CONCENTRATING AND COLLECTING OPTICAL SYSTEM USING CONCAVE TOROIDAL REFLECTORS

WIPO Patent Application WO2000022344

A9

An electromagnetic radiation source (SO), such as an arc lamp, is located at a point displaced from the optical axis of a concave toroidal reflecting surface (M1). The concave primary reflector (M1) focuses the radiation from the source (SO) at an off-axis image point that is displaced from the optical axis. The use of a toroidal reflecting surface enhances the collection efficiency into a small target (T), such as an optical fiber, relative to a spherical reflecting surface by substantially reducing aberrations caused by the off-axis geometry. A second concave reflector (M2) is placed opposite to the first reflector (M1) to enhance further the total flux collected by a small target (T). In accordance with one embodiment, the present invention is directed to devices in which the square of the off-axis distance divided by the radius of curvature is equal to or less than the extent of the source of electromagnetic radiation (yo<2>/r