ASTM E1654-94(2021)
(Guide)Standard Guide for Measuring Ionizing Radiation-Induced Spectral Changes in Optical Fibers and Cables for Use in Remote Raman FiberOptic Spectroscopy
Standard Guide for Measuring Ionizing Radiation-Induced Spectral Changes in Optical Fibers and Cables for Use in Remote Raman FiberOptic Spectroscopy
SIGNIFICANCE AND USE
4.1 Ionizing environments will affect the performance of optical fibers/cables being used to transmit spectroscopic information from a remote location. Determination of the type and magnitude of the spectral variations or interferences produced by the ionizing radiation in the fiber, or both, is necessary for evaluating the performance of an optical fiber sensor system.
4.2 The results of the test can be utilized as a selection criteria for optical fibers used in optical fiber Raman spectroscopic sensor systems.
Note 1: The attenuation of optical fibers generally increases when they are exposed to ionizing radiation. This is due primarily to the trapping of radiolytic electrons and holes at defect sites in the optical materials, that is, the formation of color centers. The depopulation of these color centers by thermal or optical (photobleaching) processes, or both, causes recovery, usually resulting in a decrease in radiationinduced attenuation. Recovery of the attenuation after irradiation depends on many variables, including the temperature of the test sample, the composition of the sample, the spectrum and type of radiation employed, the total dose applied to the test sample, the light level used to measure the attenuation, and the operating spectrum. Under some continuous conditions, recovery is never complete.
SCOPE
1.1 This guide covers the method for measuring the real time, in situ radiation-induced alterations to the Raman spectral signal transmitted by a multimode, step index, silica optical fiber. This guide specifically addresses steady-state ionizing radiation (that is, alpha, beta, gamma, protons, etc.) with appropriate changes in dosimetry, and shielding considerations, depending upon the irradiation source.
1.2 The test procedure given in this guide is not intended to test the other optical and non-optical components of an optical fiber-based Raman sensor system, but may be modified to test other components in a continuous irradiation environment.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1654 −94 (Reapproved 2021)
Standard Guide for
Measuring Ionizing Radiation-Induced Spectral Changes in
Optical Fibers and Cables for Use in Remote Raman
FiberOptic Spectroscopy
This standard is issued under the fixed designation E1654; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Radiation-Induced Attenuation in Silica-Based Optical
Fibers and Cables for Use inRemoteFiber-Optic Spec-
1.1 This guide covers the method for measuring the real
troscopyand BroadbandSystems
time,insituradiation-inducedalterationstotheRamanspectral
2.2 EIA Standards:
signal transmitted by a multimode, step index, silica optical
2.2.1Test or inspection requirements include the following
fiber. This guide specifically addresses steady-state ionizing
references:
radiation (that is, alpha, beta, gamma, protons, etc.) with
EIA-455-57Optical Fiber End Preparation and Examination
appropriatechangesindosimetry,andshieldingconsiderations,
EIA-455-64ProcedureforMeasuringRadiation-InducedAt-
depending upon the irradiation source.
tenuation in Optical Fibers and Cables
1.2 The test procedure given in this guide is not intended to 4
2.3 Military Standard:
test the other optical and non-optical components of an optical
MIL-STD-2196-(SH)Glossary of Fiber Optic Terms
fiber-based Raman sensor system, but may be modified to test
other components in a continuous irradiation environment.
3. Terminology
1.3 The values stated in SI units are to be regarded as
3.1 Definitions—Refer to the following documents for the
standard. No other units of measurement are included in this
definition of terms used in this guide: MIL-STD-2196-(SH)
standard.
and Guide E1614.
1.4 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 Ionizing environments will affect the performance of
priate safety, health, and environmental practices and deter- optical fibers/cables being used to transmit spectroscopic
mine the applicability of regulatory limitations prior to use. information from a remote location. Determination of the type
1.5 This international standard was developed in accor- and magnitude of the spectral variations or interferences
dance with internationally recognized principles on standard- produced by the ionizing radiation in the fiber, or both, is
ization established in the Decision on Principles for the necessary for evaluating the performance of an optical fiber
Development of International Standards, Guides and Recom- sensor system.
mendations issued by the World Trade Organization Technical
4.2 The results of the test can be utilized as a selection
Barriers to Trade (TBT) Committee.
criteria for optical fibers used in optical fiber Raman spectro-
scopic sensor systems.
2. Referenced Documents
NOTE 1—The attenuation of optical fibers generally increases when
2.1 ASTM Standards:
theyareexposedtoionizingradiation.Thisisdueprimarilytothetrapping
E1614 Guide for Procedure for Measuring Ionizing
ofradiolyticelectronsandholesatdefectsitesintheopticalmaterials,that
is, the formation of color centers.The depopulation of these color centers
by thermal or optical (photobleaching) processes, or both, causes
recovery, usually resulting in a decrease in radiationinduced attenuation.
