Two-dimensional optical position sensor

A novel two dimensional optical position sensor based on confinement of luminescence within a flat panel is described. The basis of the sensor is a flat luminescent panel, such as those used in luminescent solar energy concentrators. In these concentrators, a glass or plastic plate is either coated or impregnated with a fluorescent material. The incident radiation produces luminescent emission, much of which is confined within the plate through total internal reflection, and is thus guided to solar cells which line the thin edges of the plate. In order to use such a plate as a position sensor, four detectors are placed along two orthogonal axes at the edges of the plate, and the plate is illuminated with a spot of light. The spot of light induces luminescence, which is detected by the four detectors. The detectors' output is processed to provide position information. Position sensors based on the above idea were constructed, using both microscope slides coated with a fluorescent dye, and poly(methyl methacrylate) plates which were cast in the presence of a fluorescent dye so that they exhibited fluorescence throughout their volume. The results showed that the detector output varied monotonically with position. This paper presents the results obtained to date, together with a theory which relates the detector output to position. Suggestions for the improvement of the sensor, particularly in the areas of materials processing and sensor geometry, are provided.