• The photometry lab in optical radiation metrology (ORM) keeps measurement standards and equipment for the measurement of luminous flux, luminous intensity and colour temperature of light sources and calibration of illuminance, luminance meters.


• The SI base unit of luminous intensity, the candela, has been realised at ORM of National Metrology Centre (NMC) since 2003. Three temperature stabilised trap-photometers with precision apertures and V(λ)correction filters were constructed and fully characterised. The relative expanded uncertainty at a confidence level of approximately 95% (k = 2) of the luminous responsivity of these trap-photometers is better than ±0.52%.


• Our recent R&D effort is focused on developing measurement standards and measurement techniques for white LED and solid state lighting (SSL) which have shown great potential as a new type of green (energy saving) light source.
  

Integrating sphere for luminous flux measurement

8 - m optical bench for lux meter calibration