1、Designation:C164812Standard Guide forChoosing a Method for Determining the Index of Refractionand Dispersion of Glass1This standard is issued under the fixed designation C1648;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year
2、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 identifies and describes seven test methodsfor measuring the index of refraction of glass,with commentsreleva
3、nt to their uses such that an appropriate choice of methodcan be made.Four additional methods are mentioned by name,and brief descriptive information is given in Annex A1.Thechoice of a test method will depend upon the accuracyrequired,the nature of the test specimen that can be provided,the instrum
4、entation available,and(perhaps)the time requiredfor,or the cost of,the analysis.Refractive index is a functionof the wavelength of light;therefore,its measurement is madewith narrow-bandwidth light.Dispersion is the physical phe-nomenon of the variation of refractive index with wavelength.The nature
5、 of the test-specimen refers to its size,form,andquality of finish,as described in each of the methods herein.The test methods described are mostly for the visible range ofwavelengths(approximately 400 to 780m);however,somemethods can be extended to the ultraviolet and near infrared,using radiation
6、detectors other than the human eye.1.1.1 List of test methods included in this guide:1.1.1.1 Becke line(method of central illumination),1.1.1.2 Apparent depth of microscope focus(the method ofthe Duc de Chaulnes),1.1.1.3 Critical Angle Refractometers(Abbe type and Pul-frich type),1.1.1.4 Metricon2sy
7、stem,1.1.1.5 Vee-block refractometers,1.1.1.6 Prism spectrometer,and1.1.1.7 Specular reflectance.1.1.2 Test methods presented by name only(see AnnexA1):1.1.2.1 Immersion refractometers,1.1.2.2 Interferometry,1.1.2.3 Ellipsometry,and1.1.2.4 Method of oblique illumination.1.2 This standard does not pu
8、rport 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.1.3 WarningRefractive index liquids are used in
9、 severalof the following test methods.Cleaning with organic liquidsolvents also is specified.Degrees of hazard associated withthe use of these materials vary with the chemical nature,volatility,and quantity used.See manufacturers literature andgeneral information on hazardous chemicals.2.Referenced
10、Documents2.1 ASTM Standards:3E167 Practice for Goniophotometry of Objects and Materi-als(Withdrawn 2005)4E456 Terminology Relating to Quality and Statistics3.Terminology3.1 Definitions:3.1.1 dispersion,nthe physical phenomenon of the varia-tion of refractive index with wavelength.3.1.1.1 DiscussionT
11、he term,“dispersion,”is commonlyused in lieu of the more complete expression,“reciprocalrelative partial dispersion.”A dispersion-number can be de-fined to represent the refractive index as a function of wave-length over a selected wavelength-range;that is,it is acombined measure of both the amount
12、that the index changesand the non-linearity of the index versus wavelength relation-ship.3.1.2 resolution,nas expressed in power of 10,a com-monly used term used to express the accuracy of a test methodin terms of the decimal place of the last reliably measured digitof the refractive index which is
13、expressed as the negativepower of 10.As an example,if the last reliably measured digitis in the fifth decimal place,the method would be designated a10-5method.1This guide is under the jurisdiction of ASTM Committee C14 on Glass andGlass Products and is the direct responsibility of Subcommittee C14.1
14、1 on OpticalProperties.Current edition approved Oct.1,2012.Published November 2012.Originallyapproved in 2006.Last previous edition approved in 2006 as C1648-06.DOI:10.1520/C1648-12.2Metricon is a trademark of Metricon Corporation 12 North Main Street,P.O.Box 63,Pennington,New Jersey 08534.3For refe
15、renced 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 ASTM website.4The last approved version of this historical standard is referenced onwww.
16、astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2 Symbols:n=index of refraction=Abbe-number;a representation of particular relativepartial dispersionsD=Abbe-number determined with spectral lines D,C,and Fe=Abbe-number determined with spectral lines e,C,and FD=the spectral emission line of the sodium doublet atnominally 589.3 nm(which is the mid-point of the doublet thathas lines at 589.0 nm and 589.6 nm)C=the spectral emiss
