SIST EN 61757-1:2001

SLOVENSKI STANDARD
SIST EN 61757-1:2001
01-februar-2001
Fibre optic sensors - Part 1: Generic specification (IEC 61757-1:1998)
Fibre optic sensors -- Part 1: Generic specification
LWL-Sensoren -- Teil 1: Fachgrundspezifikation
Capteurs à fibres optiques -- Partie 1: Spécification générique
Ta slovenski standard je istoveten z: EN 61757-1:1999
ICS:
33.180.99 'UXJDRSUHPD]DRSWLþQD Other fibre optic equipment
YODNQD
SIST EN 61757-1:2001 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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NORME
CEI
INTERNATIONALE
IEC
61757-1
INTERNATIONAL
QC 890000
STANDARD
Première édition
First edition
1998-11
Capteurs à fibres optiques –
Partie 1: Spécification générique
Fibre optic sensors –
Part 1: Generic specification
 IEC 1998 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun any form or by any means, electronic or mechanical,
procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in
copie et les microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
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CODE PRIX
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PRICE CODE U
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

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61757-1 © IEC:1998 – 3 –3
CONTENTS
Page
FOREWORD . 5
INTRODUCTION . 7
Clause
1 Scope. 9
2 Normative references. 9
3 Definitions. 13
4 Units and symbols, dimensions. 19
4.1 Units and symbols. 19
4.2 Dimensions. 19
5 Quality assessment procedures. 19
6 Test and measurement procedures . 21
6.1 General. 21
6.2 Standard conditions for testing . 21
6.3 Visual inspection. 23
6.4 Dimensions. 23
6.5 Metrological features. 23
6.6 Optical tests. 25
6.7 Electrical tests. 25
6.8 Mechanical tests. 27
6.9 Climatic and environmental tests . 27
6.10 Resistance to solvents and contaminating fluids . 29
6.11 Long-term behaviour of the fibre optic sensor . 29
7 Classification . 31
7.1 Measurand. 31
7.2 Transduction principle. 37
7.3 Spatial distribution. 39
7.4 Interface level. 39
8 Marking, labelling, packaging . 41
8.1 Marking of component. 41
8.2 Marking of sealed package. 41
9 IEC type designation . 41
10 Safety aspects. 41
10.1 Personal safety. 43
10.2 Intrinsic safety in flammable atmospheres . 43
11 Ordering information. 43
12 Drawings included in the sectional and detail specifications . 43
Annex A (informative) Examples of fibre optic sensors . 45

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61757-1 © IEC:1998 – 5 –5
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_________
FIBRE OPTIC SENSORS –
Part 1: Generic specification
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 61757-1 has been prepared by subcommittee 86C: Fibre optic
systems and active devices, of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86C/222/FDIS 86C/227/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.
Annex A is for information only.
The QC number that appears on the front cover of this publication is the specification number
in the IEC quality assessment system for electronic components (IECQ).

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61757-1 © IEC:1998 – 7 –7
INTRODUCTION
This part of IEC 61757 is a generic specification and reflects the work accomplished, especially
concerning general test methods and classification for fibre optic sensors. The purpose of this
generic specification is to promote international trade, eliminate misunderstandings or
confusion between manufacturers and buyers, and provide assistance to the purchaser in
selecting consistently high quality products for his or her particular application.
This generic specification has been designed to be used as a common working and discussion
tool by the vendor of components and subassemblies intended to be integrated in fibre optic
sensors, as well as by designers, manufacturers and users of fibre optic sensors.
Annex A gives examples of fibre optic sensors to better illustrate the classification scheme.
The examples given are illustrative only and are not limitative, nor do they constitute a
recommendation or endorsement of a particular transduction principle.

