SAE J 964-2003 Recommended Practice for Measuring Haze and Reflectance of Mirrors.pdf

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4、70 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit HTTP:/STANDARDS.SAE.ORG/J964_2016111 SURFACE VEHICLE RECOMMENDED PRACTICE J964 NOV2016 Issued 1966-06 Revised 1998-01R

5、eaffirmed 2016-11 Superseding J964 FEB2009 Recommended Practice for Measuring Haze and Reflectance of Mirrors RATIONALE J964 has been reaffirmed to comply with the SAE five year review policy. 1. ScopeThis SAE Recommended Practice describes methods for determining total and specular reflectancefor m

6、irrors with flat and curved surfaces and a method for determining diffuse reflectance and haze for mirrorswith flat surfaces.2. References 2.1 Applicable PublicationsThe following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated, the latest revi

7、sion of SAE publications shall apply.2.1.1 SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J264Vision Glossary2.1.2 ASTM PUBLICATIONAvailable from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.ASTM E 429Standard Test Method for Measurement and

8、 Calculation of Reflecting Characteristics ofMetallic Surfaces Using Integrating Sphere Instruments 3. Apparatus3.1 General DescriptionThe apparatus shall consist of a light source, a sample holder, a receiver unit with aphotodetector and indicating meter and a means for negating the effects of extr

9、aneous light. (See Figures 1,2, and 3.)When measuring non-flat (convex or aspheric) mirrors or measuring diffuse reflectance, the receiver shallincorporate a light-integrating sphere. (See Figure 1.)3.1.1 When measuring diffuse reflectance, the receiver unit shall incorporate a light-integrating sph

10、ere with meansfor excluding the specular beam. (See Figure 2.)3.1.2 When measuring prismatic mirrors, the apparatus shall measure only specularly reflected light and have ameans for separately measuring the light reflected from the front and back surfaces of the prism. (SeeFigure 3.)FIGURE 1SCHEMATI

11、C OF REFLECTOMETER WITH A FIXED RECEIVER AND A SAMPLE HOLDERWHICH LOCATES THE SAMPLE DIRECTLY ADJACENT TO THE SPHERE. THIS UNIT CAN BE USEDTO MEASURE TOTAL REFLECTANCE OF FLAT AND NON-FLAT MIRRORS.FIGURE 2SCHEMATIC OF A REFLECTOMETER WITH THE MEANS FOR EXCLUDING THE SPECULARLYREFLECTED BEAM. THIS UN

12、IT COULD BE USED FOR MEASURING TOTAL REFLECTANCE OF FLAT ANDNON-FLAT MIRRORS, AND DIFFUSE REFLECTANCE OF FLAT MIRRORS._ SAE INTERNATIONAL J964 NOV2016 1 of 4FIGURE 3SCHEMATIC OF A GENERALIZED REFLECTOMETER WITH MOVEABLE DETECTOR. TO USE THEDIRECT CALIBRATON METHOD, THE DETECTOR IS LOCATED DIRECTLY I

13、N LINE WITH THE LIGHT SOURCE.TO MEASURE REFLECTANCE, THE DETECTOR IS MOVED TO INTERCEPT THE BEAMS SPECULARLYREFLECTED FROM SURFACES OF THE MIRRORS.3.2 Characteristics of the Light SourceThe light source shall consist of an incandescent tungsten filamentlamp operating at a nominal color temperature o

14、f 2856 K (CIE Illuminant A), or any combination of light sourceand filters which provide the equivalent of Illuminant A. Optics associated with the source shall provide a nearcollimated beam. A voltage stabilizer is recommended for maintaining a fixed lamp voltage during instrumentoperation.When the

15、 receiver does not include an integrating sphere, the reflected beam shall cover at least 50%, but notmore than 100%, of the sensitive area of the photodetector. The beam should cover the same section of thephotodetector during measurements as was covered during calibration. 3.3 Characteristics of t

16、he ReceiverThe spectral response of the receiver shall match the 1924 CIE standardluminous efficiency function V() for photopic vision. Any combination of photodetector and filters which givesthe equivalent of V() may be used.3.4 Characteristics of the Integrating SphereWhen an integrating sphere is

17、 used in the receiver section, itshall have a minimum diameter of 127 mm (5 in). The interior surface of the sphere shall be coated with amatte (diffusive) spectrally non-selective white coating. The ports for the sample, the incident beam, andspecularly reflected beam (if present) shall be large en

18、ough to admit the entire beam, but shall not, in total,exceed 5% of the area of the sphere._ SAE INTERNATIONAL J964 NOV2016 2 of 4The photodetector shall be located so that it cannot receive direct light from either the incident or reflectedbeams.If diffuse reflectance is to be measured, the sphere

19、shall have an additional port for the exclusion of thespecularly reflected beam. (See Figure 2.) This port shall be located such that the reflected beam is centeredin it and shall be large enough that the beam is surrounded by an annulus of 0.6 degrees 0.2 degrees asmeasured from the sample port. Tw

20、o covers should be provided for this port: a black cover or light trap and awhite cover with a coating similar to the interior of the sphere. The first is used when measuring diffusereflectance and the second, when measuring total reflectance.3.5 Electrical Characteristics of the Photodetector Indic

