1、Designation: E1767 11Standard Practice forSpecifying the Geometries of Observation and Measurementto Characterize the Appearance of Materials1This standard is issued under the fixed designation E1767; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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.INTRODUCTIONThe appearance of objects depends on how they are illuminated and viewed. When measureme
3、ntsare made to characterize appearance attributes such as color or gloss, the measured values depend onthe geometry of the illumination and the instrumentation receiving light from the specimen. Thispractice for specifying the geometry in such applications is largely based on an international standa
4、rdISO 5/1, dealing with the precise measurement of optical density in photographic science, based onan earlier American National Standard.2,31. Scope1.1 This practice describes the geometry of illuminating andviewing specimens and the corresponding geometry of opticalmeasurements to characterize the
5、 appearance of materials. Itestablishes terms, symbols, a coordinate system, and functionalnotation to describe the geometric orientation of a specimen,the geometry of the illumination (or optical irradiation) of aspecimen, and the geometry of collection of flux reflected ortransmitted by the specim
6、en, by a measurement standard, or bythe open sampling aperture.1.2 Optical measurements to characterize the appearance ofretroreflective materials are of such a special nature that theyare treated in other ASTM standards and are excluded from thescope of this practice.1.3 The measurement of transmit
7、ted or reflected light fromareas less than 0.5 mm in diameter may be affected by opticalcoherence, so measurements on such small areas are excludedfrom consideration in this practice, although the basic conceptsdescribed in this practice have been adopted in that field ofmeasurement.1.4 The specific
8、ation of a method of measuring the reflect-ing or transmitting properties of specimens, for the purpose ofcharacterizing appearance, is incomplete without a full descrip-tion of the spectral nature of the system, but spectral conditionsare not within the scope of this practice. The use of functional
9、notation to specify spectral conditions is described in ISO 5/1.2. Referenced Documents2.1 ASTM Standards:4E284 Terminology of Appearance2.2 Other Standard:ISO 5/1 PhotographyDensity MeasurementsPart 1:Terms, Symbols and Notations53. Terminology3.1 Definitions:3.1.1 The terminology used in this prac
10、tice is in accordancewith Terminology E284.3.2 Definitions of Terms Specific to This Standard:3.2.1 anormal angle, nan angle measured from the nor-mal, toward the reference plane, to the central axis of adistribution, which may be an angular distribution of flux in anincident beam or distribution of
11、 sensitivity of a receiver.3.2.2 aspecular angle, nthe angle subtended at the originby the specular axis and the axis of the receiver, the positivedirection being away from the specular axis.3.2.3 aspecular azimuthal angle, nthe angle subtended, atthe specular axis in a plane normal to the specular
12、axis, by theprojection of the axis of the receiver and the projection of thex-axis on that plane, measured from the projection of the x-axisin a right-handed sense with respect to the specular axis.3.2.4 efflux, nradiant flux reflected by a specimen orreflection standard, in the case of reflection o
13、bservations ormeasurements, or transmitted by a specimen or open sampling1This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and is the direct responsibility of Subcommittee E12.03 on Geometry.Current edition approved Nov. 1, 2011. Published December 2011. Originall
14、yapproved in 1995. Last previous edition approved in 2004 as E1767 04. DOI:10.1520/E1767-11.2ISO1/5 Photograhpy Density Measurements Part 1: Terms, symbols, andnotations.3ANSI PH2.361974American National Standards terms, symbols, and notationfor optical transmission and reflection measurements.4For
15、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.5Available from American National Standards Institute (ANSI), 25 W
16、. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.aperture, in the case of transmission observations or measure-ments, in the direction of the receiver.3.2.5 efflux, adjassoc
17、iated with the radiant flux reflectedby a specimen or reflection standard, in the case of reflectionobservations or measurements, or transmitted by a specimen oropen sampling aperture, in the case of transmission observa-tions or measurements, in the direction of the receiver.3.2.6 efflux region, nr
18、egion in the reference plane fromwhich flux is sensed by the observer.3.2.7 influx, nradiant flux received from the illuminator ata specimen, a reflection standard, or open sampling aperture.3.2.8 influx, adjassociated with radiant flux received fromthe illuminator at a specimen, a reflection standa