This guide is under the jurisdiction of ASTM Committee E13 on Molecular
Recovery of the attenuation after irradiation depends on many variables,
Spectroscopy and Separation Science and is the direct responsibility of Subcom-
including the temperature of the test sample, the composition of the
mittee E13.09 on Fiber Optics, Waveguides, and Optical Sensors.
sample, the spectrum and type of radiation employed, the total dose
Current edition approved Sept. 1, 2021. Published September 2021. Originally
approved in 1994. Last previous version approved in 2013 as E1654–94 (2013).
DOI: 10.1520/E1654-94R21.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from Electronic Industries Alliance (EIA), 2500 Wilson Blvd.,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Arlington, VA 22201.
Standards volume information, refer to the standard’s Document Summary page on Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
the ASTM website. Philadelphia, PA 19111-5094, http://quicksearch.dla.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1654 − 94 (2021)
applied to the test sample, the light level used to measure the attenuation,
identifies the equipment necessary to accomplish this test
and the operating spectrum. Under some continuous conditions, recovery
procedure.
is never complete.
5.2 Light Source—A laser source shall be used for the
5. Apparatus
Ramananalysis,andthewavelengthmustbechosensothatthe
5.1 ThetestschematicisshowninFig.1.Thefollowinglist fluorescentsignalsfromtheopticalcomponents(especiallythe
FIG. 1 Test Configuration
E1654 − 94 (2021)
spectralactivatorsampleandopticalfibers)areminimized,and same uniform geometry as the actual fiber core material to
sothatthewavelengthcorrespondstothespectralsensitivityof ensure that dose-buildup effects are comparable to the fiber
the detection scheme. Typically, the wavelength range ex- core and the dosimeter. The dose should be expressed in gray
ploited spans from 0.4µm to 1.06 µm. The laser source must calculated for the core material.
have sufficient power to obtain the desired minimum signal-
5.9 Temperature-Controlled Container—Unless otherwise
to-noise ratio (S/N) (see 10.3).
specified, the temperature-controlled container shall have the
5.3 Focusing/Collection Optics—A number of optical ele-
capability of maintaining the specified temperature to 23°C 6
ments are needed for the launch and collection of light
2°C. The temperature of the sample/container should be
radiation into and from the optical fibers (interfacing, sample
monitored prior to and during the test.
and reference), and other instrumentation (light source,
5.10 Collection Optics into Detection System—Anappropri-
spectrograph, detector). The minimal requirement for these
atecollectionconfigurationshallbeusedatthedistalendofthe
elements shall be that the numerical aperture of the compo-
sampleandreferenceopticalfibers.Itisrecommendedthatthe
nents are matched for efficient coupling. Optics may also be
collection and focusing optic(s) is f/number matched to the
necessary to enhance the interaction of the input light with the
numerical aperture of the fibers and detection system.
spectral activator.
5.10.1 Raman analysis requires that the laser line be elimi-
5.4 Interfacing Optical Fiber—The primary requirement of
natedpriortodetection.Alaserreject(orlongpassfilter)must
the interfacing optical fiber is to provide the minimum power
be used at the entrance to the detection system. The filter
−1
to the activator sample at the proper wavelength(s). The fiber
should pass all energy at 500 cm below the laser excitation
lengthmaybeadjustedsothatthepowerrequirementsaremet.
line. The filter should be placed between the optical elements
prior to the spectrometer.
5.5 Light Radiation Filtering—Itisimportantthatallneigh-
boring laser lines are removed from the source beam prior to
5.11 Optical Detection—An optical detector with a known
interaction with the spectral activator. This can be accom-
responseovertherangeofintensitiesthatareencounteredshall
plished before or after the interfacing optical fiber. Placement
be used. A typical system for Raman might include a single-
of the filter before the interfacing fiber will eliminate the
point detector (that is, PMT) or a multichannel analyzer (that
neighboring laser lines, but any fluorescence and Raman
is, CCD array). The spectrograph must exhibit fast scanning
scattering due to the fiber or associated optics will be allowed
capabilities. As Fig. 1 indicates, it is recommended that a
to interact with the sample. Placement of the laser pass filter
single-imaging spectrometer be used with a 2D CCD detector
aftertheinterfacingfiberispreferablebecauseitwilleliminate
so that the output from the reference and sample fibers can be
any signals created within the fiber. If it is necessary to place
evaluated simultaneously. Two spectrometers operating simul-
the filter before the interfacing fiber, then the fiber should be
taneously may also be used.
kept as short as possible (several metres).
