The problem of tracking hands and fingers on natural scenes has received much attention using passive acquisition vision systems and computationally intense image processing. We are currently studying a simple active tracking system using a laser diode, steering mirrors, and a single non-imaging detector, which is capable of acquiring three dimensional coordinates in real time without the need of any image processing at all. Essentially, it is a smart rangefinder scanner that instead of continuously scanning over the full field of view restricts its scanning area, on the basis of a real-time analysis of the backscattered signal, to a very narrow window precisely the size of the target. The complexity of the whole setup is equivalent to that of a portable laser-based barcode reader, making the system compatible with wearable computers. Categories & Subject Descriptors: H.5.2 [Information interfaces and presentation]: User Interfaces ? Input