Colour Measurements
The colour of a material or object can be represented by its spectral ‘finger-print’ (e.g. its spectral reflectance or transmittance) or in terms of colorimetric values such as (but not limited to) x, y, u', v', L*, a*, b*. These can be calculated for CIE 2° and 10° Standard Observers and CIE Standard Illuminants A, C, D50, D65.
NPL measures the colour of reflective samples using a calibrated spectrophotometer which may be used in 0°:45°a, specular included (8°:di) and specular excluded (8°:de) geometries and has a resolution down to 1 nm over the spectral range 380 nm to 780 nm. The results are traceable to the ‘NPL – 2007’ spectral reflectance scale and are typically quoted for a temperature of 23 °C. Services for colour of transmissive materials are also available.
Clients will receive a UKAS accredited calibration certificate (available as both electronic and hard copy).
Publications
- Surface colour measurements, Clarke, P J, Measurement Good Practice Guide No. 96, October 2006.
- Uncertainties in surface colour measurements, Gardner, J L, Measurement Good Practice Guide No. 95 , October 2006.
- The uncertainty of surface colour measurements made with commercially-available diode-array instrumentation and recommended calibration protocols, Hanson, A R, Pointer, M R, Clarke, P J, DQL-OR 005, October 2004.
Contact
Customer Service tel: +44 20 8943 6151
E-mail: optical_enquiries@npl.co.uk