1、Designation: E808 01 (Reapproved 2016)Standard Practice forDescribing Retroreflection1This standard is issued under the fixed designation E808; 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
2、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 retroref
3、lectors, 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 is
4、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:2E284 Terminology of Appearance2.2 Federal Standard:Fed. Std. No. 370 Instrumental Ph
5、otometric 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 E284 are appli-cable to this standard.3.1.1 In accordance with the convention appe
6、aring in theSignificance and Use section of Terminology E284, the super-script 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 observation
7、ofluminance as defined by the CIE V () spectral weighting function for thephotopic observer. Analogous terms for other purposes can be defined byusing appropriate spectral weighting.3.2 Definitions:3.2.1 The delimiting phrase “in retroreflection” applies toeach of the following definitions when used
8、 outside the contextof this or other retroreflection standards.3.2.2 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.3.2.2.1 DiscussionRMdepends
9、on the spectral composi-tion of the illumination which is usually CIE illuminant A.3.2.3 coeffcient of luminous intensity, RI,nof aretroreflector, ratio of the luminous intensity (I) of the retrore-flector in the direction of observation to the illuminance (E)at the retroreflector on a plane perpend
10、icular to the direction ofthe incident light, expressed in candelas per lux (cdlx1). RI=(I/E).3.2.3.1 DiscussionIn a given measurement one obtains theaverage RIover the solid angles of incidence and viewingsubtended by the source and receiver apertures, respectively. Inpractice, I is often determine
11、d 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.3.2.3.2 DiscussionAlso called coeffcient of (retrore-flected) luminous intensity. Equivalent commonly used termsare CIL and
12、SI (specific intensity). CIE Publication 54 uses thesymbol R for RI. The ASTM recommendation is to use thesymbol RI.3.2.4 coeffcient of retroreflected luminance, RL,nthe ratioof 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/Acos! 5 I/EAcos! 5 RA/cos! (1)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 edition approved J
14、an. 1, 2016. Published January 2016. Originallyapproved in 1981. Last previous edition approved in 2009 as E808 01 (2009).DOI: 10.1520/E0808-01R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandard
15、s volume information, 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 (Internat
16、ional Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970, http:/www.cie-usnc.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1where:A = surface area of the sample, and = vie
17、wing angle.3.2.4.1 DiscussionThe units millicandela per square metreper 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 alleq
18、uivalent, but RLis preferred.3.2.4.2 DiscussionRLdepends on the spectral compositionof the illumination which is usually CIE illuminant A.3.2.5 coeffcient of (retroreflected) luminous flux, R,ntheratio of the luminous flux per unit solid angle, /, in thedirection of observation to the total flux inc
19、ident on theeffective retroreflective surface, expressed in candelas perlumen (cdlm1).R5 /!/ 5 I/ 5 RA/cos (2)3.2.5.1 DiscussionThe units for this photometric quantity,candelas per lumen, are sometimes abbreviated as CPL.3.2.5.2 DiscussionRdepends on the spectral composi-tion of the illumination whi
20、ch is usually CIE illuminant A.3.2.6 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.3.2.6.1 DiscussionThe equivalent inch-pound units for
21、coefficient 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 R. The
22、termcoefficient of retroreflection and the symbol RAalong with theSI units of candelas per lux per square metre are recommendedby ASTM.3.2.6.2 DiscussionThe radiometric BRDF is not the ana-logue of RAbut rather of R.3.2.6.3 DiscussionRAdepends on the spectral composi-tion of the illumination which i
23、s usually CIE illuminant A.3.2.7 co-entrance angle, e, nthe complement of the anglebetween the retroreflector axis and the illumination axis.3.2.7.1 Discussione=90-. Range 0e, the receiver over the source, for testing.FIG. 7 RM (Road Marking) SystemE808 01 (2016)7several angles, can no longer be app
24、lied. Therefore, byconvention, 1=; 2=0; =s; =0; and = the projection ofsinto a plane perpendicular to the illumination axis, that is,=tan1(tans/cos).7.3 When = 0, the illumination axis and the retroreflectoraxis coincide. In this special case, the definition of the entrancehalf-plane, which is used
25、in the definition of two angles, sand, can no longer be applied. Therefore, by convention,s= 0; = =-.8. Specification Conventions8.1 If the retroreflector has a datum mark and the rotationangle is unspecified, it has been a common practice toconsider = 0. This practice is deprecated by ASTM becauset
26、he presence of a datum mark indicates that the retroreflector issensitive to rotation. ASTM recommends that the conditionsdesired for test be completely specified.8.2 When the entrance angle alone is specified withoutreference to components, it has been a common practice in theUnited States to consi
27、der 2=0 and 1=. Because the use ofsuch conventions results in misunderstandings and conflictingstandards, ASTM deprecates the use of this convention andrecommends that the conditions desired for test be completelyspecified. Note in particular that for sign sheeting 2=0, 1=is a poor representation of
