Performance analysis of an imaging spectro-chroma meter
P. Fiorentin, Elena Pedrotti, Alessandro Scroccaro · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2008
The paper considers the possibility of realizing an image spectro-chroma meter by a scientific grade CCD camera and a tunable narrow band filter bench. The presented system allows at recording a multi spectral imaging of the scene, acting as a spectroradiometer with a high spatial resolution and a spectral resolution depending on the bandwidth of the filters. The characterization of the constituting components is briefly described and some evaluations of their performances are presented. In particular, the spectral transmission coefficients of the filters are evaluated together with the power spectral responsivity of the CCD camera. As an example of application, the light reflected by coloured sample is considered and both the spectral radiance and the correspondent colour coordinates are determined. A comparison between measurements obtained by the CCD spectro-chroma meter and by a spectroradiometer allows at quantifying the performance of the new system: for every coloured light, the measured spectral radiance differs less than 2%, so as the luminance value, when a light approximating the Illuminant A is considered. For the same white source, the errors on x and y coordinates are always less 0.002.The system is also used to measure the spectral reflection coefficient of the same coloured samples obtaining performances close to the ones of a good spectroradiometer. The error on spectral reflectivity is about 5% and the error on the CIE 1976 (L*a*b*) coordinates is of the order of ΔE*=3 under the Illuminant A.