ASTM E2630-08

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E2630 – 08
Standard Test Method for
Luminance Ratio of a Fluorescent Specimen using a Narrow
Band Source
This standard is issued under the fixed designation E2630; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Measurement of Reflection and Transmission Properties of
Materials
1.1 This test method covers the instrumental measurement
E284 Terminology of Appearance
of the luminance ratio of a fluorescent coating or sheet sample
E1164 Practice for Obtaining Spectrometric Data for
when illuminated by a narrow band source.
Object-Color Evaluation
1.2 This test method is generally applicable to any coating
E1488 Guide for Statistical Procedures to Use in Develop-
orsheetingmaterialhavingcombinedfluorescentandreflective
ing and Applying Test Methods
properties, where the fluorescence is activated by 405 nm light.
E2501 Specification for Light Source Products for Inspec-
1.3 This test method is intended as a companion to Speci-
tion of Fluorescent Coatings
fication E2501 to support the development and specification of
2.2 Other Documents:
industrial coatings that are used in a system for detection of
ISO 10527:2007(E)/CIE S 014-1/E:2006 CIE Standard
coating defects when inspected with the Specification E2501
Colorimetric Observers
light source. This test method establishes a quantitative mea-
CIE Publication 69:1987 Methods of characterizing illumi-
sure of the optical property of a coating that correlates to its
nance meters and luminance meters: Performance, char-
abilitytoenhancedefectcontrastunderthespecifiedinspection
acteristics and specificaitons
light source.
2.3 SSPC:
1.4 The values stated in SI units are to be regarded as
SSPC-SP 10/NACE No. 2 Near-White Blast Cleaning
standard. No other units of measurement are included in this
standard.
3. Terminology
1.5 This standard does not purport to address all of the
3.1 The definitions contained in Guide E179, Terminology
safety concerns, if any, associated with its use. It is the
E284, and Practice E1164 are applicable to this test method.
responsibility of the user of this standard to establish appro-
3.2 The definitions for coating defects, discontinuity, holi-
priate safety and health practices and determine the applica-
day, and pinhole are contained in Practice D5162.
bility of regulatory limitations prior to use.
3.3 Definitions of Terms Specific to This Standard:
2. Referenced Documents 3.3.1 luminance ration, n—luminanceofthesampleundera
2 given narrow band 405 nm source divided by the luminance of
2.1 ASTM Standards:
a 25 % reflecting Lambertian diffuser under the same narrow
D2805 Test Method for Hiding Power of Paints by Reflec-
band 405 nm source.
tometry
D4356 Practice for Establishing Consistent Test Method
4. Summary of Test Method
Tolerances
4.1 Thistestmethodprovidesaprocedureformeasuringthe
D5162 Practice for Discontinuity (Holiday)Testing of Non-
luminance ratio of a fluorescent, reflective coating compared to
conductive Protective Coating on Metallic Substrates
a 25 % reflecting Lambertian diffuser, which is similar to steel
E179 Guide for Selection of Geometric Conditions for
grit blasted to an SSPC-SP 10/NACE No. 2 near-white metal
blast.
This test method is under the jurisdiction of ASTM Committee E12 on Color
4.2 This test method requires the use of a luminance meter,
and Appearance and is the direct responsibility of Subcommittee E12.05 on
a narrow band 405 nm source and a calibrated non-fluorescent
Fluorescence.
reflectance standard.
Current edition approved June 1, 2008. Published July 2008. DOI: 10.1520/
E2630-08.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM AvailablefromU.S.NationalCommitteeoftheCIE(InternationalCommission
Standards volume information, refer to the standard’s Document Summary page on on Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 Pond
the ASTM website. St., Salem, MA 01970, http://www.cie-usnc.org.
3 5
Withdrawn. The last approved version of this historical standard is referenced Available from Society for Protective Coatings (SSPC), 40 24th St., 6th Floor,
on www.astm.org. Pittsburgh, PA 15222-4656, http://www.sspc.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2630 – 08
under the source described in 6.1 and a fluorescent sample similar to the
5. Significance and Use
test sample, which are calibrated for luminance ratio under the source
5.1 The test method is suitable for the development, speci-
described in 6.1.
fication and quality control testing of fluorescent and non-
NOTE 6—An informational appendix (Appendix X1) is provided that
fluorescent coatings that are intended to be inspected for
briefly summarizes the method for calculating the spectral mismatch
defects under Specification E2501 illumination. correction factors or the ratio of such.
6.2.3 If the luminance meter is spectrally based, the out-of-
-5
6. Apparatus
band stray light rejection shall be better than 1 310 .
