1 m horizontally from a perimeter boundary as shown in Figure 3.

– 12 – 60825-12  IEC:2004(E)
The FSOCS emissions crossing or received in an unrestricted location shall be access level 1

or 2.
The open beam laser transmitters that are used in FSOCS and are installed without added

conditions in unrestricted locations shall be Class 1 or Class 2.

Restricted
3 m
Unrestricted Public
3 m
rooftop
1 m
Inaccessible
2,5 m
space
Unrestricted
1 m
2,5 m
Openable
window
2,5 m Unrestricted
3 m 1 m
Inaccessible
Porch space
Residential
or
3 m 3 m
Restricted Restricted
office space
Unrestricted
3 m 3 m
Unrestricted
unrestricted
Volume under and within dashed line is
restricted
Volume under and within gray line is
Volume outside of gray line is inaccessible space
IEC  092/04
Figure 3 – Examples of external location types
4.2.1.1 Use of Class 1M and Class 2M laser products in unrestricted locations
Installation and use of Class 1M or 2M transmitters in unrestricted locations is permitted if all
the following conditions are satisfied:
1) The transmitter shall be installed and comply with at least one of the following:
a) The use of optical aids within the NHZ-Aided is not a reasonably foreseeable event.
• Collimated beam transmitters
For collimated beam transmitters, transmitters that do not satisfy condition 1 of
Table 10 in IEC 60825-1, the installation shall not allow access to the NHZ-Aided
with binoculars or telescopes at distances greater than 2 m from the transmitter.
For example, locating Class 1M or 2M equipment near the edge of an unrestricted
roof is permissible provided that all points within the NHZ-Aided at distances
greater than 2 m from the transmitter are in a restricted location, (beyond the 1 m

60825-12  IEC:2004(E) – 13 –
extension of the unrestricted location next to the roof edge as indicated in

Figure 3). This condition is illustrated in Figure 4.

NOTE It is not considered a reasonably foreseeable event to make use of binoculars or telescopes at

distances closer than 2 m from a transmitter. However, transmitters should be placed as close to a

window or roof edge as reasonably possible.

• Diverging beam transmitters
For diverging beam transmitters, transmitters that do not satisfy condition 2 of

Table 10 in IEC 60825-1, the installation shall not allow access to the NHZ-Aided

with eye loupes or magnifiers at distances closer than 100 mm from the transmitter.

For example, locating a Class 1M or 2M wireless transmitter on a ceiling is

permissible provided that a window or other barrier prevents access to points within

the beam path closer than 100 mm from the transmitter.
NOTE Determination of what constitutes a reasonably foreseeable event is the responsibility of the
operating organisation (EN 1050 is a risk assessment standard, for example).
b) The transmitter shall provide an interlock connector that is interfaced with an IPS at
the time of installation so that the accessible energy is limited to access level 1 or 2 as
indicated in Figure 5.
2) The installation shall ensure that there is no laser energy reflected back into the
unrestricted location (from a window for example) that exceeds access level 1 or 2;
3) The transmitter and/or shielding shall require a special tool to move/remove it, and a label
that is visible to warn of the hazard before and after the transmitter or shielding is
displaced. Alternatively, the transmitter and/or shielding shall be equipped with an
interlock.
Unrestricted rooftop
< 2 m
Restricted location or
inaccessible space
Class 1M or 2M FSOCS
transmitter
1-meter extension of unrestricted
location from roof edge
IEC  093/04
Figure 4 – Class 1M or 2M transmitter near edge of unrestricted rooftop

– 14 – 60825-12  IEC:2004(E)
Ceiling
Transmitter
P
IPS
NHZ-Aided
< MPE with optical aids
(outside of NHZ-Aided)
P
=
IPS Installation protection system
monitoring profile
Floor
This is an example of an IPS that monitors the NHZ-Aided of a Class
1M transmitter. Power would be reduced to below the optically-aided
MPE level if the monitored volume has been violated.
IEC  094/04
Figure 5 – Class 1M transmitter in unrestricted location
4.2.1.2 Use of Class 3R equipment in unrestricted locations
Installation and use of a Class 3R FSOCS transmitter in an unrestricted location is permitted if
the following conditions are satisfied:
1) The transmitter shall be installed and comply with at least one of the following:
a) an eye exposure within the NHZ and the use of optical aids within the NHZ-Aided are
not reasonably foreseeable events, or
b) the transmitter shall provide an interlock connector that is interfaced with an IPS at the
time of installation so that the accessible energy is limited to access level 1 or 2 as
indicated in Figure 5.
NOTE Determination of what constitutes a reasonably foreseeable event is the responsibility of the
operating organisation (EN 1050 is a risk assessment standard, for example).
2) The installation shall ensure that there is no laser energy reflected back into the
unrestricted location (from a window for example) that exceeds access level 1 or 2.
3) The transmitter and/or shielding shall require a special tool to move/remove it, and a label
is visible to warn of the hazard before and after the transmitter or shielding is displaced.
Alternatively, the transmitter and/or shielding shall be equipped with an interlock.

