ASTM E1336-11(2017)
(Test Method)Standard Test Method for Obtaining Colorimetric Data From a Visual Display Unit by Spectroradiometry
Standard Test Method for Obtaining Colorimetric Data From a Visual Display Unit by Spectroradiometry
SIGNIFICANCE AND USE
5.1 The most fundamental method for obtaining CIE tristimulus values or other color coordinates for describing the colors of visual display units (VDUs) is by the use of spectroradiometric data. (See CIE No. 18 and 63.) These data are used by summation together with numerical values representing the 1931 CIE Standard Observer and normalized to Km, the maximum spectral luminous efficacy function.
5.2 The special requirements for characterizing VDUs possessing narrow or discontinuous spectra are presented and discussed. Modifications to the requirements of Practice E308 are given to correct for the unusual nature of narrow or discontinuous sources.
SCOPE
1.1 This test method prescribes the instrumental measurements required for characterizing the color and brightness of VDUs.
1.2 This test method is specific in scope rather than general as to type of instrument and object.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Buy Standard
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1336 − 11 (Reapproved 2017)
Standard Test Method for
Obtaining Colorimetric Data From a Visual Display Unit by
Spectroradiometry
This standard is issued under the fixed designation E1336; 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.
INTRODUCTION
The fundamental procedure for characterizing the color and luminance of a visual display unit
(VDU) is to obtain the spectroradiometric data under specified measurement conditions, and from
these data to compute CIE chromaticity coordinates and absolute luminance values based on the 1931
CIE Standard Observer.The considerations involved and the procedures to be used to obtain precision
colorimetric data for this purpose are contained in this test method. The values and procedures for
computing CIE chromaticity coordinates are contained in Practice E308.The procedures for obtaining
spectroradiometric data are contained in Test Method E1341. This test method includes some
modifications to the procedures given in Practice E308 that are necessary for computing the absolute
luminance values of VDUs. This procedure is intended to be generally applicable to any VDU device,
including but not limited to cathode ray tubes (CRT), liquid crystal displays (LCD), and electrolu-
minescent displays (ELD).
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method prescribes the instrumental measure-
E284 Terminology of Appearance
ments required for characterizing the color and brightness of
E308 PracticeforComputingtheColorsofObjectsbyUsing
VDUs.
the CIE System
1.2 This test method is specific in scope rather than general
E1341 Practice for Obtaining Spectroradiometric Data from
as to type of instrument and object.
Radiant Sources for Colorimetry
1.3 The values stated in SI units are to be regarded as
2.2 CIE Publications:
standard. No other units of measurement are included in this
Publication CIE No. 18 Principles of Light Measurements
standard.
Publication CIE No. 15.2 Colorimetry, 2nd ed., 1986
Publication CIE No. 63 Spectroradiometric Measurement of
1.4 This standard does not purport to address all of the
Light Sources, 1984
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 2.3 IEC Publications:
priate safety and health practices and determine the applica- Publication No. 441 Photometric and Colorimetric Methods
bility of regulatory limitations prior to use. of Measurement of the Light Emitted by a Cathode-Ray
Tube Screen, 1974
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3. Terminology
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1 The definitions of appearance terms in Terminology
mendations issued by the World Trade Organization Technical
E284 are applicable to this test method.
Barriers to Trade (TBT) Committee.
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
This test method is under the jurisdiction of ASTM Committee E12 on Color Standards volume information, refer to the standard’s Document Summary page on
andAppearance and is the direct responsibility of Subcommittee E12.06 on Display, the ASTM website.
Imaging and Imaging Colorimetry. Available from CIE (International Commission on Illumination), http://
Current edition approved May 1, 2017. Published May 2017. Originally www.cie.co.at or http://www.techstreet.com.
approved in 1991. Last previous edition approved in 2011 as E1336 – 11. DOI: Available from International Electrotechnical Commission (IEC), 3 rue de
10.1520/E1336-11R17. Varembé, Case postale 131, CH-1211, Geneva 20, Switzerland, http://www.iec.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1336 − 11 (2017)
4. Summary of Test Method 7.2 Calibration Sources:
7.2.1 The standard calibration source for spectroradiometry
4.1 Procedures are given for obtaining spectroradiometric
is a tungsten-filament lamp operated at a specified current. It is
data and for the calculation of CIE tristimulus values and other
preferable to have more than one standard lamp to permit
color coordinates to describe the colors of VDUs. Modifica-
cross-checks and to allow calibration at a range of luminance
tions to the standard calculation procedures of Practice E308
levels.
are described.
