Patent ID: 7436594

Claim:
An electrically controllable light diffuser comprising: an optical medium and an electro-optic medium arranged with an effective optical interface between a first surface of the optical medium and a first surface of the electro-optic medium; and transparent electrodes arranged for providing an electric field across the electro-optic medium so as to allow control of the refractive index of the electro-optic medium by application or non-application of an electric field across the electro-optic medium, wherein one of the first surface of the optical medium and the first surface of the electro-optic medium is structured with a surface profile, the surface profile comprising plural surface angles, wherein the plural surface angles comprise a distribution of facet angles which vary on a scale larger than a diffraction limit, but smaller than a sub-pixel spacing, the distribution configured to provide an effect observed as one of a diffuser with respect to the spacing of sub-pixels, wherein the effective optical interface acts overall as the diffuser, further having an angular diffusion profile with a vertical scattering component of less than one percent (1%) and a horizontal scattering component of approximately ten percent (10%), such that (i) when the refractive index of the electro-optic medium is controlled by application or non-application of an electric field to be substantially equal to the refractive index of the optical medium there is substantially no refraction arising from the effective optical interface between the first surface of the optical medium and the first surface of the electro-optic medium, and such that (ii) when the refractive index of the electro-optic medium is controlled by application or non-application of an electric field to be different from the refractive index of the optical medium refraction does take place at the effective optical interface between the first surface of the optical medium and the first surface of the electro-optic medium and, by virtue of there being plural surface angles, the refraction directs light to a corresponding plurality of angles thereby providing a diffusion effect.