A light diffuser panel for coupling to an optical element, includes a substrate with a first surface that is diffusive to a plurality of wavelengths of light and a second surface, wherein the substrate comprises a material with a refractive index nin that is greater than a refractive index nd of a medium outside of the first surface, λmin is a minimum wavelength of the plurality of wavelengths of light, λmax is a maximum wavelength of the plurality of wavelengths of light, the first surface is a diffractive grating surface with a grating period P, the grating period P is greater than λmax/(nd+nin), and P is smaller than λmin.