IEC TR 60825-10:2002

TECHNICAL IEC
REPORT
TR 60825-10
First edition
2002-02
Safety of laser products –
Part 10:
Application guidelines and
explanatory notes to IEC 60825-1
Sécurité des appareils à laser –
Partie 10:
Guide d'application et notes explicatives
concernant la CEI 60825-1
Reference number
IEC/TR 60825-10:2002(E)
Publication numbering
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TECHNICAL IEC
REPORT
TR 60825-10
First edition
2002-02
Safety of laser products –
Part 10:
Application guidelines and
explanatory notes to IEC 60825-1
Sécurité des appareils à laser –
Partie 10:
Guide d'application et notes explicatives
concernant la CEI 60825-1
 IEC 2002  Copyright - all rights reserved
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mechanical, including photocopying and microfilm, without permission in writing from the publisher.
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For price, see current catalogue

– 2 – TR 60825-10  IEC:2002(E)

CONTENTS
FOREWORD.3

INTRODUCTION.4

1 Scope.5

2 Object .5

3 Reference documents .5

4 Definitions .5

5 Why laser radiation is hazardous .5
6 Units.9
7 Maximum permissible exposures (MPEs) .9
8 The classification system .12
8.1 Laser product classification.12
8.1.1 Class 1 and 1M laser products .12
8.1.2 Class 2 and 2M laser products .13
8.1.3 Class 3R laser products .13
8.1.4 Class 3B laser products .13
8.1.5 Class 4 laser products .13
8.1.6 Product modification .13
8.2 Procedures for hazard control .13
9 Intrabeam viewing.15
9.1 General .15
9.2 Nominal ocular hazard distance (NOHD) .18
9.3 NOHD calculation – CW output .21
9.4 NOHD calculation for pulsed laser products .21
9.5 NOHD for magnifying optics.23
9.6 Specular reflections .26
9.7 Atmospheric attenuation .28
10 Extended source viewing .28
10.1 General .28
10.2 Extended sources .28
10.3 Calculation of r .33
NOHD
Annex A (normative) Flowcharts .34

TR 60825-10  IEC:2002(E) – 3 –

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
SAFETY OF LASER PRODUCTS –
Part 10: Application guidelines and explanatory notes

to IEC 60825-1
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 specifications, 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 technical report may be the subject of
patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
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".
Technical reports do not necessarily have to be reviewed until the data they provide are
considered to be no longer valid or useful by the maintenance team.
IEC 60825-10, which is a technical report, has been prepared by subcommittee 76: Optical

radiation safety and laser equipment.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
76/217/CDV 76/229/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.
This publication has been drafted in accordance with the ISO/IEC Directives.
This document, which is purely informative, is not to be regarded as an International Standard.

– 4 – TR 60825-10  IEC:2002(E)

INTRODUCTION
This technical report is an informative document providing a simplified introduction to laser

hazard concepts, classification, intrabeam viewing and extended source viewing used in

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

user’s guide.
This technical report does not replace IEC 60825-1; however, if there is any real or apparent

conflict between this technical report and the standard, the standard must prevail.

TR 60825-10  IEC:2002(E) – 5 –

SAFETY OF LASER PRODUCTS –
Part 10: Application guidelines and explanatory notes

to IEC 60825-1
1 Scope
This technical report gives information on the physics relating to the dangers posed by laser
products. It complements, but does not replace, the information in IEC 60825-1 by explaining
the underlying principles. The application of this technical report is limited to laser products
with finite accessible emissions of laser radiation.
2 Object
This technical report provides a user of IEC 60825-1 with background information for that
standard (specifically the laser hazard, classification system, intrabeam viewing and extended
source viewing), giving the user an insight into the physics behind that standard, so that the
user may correctly interpret its requirements.
3 Reference documents
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 – Equipment classification, requirements and
user’s guide
Amendment 1 (1997)
Amendment 2 (2001)
4 Definitions
For the purpose of this technical report, the definitions in IEC 60825-1 apply.
5 Why laser radiation is hazardous
Electromagnetic radiation is not normally considered dangerous. However, the simple analysis
below shows that a 1 W laser can introduce more than five orders of magnitude greater light
into the eye (at 1 m distance) than an incandescent bulb of equal power placed at the same
distance, and more than one order of magnitude greater than that of the sun.
Laser radiation in the optical hazard region from 400 nm to 1 400 nm is focused to a small spot
on the retina. This increases the hazard in that region. The current example illustrates the
effect in the optical hazard region.
___________
There exists a consolidated edition (2001) that includes IEC 60825-1 (1993) and its Amendment 1 (1997) and
Amendment 2 (2001).
– 6 – TR 60825-10  IEC:2002(E)

Moreover, unlike the incandescent light bulb, laser light in the ocular hazard region may be
focused to a small point on the retina measuring a few microns across. By comparison, the

image of the sun on the retina would be of the order of 0,15 mm on the retina. The effect of an

exposure to laser radiation could therefore be considerably worse than indicated by the

analysis below.
Consider a light bulb producing 1 W of optical radiation (see Figure 1) typical of the interior

light of a car. Light from the globe at 1 m has irradiance (power density) given by the power of

the light globe divided by the surface area of a sphere whose radius is 1 m, as shown by the

following equation:
1,0 W
– 2 −2
= 8,0 ×10 (1)
W ⋅ m
4π(1,0 m
)
NOTE The surface area of a sphere of radius r is given by 4πr .
Compare this with radiation from a 1,0 W laser in the ocular hazard region with a 1 mm beam
diameter at 1 m from the laser, with an approximate irradiance of:
1,0 W
6 –2
= 1,3 × 10 W ⋅ m (2)
π 2
–3
()1,0 × 10 m
NOTE The area of a circle of diameter d is given by πd /4.
Throughout IEC 60825-1 it is assumed that the diameter of the pupil of the eye is 7 mm. This is
a worst case occurring when the ambient light level is low. Under these circumstances the light
from the globe entering a pupil having an area of:
π 2
–5
–3 2
= 3,8×10 (3)
m
(7× 10 )
would be
–2 –2 –5 2 –6
(8,0 × 10 W ⋅ m ) × (3,8 × 10 m ) = 3,0 × 10 W (4)

TR 60825-10  IEC:2002(E) – 7 –

1,0 m
Irradiance =
-2 -2
8,0 × 10 W·m
-6
W
3,0 × 10
...