ASTM G130-95
(Test Method)Standard Test Method for Calibration of Narrow- and Broad-Band Ultraviolet Radiometers Using a Spectroradiometer
Standard Test Method for Calibration of Narrow- and Broad-Band Ultraviolet Radiometers Using a Spectroradiometer
SCOPE
1.1 This test method covers the calibration of ultraviolet light-measuring radiometers possessing either narrow- or broad-band spectral response distributions using either a scanning or a linear-diode-array spectroradiometer as the primary reference instrument. For transfer of calibration from radiometers calibrated by this test method to other instruments, Test Method E824 should be used. Note 1-Special precautions must be taken when a diode-array spectroradiometer is employed in the calibration of filter radiometers having spectral response distributions below 320-nm wavelength. Such precautions are described in detail in subsequent sections of this test method.
1.2 This test method is limited to calibrations of radiometers against light sources that the radiometers will be used to measure during field use. Note 2-For example, an ultraviolet radiometer calibrated against natural sunlight cannot be employed to measure the total ultraviolet irradiance of a fluorescent ultraviolet lamp.
1.3 Calibrations performed using this test method may be against natural sunlight, Xenon-arc burners, metal halide burners, tungsten and tungsten-halogen lamps, fluorescent lamps, etc.
1.4 Radiometers that may be calibrated by this test method include narrow-, broad-, and wide-band ultraviolet radiometers, and narrow-, broad, and wide-band visible-region-only radiometers, or radiometers having wavelength response distributions that fall into both the ultraviolet and visible regions. Note 3-For purposes of this test method, narrow-band radiometers are those with [delta][lambda] [∧lt;=] 20 nm, broad-band radiometers are those with 20 nm [∧lt;=] [delta][lambda] [∧lt;=] 70 nm, and wide-band radiometers are those with [delta][lambda] [>=] 70 nm. Note 4-For purposes of this test method, the ultraviolet region is defined as the region from 285 to 400-nm wavelength, and the visible region is defined as the region from 400 to 750-nm wavelength. The ultraviolet region is further defined as being either UV-A with radiation of wavelengths from 315 to 400 nm, or UV-B with radiation from 285 to 315-nm wavelength.
1.5 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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Designation: G 130 – 95
Standard Test Method for
Calibration of Narrow- and Broad-Band Ultraviolet
Radiometers Using a Spectroradiometer
This standard is issued under the fixed designation G 130; 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 (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Accurate and precise measurements of ultraviolet irradiance are required in the determination of the
radiant exposure of both total and selected narrow bands of ultraviolet radiation for the determination
of exposure levels in (1) outdoor weathering of materials, (2) indoor accelerated exposure testing of
materials using manufactured light sources, and (3) UV-A and UV-B ultraviolet radiation in terms both
of the assessment of climatic parameters and the changes that may be taking place in the solar
ultraviolet radiation reaching earth.
Although meteorological measurements usually require calibration of pyranometers and radiom-
eters oriented with axis vertical, applications associated with materials testing require an assessment
of the calibration accuracy at orientations with the axis horizontal (usually associated with testing in
indoor exposure cabinets) or with the axis at angles typically up to 45° or greater from the horizontal
(for outdoor exposure testing). These calibrations also require that deviations from the cosine law, tilt
effects, and temperature sensitivity be either known and documented for the instrument model or
determined on individual instruments.
This test method requires calibrations traceable to primary reference standards maintained by the
National Institute of Standards and Technology (NIST).
1. Scope 1.3 Calibrations performed using this test method may be
against natural sunlight, Xenon-arc burners, metal halide
1.1 This test method covers the calibration of ultraviolet
burners, tungsten and tungsten-halogen lamps, fluorescent
light-measuring radiometers possessing either narrow- or
lamps, etc.
broad-band spectral response distributions using either a scan-
1.4 Radiometers that may be calibrated by this test method
ning or a linear-diode-array spectroradiometer as the primary
include narrow-, broad-, and wide-band ultraviolet radiom-
reference instrument. For transfer of calibration from radiom-
eters, and narrow-, broad, and wide-band visible-region-only
eters calibrated by this test method to other instruments, Test
radiometers, or radiometers having wavelength response dis-
Method E 824 should be used.
tributions that fall into both the ultraviolet and visible regions.
NOTE 1—Special precautions must be taken when a diode-array spec-
NOTE 3—For purposes of this test method, narrow-band radiometers are
troradiometer is employed in the calibration of filter radiometers having
those with Dl # 20 nm, broad-band radiometers are those with 20 nm
spectral response distributions below 320-nm wavelength. Such precau-
#Dl # 70 nm, and wide-band radiometers are those with Dl $ 70 nm.
tions are described in detail in subsequent sections of this test method.