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61757-1 © IEC:1998 – 9 –9
FIBRE OPTIC SENSORS –
Part 1: Generic specification
1 Scope
This part of IEC 61757 is a generic specification covering optical fibres, components and sub-
assemblies as they pertain specifically to sensing applications, in those aspects not already
addressed by previous or concurrent standardization efforts.
A fibre optic sensor contains an optical or optically powered sensing element in which the
information is created by reaction of light to a measurand. The sensing element can be the
fibre itself or an optically powered element inserted along the optical path. In a fibre optic
sensor, one or more light parameters are directly or indirectly modified by the measurand
somewhere in the optical path, contrary to an optical data link where the information is merely
transmitted from the transmitter to the receiver.
The object of this generic specification is to define, classify and provide the framework for
specifying fibre optic sensors, and their specific components and subassemblies. Fibre optic
sensors are devices for extracting information from the environment using fibre optic
technology.
2 Normative references
The following normative documents contain provisions, which, through reference in this text,
constitute provisions of this part of IEC 61757. 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 61757 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 60027-1 (all parts), Letter symbols to be used in electrical technology
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60068-1, Environmental testing – Part 1: General and guidance
IEC 60068-2-1, Environmental testing – Part 2: Tests – Tests A: Cold
IEC 60068-2-2, Environmental testing – Part 2: Tests – Tests B: Dry heat
IEC 60068-2-3, Environmental testing – Part 2: Tests – Test Ca: Damp heat, steady state
IEC 60068-2-5, Environmental testing – Part 2: Tests – Test Sa: Simulated solar radiation at
ground level
IEC 60068-2-6, Environmental testing – Part 2: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-9, Environmental testing – Part 2: Tests – Guidance for solar radiation testing

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61757-1 © IEC:1998 – 11 –11
IEC 60068-2-10, Environmental testing – Part 2: Tests – Test J and guidance: Mould growth
IEC 60068-2-11, Environmental testing – Part 2: Tests – Test Ka: Salt mist
IEC 60068-2-13, Environmental testing – Part 2: Tests – Test M: Low air pressure
IEC 60068-2-14, Environmental testing – Part 2: Tests – Test N: Change of temperature
IEC 60068-2-27, Environmental testing – Part 2: Tests – Test Ea and guidance: Shock
IEC 60068-2-29, Environmental testing – Part 2: Tests – Test Eb and guidance: Bump
IEC 60068-2-42, Environmental testing – Part 2: Tests – Test Kc: Sulphur dioxide test for
contacts and connections
IEC 60068-2-43, Environmental testing – Part 2: Tests – Test Kd: Hydrogen sulphide test for
contacts and connections
IEC 600143, Series capacitors for power systems
IEC 60255-3, Electrical relays – Part 3: Single input energizing quantity measuring relays with
dependent or independent time
IEC 60617-1 (all parts), Graphical symbols for diagrams
IEC 60695-2-2, Fire hazard testing – Part 2: Test methods – Section 2: Needle-flame test
IEC 60794-1, Optical fibre cables – Part 1: Generic specification
IEC 60825-1, Safety of laser products – Part 1: Equipment classification, requirements and
user’s guide
IEC 60874-1, Connectors for optical fibres and cables – Part 1: Generic specification
IEC 61000-4-2, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 2: Electrostatic discharge immunity test
IEC 61000-4-3, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 3: Radiated, audio-frequency, electromagnetic field immunity test
IEC 61000-4-4, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test. Basic EMC publication
IEC 61000-4-5, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 5: Surge immunity test
IEC QC 001001, Basic rules of the IEC Quality Assessment System for Electronic Components
(IECQ)
IEC QC 001002, Rules of procedure of the IEC Quality Assessment System for Electronic Components
(IECQ)

