Past Uses
A major early use for galvanometers was for finding faults in telecommunications cables. They were superseded in this application late in the 20th century by time-domain reflectometers.
Probably the largest use of galvanometers was the D'Arsonval/Weston type movement used in analog meters in electronic equipment. Since the 1980s, galvanometer-type analog meter movements have been displaced by analog to digital converters (ADCs) for some uses. A digital panel meter (DPM) contains an analog to digital converter and numeric display. The advantages of a digital instrument are higher precision and accuracy, but factors such as power consumption or cost may still favor application of analog meter movements.
Galvanometer mechanisms were also used to position the pens in analog strip chart recorders such as used in electrocardiographs,electroencephalographs and polygraphs. Strip chart recorders with galvanometer driven pens may have a full scale frequency response of 100 Hz and several centimeters deflection. The writing mechanism may be a heated tip on the needle writing on heat-sensitive paper, or a hollow ink-fed pen. In some types the pen is continuously pressed against the paper, so the galvanometer must be strong enough to move the pen against the friction of the paper. In other types, such as the Rustrak recorders, the needle is only intermittently pressed against the writing medium; at that moment, an impression is made and then the pressure is removed, allowing the needle to move to a new position and the cycle repeats. In this case, the galvanometer need not be especially strong.
Galvanometer mechanisms were also used in exposure mechanisms in film cameras.
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 systems. For example, for material processing with high-power lasers, mirror galvanometer are typically high power galvanometer mechanisms used with closed loop servo control systems. The newest galvanometers designed for beam steering applications can have frequency responses over 10 kHz with appropriate servo technology. Closed-loop mirror galvanometers are also used in stereolithography, in laser sintering, in laser engraving, in laser beam welding, in laser TV, in laser displays, and in imaging applications such as Optical Coherence Tomography (OCT) retinal scanning. Almost all of these galvanometers are of the moving magnet type.
Open loop, or resonant mirror galvanometers, are mainly used in laser-based barcode scanners, in some printing machines, in some imaging applications, in military applications, and in space systems. Their non-lubricated bearings are especially of interest in applications that require a high vacuum.
A galvanometer mechanism is used for the head positioning servos in hard disk drives and CD and DVD players. These are all of the moving coil type, in order to keep mass, and thus access times, as low as possible.
A major early use for galvanometers was for finding faults in telecommunications cables. They were superseded in this application late in the 20th century by time-domain reflectometers.
Probably the largest use of galvanometers was the D'Arsonval/Weston type movement used in analog meters in electronic equipment. Since the 1980s, galvanometer-type analog meter movements have been displaced by analog to digital converters (ADCs) for some uses. A digital panel meter (DPM) contains an analog to digital converter and numeric display. The advantages of a digital instrument are higher precision and accuracy, but factors such as power consumption or cost may still favor application of analog meter movements.
Galvanometer mechanisms were also used to position the pens in analog strip chart recorders such as used in electrocardiographs,electroencephalographs and polygraphs. Strip chart recorders with galvanometer driven pens may have a full scale frequency response of 100 Hz and several centimeters deflection. The writing mechanism may be a heated tip on the needle writing on heat-sensitive paper, or a hollow ink-fed pen. In some types the pen is continuously pressed against the paper, so the galvanometer must be strong enough to move the pen against the friction of the paper. In other types, such as the Rustrak recorders, the needle is only intermittently pressed against the writing medium; at that moment, an impression is made and then the pressure is removed, allowing the needle to move to a new position and the cycle repeats. In this case, the galvanometer need not be especially strong.
Galvanometer mechanisms were also used in exposure mechanisms in film cameras.
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 systems. For example, for material processing with high-power lasers, mirror galvanometer are typically high power galvanometer mechanisms used with closed loop servo control systems. The newest galvanometers designed for beam steering applications can have frequency responses over 10 kHz with appropriate servo technology. Closed-loop mirror galvanometers are also used in stereolithography, in laser sintering, in laser engraving, in laser beam welding, in laser TV, in laser displays, and in imaging applications such as Optical Coherence Tomography (OCT) retinal scanning. Almost all of these galvanometers are of the moving magnet type.
Open loop, or resonant mirror galvanometers, are mainly used in laser-based barcode scanners, in some printing machines, in some imaging applications, in military applications, and in space systems. Their non-lubricated bearings are especially of interest in applications that require a high vacuum.
A galvanometer mechanism is used for the head positioning servos in hard disk drives and CD and DVD players. These are all of the moving coil type, in order to keep mass, and thus access times, as low as possible.