1、Designation: E810 03 (Reapproved 2013)Standard Test Method forCoefficient of Retroreflection of Retroreflective SheetingUtilizing the Coplanar Geometry1This standard is issued under the fixed designation E810; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, the year 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 test method describes an instrument measurementof the retroreflective perf
3、ormance of retroreflective sheeting.1.2 The user of this test method must specify the entranceand observation angles to be used, and may specify the rotationangles.1.3 This test method is intended as a laboratory test andrequires a facility that can be darkened sufficiently so that straylight does n
4、ot affect the test results. The testing apparatus mustbe able to achieve the coplanar geometry.1.4 Portable and bench retroreflection measuring equipmentmay be used to determine RAvalues provided the geometry andappropriate substitution standard reference panels, measured inaccordance with this test
5、 method, are utilized. In this case themethods of Procedure B in Practice E809 apply. Additionalinformation on the use of portable retroreflectometers may befound in Test Method E1709.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is ther
6、esponsibility 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 Practice for Computing the Colors of Objects by Using
7、the CIE SystemE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE808 Practice for Describing RetroreflectionE809 Practice for Measuring Photometric Characteristics ofRetroreflectorsE1709 Test Method for Measurement of RetroreflectiveSigns Using a Portabl
8、e Retroreflectometer at a 0.2 DegreeObservation Angle2.2 Other Document:CIE Publication No 54 RetroreflectionDefinition andMeasurement33. Terminology3.1 The terms and definitions in Terminology E284 andPractice E808 apply to this test method.3.2 Definitions:3.2.1 coeffcient of retroreflection, RAof
9、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.3.2.1.1 DiscussionThe equivalent inchpound units forcoefficient of retroreflection are candelas per foot-candle persquare foot (
10、cdfc1ft2). The SI and inch pound units arenumerically equal, because the units of RAreduce to 1/sr. Anequivalent term used for coefficient of retroreflection is specificintensity per unit area, with symbol SIA or the CIE symbol R.The term coefficient of retroreflection and the symbol RAalongwith the
11、 SI units of candelas per lux per square meter(cdlx1m2) are recommended by ASTM.3.2.1.2 DiscussionRAis a useful engineering quantity fordetermining the photometric performance of such retroreflec-tive surfaces as highway delineators or warning devices. RAmay also be used to determine the minimum are
12、a of retrore-flective sheeting necessary for a desired level of photometricperformance. RAhas been used extensively in the specificationof retroreflective sheeting.3.2.2 coplanar geometry, nretroreflection geometry inwhich the retroreflector axis, illumination axis, and observationaxis lie in one pl
13、ane.3.2.2.1 DiscussionIn the coplanar geometry: the secondentrance angle component, 2, is equal to 0; presentationangle, , is equal to either 0 or 180; orientation angle, s,isequal to either the rotation angle, ,orto + 180 or 180.1This test method is under the jurisdiction of ASTM Committee E12 on C
14、olorand Appearance and is the direct responsibility of Subcommittee E12.10 onRetroreflection.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 1981. Last previous edition approved in 2008 as E810 03 (2008).DOI: 10.1520/E0810-03R13.2For referenced ASTM standards, vi
15、sit 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 the CIE Webshop at http:/www.cie.co.at.Copyright ASTM International, 100 Barr H
16、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 datum axis, na designated half-line from the retrore-flector center perpendicular to the retroreflector axis.3.2.4 datum mark, nan indication on the retroreflector, offthe retroreflector axis, that establishes the direct
17、ion of thedatum axis.3.2.5 entrance angle, ,nthe angle between the illumina-tion axis and the retroreflector axis.3.2.5.1 DiscussionThe entrance angle is usually no largerthan 90, but for completeness its full range is defined as 0 180. In the CIE (goniometer system) is resolved into twocomponents 1
18、and 2. Since by definition is always positive,the common practice of referring to the small entrance anglesthat direct specular reflections away from the photoreceptor asa negative value is deprecated byASTM. The recommendationis to designate such negative values as belonging to 1.3.2.6 goniometer,
19、nan instrument for measuring or settingangles.3.2.7 illumination axis, nthe half-line from the retroreflec-tor center through the source point.3.2.8 observation angle, ,nthe angle between the illu-mination axis and the observation axis.3.2.8.1 DiscussionThe observation angle is never nega-tive and i
