Solid state lenses, lens blanks, and lens components formed of compressible mixed powders of two or more optical substances where the mixing ratio has been deliberately varied from place to place within the volume of the optical component to produce optically useful variations in the local refractive....http://www.google.es/patents/US7959286?utm_source=gb-gplus-sharePatente US7959286 - Solid state lenses and lens components
