Measuring the photometric quantities of an LED

2019/09/23
Article by Dr. Günther Leschhorn

Before the LED started its triumphal march into the lighting industry, the world of light bulbs was relatively simple. A broken 40 Watt bulb was easily replaced in the DIY store. But with LED technology the situation is different: the user is faced with a multitude of new terms such as luminous flux, color temperature or color rendering index (CRI) that are stated on the packaging, but not explained. The purchase of a 40 Watt lamp has thus become a “Check list for the purchase of a new LED lamp from a retailer” [1]. The user must familiarize him- or herself with new values and terms, and expects consistency. That in turn is a challenge for lamp and luminaire manufacturers: How are these quantities correctly measured on a comparable basis? What constitutes a precise measurement?

published in Elektronik Praxis SH13/2019