NOTE 4—For purposes of this test method, the ultraviolet region is
1.2 This test method is limited to calibrations of radiometers
defined as the region from 285 to 400-nm wavelength, and the visible
against light sources that the radiometers will be used to
region is defined as the region from 400 to 750-nm wavelength. The
measure during field use.
ultraviolet region is further defined as being either UV-A with radiation of
NOTE 2—For example, an ultraviolet radiometer calibrated against wavelengths from 315 to 400 nm, or UV-B with radiation from 285 to
natural sunlight cannot be employed to measure the total ultraviolet 315-nm wavelength.
irradiance of a fluorescent ultraviolet lamp.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1 responsibility of the user of this standard to establish appro-
This test method is under the jurisdiction of ASTM Committee G-3 on
priate safety and health practices and determine the applica-
Durability of Nonmetallic Materialsand is the direct responsibility of Subcommittee
G03.09 on Solar and Ultraviolet Radiation Measurement Standards.
bility of regulatory limitations prior to use.
Current edition approved April 15, 1995. Published July 1995.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G 130
2. Referenced Documents ultraviolet radiometers. An ASTM test method describing this
procedure is under development by Subcommittee G03.09 on
2.1 ASTM Standards:
2 Radiometry.
E 772 Terminology Relating to Solar Energy Conversion
4.2 The accuracy of this calibration technique is dependent
E 824 Test Method for Transfer of Calibration from Refer-
2 on the condition of the light source (for example, cloudy skies,
ence to Field Pyranometers
polluted skies, aged lamps, defective luminaires, etc.), and on
3. Terminology source alignment, source to receptor distance, and source
power regulation.
3.1 Definitions:
3.1.1 broad-band radiometer—a relative term generally
NOTE 5—It is conceivable that a radiometer might be calibrated against
applied to radiometers with interference filters or cut-on/cut-off
a light source that represents an arbitrarily chosen degree of aging for its
class in order to present to both the test and reference radiometers a
filter pairs having a FWHM between 20 and 70 nm and with
spectrum that is most typical for the type.
tolerances in center (peak) wavelength and FWHM no greater
than 62 nm.
4.3 Spectroradiometric measurements performed using ei-
3.1.2 diode array detector—a detector with from 50 to 1000
ther an integrating sphere or a cosine receptor (such as a shaped
silicon photodiodes affixed side-by-side in a linear array and
TFE,or Al O diffuser plate) provide a measurement of
2 3
mounted in the focal plane of the exit slit of a monochromator.
hemispherical spectral irradiance in the plane of the sphere’s
3.1.3 full width at half maximum (FWHM)—in a bandpass
entrance port. As such, the aspect relative to the reference light
filter, FWHM is the interval between wavelengths at which
source must be defined (azimuth and tilt from the horizontal for
transmittance is 50 % of the peak, frequently referred to as
solar measurements, normal incidence with respect to the beam
bandwidth.
component of sunlight, or normal incidence and the geometri-
3.1.4 narrow-band radiometer—a relative term generally
cal aspect with respect to an artificial light source, or array). It
applied to radiometers with interference filters with FWHM
is important that the geometrical aspect between the plane of
#20 nm and with tolerances in center (peak) wavelength and
the spectroradiometer’s source optics and that of the radiom-
FWHM no greater than6 2 nm.
eter being calibrated be as nearly identical as possible.
3.1.5 scanning monochromator—a monochromator that
NOTE 6—When measuring the hemispherical spectral energy distribu-
uses either a single, or several interchangeable, detector(s)
tion of an array of light sources (for lamps), normal incidence is defined
mounted at the exit slit, that is presented with dispersed light
by the condition obtained when the plane of the sphere’s aperture is
by sweeping the spectrum across the slit to illuminate the
parallel to the plane of the lamp, or burner, array.
detector with a succession of different very narrow wavelength
4.4 Calibration measurements performed using a spectrora-
light distributions. The detector may be either a photomulti-
diometer equipped with a pyrheliometer-comparison tube (a
plier tube (PMT) or silicon photodiode (visible), or a PMT or
sky-occluding tube), regardless of whether affixed directly to
an ultraviolet-enhanced silicon photodiode (ultraviolet and
the monochromator’s entrance slit, to the end of a fibre optic
visible), or a lead sulfide cell or other solid state detector (near
bundle, or to the aperture of an integrating sphere, shall not be
infrared), etc. The dispersed spectrum is swept across the
performed unless the radiometer being calibrated is a true
monochromator’s exit slit using a mechanical stage that rotates
pyrheliometer (that is, unless it possesses a view-limiting
either a prism or a grating dispersive element, usually under the
device having the approximate optical constants of the spec-
control of an external microprocessor or computer.
troradiometer’s pyrheliometer-comparison tube).
