Abstract: The invention relates to an optical element in the form of a body (fluorescent body) which comprises a material with an index of refraction greater than one, contains fluorescent particles, and manifests at least one output coupling zone (light outlet window). This element is characterized, in accordance with the invention, by its use for collecting, conducting, and focused output coupling of optical radiation. The fluorescent body primarily serves the purpose of collecting natural or artificially produced radiation in large areas, and to focus it on a small-area, relatively weak receiver; or, with and without a light valve, for the purpose of representation of information (or data).

Abstract: A display apparatus has a passive electro-optical display. The apparatus has a housing with a lower part in a form of a rectangle which is open upwardly and has a cover which carries the display in a position inclined with respect to the plane of the base of the rectangular-shaped lower part of the housing. The display apparatus has a cover surface which is formed at least in one area of a plate which supports the display, the plate consisting of a material having an index of refraction which is greater than one, and which contains particles which are fluorescent. That portion of the cover also has a plurality of light emergence windows aligned with the various elements of the display and is advantageously metallized at its peripheral edges. The display is supported on the surface of the cover and the cover includes transitions from one planer area to another which are defined in accordance with the relationR.gtoreq.(d.multidot.n.sub.f)/(n.sub.f -n.sub.