LED Flicker – Into the Danger Zone?

11 Nov 2019

All types of lamps suffer with flicker, LEDs included. Mains frequency feed-through onto the DC drive signal, or low frequency effects as the PWM signal is dimmed can both cause LED outputs to suffer from flicker. The key questions are, to what degree and does the flicker present a danger to health and safety? The new Viso Systems Labflicker meter from Pro-Lite Technology is a convenient, high speed photometer that provides for measurements of the most common flicker metrics (IES flicker index, flicker percentage, flicker frequency, SVM and JA8).

Standard illuminance photometers ("lux meters" in the vernacular) are simply too slow to see the flicker that can be present in the output of a lamp. This is a deliberate technique to avoid the meter readings jumping around constantly while you are trying to take a measurement. Most commercial photometers will sample the light source a maximum of 2-3 times a second. Consider that "visible" flicker at 3-70Hz can lead to epileptic seizures (most severe at 16Hz), whereas "invisible” flicker can lead to migraines, headaches and eye strain (e.g. 100Hz flicker from fluorescent lamps equipped with magnetic ballasts). For a photometer to be able to see and quantify flicker, it must sample many times faster than the highest flicker frequency that you wish to detect.

The VISO Labflicker is designed to sample the light with a bandwidth of 5,000 Hz and can record illuminance at up to 11,000 lux. To operate the Labflicker, simply plug it into your Windows PC via the supplied USB cable. Labflicker is controlled from the VISO Light Inspector software, the same application that also operates the VISO range of goniophotometers. VISO Light Inspector software will compute all of the common flicker metrics, including: IES Flicker Frequency; IES Flicker Percentage; IES Flicker Index; Flicker FFT (Flicker Fourier Transform); SVM (Stroboscopic Visibility Measure); JA8/JA10 (the metric defined in the California Energy Commission); PstLM (the short term flicker indicator defined in IEC TR 61547-1:2017).

For further information: http://www.pro-lite.co.uk/File/viso_flicker_meter.php

About Pro-Lite Technology

Pro-Lite is a supplier of specialist equipment and services with a technical focus in the following areas of photonics: instruments for measuring light and the optical properties of materials; photometry; lasers and laser safety equipment; opto-mechanics and nano-positioning equipment; optics and optical materials; and spectroscopy and spectral imaging. Pro-Lite Technology Ltd is part of the Pro-Lite Group of Companies, which includes Photometric & Optical Testing Services, SphereOptics Germany, Pro-Lite France and Pro-Lite Iberia.

Issued by: Robert Yeo, Pro-Lite Technology Ltd, robert.yeo@pro-lite.co.uk +44 (0) 1234 436110