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61757-1 © IEC:1998 – 13 –13
ISO 129, Technical drawings – Dimensioning – General principles, definitions, methods of
execution and special indications
ISO 286-1, ISO system of limits and fits – Part 1: Bases of tolerances, deviations and fit
ISO 370, Toleranced dimensions – Conversion from inches into millimetres and vice versa
ISO 1101, Technical drawings – Geometrical tolerancing – Tolerances of form, orientation,
location and run-out – Generalities, definitions, symbols, indications on drawings
3 Definitions
For the purpose of this part of IEC 61757, the following definitions apply:
3.1
fibre optic sensor
sensor relying on the optical characteristics of optical fibre(s) to extract or relay environmental
information for control or measurement purposes. It includes an optical or optically powered
sensing element and may include one or more of the following (see figures 1 and 2):
– optical fibre lead;
– signal conditioning
3.2
intrinsic fibre optic sensor
fibre optic sensor whose sensing element consists of one or more optical fibre(s) in which
one or more of the propagation, reflection or light emission characteristics depend on the
measurand
3.3
extrinsic fibre optic sensor
fibre optic sensor in which the characteristics of the light are affected externally to the optical
fibre(s) by the measurand
3.4
optical or optically powered sensing element
device which accepts information in the form of a physical quantity and converts it to
information in the form of an optical quantity, according to a definite law
3.5
single-point fibre optic sensor
fibre optic sensor which provides a measurement of a measurand by means of a discrete
sensing element
3.6
multiple-point fibre optic sensor
fibre optic sensor which includes a number of multiplexed single-point sensors
3.7
extended fibre optic sensor
fibre optic sensor which provides a measurement of a measurand over an extended region by
means of a continuous sensing element

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61757-1 © IEC:1998 – 15 –15
3.8
distributed fibre optic sensor
fibre optic sensor which provides a spatially resolved measurement of a measurand over an
extended region by means of a continuous sensing element
3.9
optical source
device which supplies the optical energy required to allow the interaction between the sensing
element and the measurand. It contains, as a minimum, a luminous source and it may contain
signal conditioning. When the optical energy is generated by the phenomenon sensed, no
optical source is required
3.10
optical receiver
device which receives the light affected by the measurand and converts it into a quantity,
generally electric, according to a predetermined law. It may contain one or more photo-
detectors, signal conditioners and communication interfaces
3.11
optical fibre lead(s)
optical fibre line(s) which connect the sensing element to the optical source and to the optical
receiver.
When present, these leads must remain unaffected by the measurand
3.12
optical interface
arbitrary point at which the effect of the measurand on the sensing element is optically defined
3.13
signal interface
arbitrary point at which the effect of the measurand is present in a form directly usable for
control or measurement purposes. The optical interface(s) and the signal interface(s) can in
some cases coincide

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61757-1 © IEC:1998 – 17 –17
Signal
Optical
interface
interface
Phenomenon
Sensing Optical
element receiver
Optical fibre lead(s)
Optical or optically
Optical
powered element
source
or sensitive fibre
Signal conditioning
IEC  1 499/98
Figure 1
Signal
Optical
interface
interface
Phenomenon
Sensing
element
Optical
receiver
Optical fibre lead
Optical or optically
powered element
or sensitive fibre
signal conditioning
IEC  1 500/98
Figure 2

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61757-1 © IEC:1998 – 19 –19
4 Units and symbols, dimensions
4.1 Units and symbols
Units and graphical symbols should, whenever possible, be taken from IEC 60027 and
IEC 60617.
4.2 Dimensions
4.2.1 Details in sectional and detail specifications
Detail specifications shall provide information on maximum dimensions and tolerances on
operating parameters such as optical power, electrical signal levels or electrical power
requirements at the appropriate interface, to allow the user to design the sensor into the
equipment or system.
Dimensions and variations in drawings shall be given in accordance with the relevant ISO
publications, for example ISO 129, ISO 286-1 or ISO 1101.
Permissible variations shall be stated where necessary; basic values without tolerances, or
simple maxima or minima shall be given where sufficient.
4.2.2 Dimensional units in the detail specification
The dimensions and deviations may be given in both millimetres and inches. The original
system of units shall be stated.
Independently of the system of units, the highest accuracy required by the dimensions shall be
such that the values, the first significant digit of which is 1 or 2, shall not comprise more than
five digits. Those having the first significant digit between 3 and 9 shall not have more than
four digits.
4.2.3 Conversion of inch dimensions into millimetres and vice versa
Where mechanical and optical considerations permit, in the conversion of dimensions, values
shall be rounded to the nearest 0,01 mm or 0,0005 in. This also holds good for the conversion
between the systems of units after the exact calculation according to ISO 370 has been made.
4.2.4 Note in detail specifications concerning conversion for toleranced inch
dimensions into millimetres and vice versa
A note shall be added in each detail specification reading: "The value for dimensions in.*. are
derived from those in.*. but are not necessarily exact according to ISO 370. They are,
however, to be considered as acceptable alternatives to the original values with regard to accuracy."
5 Quality assessment procedures
The present generic specification provides the normative references, definitions, test and
measurement procedures, and classification criteria applicable to fibre optic sensors in general.
Because of the wide variety of fibre optic sensor classes, the sectional specifications shall
prescribe those tests which are applicable to each particular class of fibre optic sensors.
The sectional specifications shall also prescribe the other quality assessment procedures
applicable to each particular class of fibre optic sensor in agreement with IEC QC 001001
and IEC QC 001002. The detail specifications shall describe which of the tests prescribed
in the relevant sectional specifications are applicable to a particular style or variant of a fibre
optic sensor.