6.1 Illuminator: 6.2.4 The field-of-view of the luminance meter and the
6.1.1 The source shall have a peak wavelength of 405 nm distance from the sample surface shall be such that the viewed
(61 nm), a symmetric unimodal distribution with a full width region shall be larger than 2.5 cm with no dimension smaller
half maximum of 16 nm (62 nm). The shape of the spectral than 1.3 cm.
distribution shall be triangular, Gaussian or isosceles trapezoi-
NOTE 7—The viewing area of the luminance meter depends on the field
dal where the width of the peak shall be less than one sixth the
of view and the distance from the sample. The viewing area for a circular
size of the base.
aperture is calculated by using the following equation:
NOTE 1—A uniform or rectangular distribution does not meet this
viewing area 5 ~tan~v/2!· d! · p / cos~45°! (1)
condition.
NOTE 2—An informational appendix (Appendix X1) is provided that where:
briefly summarizes the reasons for the choices of tolerances in this test v = field of view of the luminance meter and
d = distance between the luminance meter and the test sample.
method.
6.2.5 The luminance meter shall be insensitive to the
6.1.2 The integrated irradiance over the wavelength range
490 to 760 nm shall be less than 0.01 % of the integrated polarization of the light.
6.2.6 The linearity of the luminance meter over the range of
irradiance over the wavelength range 380 to 760 nm.
measurements shall be within 1 %. Correction factors may be
NOTE 3—The light from 490 to 760 nm is typically from fluorescence
used to ensure a linear response.
generated in the light source. This light is heavily weighted by the
6.2.7 The stability of the luminance meter over the duration
luminousefficacyfunction,V(l),resultinginlargeerrorsintheluminance
of the measurements shall not vary more than 1 %.
ratio measurement. The fluorescence can be eliminated with a blue-green
colored glass filter that has an internal transmittance at a reference 6.2.8 The out-of-view sensitivity, described in CIE Publica-
thickness of 1 mm greater than 0.90 at 405 nm and less than 0.05 across
tion 69, of the luminance meter shall be less than 0.5 %.
the wavelength range of 500 to 680 nm.
6.3 Non-fluorescent Reflectance Standard:
6.1.3 The source shall produce a minimum irradiance suf- 6.3.1 The non-fluorescent reflectance standard shall be cali-
brated in a 0°:45° geometry for luminous reflectance under the
ficient to ensure a signal-to-noise ratio of 100 to 1 for the
luminance meter described in 6.2. source described in 6.1with an expanded uncertainty (k=2)of
less than 1 %.
NOTE 4—An irradiance of 10 W/m is typically sufficient.
NOTE 8—The magnitude of the luminous reflectance of the non-
6.1.4 Theilluminatedareashallbeatleasttwicetheviewing
fluorescent reflectance standard is somewhat arbitrary, because it is
area of the luminance meter. The minimum viewing area is
normalized to 0.25 in the calculations shown in 10.1. Typically, the
specified in 6.2.4.
magnitude of the luminous reflectance of the non-fluorescent reflectance
6.1.5 The source irradiance shall be stable to 1 % over the
standard is above 0.9 in order to have a larger signal-to-noise ratio.
time frame of the measurements.
6.3.2 The non-fluorescent reflectance standard shall have an
6.1.6 The illuminance on the sample surface shall be uni-
integrated radiance over the wavelength range 490 to 760 nm
form within 65 % of the average illuminance normal to the
lessthan0.05 %oftheintegratedradianceoverthewavelength
source. The illuminator may be collimated or not.
range 380 to 760 nm under the illuminator specified in 6.1.
6.2 Luminance Meter:
6.3.3 Thenon-fluorescentreflectancestandardshallproduce
6.2.1 The responsivity and range of the luminance meter
a diffuse distribution when illuminated.
shall be sufficient so that readings of both the non-fluorescent
reflectance standard and the fluorescent sample are measured
7. Test Specimen
with a resolution of at least 1 part in 100.
