1、Designation: E 808 01 (Reapproved 2009)Standard Practice forDescribing Retroreflection1This standard is issued under the fixed designation E 808; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides terminology, alternative geo-metrical coordinate systems, and procedures for designatingangles in descriptions of retror
3、eflectors, specifications forretroreflector performance, and measurements of retroreflec-tion.1.2 Terminology defined herein includes terms germane toother ASTM documents on retroreflection.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
4、s 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 ASTM Standards:2E 284 Terminology of Appearance2.2 Federal Standard:Fed. Std. No. 370 Instrumental
5、 Photometric Measurementsof Retroreflecting Materials and Retroreflecting Devices32.3 CIE Document:CIE Publication No. 54 Retroreflection-Definition and Mea-surement43. Terminology3.1 Terms and definitions in Terminology E 284 are appli-cable to this standard.3.1.1 In accordance with the convention
6、appearing in theSignificance and Use section of Terminology E 284, thesuperscript B appearing after CIE at the end of a definitionindicates that the given definition is a modification of that citedwith little difference in essential meaning.NOTE 1The terminology given here describes visual observati
7、on ofluminance as defined by the CIE V (l) spectral weighting function for thephotopic observer. Analogous terms for other purposes can be defined byusing appropriate spectral weighting.3.2 Definitions: The delimiting phrase “in retroreflection”applies to each of the following definitions when used
8、outsidethe context of this or other retroreflection standards.3.2.1 coeffcient of line retroreflection, RM, nof a retrore-flecting stripe, the ratio of the coefficient of luminous intensity(RI) to the length (l), expressed in candelas per lux per metre(cdlx1m1). RM= RI/l.3.2.1.1 DiscussionRMdepends
9、on the spectral composi-tion of the illumination which is usually CIE illuminant A.3.2.2 coeffcient of luminous intensity, RI, nof a retrore-flector, ratio of the luminous intensity (I) of the retroreflector inthe direction of observation to the illuminance (E)attheretroreflector on a plane perpendi
10、cular to the direction of theincident light, expressed in candelas per lux (cdlx1). RI=(I/E).3.2.2.1 DiscussionIn a given measurement one obtainsthe average RIover the solid angles of incidence and viewingsubtended by the source and receiver apertures, respectively. Inpractice, I is often determined
11、 as the product of the illuminanceat the observer and the distance squared (I=Erd2). RIdependson the spectral composition of the illumination which is usuallyCIE illuminant A.3.2.2.2 DiscussionAlso called coeffcient of (retrore-flected) luminous intensity. Equivalent commonly used termsare CIL and S
12、I (specific intensity). CIE Publication 54 uses thesymbol R for RI. The ASTM recommendation is to use thesymbol RI.3.2.3 coeffcient of retroreflected luminance, RL, ntheratio of the luminance, L, in the direction of observation to thenormal illuminance, E, at the surface on a plane normal to theinci
13、dent light, expressed in candelas per square metre per lux(cdm2)lx1.RL5 L/E! 5 RI/A cos n! 5 I/EA cos n! 5 RA/ cos n! (1)where:1This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and is the direct responsibility of Subcommittee E12.10 on Retrore-flection.Current edi
14、tion approved Feb. 1, 2009. Published February 2009. Originallyapproved in 1981. Last previous edition approved in 2001 as E 808 - 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume info
15、rmation, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.4Available from U.S. National Committee of the CIE (International Commiss
16、ionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970, http:/www.cie-usnc.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.A = surface area of the sample, andn = viewing angle.3.2.3.
