The continuously increasing number of space debris endangers space faring especially in low earth orbits. Scientists of the German Aerospace Centre (DLR) are currently developing an optical observation system featuring a pulsed laser capable of highly accurate position determination of particles measuring only a few centimetres in diameter. Laser beams are easy to focus, which is why angular coordinates may be measured very precisely by laser tracking. Moreover, distances can be measured by determining the time-of-flight of laser pulses (laser ranging). The exhibit is a simplified set-up to demonstrate how such a 3-D position measurement is carried out.