Laser scanning
Laser scanning is the controlled deflection of laser beams, visible or invisible. Scanned laser beams are used in some 3-D printers, in rapid prototyping, in machines for material processing, in laser engraving machines, in ophthalmological laser systems for the treatment of presbyopia, in confocal microscopy, in laser printers, in laser shows, in Laser TV, and in barcode scanners. Applications specific to mapping and 3D object reconstruction are known as 3D laser scanner. Technology Scanning mirrors Most laser scanners use moveable mirrors to steer the laser beam. The steering of the beam can be one-dimensional, as inside a laser printer, or two-dimensional, as in a laser show system. Additionally, the mirrors can lead to a periodic motion - like the rotating polygon mirror in a barcode scanner or so-called resonant galvanometer scanners - or to a freely addressable motion, as in servo-controlled galvanometer scanners. One also uses the terms raster scanning and vector scanning to distinguish the two situations. To control the scanning motion, scanners need a rotary encoder and control electronics that provide, for a desired angle or phase, the suitable electric current to the motor (for a polygon mirror) or galvanometer (also called galvos). A software system usually controls