WORKSHOP – Solid-State Lighting Measurements
The workshop covers the basics of test and measurements of solid-state lighting (SSL) products and is suitable for beginners as well as experts in the field. To provide the same level of knowledge for all participants, an introduction to SSL metrology and the relevant standards such as the first international SSL standard CIE S025 are given in the beginning. Basic quantities and principles in photometry and colorimetry will be defined and proper equipment for their determination will be presented. Important aspects for color characterization, such as correlated color temperature (CCT) and color rendering index (CRI) will be included as well. Participants will learn how to evaluate the optical performance of LEDs as basic components of SSL sources.
Aftewards, the most essential measurement procedures and used instrumentation in SSL measurements will be introduced with focus on goniophotometers and integrating spheres. Goniophotometric measurements provide details of the radiation patterns for different light sources and when correctly integrated, the total luminous flux is obtained. Furthermore, in combination with a spectroradiometer, goniophotometric measurements can provide detailed analysis of the spatial distribution of all photometric and colorimetric quantities such as CCT and CRI at the same time. For fast measurements of the luminous flux an integrating sphere with a spectroradiometer is the recommended instrument. It can be easily calibrated for a direct measurement of luminous flux.
To provide further application insight to SSL measurements a comparative study of the previously introduced methods will be presented. Since CIE S025 is the first international standard on requirements to perform photometric and colorimetric measurements on LED devices the content and consequences of CIE S025 will be reviewed in most important details. Particularly, an implementation of the auxiliary photometer method for goniophotometric measurements recommended by CIE S025 will be briefly presented.