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61757-1 © IEC:1998 – 21 –21
The relevant sectional and/or detail specifications shall also specify which of the tests and
performance levels are applicable to the different elements of the fibre optic sensor, such as
the optical source, the optical receiver, the sensing element and the optical fibre leads.
Manufacturers of fibre optic sensors are responsible to insure that discrete components used
in the construction of the sensor are within the applicable specifications of the IEC Quality
Assessment System for Electronic Components (IECQ).
The omission of a particular test parameter does not absolve the manufacturer from final
responsibility for the safety of the equipment, or for the proper design of the equipment to
ensure proper functioning in the intended environment.
6 Test and measurement procedures
6.1 General
The purpose of this clause is to describe the general test and measuring methods applicable to
fibre optic sensors. This clause specifies the tests which are covered by IECQ system. These
tests are intended to address the interaction of the various components of the fibre optic
sensor as they function to translate the specified measurand to the specified output at the
optical or signal interface.
6.2 Standard conditions for testing
All discrete components (optical source, optical detector, optical fibre couplers, optical fibres,
etc.) shall be tested in accordance with applicable specifications prior to assembly of the
sensor. All components shall then be assembled and packaged in accordance with the detail
specifications and instructions for use prior to testing the sensor in accordance with this
specification.
Test and measurement equipment, including required power supplies and the source of the
measurand (tunable within the range specified in the detail specification), shall be calibrated
against standards traceable to international standards of measure. The stability of the test and
measurement equipment shall be substantially better than the specified accuracy of the sensor.
Tests shall be carried out under standard atmospheric conditions for testing as specified in
IEC 60068-1. Before measurements are made, the sensors shall be preconditioned under
standard atmospheric conditions for testing, for a time sufficient to allow each element or the
entire sensor to reach thermal stability. The above requirements shall apply, unless otherwise
specified in the sectional and/or detail specifications.
When “mounting” is specified in a test, the specimen shall be securely mounted to a rigid
support of suitable material, of dimensions and contour such that the specimen is rigidly and
completely supported as it would be in use. For free or fixed specimens, the appropriate
mounting fixtures shall be specified in the relevant sectional and/or detail specifications.
Recovery conditions for the interval following a conditioning test shall be in accordance
with the relevant IEC publications unless otherwise specified in the sectional and/or detail
specifications.