28、 the road scenario and may result inmisapplication of some materials.9. Aperture Description Conventions9.1 Since the efficiencies of retroreflectors are often rapidlyvarying functions of the observation angle and the rho angle, it is usually important to describe the apertures of the sourceand rece
29、iver that are to be used in a measurement. Thefollowing conventions for describing apertures are based on theassumptions that: (1) the luminance of the source in thedirection of the retroreflector is uniform over the sourceaperture stop, (2) the illumination axis passes through thecenter of the sour
30、ce aperture stop, (3) the responsivity of thereceiver in the direction of the retroreflector is uniform over thereceiver aperture stop, and (4) the observation axis passesthrough the center of the receiver aperture stop.9.1.1 Circular ApertureThe angular size of a circularaperture, either source or
31、receiver, should be described bygiving the angle subtended at the retroreflector center by adiameter of the aperture.9.1.2 Rectangular ApertureIf a rectangular aperture, ei-ther source or receiver, has one side parallel to the observationhalf-plane, then its angular size should be described by givin
32、gfirst the angle subtended at the retroreflector center by the sideparallel to the observation half-plane and second the anglesubtended at retroreflector center by the side perpendicular tothe observation half-plane. For example, a 0.1 by 0.2rectangular aperture has its short side parallel to the ob
33、serva-tion half-plane.10. Keywords10.1 Application system; CIE (goniometer) system; en-trance angle; Intrinsic system; observation angle; orientationangle; presentation angle; retroreflection; rotation angleAPPENDIX(Nonmandatory Information)X1. TRANSFORMATION TABLESX1.1 Equations for transformation
34、from the 1959 BrusselsCIE coordinate system (, E, V, H) to the CIE (goniometer)system (, 1, 2, ).NOTE X1.1The symbol E is used to designate the rotation angle in the1959 Brussels system to avoid confusion. 5 cos 5 cos VcosHsin 152 sin Vsin2V1 cos2V cos2H!1/2cos 15cos VcosHsin2V1 cos2V cos2H!1/2sin 2
35、52sin HcosVcos 5cos E cos H1 sin E sin V sin H sin2V1 cos2V cos2H!1/2sin 5cos E sin H sin V 2 sin E cos H sin2V1 cos2V cos2H!1/2X1.1.1 Special cases: when V =0andH = 6 90then 25790 note sign reversal!15 0 52EX1.2 Equations for transformation from CIE (goniometer)system (, 1, 2, ) to the 1959 Brussel
36、s CIE coordinatesystem (, E, V, H). 5 sin V 52sin 1cos 2sin H 52 sin 2sin221 cos21cos22!1/2cos H 5cos 1cos2sin221 cos21cos22!1/2cos E 5sin sin 1sin 21 cos cos 1sin221 cos21cos22!1/2sin E 5cos sin 1sin 22 sin cos 1sin221 cos21cos22!1/2E808 01 (2016)8X1.2.1 Special cases: when 2=0and1= 6 90then H 5 0V
37、 5790E 52X1.3 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)10 =down SAE J594f angle10 =right SAE J594f angle20, sgn(x)=+1; sgn(0)=0. This agreeswith most software, but some define sgn(0)
38、=+1.X1.4.1 Equations for transformation from Intrinsic systemto CIE system are as follows:15 tan21tan cos ! (X1.1)25 sin21sin sin ! (X1.2) 5 s2 tan21tan cos ! 2 901 2 sgncos ! (X1.3)X1.4.2 Equations for transformation from CIE system toIntrinsic system are as follows: 5 cos21cos 1 cos 2! (X1.4)s5 1
39、tan21Ssin 2tan 1D1901 2 sgn1! (X1.5) 5 tan21Stan 2sin 1D1901 2 sgn1! (X1.6)X1.4.2.1 For the special case 1=02, makes= + 90 sgn(2).For the special case 1=0=2, make s= 0.X1.4.2.2 For the special case 1=02, make = 90 sgn(2).For the special case 1=0=2, make =-.X1.4.3 Equations for transformation from Ap
40、plication sys-tem to CIE system are as follows:15 sin21sin cos s2 ! (X1.7)25 tan21tan sin s2 ! (X1.8)X1.4.4 Equations for transformation from CIE system toApplication system are as follows: 5 cos21cos 1 cos 2! (X1.9)s5 1 tan21Ssin 2tan 1D1901 2 sgn1! (X1.10)X1.4.4.1 For the special case 1=02, makes=
41、 + 90 sgn(2).For the special case 1=0=2, make s= 0.X1.4.5 Equation for transformation from Intrinsic system toApplication system is as follows: 5 s2 tan21tan cos ! 2 901 2 sgncos ! (X1.11)X1.4.5.1 For the special cases where tan is infinite, make=s.X1.4.6 Equation for transformation from Application
42、 sys-tem to Intrinsic system is as follows: 5 tan21Stan s2 !cos D1901 2 sgncos s2 !(X1.12)X1.4.6.1 For the special cases where tan(s) is infinite,make =s.X1.4.7 Equations for transformation from RM system toApplication system are as follows: 5 cos21sin a sin e 2 cos a cos b cos e! (X1.13) 5 902e (X1
43、.14) 5 d 2 tan21Stan a sin btan e1 tan a cos bD1901 1 sgn tan e1 cos a cos b! (X1.15)s5 d 2 b1180 (X1.16)X1.4.8 To transform from RM system to CIE system, firstuse the equations in X1.4.7 to transform to the Applicationsystem, then use the equations in X1.4.3 to transform to theCIE system.X1.4.9 Equ
44、ations for transformation from CIE system toRM system are as follows:a 5 sin21cos 12 ! cos 2!(X1.17)b 5 1801sgn2!cos21(X1.18)Ssin22cos 1cos12 !1 sin 1sin12 != 1 2 cos21cos22=1 2 cos212 ! cos22De 5 sin21cos 1cos 2! (X1.19)d 5 s1b 2 180 (X1.20)X1.4.9.1 To use Eq X1.20 requires first using Eq X1.18 too
45、btain b and equation Eq X1.5 to obtain s.X1.4.10 Equations for transformation between rotationangle and rho angle are as follows: 52tan21Stan s2 !cos D1 tan21Stan scos D(X1.21)190sgncos s2 ! 2 sgncos s! 5 s2 tan21Stan scos 2 tan cos2cos 1 tan stan D1Q (X1.22)Make Q=0 or Q=180 so as to produce in the
46、 samequadrant as .E808 01 (2016)9ASTM International takes no position respecting 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
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