17、1 DiscussionThe units millicandela per square me-tre per lux (mcdm2)lx1 are usually used to express the RLvalues of road marking surfaces. This quantity is also referredto as specific luminance. Historically the symbol SL was usedfor RL. In some references CRL is used. These are allequivalent, but R
18、Lis preferred.3.2.3.2 DiscussionRLdepends on the spectral composi-tion of the illumination which is usually CIE illuminant A.3.2.4 coeffcient of (retroreflected) luminous flux, RF, ntheratio of the luminous flux per unit solid angle, F8/V8, in thedirection of observation to the total flux F incident
19、 on theeffective retroreflective surface, expressed in candelas perlumen (cdlm1).RF5 F8/V8!/F5I/F5RA/cos b (2)3.2.4.1 DiscussionThe units for this photometric quantity,candelas per lumen, are sometimes abbreviated as CPL.3.2.4.2 DiscussionRFdepends on the spectral composi-tion of the illumination wh
20、ich is usually CIE illuminant A.3.2.5 coeffcient of retroreflection, RA, nof a plane retrore-flecting surface, the ratio of the coefficient of luminousintensity (RI) to the area (A), expressed in candelas per lux persquare metre (cdlx1m2). RA= RI/A.3.2.5.1 DiscussionThe equivalent inch-pound units f
21、orcoefficient of retroreflection are candelas per foot candle persquare foot. The SI and inch-pound units are numericallyequal, because the units of RAreduce to 1/sr. An equivalentterm used for coefficient of retroreflection is specific intensityper unit area, with symbol SIA or the CIE symbol R8. T
22、he termcoefficient of retroreflection and the symbol RAalong with theSI units of candelas per lux per square metre are recommendedby ASTM.3.2.5.2 DiscussionThe radiometric BRDF is not the ana-logue of RAbut rather of RF.3.2.5.3 DiscussionRAdepends on the spectral composi-tion of the illumination whi
23、ch is usually CIE illuminant A.3.2.6 co-entrance angle, e, nthe complement of the anglebetween the retroreflector axis and the illumination axis.3.2.6.1 Discussione=90-b. Range 0e, the receiver over the source, for testing.FIG. 7 RM (Road Marking) SystemE 808 01 (2009)8sin E 5cos sin b1sin b2 sin co
24、s b1sin2b21 cos2b1cos2b2!1/2X1.2.1 Special cases: when b2=0andb1= 6 90then H 5 0V 51290E 5 X1.3 In the SAE J594f system, the transformations are thesame as in Sections X1.1 and X1.2, with the followingconventions:E = SAE(SAEis rotation angle in SAE J594f)b10 =down SAE J594f angleb10 =right SAE J594f
25、 angleb20, sgn(x)=+1; sgn(0)=0. This agreeswith most software, but some define sgn(0)=+1.X1.4.1 Equations for transformation from Intrinsic systemto CIE system are as follows:b15tan1tan b cosg! (X1.1)b25sin1sin b sin g! (X1.2)5vs tan1tan g cos b! 901 sgncos g! (X1.3)X1.4.2 Equations for transformati
26、on from CIE system toIntrinsic system are as follows:b5cos1cosb1 cosb2! (X1.4)vs51tan1Ssin b2tan b1D1 90 1 sgnb1! (X1.5)g5tan1Stan b2sin b1D1 90 1 sgnb1! (X1.6)X1.4.2.1 For the special case b1=0fib2, makevs= + 90 sgn(b2).For the special case b1=0=b2, make vs= 0.X1.4.2.2 For the special case b1=0fib2
27、, makeg = 90 sgn(b2).For the special case b1=0=b2, make g =-.X1.4.3 Equations for transformation from Application sys-tem to CIE system are as follows:b15 sin1sinbcosvs ! (X1.7)b25 tan1tanb sinvs ! (X1.8)X1.4.4 Equations for transformation from CIE system toApplication system are as follows:b5cos1co
28、sb1 cosb2! (X1.9)vs51tan1Ssin b2tan b1D1 901 sgnb1! (X1.10)X1.4.4.1 For the special case b1=0fib2, makevs= + 90 sgn(b2).For the special case b1=0=b2, make vs= 0.X1.4.5 Equation for transformation from Intrinsic system toApplication system is as follows:5vs tan1tan g cos b! 901 sgncos g! (X1.11)X1.4.
29、5.1 For the special cases where tan g is infinite, make=vsg.X1.4.6 Equation for transformation from Application sys-tem to Intrinsic system is as follows:g5tan1Stanvs !cos bD1 901 sgncosvs ! (X1.12)X1.4.6.1 For the special cases where tan(vs) is infinite,make g=vs.X1.4.7 Equations for transformation
30、 from RM system toApplication system are as follows:a5cos1sin a sin e cos a cos b cos e! (X1.13)b590 e (X1.14)5d tan1Stan a sin btan e 1 tan a cos bD1 901 1 sgntan e 1 cos a cos b!(X1.15)vs5 d b 1 180 (X1.16)X1.4.8 To transform from RM system to CIE system, firstuse the equations in X1.4.7 to transf
31、orm to the Applicationsystem, then use the equations in X1.4.3 to transform to theCIE system.X1.4.9 Equations for transformation from CIE system toRM system are as follows:a 5 sin1cos b1a!cos b2! (X1.17)b 5 180 1 sgn b2!cos1Ssin2b2cosb1cosb1a! 1 sinb1sinb1a!= 1 cos2b1cos2b2=1 cos2b1a!cos2b2D(X1.18)e
32、 5 sin1cos b1cos b2! (X1.19)d 5vs1 b 180 (X1.20)X1.4.9.1 To use Eq X1.20 requires first using Eq X1.18 toobtain b and equation Eq X1.5 to obtain vs.X1.4.10 Equations for transformation between rotationangle and rho angle are as follows:r5 tan1Stanvs !cos bD1 tan1Stan vscos bD1 90sgncosvs ! sgncos vs
33、! (X1.21)5vs tan1Stan vscos b tan r cos2bcos b1tan vstan rD 1 Q (X1.22)Make Q=0 or Q=180 so as to produce in the samequadrant as r.E 808 01 (2009)9ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users o
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35、e 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 theresponsible technical c
36、ommittee, 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, 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).E 808 01 (2009)10