7.2.2 Monochromatic emission sources such as a low-
5. Significance and Use pressure mercury arc lamp or tunable laser should also be
available for use in calibrating the wavelength scale.
5.1 The most fundamental method for obtaining CIE tris-
7.2.3 The electrical supplies for the calibration sources
timulus values or other color coordinates for describing the
should be of the constant current type. The supply should be
colors of visual display units (VDUs) is by the use of
linear and not a switching supply. Current regulation should be
spectroradiometric data. (See CIE No. 18 and 63.) These data
maintained to better than 0.1 %. At this level the radiant flux
are used by summation together with numerical values repre-
from the calibration source is at least an order of magnitude
sentingthe1931CIEStandardObserverandnormalizedto K ,
m
more stable than the flux from a VDU.
the maximum spectral luminous efficacy function.
7.2.4 There should be a standard for length measurements
5.2 The special requirements for characterizing VDUs pos-
available (such as a high quality metric rule) since absolute
sessing narrow or discontinuous spectra are presented and
irradiance calibration must be performed at an exact distance
discussed. Modifications to the requirements of Practice E308
from the filament of the calibration lamp.
are given to correct for the unusual nature of narrow or
discontinuous sources.
7.3 Receiving Optics—Tomaximizethelightthroughputthe
number of optical surfaces between the source of light should
6. Requirements When Using Spectroradiometry
be kept to a minimum. In extended diffuse sources (such as
VDUs) only a set of limiting apertures will be needed. In some
6.1 When describing the measurement of VDUs by
instances, it may be desirable to image the VDU with an
spectroradiometry, the following must be specified:
6.1.1 The radiometric quantity determined, such as the intermediate focusing lens or mirror assembly. Care should be
2 2
taken to use a magnification that will adequately fill the
irradiance (W/m ) or radiance (W/m -sr), or the photometric
quantitydetermined,suchasilluminance(lm/m )orluminance entrance slit when viewing both the calibration and test source.
2 2
(lm/m -srorcd/m ).Theuseofolder,lessdescriptivenamesor
units such as phot, nit, stilb is not recommended. 8. Calibration and Verification
6.1.2 The geometry of the measurement conditions,
8.1 Calibration and its verification are essential steps in
including, whether a diffuser was used and the material from
ensuring that precise and accurate results are obtained by
which it was constructed, the distances from the VDU, the size
spectroradiometric measurements. They require the use of
of the area to be measured on the VDU, the uniformity of the
physical standards, some of which may not be normally
VDU across the area to be measured, the microstructure of the
supplied by commercial instrument manufacturers. It remains
VDU picture elements, and the presence of any special
the user’s responsibility to obtain and use the physical stan-
intermediate optical devices such as integrating spheres.
dards necessary to keep his instrument in optimum working
6.1.3 The spectral parameters, including the spectral region,
condition.
wavelength measurement interval, and spectral bandwidth.
These must be specified since the various VDU technologies
8.2 Radiometric Scale:
may demand more or less stringent requirements.
8.2.1 Zero Calibration or Its Verification—All photometric
6.1.4 The type of standard used to calibrate the system, a
devices have some inherent photocurrent, even in the absence
standard lamp, a calibrated source, or a calibrated detector, and
of light. This so called “dark current” must be measured and
the source of the calibration.
subtracted from all subsequent readings either electrically or
6.1.5 The physical and temporal characteristics of the VDU
computationally.
including, refresh or field rate, convergence and purity adjust-
8.2.2 Radiometric Scale Calibration—A physical standard
ments (if the manufacturer allows such), luminance level, and
of spectral irradiance is normally used for calibration.After the
any spectral line character in the emission from the VDU. The
dark current has been measured, the calibration source is
integration time of the detector system should be noted in
positioned in front of the receiving optics at the specified
relation to the refresh or field rate of the VDU. (See IEC No.
