ASTM_E_1614_-_94_2013.pdf

Designation:E161494(Reapproved 2013)Standard Guide forProcedure for Measuring Ionizing Radiation-InducedAttenuation in Silica-Based Optical Fibers and Cables forUse in Remote Fiber-Optic Spectroscopy andBroadband Systems1This standard is issued under the fixed designation E1614;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide covers a method for measuring the real time,in situ radiation-induced spectral attenuation of multimode,step index,silica optical fibers transmitting unpolarized light.This procedure specifically addresses steady-state ionizingradiation(that is,alpha,beta,gamma,protons,etc.)withappropriate changes in dosimetry,and shielding considerations,depending upon the irradiation source.1.2 This test procedure is not intended to test the balance ofthe optical and non-optical components of an optical fiber-based system,but may be modified to test other components ina continuous irradiation environment.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 Test or inspection requirements include the followingreferences:2.2 Military Standard:2MIL-STD-2196-(SH)Glossary of Fiber Optic Terms2.3 EIA Standards:3EIA-455-57 Optical Fiber End Preparation and ExaminationEIA-455-64 Procedure for Measuring Radiation-InducedAt-tenuation in Optical Fibers and CablesEIA-455-78A-90 Spectral Attenuation Cutback Measure-ment for Single-Mode Optical Fibers3.Terminology3.1 Definitions:3.1.1 Refer to MIL-STD-2196 for the definition of termsused in this guide.4.Significance and Use4.1 Ionizing environments will affect the performance ofoptical fibers/cables being used to transmit spectroscopicinformation from a remote location.Determination of the typeand magnitude of the spectral attenuation or interferences,orboth,produced by the ionizing radiation in the fiber isnecessary for evaluating the performance of an optical fibersensor system.4.2 The results of the test can be utilized as a selectioncriteria for optical fibers used in optical fiber spectroscopicsensor systems.NOTE1The attenuation of optical fibers generally increases whenexposed to ionizing radiation.This is due primarily to the trapping ofradiolytic electrons and holes at defect sites in the optical materials,thatis,the formation of color centers.The depopulation of these color centersby thermal and/or optical(photobleaching)processes,or both,causesrecovery,usually resulting in a decrease in radiation-induced attenuation.Recovery of the attenuation after irradiation depends on many variables,including the temperature of the test sample,the composition of thesample,the spectrum and type of radiation employed,the total doseapplied to the test sample,the light level used to measure the attenuation,and the operating spectrum.Under some continuous conditions,recoveryis never complete.1This guide is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.09 on Fiber Optics,Waveguides,and Optical Sensors.Current edition approved Jan.1,2013.Published January 2013.Originallyapproved in 1994.Last previous edition approved in 2004 as E1614 94(2004).DOI:10.1520/E1614-94R13.2Available from Standardization Documents Order Desk,Bldg.4 Section D,700Robbins Ave.,Philadelphia,PA 19111-5094,Attn:NPODS.Available from Stan-dardization Documents Order Desk,DODSSP,Bldg.4,Section D,700 RobbinsAve.,Philadelphia,PA 19111-5098,http:/dodssp.daps.dla.mil.3Available from Electronic Industries Alliance(EIA),2500 Wilson Blvd.,Arlington,VA 22201,http:/www.ecaus.org/eia.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Apparatus5.1 The test schematic is shown in Fig.1.The following listidentifies the equipment necessary to accomplish this testprocedure.5.2 Light SourceThe light source should be chosen so thatthe spectral region of interest is provided.Lamps or globars,orboth,may be used for analysis as long as they satisfy thepower,stability,and system requirements defined.In general,the silica fibers should be evaluated from 350 to 2100 nm,therefore,more than one light source or multiple testing,orboth,may be necessary.5.3 ShutterIn order to determine the background stability,the light will have to be blocked from entering the optical fiberby a shutter.5.4 Focusing/Collection OpticsA number of optical ele-ment