ASTM G130-12(2020)

4.1 This test method represents the preferable means for calibrating both narrow-band and broad-band ultraviolet radiometers. Calibration of narrow- and broad-band ultraviolet radiometers involving direct measurement of a standard source of spectral irradiance is an alternative method for calibrating ultraviolet radiometers. This approach is valid only if corrections for the spectral response of the instrument and the spectral mismatch between the calibration spectral distribution and the target spectral distribution can be computed. See Test Method E973 for a description of the spectral mismatch calculation.

4.2 The accuracy of this calibration technique is dependent on the condition of the light source (for example, cloudy skies, polluted skies, aged lamps, defective luminaires, etc.), and on source alignment, source to receptor distance, and source power regulation.

4.3 Spectroradiometric measurements performed using either an integrating sphere or a cosine receptor (such as a shaped PTFENote 6: When measuring the hemispherical spectral energy distribution of an array of light sources (for lamps), normal incidence is defined by the condition obtained when the plane of the receiver aperture is parallel to the plane of the lamp, or burner, emitting area.

4.4 Calibration measurements performed using a spectroradiometer equipped with a pyrheliometer-comparison tube (a sky-occluding tube), regardless of whether affixed directly to the monochromator's entrance slit, to the end of a fiber optic bundle, or to the aperture of an integrating sphere, shall not be performed unless the radiometer being calibrated is configured as a pyrheliometer (possesses a view-limiting device having the approximate optical constants of the spectroradiometer's pyrheliometer-comparison tube).

4.5 Spectroradiometric measurements performed using source optics other than the integrating sphere or the “standard” pyrheliometer comparison tube, shall be agreed upon in advance between all involved parties.

4.6 Calibration measurements that meet the requirements of this test method are traceable to a national metrological laboratory that has participated in intercomparisons of standards of spectral irradiance, largely through the traceability of the standard lamps and associated power supplies employed to calibrate the spectroradiometer according to G138, the manufacturer‘s specified procedures, or CIE Publication 63.

4.7 The accuracy of calibration measurements performed employing a spectroradiometer is dependent on, among other requirements, the degree to which the temperature of the mechanical components of the monochromator are maintained during field measurements in relation to those that prevailed during calibration of the spectroradiometer. [1]

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.

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.

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.

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 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.