DETERMINING THE MINIMUM TEST DISTANCE IN THE GONIOPHOTOMETRY OF LED LUMINAIRES

摘要

The CIE and IESNA have defined many different ways of specifying the test distance required to achieve meaningful measurements of the luminous intensity distribution of luminaires and other light sources on far-field goniophotometer systems. However in the photometry of light sources comprised of discrete lighting elements, such as LEDs, there can be significant errors obtained when the recommended test distances are used. This is particularly apparent for luminaires consisting of narrow-beam LEDs where there is a large non-luminous area between luminous area elements. This paper provides a summary of the recommendations for different types of luminaires as they currently stand. It also provides a recommendation for determining the minimum required test distance to produce meaningful luminous intensity distributions of LED luminaires.