ASTM F2964 : 12(2020)

1.1 This test method covers procedures for determining the uniformity of the luminance of an electroluminescent (EL) lamp. While written specifically for the purpose of evaluating EL devices, which are intrinsically very uniform, it can be applied (judiciously) to the measurement of any diffuse, essentially planar, light source. For specific purposes, it can be applied to partially assembled devices into which the illumination is installed (such as a membrane switch) as a diagnostic for the performance of the entire device. In such a case it must be understood that the results pertain only to the partial assembly and will be modified as the further assembly proceeds.

1.2 The method is to take a 2-dimensional set of measurements, sampling the surface of the unit under test with appropriate density. The method is restricted to measuring luminance only, since variations in color will also show as luminance non-uniformity especially in any photoptically calibrated measuring device.

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, health, and environmental 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.