4.2.2 Requirements for restricted locations
Restricted locations are those areas that are inaccessible by the general public but that are
accessible to authorized personnel that may not have laser safety training. Where optically-
aided viewing conditions are reasonably foreseeable, a suitable warning sign shall be
provided as indicated in Table 2.

60825-12  IEC:2004(E) – 15 –
Examples of interior restricted locations are: equipment cabinets and closets (cupboards) in
offices and industrial buildings and locked/dedicated rooms. Interior restricted locations could

be occupied by service/maintenance personnel or escorted visitors without FSOCS laser

safety training.
Restricted locations also exist outdoors. The restricted location on the exterior sides of a

building extends outward 2,5 m from the exterior surfaces, balconies or stairways of the

building as shown in Figure 3. Examples of exterior restricted locations are: limited access

areas of commercial or industrial rooftops, telephone poles, or areas where scaffolding might

exist. Exterior restricted space could be occupied by window cleaners or service/maintenance

personnel without FSOCS laser safety training.

Exterior locations are also considered restricted if either of the following conditions is
satisfied:
a) the location is within the range of 3 m to 6 m above a surface in an unrestricted location,
or
b) the location is within 2,5 m in horizontal spacing from any unrestricted location and, if
applicable, is greater than 3 m above the surface of any underlying unrestricted location.
Free space optical signals crossing or received in a restricted location shall not exceed
access level 1M or 2M, (i.e. below the MPE limits without optical aids).
The open beam laser transmitters that are used in an FSOCS and are installed without added
conditions in restricted locations shall be Class 1, 2, 1M or 2M.
4.2.2.1 Use of Class 3R laser products in restricted locations
Installation and use of Class 3R transmitters in restricted locations is permitted if all of the
following conditions are satisfied:
1) The transmitter shall be installed and comply with at least one of the following:
a) an eye exposure within the NHZ and the use of optical aids within the NHZ-Aided are
not reasonably foreseeable events, or
b) the transmitter shall have an interlock connector that shall be interfaced with an IPS
at the time of installation so that the access level shall be limited to 1, 2, 1M or 2M
as indicated in Figure 6.
2) The installation shall ensure that there is no laser energy reflected back into the
restricted location (from a window for example) that exceeds access level 1M or 2M.
3) The transmitter and/or shielding shall require a special tool to move/remove it, and a

label that is visible to warn of the hazard before and after the transmitter or shielding is
displaced. Alternatively, the transmitter and/or shielding shall be equipped with an
interlock.
4) Any additional spillover beyond the receiving terminal within the NHZ-Aided shall be
within the restricted location, or if in unrestricted location must comply with conditions in
4.2.1.1.
– 16 – 60825-12  IEC:2004(E)
Ceiling
Transmitter
P
IPS
NHZ
Window
Indoors Outdoors
< MPE without optical aids
(outside of NHZ)
P
IPS Installation protection system
=
monitoring profile
Floor
This is an example of an IPS that monitors the entire NHZ of the Class
3R transmitter. Power is reduced to the optically-unaided MPE level if
human access is detected within the monitored volume.
Additional care must be taken to monitor the NHZ when it passes from
indoors to outdoors.
IEC  094/04
Figure 6 – Class 3R transmitter in restricted location
4.2.3 Requirements for controlled locations
Controlled locations are those areas that are normally inaccessible except to authorized
personnel with appropriate laser safety training, (e.g., tower-mounted terminals, fenced/
secure areas of rooftops, locked rooms with strictly-controlled access, etc.).
Installation and use of Class 1, 2, 1M, 2M and 3R transmitters is permitted in controlled
locations without added conditions.
FSOCS emissions crossing into or received in controlled locations shall not exceed access
level 1M, 2M or 3R except as described in 4.2.3.1.
4.2.3.1 Use of Class 3B and Class 4 laser products in controlled locations
Generally, installation and use of FSOCS equipment in a manner that avoids access levels of
3B and 4 is preferred. However, provided the zone where access level 1M, 2M or 3R is

