Patent ID: 6858828

Claim:
A photocell comprising: an entry face for light; a photosensitive element; and a lightguide placed between the entry face and the photosensitive element, wherein the lightguide includes: a first volume filled with a first dielectric material with a first optical refractive index; and a second volume filled with at least a second dielectric material with a second optical refractive index less than the first optical refractive index; wherein, the first volume being bounded by an upper surface and a lower surface which lie parallel to a section of the entry face and to a section of the photosensitive element respectively, and the first volume being bound by a continuous lateral surface connecting a perimeter of the upper surface to a perimeter of the lower surface, and separating the first volume and the second volume, the second volume surrounding the first volume over at least part of a distance between the upper surface and the lower surface of the first volume; a third dielectric material with a third optical refractive index, inserted between the first volume and the second volume, and over at least part of the continuous lateral surface of the first volume, the third optical refractive index being less than the first optical refractive index; wherein the third dielectric material is a compound based on silicon oxycarbonitride.