1、Designation: E 810 03 (Reapproved 2008)Standard Test Method forCoefficient of Retroreflection of Retroreflective SheetingUtilizing the Coplanar Geometry1This standard is issued under the fixed designation E 810; the number immediately following the designation indicates the year oforiginal adoption
2、or, in the case of revision, the year of last revision. 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 an instrument measurementof the retroreflective p
3、erformance 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 doe
4、s not 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 t
5、est method, are utilized. In this case themethods of Procedure B in Practice E 809 apply. Additionalinformation on the use of portable retroreflectometers may befound in Test Method E 1709.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is
6、 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 AppearanceE 308 Practice for Computing the Colors of Objects b
7、yUsing the CIE SystemE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 808 Practice for Describing RetroreflectionE 809 Practice for Measuring Photometric Characteristicsof RetroreflectorsE 1709 Test Method for Measurement of RetroreflectiveSigns Usin
8、g a Portable Retroreflectometer2.2 Other Document:CIE Publication No 54 RetroreflectionDefinition andMeasurement33. Terminology3.1 The terms and definitions in Terminology E 284 andPractice E 808 apply to this test method.3.2 Definitions:3.2.1 coeffcient of retroreflection, RAof a plane retrore-flec
9、ting 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 (cdfc1ft2). The SI an
10、d 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 R8.The term coefficient of retroreflection and the symbol RAalongwith the SI units of candel
11、as 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 area of retrore-flecti
12、ve 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 plane.3.2.2.1 Discuss
13、ionIn the coplanar geometry: the secondentrance angle component, b2, is equal to 0; presentationangle, g, is equal to either 0 or 180; orientation angle, vs,isequal to either the rotation angle, e,ortoe + 180 or e 180.1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appe
14、arance and is the direct responsibility of Subcommittee E12.10 onRetroreflection.Current edition approved Feb. 1, 2008. Published February 2008. Originallyapproved in 1981. Last previous edition approved in 2003 as E 810 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcont
15、act 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 (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consulta
16、nts, 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.3.2.3 datum axis, na designated half-line from the retrore-flector center perpendicular to the retroreflector axis.3.2.4 da
17、tum mark, n an indication on the retroreflector,off the retroreflector axis, that establishes the direction of thedatum axis.3.2.5 entrance angle, b, nthe angle between the illumi-nation axis and the retroreflector axis.3.2.5.1 DiscussionThe entrance angle is usually no largerthan 90, but for comple
18、teness its full range is defined as 0 #b # 180. In the CIE (goniometer system) b is resolved intotwo components b1and b2. Since by definition b is alwayspositive, the common practice of referring to the small entranceangles that direct specular reflections away from the photore-ceptor as a negative
19、value is deprecated by ASTM. Therecommendation is to designate such negative values asbelonging to b1.3.2.6 goniometer, nan instrument for measuring or settingangles.3.2.7 illumination axis, nthe half-line from the retrore-flector center through the source point.3.2.8 observation angle, a, nthe angl
20、e between the illu-mination axis and the observation axis.3.2.8.1 DiscussionThe observation angle is never nega-tive and is almost always less than 10 and usually no morethan 2. The full range is defined as 0 # a 180.3.2.9 observation axis, nthe half-line from the retroreflec-tor center through the
21、observation point.3.2.10 receiver, n the 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.3.2.11 retroreflec
22、tion, 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. CIEB3.2.12 retroreflective material, na material that has a thin
23、continuous layer of small retroreflective elements on or verynear its exposed surface (for example, retroreflective sheeting,retroreflective fabrics, transfer films, beaded paint, highwaysurface signs, or pavement striping).3.2.13 retroreflective sheetinga retroreflective materialpreassembled as a t
24、hin film ready for use.3.2.14 retroreflector, na reflecting surface or device fromwhich, when directionally irradiated, the reflected rays arepreferentially returned in directions close to the opposite of thedirection of the incident rays, this property being maintainedover wide variations of the di
25、rection of the incident rays. CIE,1982B3.2.15 retroreflector axis, na designated half-line from theretroreflector center.3.2.15.1 DiscussionThe direction of the retroreflector axisis usually chosen centrally among the intended directions ofillumination; for example, the direction of the road on whic
26、h orwith respect to which the retroreflector is intended to bepositioned. The retroreflector axis usually coincides with theaxis 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
27、 near aretroreflector that is designated to be the location of the device.3.2.17 rotation angle, e, nthe angle in a plane perpendicu-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 Discussi
