1、Designation: D4061 13Standard Test Method forRetroreflectance of Horizontal Coatings1This standard is issued under the fixed designation D4061; 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 test method describes the instrumental measure-ment of the retroreflective properties of horizontal surfacingmaterials, such as traffic stri
3、pe paint systems, traffic tapes, andtraffic surface symbols.1.2 Specimen preparation, size, and shape must be deter-mined and specified by the user of this test method. Likewise,the user must specify the observation and entrance angles to beused (see Fig. 1).1.3 The geometric requirements of this te
4、st method arebased on materials for which the relative retroreflectancechanges less than approximately 50 % over the observationangle range from 0.2 to 0.5. This is illustrated in Fig. 2.1.4 This test method is a laboratory test and requires afacility that can be darkened sufficiently so that stray
5、light doesnot affect the test results. This facility must be capable ofhousing the required 15-m test distance.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety co
6、ncerns, 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.2. Referenced Documents2.1 ASTM Standards:2E284 Terminology of AppearanceE308 Pr
7、actice for Computing the Colors of Objects by Usingthe CIE SystemE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE808 Practice for Describing RetroreflectionE809 Practice for Measuring Photometric Characteristics ofRetroreflectors2.2 CIE Publication:3N
8、o. 54 Retroreflection Definition and Measurement3. Terminology3.1 The terms and definitions in Terminology E284 apply tothis test method.3.2 Definitions:3.2.1 coeffcient of retroreflected luminance, RL,nratio ofthe luminance, L, of a projected surface to the normalilluminance, E, at the surface on a
9、 plane normal to theincident light, expressed in candelas per square metre per lux(cdm2lx1).RL5 L/E! (1)3.2.2 datum mark, nin retroreflection, an indication on theretroreflector that is used to define the orientation of theretroreflector with respect to rotation about the retroreflectoraxis.3.2.2.1
10、DiscussionThe datum mark must not lie on theretroreflector axis.3.2.3 entrance angle, , nin retroreflection, angle betweenthe illumination axis and the retroreflector axis.3.2.3.1 DiscussionFor plane retroreflective surfaces, theentrance angle is no larger than 90.3.2.3.2 DiscussionThe entrance angl
11、e may be divided intocomponents 1and 2. This is described in Practice E808.Inthis test method only the component 1is used. Therefore,where only the entrance angle is specified the conventionused is 2= 0 and 1= .3.2.4 illumination axis, nin retroreflection, a line from theeffective center of the sour
12、ce aperture to the retroreflectorcenter.3.2.5 normal illuminance, Ethe illuminance on a retrore-flective surface measured in the plane that passes through the1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.
13、10 onRetroreflection.Current edition approved July 1, 2013. Published August 2013. Originallyapproved in 1989. Last previous edition approved in 2006 as D4061 94 (2006).DOI: 10.1520/D4061-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
14、iceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. National Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 0
15、1970, http:/www.cie-usnc.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1retroreflector center and is perpendicular to the illuminationaxis; measured in lux (lumensm2).3.2.6 observation angle, nangle between the axes of theinciden
16、t beam and the observed (reflected) beam, (inretroreflection, , between the illumination axis and the obser-vation axis).3.2.6.1 DiscussionThe observation angle is always posi-tive and in the context of retroreflection is restricted to smallacute angles.3.2.7 observation axis, nin retroreflection, a
17、 line from theeffective center of the receiver aperture to the retroreflectorcenter.3.2.8 receiver, nthe portion of a photometric instrumentthat receives the viewing beam from the specimen, including acollector such as an integrating sphere, if used, often themonochromator or spectral filters, the d
18、etector, and associatedoptics and electronics.3.2.9 retroreflection, nreflection in which the reflectedrays are preferentially returned in directions close to theopposite of the direction of the incident rays, this propertybeing maintained over wide variations of the direction of theincident rays. C
19、IEB3.2.10 retroreflector axis, na designated line segmentfrom the retroreflector center that is used to describe theangular position of the retroreflector.3.2.10.1 DiscussionThe direction of the retroreflector axisis usually chosen centrally among the intended directions ofillumination; for example,
