1、Designation: C 1426 99 (Reapproved 2004)Standard Practices forVerification and Calibration of Polarimeters1This standard is issued under the fixed designation C 1426; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 F 218, C 148, andC 978. The
3、se instruments include a light source and severaloptical elements (polarizers, optical retarders, filters, and soforth) that require occasional cleaning, realigning, and calibra-tion. The objective of these practices is to describe thecalibration and verification procedures required to maintainthese
4、 instruments in calibration and ensure that the opticalsetup is within specification 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 ofstr
5、ess retardation and are experienced in the practices ofmeasuring procedures described in Test Methods F 218, C 148,and C 978.2. Referenced Documents2.1 ASTM Standards:2C 148 Test Methods for Polariscopic Examination of GlassContainersC 162 Terminology of Glass and Glass ProductsC 770 Test Method for
6、 Measurement of Glass StressOptical CoefficientC 978 Test Method for Photoelastic Determination of Re-sidual Stress in a Transparent Glass Matrix Using aPolarizing Microscope and Optical Retardation Compen-sation ProceduresF 218 Test Method for Analyzing Stress in Glass3. Terminology3.1 For definiti
7、ons of terms used in these practices, seeTerminology C 162.4. Principles of Verification and Calibration Procedures4.1 Verification and calibration of polarimeters are accom-plished using the following procedures:4.1.1 Procedure A: (Verification)Measure individualcomponents and their orientation to
8、ensure that the require-ments of Test Methods F 218, C 148, and C 978 are satisfied.4.1.2 Procedure B: (Calibration)Determine the accuracyof the polarimeter using a calibrated gage or retarder.5. Auxiliary Component Requirements5.1 The following are required to verify and calibrate apolarimeter:5.1.
9、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 Quarter-Wave Plate, a Babinet com-pensator equipped polarimeter, with a monochromatic lightsource of traceable waveleng
10、th.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 gage must have sufficientretardation to calibrate the instrument within its intended userange. For example, a polarisc
11、ope/polarimeter used in TestMethods C 148 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 rectangular cross-section specimenprepared from an SRM glass having a known stress-opticalconstant, subjected to uniaxial compre
12、ssion in a calibratedtesting machine, may be used instead of a calibrated gage withknown retardation.6. Verification and Calibration Procedures6.1 Procedure AVerification and Aligning of Components:6.1.1 Verification of Polarization EffciencyUsing a light-intensity meter, measure the light intensity
13、, with polarizerscrossed (dark field) and then with polarizers parallel, 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 for.1These practices are under the jurisdiction of ASTM Comm
14、ittee C14 on Glassand Glass Products and are the direct responsibility of Subcommittee C14.04 onPhysical and Mechanical Properties.Current edition approved Oct. 1, 2004. Published November 2004.Originally approved in 1999. Last previous addition approved in 1999 asC142699.2For referenced ASTM standa
15、rds, 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 ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
16、 19428-2959, United States.6.1.2 Verification of Position of AxesUsing a referencepolarizer, verify that the polarizer, P, is oriented at 45 6 1 tothe instrument reference axis. Rotate the analyzer to attain themaximum dark field, and record the analyzer reading to thenearest degree or 0.05 fringe.
17、Repeat this measurement fivetimes and compute the average. This “zero” reading to thenearest degree or 0.05 fringe must be algebraically applied toretardations measured with this polarimeter.6.1.3 Verification of Quarter-Wave Plate, QUsing a pola-rimeter equipped with a Babinet compensator, measure
18、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 Use of a Calibrated GageThe gage must haveuniform and known direction of axes and a calibrated value ofretardation, Rc, in at least one location, m
19、arked 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 and 2). Rotate the analyzer until the black fringe movesto the calibrated gage mark. (Convert the analyzer reading toretardation in nanometers in
20、accordance with Test MethodsC 148.) Repeat five times and calculate the average retardation.The result of the measurement should equal Rcwithin 1 % or10 nm, whichever is greater.6.2.1.2 The use of strain disks (described in Test MethodsC 148) in series at a point 6.4 mm from the disks outercircumfer
21、ences, tangentially parallel or perpendicular to thepolarimeter reference direction, 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 successfu
22、lcalibration.6.2.2 Use of an SRM GlassFollowing Procedure C of TestMethod C 770, measure 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 fo
23、r measurementswith the polarimeter.7. Report7.1 Report the following in the verification 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; glas
24、s; polarimeter3SRM 709 has a stress-optical constant of 1.359 3 1012Pa1. This SRMproduces retardations from 0 to 136 nm when following Procedure C of Test MethodC 770.FIG. 1 Components of the Polarimeter Showing StressBirefringence OrientationC 1426 99 (2004)2ASTM International takes no position res
25、pecting the validity of any patent rights asserted in connection with any item mentionedin this 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
26、standard is subject to revision at any time by the responsible technical committee and must be 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 Intern
27、ational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible 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 be
28、low.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West 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).FIG. 2 Orientation of Calibrated Retardation Gage in Procedure BC 1426 99 (2004)3
