This paper reviews the use of an electro-optical tracking system and stereoscopy for robot guidance. Items affecting the the choice of technology are discussed. These include work volume, field of view, resolution and processing speed. A review is given of the advantages and disadvantages of various 3-D tracking methods such as conventional stereo vision, 3-D triangulation and laser radar. The second part of this paper describes a specific implementation of a tracking system using active targets (infrared LEDs) and position sensitive tracking devices. In particular, the optical components, detectors, hardware, algorithms and software are reviewed. Further observations are made on the problem of calibrating such a system to robot coordinate space. Lastly some findings on overall performance aspects such as reliability, accuracy and ease of integration of such a system are presented.