21、ator UnitThe photodetector output, as read on theindicating meter, shall be a linear function of the light intensity on the photosensitive area. Means (electricaland/or optical) shall be provided to facilitate zeroing and calibration adjustments. Such means shall not affectthe linearity or the spect

22、ral characteristics of the instrument. The accuracy of the receptor-indicator unit shallbe within 2% of full scale, or 10% of the magnitude of the reading, whichever is smaller.3.6 Geometric ConditionsThe angle between the perpendicular to the surface of the sample and the incidentbeam (i) shall not

23、 exceed 30 degrees. Preferably, the angle shall be 25 degrees 5 degrees. The incidentbeam, upon arrival to the test surface, shall have a diameter of not less than 13 mm (0.50 in).3.7 Sample Holder3.7.1 SPECULAR REFLECTANCEExcept when the sample is located directly adjacent to an integrating sphere,

24、 thesample holder shall be capable of locating the test sample such that the axes of the source arm and thereceptor arm intersect at the reflecting surface (see Figure 3). The reflecting surface may lie within, or ateither face of the mirror sample, depending upon whether it is a first-surface, seco

25、nd surface, or prismatic“flip” mirror.3.7.2 TOTAL OR DIFFUSE REFLECTANCEThe sample holder shall be capable of locating the test sample directlyadjacent to the integrating sphere and such that a line perpendicular to the sample at the center of theincident beam lies along a line through the center of

26、 the sphere.4. Procedure4.1 Calibration4.1.1 DIRECT CALIBRATION METHODIn the direct calibration method, air is used as the reference standard. Thismethod is for those instruments which permit the receiver to swing from a measurement position to a positiondirectly on the axis of the light source (See

27、 Figure 3). The meter is set to 100% with the receiver in direct linewith the light source. The meter is set to zero with the receiver blocked from viewing the light source eitherby swinging it away from the light source axis or by blocking the beam.It may be desired in some cases (such as when meas

28、uring low reflective surfaces) to use an intermediatecalibration point (between 0 and 100% on the scale) with this method. In such a case, a neutral density filterof known transmittance may be inserted in the optical path, and the calibration control adjusted so the meterreads the percent transmissi

29、on of the neutral density filter. This filter must be removed before making anyreflectance measurements.For measurement, the receiver is moved to a position where the angle between its axis and theperpendicular to the reflective surface of the sample equals the angle between the axis of the light so

30、urceand the perpendicular to the reflective surface._ SAE INTERNATIONAL J964 NOV2016 3 of 44.1.2 INDIRECT CALIBRATION METHODThe indirect calibration method is used with instruments with fixed sourceand receiver geometry. A properly calibrated and maintained reflectance standard is required with aref

31、lectance value as close as possible to that of the sample being measured. The reflectance standard isplaced in the sample holder and the indicating meter set to the known reflectance value. The zero may beset by preventing the detector from viewing the reflected beam or by using a second reflectance

32、 standardwith a reflectance value near zero. In the latter case, the standard is placed in the sample holder and themeter set to the known reflectance value.4.2 Reflectance Measurement 4.2.1 TOTAL REFLECTANCEThe total reflectance of a mirror sample is measured on an instrument whichincorporates an i

33、ntegrating sphere as part of the receiver unit and which locates the mirror sample directlyadjacent, and tangent to the sphere (see Figures 1 and 2). If the instrument has a specular port, the whitediffuse cover should be placed over it. The sample is placed in the sample holder and total reflectanc

34、e is read directly from the indicating meter.4.2.2 DIFFUSE REFLECTANCEThe diffuse reflectance of a mirror sample is measured on an instrument whichincorporates an integrating sphere as part of the receiver unit, which locates the sample adjacent to andtangent to the sphere, and which has a means for

35、 excluding the specularly reflected beam (see Figure 2).The black cover should be placed over the specular port.The sample is placed in the sample holder and the reflectance is read directly from the indicating meter.4.2.3 SPECULAR REFLECTANCEThe specular reflectance of a mirror sample is measured o

36、n an instrument whichprevents diffusely reflected light from entering the receiver (see Figure 3). The receiver may or may notinclude an integrating sphere. The sample is placed in the sample holder and the reflectance is read directly from the instrument indicatingmeter. Specular reflectance may al

37、so be calculated by subtracting diffuse reflectance from total reflectance.4.2.4 REFLECTED HAZETotal and diffuse reflectance is measured as in 4.2.1 and 4.2.2. Percent reflected haze iscalculated by dividing the diffuse reflectance by the total reflectance and multiplying this quantity by 100.(Eq. 1

38、)5. Notes5.1 Marginal IndiciaThe change bar (l) located in the left margin is for the convenience of the user in locatingareas where technical revisions have been made to the previous issue of the report. An (R) symbol to the leftof the document title indicates a complete revision of the report.PREPARED BY THE SAE DRIVER VISION COMMITTEEPercent HazeRdiffuseRtotal 100=_ SAE INTERNATIONAL J964 NOV2016 4 of 4