Facility for calibration of photometers for measurement of temporal light modulation

Abstract

A facility for calibration of temporal light modulation (TLM) photometers has been developed. The facility is based on a laser-fed reference integrating sphere source, the optical input power of which can be modulated with an acousto-optic modulator. A system of photodiodes, amplifiers and an analogue-to-digital converter is used to sample the temporally modulated irradiance at one of the exit ports of the source. With the facility, a TLM photometer was calibrated for display contrast ratio root mean square with an absolute combined standard uncertainty of 0.037%. In addition, the facility has been characterised with the aim of measuring flicker and stroboscopic effect, considering the Ecodesign ‘Single Lighting Regulation’. The frequency response of the facility is shown to be sufficient to accommodate measurements of flicker and the stroboscopic effect.