7.1 Prepare coating in accordance with Test Method D2805
6.2.2 If the luminance meter is filter based, the spectral
for drawdown sample for hiding power by reflectometry.
responsivity of the luminance meter shall match that of the
7.2 Alternately, prepare by spraying or drawing down on a
1931 CIE Standard Photopic Observer. (ISO 10527:2007(E)/
black substrate that has a maximum reflectance of 1 % and
CIE S 014-1/E:2006) The individual spectral mismatch correc-
does not fluoresce.
tion factors or the ratio of spectral mismatch correction factors
7.3 The coating dry film thickness shall be within the
with respect to the illuminator described in 6.1 shall be
manufacturers recommended range for the intended applica-
determined for the luminance meter to at least 1 part in 100
tion.
when measuring the non-fluorescent reflectance standard and
the fluorescent sample. 8. Calibration and Standardization
8.1 Theluminancemetershallbecalibratedaccordingtothe
NOTE 5—The ratio of the spectral mismatch correction factors may be
determined by using a non-fluorescent reflectance standard calibrated manufacturer’s specification.The individual spectral mismatch
E2630 – 08
correction factors or the ratio of spectral mismatch correction 9.4.1 Handle the samples carefully; avoid scratching or
factors with respect to the illuminator described in 6.1 shall be touching the area to be measured. To remove dust and lint use
determined for the luminance meter when measuring the dry, filtered, pressurized nitrogen.
non-fluorescentreflectancestandardandthefluorescentsample 9.5 Block the illuminator such that the non-fluorescent
to at least 1 part in 100. (See Note 5.) reflectance standard is not illuminated and measure the dark
8.2 The non-fluorescent reflectance standard shall be cali- non-fluorescent reflectance standard signal.
brated as described in 6.3.1. 9.6 Position the fluorescent sample and measure the fluo-
rescent sample with the luminance meter.
9. Procedure
9.7 Block the illuminator such that the fluorescent sample is
9.1 Fig. 1 provides a schematic for the measurement align-
not illuminated and measure the dark fluorescent sample
ment. The measurements shall be conducted in the dark such
signal.
that the signal measured in 9.5 is less than 1 part of the signal
9.8 Calculate the luminance ration using Eq 2 specified in
measured in 9.4.
10.1
9.2 Position the illuminator described in 6.1 such that the
10. Calculation
angle between the direction of illumination and the normal to
the specimen surface shall not exceed 2°. Position the lumi-
10.1 For each fluorescent sample calculate the luminance
nance meter such that the angle between the direction of
ratio using the following equation:
viewing and the normal to the specimen surface shall be 45 6
B
s – s ! F r
~
d P
B
2°.
R 5 · · (2)
L
s – s F 0.25
~ !
P P,d
NOTE 9—Fluorescent coatings inspected under a 405 nm illuminator
where:
enhance defect detection through two mechanisms: (1) enhanced contrast
B
R = luminance ratio,
between the fluorescent coating and nonfluorescent substrate; and (2)
L
uniform coating color and brightness regardless of the viewing angle. The
s = luminance signal for the fluorescent sample,
second mechanism is important for inspecting the fluorescent coating
s = dark luminance signal for the fluorescent sample,
d
along welds, in corners and on edges. Under white light inspection,
s = luminance signal for the non-fluorescent reflectance
P
defects in these areas are obscured by glare and shadows. With a 405 nm
standard,
inspection light, dark spots are unambiguously interpreted as defects.This
s = dark luminance signal for the non-fluorescent re-
P,d
effect is primarily responsible for the increased productivity and accuracy
flectance standard,
reported by coatings inspectors in field trials.The luminance ratio at a 45°
F = spectral mismatch correction factor for the fluores-
viewing angle correlates with this property better than that at a smaller
cent sample under the illuminator,
viewing angle.
F = spectral mismatch correction factor for the non-
P
9.3 The distance between the luminance meter and the
fluorescent reflectance standard under the illumina-
sample surface shall be set such that the field-of-view defines
tor, and
a region of interest that is over illuminated by the illuminator B
r = luminous reflectance of the non-fluorescent reflec-
according to 6.1.4.
tance standard under the illuminator.
9.4 Measure the non-fluorescent reflectance standard with
the luminance meter.
11. Report
11.1 The report shall contain the following information.
11.2 Sample identification including any commercial desig-
nation and manufacturer lot number.
11.3 Date of measurement.
11.4 Identification of the luminous reflectance of the non-
fluorescent reflectance standard.
11.5 Description of apparatus.
11.5.1 Peak wavelength and full width half maximum of the
illuminator.
11.5.2 Make and model number of luminance meter.
11.5.3 Distance between luminance meter and test speci-
men.
11.5.4 Filed-of-view of the luminance meter.
11.6 The luminance ratio.
12. Precision and Bias
12.1 Precision—The repeatability and the reproducibility of
thistestmethodisbeingdeterminedandwillbeavailableonor
before January 2011.
12.2 A preliminary estimate of precision has been made
based on a test method sensitivity analysis. The repeatability
FIG. 1 A Schematic of the Measurement Alignment standard deviation is expected to be less than 1.2 %. The
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