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61757-1 © IEC:1998 – 23 –23
6.3 Visual inspection
The marking of each sensor shall be in accordance with clause 8 of this generic specification,
and shall be inspected for legibility and completeness.
Visual inspection shall verify that all elements required in the detail specification are included in
the sensor and connected as described in the detail specification to ensure proper functioning.
Visual inspection shall also verify that no elements evidence any physical damage or
imperfection that could impair the functioning or lifetime of the sensor.
6.4 Dimensions
Measurements shall be as specified in clause 4 of the present specification and in the relevant
detail specification to ensure that the sensor conforms to all critical dimensions and weight as
specified therein.
6.5 Metrological features
6.5.1 General
The purpose of the tests concerning metrological features is to verify the effect of the
measurand on the sensor output at the optical or signal interface. This set of tests shall be
carried out in accordance with the climatic and environmental tests specified in 6.9.
In this generic specification a basic measurement method will be outlined. Where it is expected
that this method will require modifications to measure a particular coefficient, the modification
or separate test will be described in the relevant sectional and/or detail specifications.
6.5.2 Relation between the measurand and the corresponding characteristics of the
sensor output at the optical or the signal interface
During this test, the performance shall be measured as specified in the relevant sectional
and/or detail specification.
When this test is required, the appropriate measurand values used shall be specified in the
relevant sectional and/or detail specifications.
6.5.3 Measuring range
Under consideration.
6.5.4 Resolution
Under consideration.
6.5.5 Accuracy
Under consideration.
6.5.6 Response time
Under consideration.

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61757-1 © IEC:1998 – 25 –25
6.5.7 Ranges of the measurand which guarantee the non-deterioration or
the non-destruction of the sensing element
Under consideration.
6.6 Optical tests
6.6.1 General
In sensor configurations which permit optical testing, the following parameters may be included
in the sectional and/or detail specifications.
6.6.2 Optical power
The optical power shall be measured with a duly calibrated optical power meter.
6.6.3 Nominal wavelength and appropriate spectral characteristics
Under consideration.
6.6.4 State of polarization
Under consideration.
6.6.5 Fibre connector performance
Under consideration.
6.7 Electrical tests
6.7.1 General
The purpose of electrical tests is to verify that the fibre optic sensor has been fabricated in
accordance with safe and established design practices with regard to electrical equipment so
that the fibre optic sensor can be operated safely and reliably. The following list of parameters
may be used as a guide for determining which procedures are appropriate for those fibre optic
sensors which include electrical components or circuits.
6.7.2 Parameters and test procedures
Parameter Test procedure
Insulation resistance IEC 60060-1
Dielectric withstand at industrial frequency IEC 60060-1
Lightning impulse IEC 60060-1
Voltage stress See 6.7.3
Influence of damped oscillatory wave IEC 60255-3
Fast transients IEC 61000-4-4
Impulse sparkover voltage IEC 61000-4-5
Impulse discharge current IEC 61000-4-5
Electrostatic discharge IEC 61000-4-2
Electromagnetic field IEC 61000-4-3

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61757-1 © IEC:1998 – 27 –27
6.7.3 Voltage stress
– Influence of the level of voltage supply:
The equipment is subjected to variations of the voltage supply U between U and U as
min max
specified in the relevant detail specification.
– Slow variation of voltage supply:
The equipment installed according to the instructions given in the relevant detail
specification is powered by its rated voltage. The level of the voltage is decreased from
rated voltage to 0 V, then increased from 0 V to rated voltage, as specified in the relevant
detail specification.
– Influence of frequency:
As required by the relevant detail specification.
– Influence of a micro-cut of supply voltage:
As required by the relevant detail specification.
– Third harmonic:
As required by the relevant detail specification.
6.8 Mechanical tests
6.8.1 General
The purpose of mechanical tests is to verify that the fibre optic sensor has been fabricated in
accordance with safe and established design practices with regard to mechanical reliability.
The following list of parameters may be used as a guide for determining which procedures are
appropriate for fibre optic sensors.
6.8.2 Parameters and test procedures
Parameters Test procedure
Vibration IEC 60068-2-6
Bump IEC 60068-2-29
Shock IEC 60068-2-27
Bending of fibre leads IEC 60874-1 and IEC 60794-1
Twisting of fibre leads IEC 60874-1 and IEC 60794-1
Crushing of fibre leads IEC 60794-1
Tensile strength of fibre leads IEC 60874-1 and IEC 60794-1
Fibre connector IEC 60874-1
6.9 Climatic and environmental tests
6.9.1 General
Climatic and environmental tests are designed to verify that the influence of the specified
climatic and environmental conditions on the metrolo
...