Accuracy simulation of an LED based spectrophotometer

In this paper, the achievable accuracy of a reflectance spectrophotometer based on 18 LEDs of different peak wavelengths in the range of 390–710 nm for object illumination is reported. For simulating the accuracy, reflectance spectra of the color target ColorChecker® have been used. By weighting the reflectance spectra of the target with measured relative power distribution spectra of the employed LEDs, simulated spectral reflectance values of the target are obtained. For calculating color values, unique wavelength values must be assigned to the simulated spectral sample values. LEDs can be characterized by several wavelength parameters. It has been shown that, without applying a correction procedure, assigning the centroid-wavelength of the LEDs as color calculation basis delivers the best results. But if a linear correction matrix is introduced, an optimized equidistant wavelength assignment delivers the best results. The mean achievable precision is sufficient to determine color values below ΔEab < 0.3.