Safe laser pointers with remote directional activation

摘要

The invention relates to a system for pointing out aspects of images projected onto a viewing screen during a lecture, consisting of a laser beam generator held by the lecturer, a power supply to excite the said laser beam generator, a series of incoherent optical transmitters attached around the periphery of said viewing screen and optical detectors embedded in the tip of the said laser beam generator which respond to the light emitted by said series of optical transmitters on the viewing screen. The invention is only activated when the said laser beam generator is directed at the viewing screen because there has to be a direct line of sight between the optical transmitters attached to the periphery of the viewing screen and the detectors embedded in the tip of the laser beam generator for the laser beam to be generated. If this line of sight is broken, as would be the case if the laser beam generator was accidentally directed towards the audience and away from the viewing screen, the laser beam is automatically switched off.