exceeded is confined to a controlled location, industry standard safe practices, (e.g. IEC
60825-1), are permitted to prevent human exposure to access levels of 3B and 4. Note that
access levels of 3B or 4 are not permitted outside of a controlled location.
Open beam laser transmitters of Class 3B and 4 may be installed and used in controlled
locations if all of the following conditions are satisfied:
a) An IPS is in place that detects human entry to a volume containing the entire portion of
the NHZ that extends outside of the boundaries of the controlled location and causes
reduction of the power of the laser to a specified level within a specified time (see 4.5).
NOTE Care should be taken to determine an NHZ that includes sources of error or beam mis-steer.
b) If the receiver is located within the NHZ, any spillover beyond the receiving terminal within
the NHZ shall also be contained in a controlled location.
c) Any additional spillover beyond a receiver within the NHZ-Aided shall not enter an
unrestricted location unless conditions of 4.2.1.1 are met.

60825-12  IEC:2004(E) – 17 –
d) A laser safety officer (see IEC 60825-1) from the operating organisation shall be

responsible for establishing and implementing control measures for laser hazards within

the controlled location.
4.2.4 Requirements for inaccessible space

Inaccessible space includes all space that is in neither unrestricted, restricted, nor controlled

locations. This space extends outward horizontally

a) 2,5 m from the exterior surfaces of all buildings, or 3,5 m from locations that may be
occupied (e.g. balconies, stairways or openable windows) of all buildings, or

b) from the boundaries of restricted locations,
and extends upward vertically either from 6 m above a surface in an unrestricted location, or
from 3 m above a surface in a restricted location. These conditions are indicated in Figure 3.
Access to free space optical radiation in inaccessible space shall not exceed access level 1M,
2M or 3R.
If the NHZ from an FSOCS transmitter intercepts navigable airspace, the appropriate aviation
authorities shall be notified. There may be additional regulatory requirements if visible laser
beams are used near airports.
4.3 Classification
Classification of the optical transmitter is determined by the manufacturer based on
measurement or analysis of accessible optical radiation as specified in IEC 60825-1. Both the
primary beam and any alignment or beacon beams accessible during operation must be
considered in classifying the product and determining its use in appropriate locations as
indicated in Table 1. Verification tests shall be made under the appropriate conditions, e.g. at
accessible positions, using the limiting apertures and time durations specified in IEC 60825-1.
FSOCS equipment may be designed to operate with an APR system so that the emitted power
is reduced when a human crosses into the NHZ, or NHZ-Aided, (see 4.3.1). For FSOCS
applications, it is permissible to determine classification of FSOCS transmitters and the
access level assignment based on the emission that is accessible following a 2-second delay
from the time of initial human exposure. During the 2-second period the MPE, measured using
viewing conditions without optical aids shall not be exceeded for equipment classified as
Class 1, 2, 1M or 2M. For viewing conditions without optical aids refer to Table 7 of
IEC 60825-1. An APR system is only permitted on transmitters that are classified as Class 1,
2, 1M or 2M with the APR system enabled.
NOTE Rationale for 2 s: Because of the difficulty of a person with binoculars or other optical aid to fully align
with a free space optical beam, it is not reasonably foreseeable that a person could intercept the beam’s full power

within 2 s.
4.3.1 Automatic power reduction mechanisms (APR)
An APR system is a feature that a manufacturer may supply with an FSOCS transmitter by
which the accessible power is reduced to a specific level within a specific time, whenever
there is an event that could result in human exposure to radiation above the applicable MPE,
e.g. a person intercepting the beam or even a very small portion of the beam that would
accommodate a 50 mm, 25 mm, 7 mm or 3,5 mm or other aperture, as described in Table 10
of IEC 60825-1.
The operation of an APR system affects the classification of the FSOCS transmitter and the
access level at monitored locations as described in 4.4. The APR only refers to that
mechanism that monitors the NHZ or NHZ-Aided and reduces power. It does not extend to
installation protection systems used for limiting access in a unrestricted, restricted or
controlled location.
– 18 – 60825-12  IEC:2004(E)
FSOCS transmitters which would be Class 4 without an APR system, shall not be installed in

a manner such that access level 4 could be present in an unrestricted location in the event of

an APR failure.
4.3.1.1 APR performance requirements

An APR shall accomplish the following:

a) monitor the entire NHZ or NHZ-Aided depending on the reduced access level;

b) detect human interception of the NHZ or NHZ-Aided, as appropriate, and reduce

accessible power to a specified level within the specified time, and maintain the power at

or below th
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