20、 the direction of the road on which orwith respect to which the retroreflector is intended to bepositioned. In testing horizontal road markings the retroreflec-tor axis is usually the normal to the test surface.3.2.11 rotation angle, ,nangle indicating the orientationof the specimen when it is rotat
21、ed about a selected axis fixed init (for plane specimens, usually the specimen normal); inretroreflection, the dihedral angle from the half-plane originat-ing on the retroreflector axis and containing the positive part ofthe second axis to the half-plane originating on the retroreflec-tor axis and c
22、ontaining the datum mark.3.2.11.1 DiscussionThe rotation angle shown in Fig. 3,with the datum mark oriented away from the source, is 0.3.2.12 source, nan object that produces light or otherradiant flux.3.2.13 specific luminancesee coefficient of retroreflectedluminance.3.2.14 viewing angle, the angl
23、e between the observationaxis and the retroreflector axis.3.2.14.1 DiscussionIn testing road markings specimens,the retroreflector axis is usually the normal to the test surface(see definition of retroreflector axis).3.3 Definitions of Terms Specific to This Standard:3.3.1 co-entrance angle, c,nthe
24、complement of theentrance angle (90 ).3.3.1.1 DiscussionOn a typical test specimen, this is theangle from the plane surface of the material to the observationaxis.3.3.2 co-viewing angle, c,nthe complement of the view-ing angle (90 ).4. Summary of Test Method4.1 This test method involves the use of a
25、 light-projectorsource, a photoreceptor, a specimen holder, and a receptor-source support, all arranged with approximately 15-m separa-tion between the specimen holder and receptor-source supportin a suitable darkened area. The observation angle is generallysmall (0.2 to 2.0) and the entrance angle
26、approaches 90 (thelight is near the grazing angle).4.2 The general procedure is to determine the ratio of theretroreflected light from the test surface to the incident light onthe test surface. From these measurements, the photometricquantity, specific luminance is calculated.5. Significance and Use
27、5.1 The quantity coefficient of retroreflected luminance is ameasure of the reflected luminance in the direction of theobserver. This is the light returned by the retroreflective surfaceto the observer from the source, which in practice is the vehicleheadlamp.5.2 This test method may be used as a me
28、asure of thenighttime performance of horizontally applied surfacing mate-rials used on highway surfaces for lane markings and othertraffic control purposes.NOTE 1Includes observation angle , entrance angle , viewing anglea, co-viewing angle c, and co-entrance angle c. The retroreflector axis,illumin
29、ation axis, and observation axis all lie in the same plane.FIG. 1 Diagram Illustrating Geometry for Measurement of Hori-zontal Coatings SpecimensFIG. 2 Illustration of Typical Rate of Change of RetroreflectanceVersus Observation Angle for Horizontal Retroreflective MaterialMeasured at 86 Entrance An
30、gleD4061 1325.3 Since this test method is a laboratory procedure, testspecimens must be prepared so that they can be mounted on thespecimen holder. Specimens measured by this laboratorymethod may be used as transfer standards for the calibration ofportable instrumentation.5.4 Specimen selection and
31、preparation may significantlyinfluence the results of this test method.6. Apparatus6.1 Light Source, projector type, meeting the followingrequirements:46.1.1 Color TemperatureThe projection lamp togetherwith the projection optics shall be operated so that theyilluminate the test specimen with the sp
32、ectral energy distribu-tion of the 1931 CIE Standard Source A5(a correlated colortemperature of 2856 K). A method for determining correlatedcolor temperature is contained in Annex A3 of Practice E809.6.1.2 Exit ApertureThe source exit aperture shall be 43mm maximum diameter. This corresponds to 10 m
33、in of arcangular aperture at 15 m test distance. In practice, it isconvenient to provide the projection with a non-silvered rightangle prism so that the external physical size of the exitaperture is small, allowing its close proximity to the entranceaperture of the photoreceptor.6.1.3 Illuminated Ar
34、eaThe illumination at the specimenproduced by the projector shall be such that only the testsurface and a minimum of the background is illuminated. Thisis commonly accomplished by placing a restrictive aperture inthe projector slide port.66.1.4 Source StabilityThe source shall be regulated suchthat