distance and operated at the specified electric current. This
441.)
provides a good approximation to a Plankian radiator across
the visible spectrum. The calibration source is measured and
7. Apparatus
the values of the dark-current-corrected photocurrent are re-
7.1 The basic instrument requirement is a spectroradiomet- corded. These photocurrents are then related to the calibration
ric system designed for the measurement of spectral radiance values of spectral irradiance that were provided by the stan-
or irradiance of light sources. See Practice E1341 for details on dardizing laboratory. The ratio of spectral irradiance to photo-
each of the parts of a spectroradiometer and how to calibrate current becomes the instrument calibration factor. All subse-
and use the instrument. quent measurements are multiplied by this ratio.
E1336 − 11 (2017
...
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: E1336 − 11 (Reapproved 2017)
Standard Test Method for
Obtaining Colorimetric Data From a Visual Display Unit by
Spectroradiometry
This standard is issued under the fixed designation E1336; 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.
INTRODUCTION
The fundamental procedure for characterizing the color and luminance of a visual display unit
(VDU) is to obtain the spectroradiometric data under specified measurement conditions, and from
these data to compute CIE chromaticity coordinates and absolute luminance values based on the 1931
CIE Standard Observer. The considerations involved and the procedures to be used to obtain precision
colorimetric data for this purpose are contained in this test method. The values and procedures for
computing CIE chromaticity coordinates are contained in Practice E308. The procedures for obtaining
spectroradiometric data are contained in Test Method E1341. This test method includes some
modifications to the procedures given in Practice E308 that are necessary for computing the absolute
luminance values of VDUs. This procedure is intended to be generally applicable to any VDU device,
including but not limited to cathode ray tubes (CRT), liquid crystal displays (LCD), and electrolu-
minescent displays (ELD).
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method prescribes the instrumental measure-
E284 Terminology of Appearance
ments required for characterizing the color and brightness of
E308 Practice for Computing the Colors of Objects by Using
VDUs.
the CIE System
1.2 This test method is specific in scope rather than general
E1341 Practice for Obtaining Spectroradiometric Data from
as to type of instrument and object.
Radiant Sources for Colorimetry
1.3 The values stated in SI units are to be regarded as
2.2 CIE Publications:
standard. No other units of measurement are included in this
Publication CIE No. 18 Principles of Light Measurements
standard.
Publication CIE No. 15.2 Colorimetry, 2nd ed., 1986
Publication CIE No. 63 Spectroradiometric Measurement of
1.4 This standard does not purport to address all of the
Light Sources, 1984
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 2.3 IEC Publications:
priate safety and health practices and determine the applica- Publication No. 441 Photometric and Colorimetric Methods
bility of regulatory limitations prior to use. of Measurement of the Light Emitted by a Cathode-Ray
Tube Screen, 1974
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3. Terminology
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1 The definitions of appearance terms in Terminology
mendations issued by the World Trade Organization Technical
E284 are applicable to this test method.
Barriers to Trade (TBT) Committee.
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
This test method is under the jurisdiction of ASTM Committee E12 on Color Standards volume information, refer to the standard’s Document Summary page on
and Appearance and is the direct responsibility of Subcommittee E12.06 on Display, the ASTM website.
Imaging and Imaging Colorimetry. Available from CIE (International Commission on Illumination), http://
Current edition approved May 1, 2017. Published May 2017. Originally www.cie.co.at or http://www.techstreet.com.
approved in 1991. Last previous edition approved in 2011 as E1336 – 11. DOI: Available from International Electrotechnical Commission (IEC), 3 rue de
10.1520/E1336-11R17. Varembé, Case postale 131, CH-1211, Geneva 20, Switzerland, http://www.iec.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1336 − 11 (2017)
4. Summary of Test Method 7.2 Calibration Sources:
7.2.1 The standard calibration source for spectroradiometry
4.1 Procedures are given for obtaining spectroradiometric
is a tungsten-filament lamp operated at a specified current. It is
data and for the calculation of CIE tristimulus values and other
preferable to have more than one standard lamp to permit
color coordinates to describe the colors of VDUs. Modifica-
cross-checks and to allow calibration at a range of luminance
tions to the standard calculation procedures of Practice E308
levels.
are described.
