A diffuser unit (9, 13, 65, 81, 81', 101) for providing a chromatically tunable transmitted light by Rayleigh-like scattering of light that is incident on the diffuser unit (9, 13, 65, 81, 81', 101) by illumination with directed white light, the diffuser unit (9, 13, 65, 81, 81', 101) comprising: - a scattering layer (17, 17') comprising - a plurality of transparent nanoscale scattering elements (19, 63, 105) and - a host material (21, 61) separating the transparent nanoscale scattering elements (19, 63, 105); and a pair of areal electrical contacts for providing an electric field, in particular for interacting with the nanoscale scattering elements (19, 63, 105) and/or the host material (21, 61), wherein the areal electrical contacts extend on opposite faces of the scattering layer (17,17') and at least one of the areal electrical contacts is configured to be transparent in the visible wavelength range, wherein the scattering layer (17, 17') has a wavelength dependent ensemble light scattering cross-section amount (σ total) within the visible wavelength range that depends on - a relative refractive index between the nanoscale scattering elements (19, 63, 105) and the host material (21, 61) associated to an illumination direction, and - an effective size of the nanoscale scattering elements (19, 63, 105) associated to the illumination direction, and wherein the scattering layer (17, 17') is configured to be adaptable in the ensemble light scattering cross-section amount (σ total) by varying the relative refractive index and/or the effective size of the nanoscale scattering elements (19, 63, 105), thereby providing a changeability in the spectrum of the transmitted light wherein the scattering layer is chosen from the group consisting of: - a polymer dispersed liquid crystal layer with liquid crystals embedded in a host polymer, wherein the liquid crystals form nanodroplets that are separated by the polymer and have an anisotropy in the index of refraction; - a scattering layer comprising a liquid crystal layer with liquid crystals having an anisotropy in the index of refraction, and a plurality of nanoscale scattering elements embedded in the liquid crystal layer and having a refractive index; and - a scattering layer comprising a plurality of nanoscale scattering elements (103,105) that are geometrically asymmetric in shape and provide a dipole moment in the presence of an electric field, and a liquid-like host material layer, wherein the liquid-like host material differs in the refractive index from the refractive index of the nanoscale scattering elements, separates the nanoscale scattering elements, and allows reorientation of the nanoscale scattering element (103,105). - a scattering layer (17, 17') comprising - a plurality of transparent nanoscale scattering elements (19, 63, 105) and - a host material (21, 61) separating the transparent nanoscale scattering elements (19, 63, 105); and - a relative refractive index between the nanoscale scattering elements (19, 63, 105) and the host material (21, 61) associated to an illumination direction, and - an effective size of the nanoscale scattering elements (19, 63, 105) associated to the illumination direction, and - a polymer dispersed liquid crystal layer with liquid crystals embedded in a host polymer, wherein the liquid crystals form nanodroplets that are separated by the polymer and have an anisotropy in the index of refraction; - a scattering layer comprising a liquid crystal layer with liquid crystals having an anisotropy in the index of refraction, and a plurality of nanoscale scattering elements embedded in the liquid crystal layer and having a refractive index; and - a scattering layer comprising a plurality of nanoscale scattering elements (103,105) that are geometrically asymmetric in shape and provide a dipole moment in the presence of an electric field, and a liquid-like host material layer, wherein the liquid-like host material differs in the refractive index from the refractive index of the nanoscale scattering elements, separates the nanoscale scattering elements, and allows reorientation of the nanoscale scattering element (103,105).