3.1.6 spectroradiometer—a radiometer consisting of a
4.5 Spectroradiometric measurements performed using
monochromator with special acceptance optics mounted to the
source optics other than the integrating sphere or the “stan-
entrance aperture and a detector mounted to the exit aperture,
dard” pyrheliometer comparison tube, shall be agreed upon in
usually provided with electronic or computer encoding of
advance between all involved parties.
wavelength and radiometric intensity. The monochromator of
4.6 Calibration measurements that meet the requirements of
such instruments is either of the linear diode (often called diode
this test method are traceable to the National Institute of
array) or the scanning type.
Standards and Technology (NIST), largely through the trace-
3.1.7 wide-band radiometer—a relative term generally ap-
ability of the standard lamps and associated power supplies
plied to radiometers with combinations of cut-off and cut-on
employed to calibrate the spectroradiometer.
filters with FWHM greater than 70 nm.
4.7 The accuracy of calibration measurements performed
3.2 For other terms relating to this test method, see Termi-
employing a spectroradiometer is dependent on, among other
nology E 772.
requirements, the degree to which the temperature of the
mechanical components of the monochromator are maintained
4. Significance and Use
during field measurements in relation to those that prevailed
4.1 This test method represents the preferable means for
during calibration of the spectroradiometer.
calibrating both narrow-band and broad-band ultraviolet radi-
NOTE 7—This requirement is covered in detail in an ASTM standard
ometers. Calibration of narrow- and broad-band ultraviolet
under development in Subcommittee G03.09 on Radiometry.
radiometers involving direct comparison to a standard source
of spectral irradiance is an alternative method for calibrating
Tetrafluoroethylene such as a special grade of Teflont or an equivalent
Annual Book of ASTM Standards, Vol 12.02. material, has been found suitable.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G 130
5. Apparatus possess the optical geometry defined by the World Meteroro-
logical Organization, the principal one being a 5.6° field of
5.1 Reference Spectroradiometers:
view.
5.1.1 The spectroradiometer employed as the reference
radiometer shall, regardless of whether it consists of a scanning
NOTE 8—When the sphere’s entrance port is the occluder’s aperture
or a linear-diode-array monochromator, be calibrated within
stop, no calibration of the spectroradiometer is required independent of the
calibration with only the integrating sphere in place. If the occluder’s
the last month in accordance with the procedures specified by
aperture stop is integral with the occluder and of different smaller
CIE Publication 63 and the manufacturer.
dimension than the sphere’s entrance port, the spectroradiometer must be
5.1.1.1 It is recommended that the reference spectroradiom-
calibrated with the occluder attached to the integrating sphere . resulting
eter, or one of its exact type, has been a participating
in greater uncertainties and the possibilities of significant errors.
spectroradiometer in an intercomparison of spectroradiometers
5.2 Computational Facilities—The computer-based compu-
either managed, sponsored, or sanctioned by the National
tational facilities used to import the raw data with respect to
Institute of Standards and Technology, ASTM Committee G-3,
wavelength and intensity should be capable of providing
or another appropriate body.
analyzed spectral irradiance information integrated across any
5.1.1.2 Alternatively, it is recommended that the reference
wavelength band chosen.
spectroradiometer shall have participated in an intercompari-
5.3 Instrument Mounts:
son by measurement of a reference lamp source that is either
5.3.1 Equatorial Mount—An altazimuthal or equatorial,
managed, sponsored, or sanctioned by the National Institute of
follow-the sun mount that is equipped with a platform on
Standards and Technology, ASTM Committee G-3, or another
which the spectroradiometer is mounted is required for all
appropriate body.
hemispherical normal-incident and direct (beam) calibrations
5.1.2 If a linear diode-array spectroradiometer is used as the
measurements.
reference, it shall possess focusing optics internal to the
5.3.2 Tilt Table—A stable, adjustable tilt table having tilt
monochromator and a linear diode array detector with a
and azimuth adjustments is required for global solar radiation
sufficient number of diodes that, together, result in a resolving
measurements (for example, at horizontal orientation) and
power of 1 nm or less. The monochromator’s dispersive
hemispherical measurements at specified azimuthal and tilt
element shall be a holographic grating, and the spectroradiom-
positions.
eter’s acceptance optics shall consist of either an integrating
sphere with appropriately sized and oriented light entrance NOTE 9—An altazimuthal mount so equipped also may be used as the
tilt table.
port, or a shaped translucent diffuser plate (such as a TFE or
Al O wafer) whose deviation from true cosine response is
5.3.3 Optical Platform—A stable, platform equipped with
2 3
small and known. A further requirement is that the stray light
height adjustment is required for use in measuring the calibrat-
rejection be determined for any diode-array spectroradiometers
ing radiometers against light sources such as arrays, solar
used to perform this test method and that it be 10 or greater in
simulators, special lamps, and burners, etc.
the spectral region for which calibration is required.
NOTE 10—When using a fiber-optic/integrating sphere source configu-
5.1.2.1 A diode-array spectroradiometer shall not be used as
ration to calibrate rad
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