7.2.2 Monochromatic emission sources such as a low-
5. Significance and Use pressure mercury arc lamp or tunable laser should also be
available for use in calibrating the wavelength scale.
5.1 The most fundamental method for obtaining CIE tris-
7.2.3 The electrical supplies for the calibration sources
timulus values or other color coordinates for describing the
should be of the constant current type. The supply should be
colors of visual display units (VDUs) is by the use of
linear and not a switching supply. Current regulation should be
spectroradiometric data. (See CIE No. 18 and 63.) These data
maintained to better than 0.1 %. At this level the radiant flux
are used by summation together with numerical values repre-
from the calibration source is at least an order of magnitude
senting the 1931 CIE Standard Observer and normalized to K ,
m
more stable than the flux from a VDU.
the maximum spectral luminous efficacy function.
7.2.4 There should be a standard for length measurements
5.2 The special requirements for characterizing VDUs pos-
available (such as a high quality metric rule) since absolute
sessing narrow or discontinuous spectra are presented and
irradiance calibration must be performed at an exact distance
discussed. Modifications to the requirements of Practice E308
from the filament of the calibration lamp.
are given to correct for the unusual nature of narrow or
discontinuous sources.
7.3 Receiving Optics—To maximize the light throughput the
number of optical surfaces between the source of light should
6. Requirements When Using Spectroradiometry
be kept to a minimum. In extended diffuse sources (such as
VDUs) only a set of limiting apertures will be needed. In some
6.1 When describing the measurement of VDUs by
spectroradiometry, the following must be specified: instances, it may be desirable to image the VDU with an
intermediate focusing lens or mirror assembly. Care should be
6.1.1 The radiometric quantity determined, such as the
2 2
irradiance (W/m ) or radiance (W/m -sr), or the photometric taken to use a magnification that will adequately fill the
entrance slit when viewing both the calibration and test source.
quantity determined, such as illuminance (lm/m ) or luminance
2 2
(lm/m -sr or cd/m ). The use of older, less descriptive names or
units such as phot, nit, stilb is not recommended. 8. Calibration and Verification
6.1.2 The geometry of the measurement conditions,
8.1 Calibration and its verification are essential steps in
including, whether a diffuser was used and the material from
ensuring that precise and accurate results are obtained by
which it was constructed, the distances from the VDU, the size
spectroradiometric measurements. They require the use of
of the area to be measured on the VDU, the uniformity of the
physical standards, some of which may not be normally
VDU across the area to be measured, the microstructure of the
supplied by commercial instrument manufacturers. It remains
VDU picture elements, and the presence of any special
the user’s responsibility to obtain and use the physical stan-
intermediate optical devices such as integrating spheres.
dards necessary to keep his instrument in optimum working
6.1.3 The spectral parameters, including the spectral region,
condition.
wavelength measurement interval, and spectral bandwidth.
These must be specified since the various VDU technologies 8.2 Radiometric Scale:
may demand more or less stringent requirements.
8.2.1 Zero Calibration or Its Verification—All photometric
6.1.4 The type of standard used to calibrate the system, a
devices have some inherent photocurrent, even in the absence
standard lamp, a calibrated source, or a calibrated detector, and
of light. This so called “dark current” must be measured and
the source of the calibration.
subtracted from all subsequent readings either electrically or
6.1.5 The physical and temporal characteristics of the VDU
computationally.
including, refresh or field rate, convergence and purity adjust-
8.2.2 Radiometric Scale Calibration—A physical standard
ments (if the manufacturer allows such), luminance level, and
of spectral irradiance is normally used for calibration. After the
any spectral line character in the emission from the VDU. The
dark current has been measured, the calibration source is
integration time of the detector system should be noted in
positioned in front of the receiving optics at the specified
relation to the refresh or field rate of the VDU. (See IEC No.
distance and operated at the specified electric current. This
441.)
provides a good approximation to a Plankian radiator across
the visible spectrum. The calibration source is measured and
7. Apparatus
the values of the dark-current-corrected photocurrent are re-
7.1 The basic instrument requirement is a spectroradiomet- corded. These photocurrents are then related to the calibration
ric system designed for the measurement of spectral radiance values of spectral irradiance that were provided by the stan-
or irradiance of light sources. See Practice E1341 for details on dardizing laboratory. The ratio of spectral irradiance to photo-
each of the parts of a spectroradiometer and how to calibrate current becomes the instrument calibration factor. All subse-
and use the instrument. quent measurements are multiplied by this ratio.