20、s almost always less than 10 and usually no morethan 2. The full range is defined as 0 180.3.2.9 observation axis, nthe half-line from the retroreflec-tor center through the observation point.3.2.10 receiver, nthe portion of a photometric instrumentthat receives the viewing beam from the specimen, i
21、ncluding acollector such as an integrating sphere, if used, often themonochromator or spectral filters, the detector, and associatedoptics and electronics.3.2.11 retroreflection, nreflection in which the reflectedrays are preferentially returned in directions close to theopposite of the direction of
22、 the incident rays, this propertybeing maintained over wide variations of the direction of theincident rays. CIEB3.2.12 retroreflective material, na material that has a thincontinuous layer of small retroreflective elements on or verynear its exposed surface (for example, retroreflective sheeting,re
23、troreflective fabrics, transfer films, beaded paint, highwaysurface signs, or pavement striping).3.2.13 retroreflective sheeting, na retroreflective materialpreassembled as a thin film ready for use.3.2.14 retroreflector, na reflecting surface or device fromwhich, when directionally irradiated, the
24、reflected rays arepreferentially returned in directions close to the opposite of thedirection of the incident rays, this property being maintainedover wide variations of the direction of the incident rays. CIE,1982B3.2.15 retroreflector axis, na designated half-line from theretroreflector center.3.2
25、.15.1 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 bepositioned. The retroreflector axis usually coincides with the
26、axis of symmetry of the retroreflector. For retroreflectivesheeting the normal to the surface is chosen as the retroreflectoraxis.3.2.16 retroreflector center, nthe point on or near a ret-roreflector that is designated to be the location of the device.3.2.17 rotation angle, ,nthe angle in a plane pe
27、rpendicu-lar to the retroreflector axis from the observation half-plane tothe datum axis, measured counterclockwise from a viewpointon the retroreflector axis.3.2.17.1 DiscussionRange: 180 180. The defini-tion is applicable when entrance angle and viewing angle areless than 90. More generally, rotat
28、ion angle is the angle fromthe positive part of second axis to the datum axis, measuredcounterclockwise from a viewpoint on the retroreflector axis.3.2.17.2 DiscussionRotation of the sample about the ret-roreflector axis while the source and receiver remain fixed inspace changes the rotation angle (
29、) and the orientation angle(s) equally.3.2.18 rotationally uniform, adjhaving substantially con-stant RA, when rotated about the retroreflector axis, while thesource, receiver, retroreflector center and retroreflector axis allremain in a fixed spatial relation.3.2.18.1 DiscussionThe degree of rotati
30、onal uniformitycan be specified numerically.3.2.19 source, nan object that produces light or otherradiant flux.4. Summary of Test Method4.1 This test method involves the use of a light projectorsource, a receiver, a device to position the receiver with respectto the source and a test specimen holder
31、 in a suitable darkenedarea. The specimen holder is separated from the light source by15 m.4.2 The general procedure involved is to determine the ratioof the light retroreflected from the test surface to that incidenton the test surface.4.3 The photometric quantity, coefficient of retroreflection,is
32、 calculated from these measurements.5. Significance and Use5.1 Measurements made by this test method are related tovisual observations of retroreflective sheeting as seen by thehuman eye when illuminated by tungsten-filament light sourcessuch as a motor vehicle headlamp.5.2 The values determined rel
33、ate to the visual effects for agiven geometric configuration as specified by the user of thetest method. This test method has been found useful for tests atobservation angles between 0.1 and 2.0 (observation anglesbetween 0.1 and 0.2 may be achieved by careful design ofsource and receiver aperture c
34、onfiguration), and at entranceangles up to 60. It has been used to determine coefficient ofretroreflection values as low as 0.1 cdlx1m2, but for valuesless than 1 cdlx1m2special attention must be given to theresponsivity of the receiver and to the elimination of very smallamounts of stray light.E810
35、 03 (2013)26. Apparatus6.1 Light SourceThe light source shall be of the projectortype and shall meet the following requirements (an illuminanceat the 15 m specimen distance of about 10 lx is commonlyavailable within these restrictions):6.1.1 The spectral energy distribution of the source shall bepro
36、portional to CIE standard Source A (a correlated colortemperature of 2856 K, see Practice E308). The projectionlamp together with the projection optics shall be operated suchthat it illuminates the test specimen with this spectral powerdistribution.6.1.2 An unpolarizing light source shall be used.6.
