1、Designation: C1426 09Standard Practices forVerification and Calibration of Polarimeters1This standard is issued under the fixed designation C1426; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 Polarimeters and polariscopes used for measuring stressin glass are described in Test Methods F218, C148, and C978.These instruments include a
3、 light source and several opticalelements (polarizers, optical retarders, filters, and so forth) thatrequire occasional cleaning, realigning, and calibration. Theobjective of these practices is to describe the calibration andverification procedures required to maintain these instrumentsin calibratio
4、n and ensure that the optical setup is withinspecification for satisfactory measurements.1.2 It is mandatory throughout these practices that bothverification and calibration are carried out by qualified person-nel who fully understand the concepts used in measurements ofstress retardation and are ex
5、perienced in the practices ofmeasuring procedures described in Test Methods F218, C148,and C978.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Referenced Documents2.1 ASTM Standards:2C148 Test Methods for Polariscopic Ex
6、amination of GlassContainersC162 Terminology of Glass and Glass ProductsC770 Test Method for Measurement of Glass StressOptical CoefficientC978 Test Method for Photoelastic Determination of Re-sidual Stress in a Transparent Glass Matrix Using aPolarizing Microscope and Optical Retardation Compen-sat
7、ion ProceduresF218 Test Method for Measuring Optical Retardation andAnalyzing Stress in Glass3. Terminology3.1 For definitions of terms used in these practices, seeTerminology C162.4. Principles of Verification and Calibration Procedures4.1 Verification and calibration of polarimeters are accom-plis
8、hed using the following procedures:4.1.1 Procedure A: (Verification)Measure individualcomponents and their orientation to ensure that the require-ments of Test Methods F218, C148, and C978 are satisfied.4.1.2 Procedure B: (Calibration)Determine the accuracyof the polarimeter using a calibrated gage
9、or retarder.5. Auxiliary Component Requirements5.1 The following are required to verify and calibrate apolarimeter:5.1.1 Verification of Components (Procedure A):5.1.1.1 Verification of Polarization Effciency, a light-intensity meter, linear over the range of measured values.5.1.1.2 Verification of
10、Quarter-Wave Plate, a Babinet com-pensator equipped polarimeter, with a monochromatic lightsource of traceable wavelength.5.1.1.3 Reference Polarizer with Known Axis.5.1.2 Calibration of Polarimeter (Procedure B):5.1.2.1 Procedure B requires a gage with a calibrated,known retardation. The calibrated
11、 gage must have sufficientretardation to calibrate the instrument within its intended userange. For example, a polariscope/polarimeter used in TestMethods C148 should be calibrated using a gage exhibiting aretardation range of from 0 to 227 nm (0 to 10 temper grade).5.1.2.2 Alternately, a rectangula
12、r cross-section specimenprepared from an SRM glass having a known stress-opticalconstant, subjected to uniaxial compression in a calibratedtesting machine, may be used instead of a calibrated gage withknown retardation.6. Verification and Calibration Procedures6.1 Procedure AVerification and Alignin
13、g of Components:1These practices are under the jurisdiction of ASTM Committee C14 on Glassand Glass Products and are the direct responsibility of Subcommittee C14.04 onPhysical and Mechanical Properties.Current edition approved Nov. 1, 2009. Published January 2010. Originallyapproved in 1999. Last p
14、revious addition approved in 2004 as C142699(2004).DOI: 10.1520/C1426-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe A
15、STM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.1 Verification of Polarization EffciencyUsing a light-intensity meter, measure the light intensity, with polarizerscrossed, Ic(dark field) and then with polarizers paral
16、lel, Ip.Calculate the polarization efficiency, E, as follows:E 5Ip Ic!Ip(1)The efficiency must satisfy the requirements of the testmethod for which the polarimeter is used.6.1.2 Verification of Position of AxesUsing a referencepolarizer, verify that the polarizer, P, is oriented at 45 6 1 tothe inst
17、rument reference axis. Rotate the analyzer to attain themaximum dark field, and record the analyzer reading to thenearest degree or 0.05 fringe. Repeat this measurement fivetimes and compute the average. This “zero” reading to thenearest degree or 0.05 fringe must be algebraically applied toretardat
18、ions measured with this polarimeter.6.1.3 Verification of Quarter-Wave Plate, QUsing a pola-rimeter equipped with a Babinet compensator, measure theretardation of the quarter-wave plate. The retardation must be141 6 5 nm.6.2 Procedure BCalibration of Polarimeter Using a Cali-brated Retarder:6.2.1 Us
19、e of a Calibrated GageThe gage must haveuniform and known direction of axes and a calibrated value ofretardation, Rc, in at least one location, marked permanently onthe gage.6.2.1.1 Place the gage in the field of view with its axesaligned with the reference direction of the polarimeter (seeFigs. 1 a
20、nd 2). Rotate the analyzer until the black fringe iscentered over the calibrated gage mark (the objective is tominimize the light intensity at the gage mark.) Convert theanalyzer reading to retardation in nanometers in accordancewith Test Methods C148. Repeat five times and calculate theaverage reta
21、rdation. The result of the measurement shouldequal Rcwithin 1 % or 10 nm, whichever is greater.6.2.1.2 The use of strain disks (described in Test MethodsC148) in series at a point 6.4 mm from the disks outercircumferences, tangentially parallel or perpendicular to thepolarimeter reference direction,
22、 will give optical retardationsof 22.8, 45.6, 68.4, and so forth, with uncertainties of 64%.Five repeat retardation averages for any selected level of disksin series must be within 4 % of these values for a successfulcalibration.6.2.2 Use of an SRM GlassFollowing Procedure C of TestMethod C770, meas
23、ure the stress-optical constant of an SRMglass having a certified value for this constant.3The ratio of thecertified value of the stress-optical constant to the measuredvalue should be used as a corrective factor for measurementswith the polarimeter.7. Report7.1 Report the following in the verificat
24、ion and calibrationreport:7.1.1 Date of verification and calibration,7.1.2 Auxiliary components used,7.1.3 Significant data obtained, and7.1.4 Organization performing the calibration.8. Keywords8.1 calibration; glass; polarimeter3SRM 709 has a stress-optical constant of 1.359 3 1012Pa1. This SRMprod
25、uces retardations from 0 to 136 nm when following Procedure C of Test MethodC770.FIG. 1 Components of the Polarimeter Showing StressBirefringence OrientationC1426 092ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin thi
26、s standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be
27、 reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresp
28、onsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, We
29、st Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. 2 Orientation of Calibrated Retardation Gage in Procedure BC1426 093
