NIST Goniospectrometer for Surface Color Measurements
Maria E. Nadal, Gael Obein
The goniospectrometer at the National Institute of Standards and Technology (NIST) can measure the spectral reflectance of colored samples over a wide range of illumination and viewing angles. This capability is important for the colorimetric characterization of complex surfaces, such as gonioapparent coatings or retroreflective surfaces. Three detection and illumination systems have been implemented and are discussed. The first system is a single element silicon diode combined with monochromatic illumination. A second system, a fiber-coupled CCD array spectrometer with a white illumination source, has been added to the goniospectrometer. Unlike the first system, the array spectrometer measures the entire spectrum simultaneously, dramatically decreasing the acquisition time. The third system, a CCD imaging camera used with white light or monochromatic illumination, has been added to the detection capabilities. The imaging capabilities will allow the development of metrics to describe visual aspects that are currently judged by human observers in the manufacturing process. An example is distinctiveness of image (DOI) for various types of paints. Preliminary measurements to validate these detection systems and results are presented.
July 7-8, 2008
CIE Symposium on Advances in Photometry and Colorimetry