E1336 − 11 (2017)
8.2.3 Linearity Verification—Periodically after the radio- 1931 CIE color matching f
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1336 − 11 E1336 − 11 (Reapproved 2017)
Standard Test Method for
Obtaining Colorimetric Data From a Visual Display Unit by
Spectroradiometry
This standard is issued under the fixed designation E1336; 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.
INTRODUCTION
The fundamental procedure for characterizing the color and luminance of a visual display unit
(VDU) is to obtain the spectroradiometric data under specified measurement conditions, and from
these data to compute CIE chromaticity coordinates and absolute luminance values based on the 1931
CIE Standard Observer. The considerations involved and the procedures to be used to obtain precision
colorimetric data for this purpose are contained in this test method. The values and procedures for
computing CIE chromaticity coordinates are contained in Practice E308. The procedures for obtaining
spectroradiometric data are contained in Test Method E1341. This test method includes some
modifications to the procedures given in Practice E308 that are necessary for computing the absolute
luminance values of VDUs. This procedure is intended to be generally applicable to any VDU device,
including but not limited to cathode ray tubes (CRT), liquid crystal displays (LCD), and electrolu-
minescent displays (ELD).
1. Scope
1.1 This test method prescribes the instrumental measurements required for characterizing the color and brightness of VDUs.
1.2 This test method is specific in scope rather than general as to type of instrument and object.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E284 Terminology of Appearance
E308 Practice for Computing the Colors of Objects by Using the CIE System
E1341 Practice for Obtaining Spectroradiometric Data from Radiant Sources for Colorimetry
2.2 CIE Publications:
Publication CIE No. 18 Principles of Light Measurements
Publication CIE No. 15.2 Colorimetry, 2nd ed., 1986
Publication CIE No. 63 Spectroradiometric Measurement of Light Sources, 1984
This test method is under the jurisdiction of ASTM Committee E12 on Color and Appearance and is the direct responsibility of Subcommittee E12.06 on Display, Imaging
and Imaging Colorimetry.
Current edition approved Nov. 1, 2011May 1, 2017. Published November 2011May 2017. Originally approved in 1991. Last previous edition approved in 20032011 as
E1336 – 96 (2003).E1336 – 11. DOI: 10.1520/E1336-11.10.1520/E1336-11R17.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from U.S. National Committee of the CIE (International Commission on Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 Pond St.,
Salem, MA 01970, http://www.cie-usnc.org.http://www.cie.co.at or http://www.techstreet.com.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1336 − 11 (2017)
2.3 IEC Publications:
Publication No. 441 Photometric and Colorimetric Methods of Measurement of the Light Emitted by a Cathode-Ray Tube
Screen, 1974
3. Terminology
3.1 The definitions of appearance terms in Terminology E284 are applicable to this test method.
4. Summary of Test Method
4.1 Procedures are given for obtaining spectroradiometric data and for the calculation of CIE tristimulus values and other color
coordinates to describe the colors of VDUs. Modifications to the standard calculation procedures of Practice E308 are described.
5. Significance and Use
5.1 The most fundamental method for obtaining CIE tristimulus values or other color coordinates for describing the colors of
visual display units (VDUs) is by the use of spectroradiometric data. (See CIE No. 18 and 63.) These data are used by summation
together with numerical values representing the 1931 CIE Standard Observer and normalized to K , the maximum spectral
m
luminous efficacy function.
5.2 The special requirements for characterizing VDUs possessing narrow or discontinuous spectra are presented and discussed.
Modifications to the requirements of Practice E308 are given to correct for the unusual nature of narrow or discontinuous sources.