19、rd, or opensampling aperture.3.2.9 influx region, nregion in the reference plane onwhich flux is incident.3.2.10 optical modulation, na ratio indicating the magni-tude of the propagation by a specimen of radiant flux from aspecified illuminator or irradiator to a specified receiver, ageneral term fo
20、r reflectance, transmittance, reflectance factor,transmittance factor, or radiance factor.3.2.11 plane of incidence, nthe plane containing the axisof the incident beam and the normal to the reference plane.3.2.11.1 DiscussionThis plane is not defined if the axis ofthe incident beam is normal to the
21、reference plane.3.2.12 reference plane, nthe plane in which the surface ofa plane specimen is placed for observation or measurement, orin the case of a nonplanar specimen, the plane with respect towhich the measurement is made.3.2.13 sampling aperture, nthe region in the referenceplane on which a me
22、asurement is made, the intersection of theinflux region and the efflux region.3.2.14 specular axis, nthe ray resulting from specularreflection at an ideal plane mirror in the reference plane, of theray at the geometric axis of the incident beam.3.2.14.1 DiscussionThis term is applied to an incidentb
23、eam subtending a small angle at the origin, not to diffuse orannular illuminators.3.2.15 specular direction, nthe direction of the specularaxis, the positive direction being away from the origin.3.2.16 uniplanar geometry, ngeometry in which the re-ceiver is in the plane of incidence.3.3 Symbols:de =
24、 general symbol for diffuse geometry with specularcomponent excluded.di = general symbol for diffuse geometry with specularcomponent included.E = identifies the direction of the axis of an effluxdistribution on a diagram.g = general symbol, in functional notation, for effluxgeometry.G = general symb
25、ol, in functional notation, for influxgeometry.i = subscript for incident.I = identifies the direction of the axis of an influxdistribution on a diagram.m = subscript for half cone angle subtended by theentrance pupil of a test photometer.M = optical modulation.n = subscript for half cone angle subt
26、ended by a testsource.N = identifies the direction of the normal to the referenceplane on a diagram.o = point of origin of a rectangular coordinate system, inthe reference plane, at the center or centroid of thesampling aperture.r = subscript for reflected.S = identifies the specular direction on a
27、diagram.t = subscript for transmitted.x = distance from the origin, along the x-axis, in thereference plane, passing through point o.y = distance from the origin, along the y-axis, in thereference plane, passing through point o, and nor-mal to the x-axis.z = distance from the origin, along the z-axi
28、s, normal tothe reference plane, passing through point o, andhaving its positive direction in the direction of thevector component of incident flux normal to thereference plane.a = aspecular angle.b = aspecular azimuthal angle.d = in a pyramidal distribution, the half-angle measuredin the direction
29、normal to the plane of incidence. = in a pyramidal distribution, the half-angle measuredin the plane of incidence.h = azimuthal angle, measured in the reference plane,from the positive x-axis, in the direction of thepositive y-axis.u = anormal angle.k = half cone angle of a conical flux distribution
30、.F = radiant flux45a = general symbol for 45 annular geometry45c = general symbol for 45 circumferential geometry4. Summary of Practice4.1 This practice provides a method of specifying thegeometry of illuminating and viewing a material or thegeometry of instrumentation for measuring an attribute ofa
31、ppearance. In general, for measured values to correlate wellwith appearance, the geometric conditions of measurementmust simulate the conditions of viewing.5. Significance and Use5.1 This practice is for the use of manufacturers and users ofequipment for visual appraisal or measurement of appearance
32、,those writing standards related to such equipment, and otherswho wish to specify precisely conditions of viewing ormeasuring attributes of appearance. The use of this practicemakes such specifications concise and unambiguous. Thefunctional notation facilitates direct comparisons of the geo-metric s
33、pecifications of viewing situations and measuringinstruments.6. Coordinate System6.1 The standard coordinate system is illustrated in Fig. 1.Itis a left-handed rectangular coordinate system, following theE1767 112usual optical convention of incident and transmitted flux in thepositive direction and
34、the usual convention for the orientationof x and y for the reflection case. The coordinates are related toa reference plane in which the first surface of the specimen isplaced for observation or measurement. The origin is in thereference plane at the center or centroid of the samplingaperture.6.2 In