35、the illumination at the test surface does not change bymore than 61 % for the duration of the test.6.1.5 Illumination UniformityThe illumination producedon the specimen surface shall be uniform within 65 % of theaverage illuminance normal to the source at the test distance.6.2 Photoreceptor,7meeting
36、 the following requirements:6.2.1 SensitivityThe photoreceptor shall have sufficientsensitivity and range so that readings of both the incidentilluminance and the retroreflected light at the observationposition can be measured with a resolution of at least 1 part in50 on the readout scale.6.2.2 Spec
37、tral ResponseThe spectral response of the pho-toreceptor shall match that of the 1931 CIE Standard PhotopicObserver.8See Annex A1 of Practice E809.6.2.3 StabilityThe receptor response shall not vary morethan 61 % for the duration of the test.4A commercial slide projector with 7-in. F-3.5 lens and wi
38、th the heat absorbingfilter removed has been found satisfactory as a light source. Such a projector mustbe run at reduced voltage to achieve the required color temperature and to provideadequate lamp stability.5See Practice E308, Table 3.6A slide with a 3- by 15-mm opening has been found satisfactor
39、y.7Commercially available instruments commonly referred to as telephotometershave been found satisfactory for this purpose.8The 1931 CIE Standard Photopic Observer is identical to the y-bar function ofthe 1931 CIE Standard Colorimetric Observer, which is tabulated in Practice E308,Table 1.FIG. 3 Arr
40、angement of Test ApparatusD4061 1336.2.4 LinearityThe linearity of the photometric scale overthe range of readings to be taken shall be within 61%.Correction factors may be used to ensure linear response. Amethod for determining linearity is contained in Practice E809,Annex A2.6.2.5 Field of ViewThe
41、 field of view shall be limited byuse of light baffles or a field aperture on the instrument so thatthe entire test specimen is fully within the field of view yet asmuch stray light is rejected as is practical. A background lightlevel less than 5 % of smallest m1reading (see 8.6) is desirable.When b
42、ackground levels are greater than 5 %, careful attentionmust be given to noise levels.6.2.5.1 In this test, the receptors field of view must alwaysbe larger than the projected area of the test specimen.6.2.6 Entrance ApertureThe photoreceptor shall be pro-vided with an entrance aperture of 43 mm max
43、imum diameter.This is equivalent to 10 min angular aperture at 15 m. Thephysical size of the entrance aperture must be small so that thephotoreceptor may be positioned physically close to the sourceexit aperture.6.3 Specimen HolderThe specimen holder, commonlycustom built to fit the desired specimen
44、 size and shape, mustmeet the following requirements (see Fig. 4 and Fig. 5).6.3.1 Angular AccuracyThe test surface must be position-able so that the entrance angle is accurate to within 0.5 % of itscomplement (that is, for 86 entrance angle, the angle must beaccurate to 0.005 4 = 0.02). This accura
45、cy may be obtainedby providing an optical means to align the test surface to 90entrance angle and then adjusting to the desired entrance angle.(See Figs. 6-9 for examples of angular setting devices.)6.3.2 Entrance Angle AxisA means must be provided tochange the entrance angle such that the axis of r
46、otation iscontained in the plane of the test surface if several entranceangles are to be used.6.3.3 Leading Edge ReflectionsThe specimen holder mustbe provided with a means of eliminating reflections from theleading edge of the specimen, and the holder itself must benon-reflective.6.3.4 Incident Lig
47、ht Measurement ProvisionIt is desirablethat the specimen holder be such that the photoreceptor caneasily be substituted for the specimen, which is required whenincident light measurements are taken.6.4 Receptor-Source SupportA device that adequatelysupports and separates the photoreceptor from the s
48、ource at theobservation position. The required accuracy of separation ofthe source exit aperture from the photoreceptor entranceaperture is dependent on the properties of the test specimen.For most horizontal surfacing materials, the divergence pat-terns are gradual and a positioning accuracy of 61m
49、m(or60.5 % of the resolution) at 15 m test distance is adequate. Acommon method of fixing this distance is to provide a bar withholes machined in it at separations corresponding to the desiredobservation angles. In this method, the minimum practicalobservation angle is about 0.2.6.5 Photometric SiteSufficient space is required so thatthe projector source and test surface can be separated by about15 m. This facility must be such that stray light does notappreciably affect the test resu
