Patent ID: 8622560

Claim:
A chromatically non-uniform illumination device comprising: an artificial light source with a spectral bandwidth of at least 100 nm in the range of wavelengths between 400 nm and 700 nm, the artificial light source comprising one or more active elements which emit photons or which absorb photons and then re-emit photons at a higher wavelength; and a chromatic diffuser located downstream the artificial light source, which comprises elements of a first non-liquid material transparent to visible light, the elements of the first non-liquid material being dispersed in a second non-liquid material transparent to visible light, the typical linear dimension d of the dispersed elements of the first non-liquid material satisfying the condition 5 nm≦d≦300 nm; wherein the chromatic diffuser is non-absorbent in the range of wavelengths between 400 nm and 700 nm, and a maximum dimension L max of the chromatic diffuser is equal to or greater than twice a minimum dimension d min of a projection of the largest of said active elements on a first plane perpendicular to a first direction, wherein said maximum dimension L max is defined as the greatest between: a transverse dimension, defined as the maximum distance between couples of points belonging to the projection of the chromatic diffuser on the first plane; and a longitudinal dimension, defined as the maximum distance between couples of points belonging to the projection of the chromatic diffuser on a second plane parallel to the first direction; and wherein: a. in case the artificial light source is anisotropic, said first direction is the maximum emission direction of said artificial light source; otherwise b. in case the artificial light source is isotropic, said first direction is defined by a straight line that joins the closest points of said artificial light source and chromatic diffuser.