35、struments are usually designed to minimize the varia-tion of the product of illumination and receiver sensitivity, as afunction of the azimuthal direction. That practice minimizesthe variation in modulation as the specimen is rotated in itsown plane. Even in instruments with an integrating sphere,re
36、sidual variation of the product, known as “directionality,” cancause variations in measurements of textured specimens ro-tated in their plane. To minimize variation among routineproduct measurements due to this effect, the “warp,” “grain,”or other “machine direction” of specimens must be consistentl
37、yoriented with respect to the x-axis, which is directed accordingto the following rules, intended to place the positive x-axis inthe azimuthal direction for which the product of illuminationand receiver sensitivity is a minimum.6.2.1 For an integrating-sphere instrument with diffuse illu-mination, t
38、he positive x-axis is directed toward the projectionof the center of the exit port on the reference plane.6.2.2 For an integrating-sphere instrument with diffuse col-lection, the positive x-axis is directed toward the projection ofthe center of the entrance port on the reference plane.6.2.3 For an i
39、nstrument with annular (circumferential)45:0 or 0:45 geometry, the positive x-axis is in theazimuthal direction for which the product of illumination andreceiver sensitivity is a minimum.6.2.4 For an instrument with highly directional illumination,off the normal, such as is used in the measurement o
40、f gloss orgoniochromatism, the positive x-axis is directed along theprojection of the specular direction on the reference plane.6.3 Anormal angles are specified with respect to rayspassing through the origin. (In a later section of this standard,allowance is made for the size of the sampling apertur
41、e by thetolerances on the influx and efflux angles.) Anormal angles ofincident and reflected rays are measured from the negativez-axis. Anormal angles of transmitted rays are measured fromthe positive z-axis.6.4 The azimuthal angle of a ray is the angle h, measured inthe reference plane from the pos
42、itive x-axis in the direction ofthe positive y-axis, to the projection of the ray on the referenceplane. The direction of a ray is given by u and h, in that order.Angle h is less than 360 and u is 180 or less, and usually lessthan 90.6.5 In gonioradiometry and goniospectrometry, the effluxangle uror
43、 utmay be measured from the normal, but forreflection measurements to characterize goniochromatism, it isoften measured from the specular axis. The aspecular angle ais the angle subtended at the origin by the specular axis and theaxis of the receiver. In most gonioradiometric measurements,the axis o
44、f the receiver is in the plane of incidence and theaspecular angle is measured in that plane. In that case, thepositive direction of a is from the specular direction toward thenormal.6.6 If the axis of the receiver is not in the plane of incidence,the direction of the axis may be described in terms
45、of anormaland azimuthal angles, as defined in 6.5, but an aspecularazimuthal angle b may be useful. The aspecular azimuthalangle is a special kind of azimuthal angle, measured in a planenormal to the specular axis, with positive direction in theright-handed sense. (With the right thumb along the spe
46、cularaxis and directed away from the origin, the right hand fingerspoint in the positive direction of b.) See Fig. 2. The aspecularazimuthal angle is measured from the projection of the x-axison the plane normal to the specular axis, to the direction of theaxis of the receiver. As the angle of incid
47、ence approaches zeroFIG. 1 Coordinate System for Describing the Geometric Factors Affecting Transmission and Reflection MeasuresE1767 113(near normal to the specimen), the aspecular azimuthal angleapproaches the azimuthal angle. Aspecular angular excursionsof the receiver may be completely described
48、 in terms of thecomponents a and b. When a and b are used to define thedirection of the receiver, a is always positive.6.7 Subscripts i, r, and t are used to identify fluxes or theangles describing them as incident, reflected, or transmitted,respectively.6.8 If specimen thickness must be taken into
49、account, effluxangles may be described relative to a secondary origin o8displaced in the positive z direction by the thickness h of thespecimen. Then x8 = x, y8 = y, and z8 = z-h.7. Conical Description7.1 Given this standard coordinate system, any distributionof the influx and efflux may be described, but the descriptionmay be very complicated. Fortunately, most such distributionsin instruments used to measure appearance can be approxi-mated by uniform pencils bounded by right circular cones. Theeye, the receiver in the case of visual observat