28、on Range: 180 e # 180. The defi-nition is applicable when entrance angle and viewing angle areless than 90. More generally, rotation 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 DiscussionRota
29、tion of the sample about the ret-roreflector axis while the source and receiver remain fixed inspace changes the rotation angle (e) and the orientation angle(vs) equally.3.2.18 rotationally uniform, adjhaving substantially con-stant RA, when rotated about the retroreflector axis, while thesource, re
30、ceiver, retroreflector center and retroreflector axis allremain in a fixed spatial relation.3.2.18.1 DiscussionThe degree of rotational 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
31、 use of a light projectorsource, a receiver, a device to position the receiver with respectto the source and a test specimen holder 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 retro
32、reflected from the test surface to that incidenton the test surface.4.3 The photometric quantity, coefficient of retroreflection,is calculated from these measurements.5. Significance and Use5.1 Measurements made by this test method are related tovisual observations of retroreflective sheeting as see
33、n by thehuman eye when illuminated by tungsten-filament light sourcessuch as a motor vehicle headlamp.5.2 The values determined relate 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 a
34、ngles between 0.1 and 2.0 (observation anglesbetween 0.1 and 0.2 may be achieved by careful design ofsource and receiver aperture configuration), 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 cdlx1m
35、2special attention must be given to theresponsivity of the receiver and to the elimination of very smallamounts of stray light.6. Apparatus6.1 Light SourceThe light source shall be of the projectortype and shall meet the following requirements (an illuminanceE 810 03 (2008)2at the 15 m specimen dist
36、ance of about 10 lx is commonlyavailable within these restrictions):6.1.1 The spectral energy distribution of the source shall beproportional to CIE standard Source A (a correlated colortemperature of 2856 K, see Practice E 308). The projectionlamp together with the projection optics shall be operat
37、ed suchthat it illuminates the test specimen with this spectral powerdistribution.6.1.2 An unpolarizing light source shall be used.6.1.3 The source aperture shall be a standard circularaperture as defined in Practice E 809. For measurements atobservation angles (a) of 0.2# a #2.0, the exit aperture
38、ofthe source shall be uniformly radiant, circular and 26 mm (62mm) in diameter. This corresponds to 0.1 angular aperture at15 m test distance. For measurements at observation angles (a)of 0.1 # a 0.2, the exit aperture of the source shall beuniformly radiant, circular and 13 mm (61 mm) in diameter.T
39、his 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 the test specimen and only aminimum of the background is illuminated. This is commonlyaccomplished by placing a restrictive aperture in the projectorslide po
40、rt.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 test.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
41、.2 ReceiverThe receiver shall meet the requirements thatfollow. (In this test, for 10 lx incident upon a 1 cdlx1m2retroreflective sheeting test specimen with area of 0.04 m2, theincident normal illuminance at the receiver will be about1.8 3 103lx).6.2.1 The responsivity and range of the receiver sha
42、ll besufficient so that readings of both the incident normal illumi-nance (at the specimen) and the retroreflected light at theobservation position 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 19
43、31 CIE Standard Photopic Observer (see AnnexA1 of Practice E 809).6.2.3 The receiver shall be insensitive to the polarization oflight.6.2.4 The linearity of the photometric scale over the rangeof readings to be taken shall be within 61 %. Correctionfactors may be used to ensure a linear response. Li
44、nearityverification tests must be made utilizing the entire receiverreadout device including the detector, load, range selectionsystem and readout display 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
45、 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 within 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
46、The receiver aperture shall be a standard circularaperture as defined in Practice E 809. For measurements atobservation angles (a) of 0.2#a#2.0, the receiver shall beprovided with an entrance aperture 26 mm (62 mm) indiameter. This corresponds to 0.1 angular aperture at 15 m testdistance. For measur
47、ements at observation angles (a) of 0.1#a 0.2, the receiver shall be provided with an entranceaperture 13 mm (61 mm) in diameter. This corresponds to a0.05 angular aperture at 15 m test distance. The size of theentrance aperture stop must be small so that the receiver maybe positioned physically clo
48、se to the source exit aperturewithout shadowing any of the illuminating light beam.6.3 Test Specimen Goniometer (Test Specimen Holder)The specimen holder must 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
49、 contained in the plane of the specimen surface if severalentrance angles are to be used.6.3.1.1 The entrance angle component b1is used to set thegoniometer when no specific component is specified (seePractice E 808).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 3 60 = 60.3). This is obtainable by providingan accurate optical means to a