5.11.1 The optical detection system must be capable of
−1 −1
5.6 Spectral Activator Sample—The spectral activator used
obtaining the Raman spectrum from 500cm to 3000 cm
must demonstrate a strong, well-characterized Raman spectral from the excitation frequency.
signal. The sample may be either liquid, gas, or solid, depend-
5.12 Recorder System—Asuitable data recording, such as a
ing on the requirements of the optical fiber arrangement. It is
computer data acquisition system, is recommended.
recommendedthataliquidbeused,sincetheRamanscattering
5.13 Ambient Light Shielding—The irradiated fiber length
in the proposed configuration will launch similarly into the
shallbeshieldedfromambientlighttopreventphotobleaching
sample and reference fibers. Standard recommended samples
byanyexternallightsourcesandtoavoidbaselineshiftsinthe
are:acetonitrile,benzene,andcarbontetrachloride.Thesample
zero light level. An absorbing fiber coating or jacket can be
should be contained in a standard spectroscopic rectangular
used as the light shield provided that it has been demonstrated
silica cuvette.
to block ambient light and its influence on the dose within the
5.7 Optical Interconnections—The input and output ends of
fiber core has been taken into consideration.
the interfacing, reference, and sample optical fibers shall have
astabilizedopticalinterconnection,suchasaclamp,connector, NOTE2—Theaveragetotaldoseshouldbeexpressedingray(Gy,where
1 Gy=100 rads) to a precision of 65%, traceable to national standards.
splice, or weld. During an attenuation measurement, the
For typical silica core fibers, dose should be expressed in gray calculated
interconnection shall not be changed or adjusted.
for SiO , that is, Gy(SiO ).
2 2
5.8 Irradiation System—The irradiation system should have
the following characteristics:
6. Hazards
5.8.1 Dose Rate—ACo orotherirradiationsourceshallbe
6.1 Carefully trained and qualified personnel must be used
used to deliver radiation at dose rates ranging from 10Gy
to perform this test procedure since radiation (both ionizing
(SiO )/min to 100 Gy (SiO )/min. (See Note 2.)
2 2
and optical), as well as electrical, hazards will be present.
5.8.2 Radiation Energy—The energy of the gamma rays
emitted by the source should be greater than 500 KeVto avoid
7. Test Specimens
serious complications with the rapid variations in total dose as
a function of depth within the test sample. 7.1 Sample Optical Fiber—The sample fiber shall be a
5.8.3 Radiation Dosimeter—Dosimetry traceable to Na- previously unirradiated step-index, multimode fiber. The fiber
tionalStandardsshallbeused.Doseshouldbemeasuredinthe shall be long enough to have an irradiated test length of 50m
E1654 − 94 (2021)
6 5 m and to allow coupling between the optical instrumen- 9.1.1 The intensity (counts per second) detected from the
tation outside the radiation chamber and the sample area. sample and reference fibers prior to irradiation shall be within
10%.
7.2 The test specimen may be an optical-fiber cable
assembly, as long as the cable contains at least one of the
9.2 Baseline Stability—Verify the baseline stability for a
specified fibers for analysis. time comparable to the attenuation measurement with the light
source turned off. Record the maximum fluctuation in output
7.3 Test Reel—The test reel shall not act as a shield for the
power and reject any subsequent measurement if the transmit-
radiation used in this test or, alternatively, the dose must be
tedpoweroutoftheirradiatedfiberisnotgreaterthantentimes
measured in a geometry duplicating the effects of reel attenu-
the recorded baseline.
ation. The diameter of the test reel and the winding tension of
the fiber can influence the observed radiation performance,
10. Procedure
therefore, the fiber should be loosely wound on a reel diameter
10.1 Place the reel of fiber or cable in the attenuation test
exceeding 10 cm.
setup as shown in Fig. 1. Couple the light source into the end
7.4 Fiber End Preparation—Prepare the test sample such
of the interfacing fiber.
thatitsendfacesaresmoothandperpendiculartothefiberaxis,
10.2 Position the output end of the interfacing fiber such
in accordance with EIA-455-57.
thatallthelightexitingthefiberimpingesthespectralactivator
7.5 Reference Fiber—The reference fiber shall have the
sample. Position the sample and reference fibers to collect the
same requirements as the sample fiber. It should have similar
spectral energy scattered (see Note 3).
characteristics, be packaged in the same configuration, and
10.3 Positionthelightexitingthefibersforcollectionbythe
should be used in an identical fashion as the sample fiber
detectionscheme.Thespectraobtainedthroughthesampleand
except for the radiation exposure.
reference fibers must exhibit a minimum signal-to-noise ratio
8. Radiation, Calibration, and Stability
(S/N)of9priortoirradiationfortheprimaryRamanpeaks(see
8.1 Calibration of Radiation Source—Make calibration of
Note 4).
the radiation source for dose uniformity and dose level at the
10.4 Stabilize the test sample in the temperature chamber at
location of the device under test (DUT) and at a minimum of
23°C 6 2°C prior to proceeding (see Note 5).
four other locations, prior to introduction of fiber test samples.
10.5 Obtain the system stability and baseline.
The variation in dose across the fiber reel volume shall not
exceed 610%. If thermoluminescent detectors (TLDs) are
10.6 RecordtheRamanspectrumfromthetestsampleprior
used for the measurements, use four TLDs to sample dose
to, and for the duration of the ionizing radiation cycle. Also
distribution at each location. Average the readings from the
recordtheoutputspectraforatleast3600saftercompletionof
multipleTLDsateachlocationtominimizedoseuncertainties.
the irradiation process (see Note 5).
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