1、Designation: D 4061 94 (Reapproved 2006)Standard Test Method forRetroreflectance of Horizontal Coatings1This standard is issued under the fixed designation D 4061; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. 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 This test method describes the instrumental measure-ment of the retroreflective properties of horizontal surfacingmaterials,
3、 such as traffic stripe 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 re
4、quirements of this test 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 suffic
5、iently so that stray 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 as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to addre
6、ss 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.2. Referenced Documents2.1 ASTM Standards:2E 284 Terminolo
7、gy of AppearanceE 308 Practice for Computing the Colors of Objects byUsing the CIE SystemE 808 Practice for Describing RetroreflectionE 809 Practice for Measuring Photometric Characteristicsof Retroreflectors2.2 CIE Publication:3No. 54 Retroreflection Definition and Measurement3. Terminology3.1 The
8、terms and definitions in Terminology E 284 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 normal illumi-nance, E, at the surface on a plane normal to the incidentlight, expressed in candelas per squa
9、re 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 DiscussionThe datum mark must not lie on theretroreflector axis.1T
10、his test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.10 onRetroreflection.Current edition approved July 1, 2006. Published July 2006. Originally approvedin 1989. Last previous edition approved in 2000 as D 4061 94
11、 (2000).2For referenced 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.3Available from U.S. National Committee of the CIE (I
12、nternational Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970.NOTE 1Includes observation angle a, entrance angle b, viewing anglena, co-viewing angle nc, and co-entrance angle bc. The retroreflector axis,illumination axis, and observation a
13、xis all lie in the same plane.FIG. 1 Diagram Illustrating Geometry for Measurement ofHorizontal Coatings Specimens1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3 entrance angle, b, nin retroreflection, angle be-tween the illumi
14、nation 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 angle may be dividedinto components b1and b2. This is described in Practice E 808.In this test method only the component b1is used. Ther
15、efore,where only the entrance angle b is specified the conventionused is b2= 0 and b1= b.3.2.4 illumination axis, n in retroreflection, a line fromthe effective center of the source aperture to the retroreflectorcenter.3.2.5 normal illuminance, E the illuminance on a ret-roreflective surface measure
16、d in the plane that passes throughthe retroreflector center and is perpendicular to the illuminationaxis; measured in lux (lumensm2).3.2.6 observation angle, nangle between the axes of theincident beam and the observed (reflected) beam, (in retrore-flection, a, between the illumination axis and the
17、observationaxis).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, n in retroreflection, a line from theeffective center of the receiver aperture to the retroreflectorcenter.3.2.8 receiver, nth
18、e 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 detector, and associatedoptics and electronics.3.2.9 retroreflection, nreflection in which the reflected
19、rays 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. CIEB3.2.10 retroreflector axis, na designated line segmentfrom the retroreflector center that is used to
20、 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, the direction of the road on which orwith respect to which the retroreflector is intended to bepositio
21、ned. In testing horizontal road markings the retroreflec-tor axis is usually the normal to the test surface.3.2.11 rotation angle, e, nangle indicating the orientationof the specimen when it is rotated about a selected axis fixed init (for plane specimens, usually the specimen normal); inretroreflec
22、tion, 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 containing the datum mark.3.2.11.1 DiscussionThe rotation angle shown in Fig. 3,with the datum mark or
23、iented 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, nthe angle between the observationaxis and the retroreflector axis.3.2.14.1 DiscussionIn testing road marking
24、s 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, bc, nthe complement of theentrance angle (90 b).3.3.1.1 DiscussionOn a typical test specimen, this is thean
25、gle from the plane surface of the material to the observationaxis.3.3.2 co-viewing angle, nc, nthe complement of the view-ing angle (90 h).4. Summary of Test Method4.1 This test method involves the use of a light-projectorsource, a photoreceptor, a specimen holder, and a receptor-source support, all
26、 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 approaches 90 (thelight is near the grazing angle).4.2 The general procedure is to determine t
27、he 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 Use5.1 The quantity coefficient of retroreflected luminance is ameasure of the reflected luminanc
28、e 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 measure of thenighttime performance of horizontally applied surfacing mate-rials used on highway
29、 surfaces for lane markings and othertraffic control purposes.5.3 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 ofpo
30、rtable instrumentation.FIG. 2 Illustration of Typical Rate of Change of RetroreflectanceVersus Observation Angle for Horizontal Retroreflective MaterialMeasured at 86 Entrance AngleD 4061 94 (2006)25.4 Specimen selection and preparation may significantlyinfluence the results of this test method.6. A
31、pparatus6.1 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 spectral energy distribu-tion of the 1931 CIE Standard Source A5(a correlated
32、 colortemperature of 2856 K). A method for determining correlatedcolor temperature is contained in Annex A3 of Practice E 809.6.1.2 Exit ApertureThe source exit aperture shall be 43mm maximum diameter. This corresponds to 10 min of arcangular aperture at 15 m test distance. In practice, it isconveni
33、ent 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 AreaThe illumination at the specimenproduced by the projector shall be such
34、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 the illumination at the test surface does not change bymore than 61 % for
35、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 the following requirements:6.2.1 SensitivityThe photoreceptor shall have
36、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 Spectral ResponseThe spectral response of the pho-toreceptor shall match that
37、of the 1931 CIE Standard PhotopicObserver.8See Annex A1 of Practice E 809.6.2.3 StabilityThe receptor response shall not vary morethan 61 % for the duration of the test.6.2.4 LinearityThe linearity of the photometric scale overthe range of readings to be taken shall be within 61%.4A commercial slide
38、 projector with 7-in. F-3.5 lens and with 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 E 308, Table 3.6A slide with a 3- by
39、15-mm opening has been found satisfactory.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 tabul
40、ated in Practice E 308,Table 1.FIG. 3 Arrangement of Test ApparatusD 4061 94 (2006)3Correction factors may be used to ensure linear response. Amethod for determining linearity is contained in PracticeE 809, Annex A2.6.2.5 Field of ViewThe field of view shall be limited byuse of light baffles or a fi
41、eld 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 background levels are greater than 5 %, careful attentionmust b
42、e 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 maximum diameter.This is equivalent to 10 min angular aperture at
43、 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 size and shape, mustmeet the following requirements (see Fig.
44、 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 3 4 = 0.02). This accuracy may be ob-tained by providing an optical means to align t
45、he test surface to90 entrance angle and then adjusting to the desired entranceangle. (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 rotation iscontained in the plane of the test surface if se
46、veral 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 Light Measurement ProvisionIt is desirablethat the specimen h
47、older 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 source at theobservation position. The required accuracy of
48、 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 61mm(or60.5 % of the resolution) at 15 m test distance is ade
49、quate. 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 results. Flat black paint, blackcurtains, black tape, and other means shall be used to
