Editing Galvanometer (section)

===Modern uses===
Most modern uses for the galvanometer mechanism are in positioning and control systems. Galvanometer mechanisms are divided into moving magnet and moving coil galvanometers; in addition, they are divided into ''closed-loop'' and ''open-loop'' - or ''resonant'' - types.

''Mirror'' galvanometer systems are used as beam positioning or beam steering elements in [[laser scanning|laser scanning systems]]. For example, for material processing with high-power lasers, closed loop mirror galvanometer mechanisms are used with [[Servomechanism|servo]] control systems. These are typically high power galvanometers and the newest galvanometers designed for beam steering applications can have frequency responses over 10&nbsp;kHz with appropriate servo technology. Closed-loop mirror galvanometers are also used in similar ways in [[stereolithography]], [[Direct metal laser sintering|laser sintering]], [[laser engraving]], [[laser beam welding]], [[laser TV]]s, [[laser display]]s and in imaging applications such as retinal scanning with [[Optical coherence tomography|Optical Coherence Tomography]] (OCT) and [[Scanning laser ophthalmoscopy|Scanning Laser Ophthalmoscopy]] (SLO). Almost all of these galvanometers are of the moving magnet type. The closed loop is obtained measuring the position of the rotating axis with an infrared emitter and 2 photodiodes. This feedback is an analog signal.

Open loop, or resonant mirror galvanometers, are mainly used in some types of laser-based bar-code scanners, printing machines, imaging applications, military applications and space systems. Their non-lubricated bearings are especially of interest in applications that require functioning in a high [[vacuum]].
[[File:Autoexpmeter.JPG|thumb|320px|right|A galvanometer mechanism (center part), used in an automatic exposure unit of an [[8 mm film]] [[movie camera|camera]], together with a [[photoresistor]] (seen in the hole on top of the leftpart).]]
Moving coil type galvanometer mechanisms (called 'voice coils' by hard disk manufacturers) are used for controlling the ''head positioning'' servos in [[hard disk drive]]s and CD/DVD players, in order to keep mass (and thus access times), as low as possible.