Choosing Optimal Wavelengths for Colour Laser Scanners

Multiple sets of measured reflectance data were analysed to determine the combination of three laser wavelengths that would minimise the mean colorimetric difference between the laser illumination and D65. The optimum wavelengths for blue, green and red lasers were found to be in the ranges 450-460, 530-540 and 595-605 nm, close to Thornton's 'prime wavelengths of vision'. These optima were independent of both samples and colour difference metrics. The results were compared with the colorimetric performance of a commercial 3D colour laser scanner, in which the laser wavelengths are 473, 532 and 635 nm. It was found that two additional laser wavelengths would have to be added to the scanner to achieve a degree of colorimetric accuracy similar to the optimum three laser wavelengths. The effects on colour image rendering of the actual vs optimal wavelengths were demonstrated on a hyperspectral image.