6. Requirements When Using Spectroradiometry
6.1 When describing the measurement of VDUs by spectroradiometry, the following must be specified:
2 2
6.1.1 The radiometric quantity determined, such as the irradiance (W/m ) or radiance (W/m -sr), or the photometric quantity
2 2 2
determined, such as illuminance (lm/m ) or luminance (lm/m -sr or cd/m ). The use of older, less descriptive names or units such
as phot, nit, stilb is not recommended.
6.1.2 The geometry of the measurement conditions, including, whether a diffuser was used and the material from which it was
constructed, the distances from the VDU, the size of the area to be measured on the VDU, the uniformity of the VDU across the
area to be measured, the microstructure of the VDU picture elements, and the presence of any special intermediate optical devices
such as integrating spheres.
6.1.3 The spectral parameters, including the spectral region, wavelength measurement interval, and spectral bandwidth. These
must be specified since the various VDU technologies may demand more or less stringent requirements.
6.1.4 The type of standard used to calibrate the system, a standard lamp, a calibrated source, or a calibrated detector, and the
source of the calibration.
6.1.5 The physical and temporal characteristics of the VDU including, refresh or field rate, convergence and purity adjustments
(if the manufacturer allows such), luminance level, and any spectral line character in the emission from the VDU. The integration
time of the detector system should be noted in relation to the refresh or field rate of the VDU. (See IEC No. 441.)
7. Apparatus
7.1 The basic instrument requirement is a spectroradiometric system designed for the measurement of spectral radiance or
irradiance of light sources. See Practice E1341 for details on each of the parts of a spectroradiometer and how to calibrate and use
the instrument.
7.2 Calibration Sources:
7.2.1 The standard calibration source for spectroradiometry is a tungsten-filament lamp operated at a specified current. It is
preferable to have more than one standard lamp to permit cross-checks and to allow calibration at a range of luminance levels.
7.2.2 Monochromatic emission sources such as a low-pressure mercury arc lamp or tunable laser should also be available for
use in calibrating the wavelength scale.
7.2.3 The electrical supplies for the calibration sources should be of the constant current type. The supply should be linear and
not a switching supply. Current regulation should be maintained to better than 0.1 %. At this level the radiant flux from the
calibration source is at least an order of magnitude more stable than the flux from a VDU.
7.2.4 There should be a standard for length measurements available (such as a high quality metric rule) since absolute irradiance
calibration must be performed at an exact distance from the filament of the calibration lamp.
7.3 Receiving Optics—To maximize the light throughput the number of optical surfaces between the source of light should be
kept to a minimum. In extended diffuse sources (such as VDUs) only a set of limiting apertures will be needed. In some instances,
it may be desirable to image the VDU with an intermediate focusing lens or mirror assembly. Care should be taken to use a
magnification that will adequately fill the entrance slit when viewing both the calibration and test source.
Available from International Electrotechnical Commission (IEC), 3 rue de Varembé, Case postale 131, CH-1211, Geneva 20, Switzerland, http://www.iec.ch.
E1336 − 11 (2017)
8. Calibration and Verification
8.1 Calibration and its verification are essential steps in ensuring that precise and accurate results are obtained by
spectroradiometric measurements. They require the use of physical standards, some of which may not be normally supplied by
commercial instrument manufacturers. It remains the user’s responsibility to obtain and use the physical standards necessary to
keep his instrument in optimum working condition.
8.2 Radiometric Scale:
8.2.1 Zero Calibration or Its Verification—All photometric devices have some inherent photocurrent, even in the absence of
light. This so called “dark current” must be measured and subtracted from all subsequent readings either electrically or
computationally.
8.2.2 Radiometric Scale Calibration—A physical standard of spectral irradiance is normally used for calibration. After the dark
current has been measured, the calibration source is positioned in front of the receiving optics at the specified distance and operated
at the specified electric current. This provides a good approximation to a Plankian radiator across the visible spectrum. The
calibration source is measured and the values of the dark-current-corrected photocurrent are recorded. These photocurrents are then
related to the calibration values of spectral irradiance that were provided by the standardizing laboratory. The ratio of spectral
irradiance to photoc
...
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