The fundamental method for obtaining CIE tristimulus values or other color coordinates for describing the colors of radiant sources is by the use of spectroradiometric measurements. These measurements are used by summation together with numerical values representing the CIE 1931 Standard Observer (CIE Publication 15:2004) and normalized to K_m, the maximum spectral luminous efficacy function, with a value of 683 lm/W.

This practice provides a procedure for selecting the operating parameters of spectroradiometers used for providing the desired precision spectroradiometric data, for their calibration, and for the physical standards required for calibration.

Special requirements for characterizing sources of light possessing narrow or discontinuous spectra are presented and discussed. Modifications to the procedures of Practice E 308 are given to correct for the unusual nature of narrow or discontinuous sources.

1.1 This practice prescribes the instrumental measurement requirements, calibration procedures, and physical standards needed for precise spectroradiometric data for characterizing the color and luminance of radiant sources.

1.2 This practice lists the parameters that must be specified when spectroradiometric measurements are required in specific methods, practices, or specifications.

1.3 This practice describes the unique calculation procedures required to determine basic colorimetric data of luminous sources.

1.4 This practice is general in scope rather than specific as to instrument, object, or material.

1.5 The values stated in SI units are to be regarded as the standard.

1.6 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.