Whereas a goniophotometer can only measure the illuminance and colour from the lamp one direction at a time, a CCD-based imaging photometer can measure millions of angles simultaneously.
The imaging photometer, called ProMetric, is manufactured by Radiant Imaging and sold and supported by Pro-Lite. It’s a 1536 x 1024 pixel camera with 16,000:1 photometric sensitivity and spectral response accurately matched to the CIE tristimulus observer functions. RI have also developed an additional software application for the ProMetric camera that will automatically find the low beam cutoff kink, align the camera image to this position and measure the illuminance at the specified test points. In addition, the software provides a “bird’s eye” rendition of the illumination pattern.
Hector Fratty, late of Valeo Lighting Systems R&D, says lighting suppliers need high accuracy measurements in research and development phases and they have to pay a great deal of money for it. But for most applications, an expensive goniophotometer isn’t needed. A low-cost device with rapid measurement and 3% accuracy could be optimal.