Thin-film luminescent concentrators for position-sensitive devices

The output emittance at the edge of a luminescent concentrator (LC) depends on the physical properties of the dye and matrix used, the spectral intensity of the incident light, and the geometric parameters of the LC. If a projection of the light source on a LC is smaller than its aperture, the LC's output signal will also depend on the position of the projection. This LC feature opens the possibility of determining the position of the light spot and thus building a new type of position-sensitive device. The advantage of LC position-sensitive devices compared with CCD-based sensors is their greater simplicity; LC detection devices have larger linear range than conventional position-sensitive sensors based on discrete photodetectors. Here we describe our study of LC's as two-dimensional position-sensitive elements and analyze, by ray-tracing simulation, different LC designs to get improved linear response. In addition, we discuss experimental results showing real characteristics of position-sensitive devices based on the integration of LC's with photodetectors. We found that spatial resolution of a 12-mm-radius LC-based sensor is of the order of 13 mum within the linear range +/-5 mm.