Integrating service for large luminaires

February 19, 2013 // By Christoph Hammerschmidt
Photometric & Optical Testing offers light measurement services using an integrating sphere with a diameter of 3 meters. The size of the instrument enables measurements of large luminaires like street light etc.

The large sphere service employs a state-of-the-art 3m Labsphere Illumia integrating sphere that conforms to the exacting requirements given in IES LM-79-08 and in BS EN 13032. The sphere provides for 2pi and 4pi measurements of spectral radiant flux, luminous flux, scotopic flux, S:P ratio, CIE chromaticity, correlated colour temperature (CCT) and colour rendering index (CRI, RA).

Non-spherical integrators (typically cubes or other geodesic shapes) suffer from an uneven luminance distribution, a problem compounded when used to measure directional light sources such as solid state lighting. Photometric & Optical Testing 3m sphere will give accurate and repeatable results even with narrow beam angle spotlights and downlighter fittings. Moreover, the sphere is coated with Labsphere's proprietary 98% reflectance Spectralflect sphere paint. Compared to lower reflectance coatings, the integrating sphere is non-directional which translates into correct right lumen reading regardless of the size, position and beam shape from the light source under test. The company performs auxiliary correction as standard to ensure that the self absorption of the device under test is corrected, while the high speed array spectrometer used in the test gives near instantaneous readings of both photopically and scotopically-weighted flux.

The 3m sphere service compliments the company's existing 0.5m and 1m sphere service and goniophotometric service for the generation of photometric data files in standard .ies and .ldt formats. Photometric Testing also offers design consultancy, on-site photometric and light nuisance evaluations as well as photobiological safety testing and training courses in photometry and in photobiological safety.

For more information visit