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Single- and Dual-Axis Scanning Galvo Systems for Small Beam Diameters
1.2 System Description
1.2.1 Introduction
Galvo Scanners are widely used in applications such as laser etching, confocal
microscopy, and laser imaging.
A galvanometer is a precision motor with a limited travel, usually much less than 360
degrees, whose acceleration is directly proportional to the current applied to the motor
coils. When current is applied, the motor shaft rotates through an arc. Motion is
stopped by applying a current of reverse polarity. If the current is removed, the motor
comes to rest under friction.
Typically, the term 'Galvo' refers only to the motor assembly, whereas a 'Galvo
Scanner' would include the motor, together with a mirror, mirror mount and driver
electronics.
A description of each component in the system is contained in the following sections.
1.2.2 The Galvanometer
The galvanometer consists of two main components: a motor that moves the mirror
and a detector that feeds back mirror position information to the system.
Fig. 1.2 GVS002 Dual Axis Galvo/Mirror Assembly
Our galvo motor features a moving magnet, which means that the magnet is part of
the rotor and the coil is part of the stator. This configuration provides faster response
and higher system-resonant frequencies when compared to moving coil
configurations.
Mirror position information is provided by an optical position detector, which consists
of two pairs of photodiodes and a light source. As the galvo and mirrors are moved,
differing amounts of light are detected by the photodiodes and the current produced
is relative to the galvo actuator position.
X-Axis Mirror
Y-Axis Mirror
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