Method for illumination and system for determining spectral distribution of light for illumination

A system for determining a spectral distribution of light for illumination, the system including:

• a first light source that emits light that has an average color rendering index of 40 or greater, a color temperature in the range from 3000 K to 10000 K and a continuous spectrum in the wavelength range from 380 nanometers and 780 nanometers;
• a spectral radiance meter;
• and
• a processor connected to the spectral radiance meter,
• wherein the system is configured such that a value or values of representative wavelength and a value or values of comparative wavelength are determined in a method for illumination of an object to be observed and the background, the method comprising the steps of:
• determining a color matching function and obtaining an xy chromaticity diagram using the color matching function;
• obtaining a relationship between wavelength and spectral radiance of the object to be observed while the object to be observed and the background are illuminated by the first light source and determining a value of representative wavelength that corresponds to a maximum value of the spectral radiance of the object to be observed plotted against wavelength or values of representative wavelength that correspond to maximum values of the spectral radiance of the object to be observed plotted against wavelength;
• determining a value of comparative wavelength for the value or values of representative wavelength using the value or values of representative wavelength and the xy chromaticity diagram so as to increase a contrast ratio between the object to be observed and the background;
• and
• illuminating the object to be observed and the background with light of the value or values of representative wavelength and light of the value of comparative wavelength.