37、1.3 The source aperture shall be a standard circularaperture as defined in Practice E809. For measurements atobservation angles () of 0.2 2.0, the exit aperture ofthe source shall be uniformly radiant, circular and 26 mm (62mm) in diameter. This corresponds to 0.1 angular aperture at15 m test distan
38、ce. For measurements at observation angles ()of 0.1 0.2, the exit aperture of the source shall beuniformly radiant, circular and 13 mm (61 mm) in diameter.This corresponds to 0.05 angular aperture at 15 m testdistance.6.1.4 The illumination at the sample produced by theprojector shall be such that t
39、he test specimen and only aminimum of the background is illuminated. This is commonlyaccomplished by placing a restrictive aperture in the projectorslide port.6.1.5 The source shall be regulated such that the illumi-nance at the test surface does not change by more than 61%for the duration of the te
40、st.6.1.6 The illuminance produced on the sample surface shallbe uniform within 65 % of the average illuminance normal tothe source at the distance of 15 m.6.2 ReceiverThe receiver shall meet the requirements thatfollow. (In this test, for 10 lx incident upon a 1 cdlx1m2retroreflective sheeting test
41、specimen with area of 0.04 m2, theincident normal illuminance at the receiver will be about1.8103lx).6.2.1 The responsivity and range of the receiver shall besufficient so that readings of both the incident normal illumi-nance (at the specimen) and the retroreflected light at theobservation position
42、 can be measured with a resolution of atleast 1 part in 50 on the readout scale.6.2.2 The spectral responsivity of the receiver shall matchthat of the 1931 CIE Standard Photopic Observer (see AnnexA1 of Practice E809).6.2.3 The receiver shall be insensitive to the polarization oflight.6.2.4 The line
43、arity of the photometric scale over the rangeof readings to be taken shall be within 61 %. Correctionfactors may be used to ensure a linear response. Linearityverification tests must be made utilizing the entire receiverreadout device including the detector, load, range selectionsystem and readout d
44、isplay device.6.2.5 The stability of the receiver shall be such that readingsfrom a constant source do not vary any more than 1 % for theduration of the test.6.2.6 The field of view shall be limited by use of lightbaffles or a field aperture on the instrument so that the entiretest sample is fully w
45、ithin the field of view, rejecting stray lightas much as practical.Abackground light level mbless than 5 %of the smallest m1reading is acceptable.6.2.7 The receiver aperture shall be a standard circularaperture as defined in Practice E809. For measurements atobservation angles () of 0.2 2.0, the rec
46、eiver shall beprovided with an entrance aperture 26 mm (62 mm) indiameter. This corresponds to 0.1 angular aperture at 15 m testdistance. For measurements at observation angles () of 0.1 0.2, the receiver shall be provided with an entranceaperture 13 mm (61 mm) in diameter. This corresponds to a0.05
47、 angular aperture at 15 m test distance. The size of theentrance aperture stop must be small so that the receiver maybe positioned physically close to the source exit aperturewithout shadowing any of the illuminating light beam.6.3 Test Specimen Goniometer (Test Specimen Holder)The specimen holder m
48、ust hold a 200 mm square specimen andmeet the following requirements (see Fig. 1):6.3.1 A means must be provided to rotate the specimen onan axis contained in the plane of the specimen surface if severalentrance angles are to be used.6.3.1.1 The entrance angle component 1is used to set thegoniometer
49、 when no specific component is specified (seePractice E808).6.3.2 The specimen surface must be positionable so that theentrance angle is accurate to within 0.5 % of its complement(that is, for a 30 entrance angle this angle must be accuratelyset to 6 0.005 60 = 60.3). This is obtainable by providingan accurate optical means to align the test surface to the “ 0degree” entrance angle and then adjusting the angular setting(within the requi
