Pro-Lite Technology is distributing Radiant Imaging’s ProMetric Imaging Sphere in the UK. The IS-LI is the only non-moving-part goniophotometer on the market – it measures the luminous intensity distribution from an LED over a complete hemisphere (2p steradians) in a couple of seconds. It does this without any moving parts. It also provides the variation of colour (as well as colour temperature and colour difference) with view angle into the bargain.
An LED is positioned in the centre of a 50cm dome; the LED creates an illumination pattern on the inside of the dome; a convex mirror placed to one side images the illumination pattern; finally, a ProMetric CCD-based imaging photometer views the mirror, and hence views the entire hemispheric illumination pattern from the LED. The net result is that the ProMetric camera records the intensity and view angle variation for all angles in a single measurement that takes just a second or two.