ASTM E1897-97(2002)e1
(Test Method)Standard Test Methods for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging Radiometers
Standard Test Methods for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging Radiometers
SIGNIFICANCE AND USE
The transmittance of an attenuating medium can cause errors for an infrared thermographer using an infrared imaging radiometer to measure the temperature of a specimen through the medium. Three test methods are given for measuring and compensating for this error source.
5.1.1 A test method is given for measuring the transmittance of an attenuating medium.
5.1.2 A test method is given for compensating for errors when measuring the temperature of a specimen having a known emissivity through an attenuating medium with a known transmittance.
5.1.3 A test method is given for measuring and compensating for transmittance and emissivity errors when the specimen temperature is known.
These test methods can be used in the field or laboratory using commonly available materials.
These test methods can be used with any infrared radiometers that have the required computer capabilities.
SCOPE
1.1 These test methods cover procedures for measuring and compensating for transmittance when using an infrared imaging radiometer to measure the temperature of a specimen through an attenuating medium, such as a window, filter or atmosphere.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 These test methods may involve use of equipment and materials in the presence of heated or electrically-energized equipment, or both.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:E1897–97 (Reapproved 2002)
Standard Test Methods for
Measuring and Compensating for Transmittance of an
Attenuating Medium Using Infrared Imaging Radiometers
This standard is issued under the fixed designation E1897; 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.
´ NOTE—Removed Footnote 2 in August 2002 since the organization is no longer in business.
1. Scope 3.1.4 infrared thermographer—the person using an infrared
imaging radiometer.
1.1 These test methods cover procedures for measuring and
3.1.5 reflected temperature—the temperature of the energy
compensating for transmittance when using an infrared imag-
incident upon and reflected by the measurement surface of the
ing radiometer to measure the temperature of a specimen
specimen.
through an attenuating medium, such as a window, filter or
3.1.6 window—a semi-transparent material that separates
atmosphere.
conditioned and unconditioned atmospheres and attenuates
1.2 The values stated in SI units are to be regarded as the
certain wavelengths of radiation.
standard.
3.2 See also Terminology E1316.
1.3 These test methods may involve use of equipment and
materials in the presence of heated or electrically-energized
4. Summary of Test Method
equipment, or both.
4.1 Using the computer built into an infrared imaging
1.4 This standard does not purport to address all of the
radiometer, a method is given for measuring the transmittance
safety concerns, if any, associated with its use. It is the
of an attenuating medium.
responsibility of the user of this standard to establish appro-
4.2 Using the computer built into an infrared imaging
priate safety and health practices and determine the applica-
radiometer, a method is given for compensating for errors
bility of regulatory limitations prior to use.
when measuring the temperature of a specimen through an
2. Referenced Documents attenuating medium when the emissivity of the specimen and
the transmittance of the attenuating medium are known.
2.1 ASTM Standards:
4.3 Using the computer built into an infrared imaging
E1316 Terminology for Nondestructive Examinations
radiometer, a method is given for measuring and compensating
3. Terminology for unknown transmittance and emissivity errors when the
specimen temperature is known.
3.1 Definitions of Terms Specific to This Standard:
3.1.1 attenuating medium—a semi-transparent solid, liquid
5. Significance and Use
or gas, such as a window, filter, external optics and/or an
5.1 The transmittance of an attenuating medium can cause
atmosphere that attenuates radiation.
errors for an infrared thermographer using an infrared imaging
3.1.2 blackbody simulator—a device with an emissivity
radiometer to measure the temperature of a specimen through
close to 1.00 that can be heated or cooled to a stable
the medium. Three test methods are given for measuring and
temperature.
compensating for this error source.
3.1.3 filter—a semi-transparent material that attenuates cer-
5.1.1 Atest method is given for measuring the transmittance
tain wavelengths of radiation.
of an attenuating medium.
5.1.2 A test method is given for compensating for errors
when measuring the temperature of a specimen having a
These test methods are under the jurisdiction of ASTM Committee E07 on
known emissivity through an attenuating medium with a
Nondestructive Testing and is the direct responsibility of Subcommittee E07.10 on
known transmittance.
Emerging NDT Methods.
5.1.3 A test method is given for measuring and compensat-
Current edition approved July 10, 1997. Published December 1997. DOI:
10.1520/E1897-97R02E01.
ing for transmittance and emissivity errors when the specimen
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
temperature is known.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.2 These test methods can be used in the field or laboratory
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. using commonly available materials.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E1897–97 (2002)
5.3 These test methods can be used with any infrared 8.1.1 Place the infrared imaging radiometer on the tripod or
radiometers that have the required computer capabilities. support device at the desired location and distance from the
blackbody simulator.
6. Interferences 8.1.2 Point the infrared imaging radiometer at the black-
body simulator and focus on a portion that has an emissivity of
6.1 Test Method for Measuring the Transmittance of an
0.95 or greater. Make sure that the blackbody simulator is at a
Attenuating Medium:
stable temperature at least 20°C above the ambient tempera-
6.1.1 This test method requires a blackbody simulator with
ture.
an emissivity of 0.95 or greater that is at least 20°C warmer
8.1.3 Use an appropriate infrared imaging radiometer mea-
than ambient temperature. Potential errors can be minimized
surement function (such as spot temperature, crosshairs or
by ensuring the stability of the temperature difference between
isotherm) to measure and compensate for the reflected tem-
the source and the ambient temperature during the test. Also,
perature error incident upon the blackbody simulator.
the transmittance measurement accuracy can be increased by
8.1.4 With the imager’s computer emittance control still set
increasing this temperature difference.
to 1.00, measure and record the apparent temperature of this
6.1.2 Errors can be minimized by ensuring that the tempera-
same portion of the blackbody simulator.
ture of the attenuating medium is as close as possible to the
8.1.5 Position the attenuating medium between the imager’s
reflected temperature incident upon the specimen.
detector or lens and the blackbody simulator.
6.1.3 The compositions and thicknesses of attenuating me-
8.1.6 Without moving the imager, adjust its computer’s
dia can vary within the same specimen. Errors can be mini-
emissivity control until the imager’s computer indicates the
mized by measuring through the same portion of the specimen
same temperature recorded in 8.1.4.The indicated “emissivity”
every time.
value is the transmittance of the attenuating medium, at this
6.2 Test Method for Compensating for Unknown Errors
blackbody simulator temperature and radiometer’s
...
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