Galvanometer motor (galvo scanner motor)

01

Match mirror aperture to speed

Thorlabs describes a galvo as a galvanometer-based scanning motor with an optical mirror on the shaft and a detector that feeds position back to the control board; it chose a moving-magnet design over a stationary magnet and rotating coil to give the fastest response and highest system resonant frequency. Its GVS series lists a maximum mechanical scan angle of ±12.5° (reduced for larger beams), full-scale bandwidth of DC to 100 Hz for a square wave and 250 Hz for a sine wave, small-angle (±0.2°) bandwidth to 1 kHz and a small-angle step response of 300 µs. [1]

Scanner Optics, a galvo maker linked to this page, lists its ST-galvo series from ≤7 mm to 50–120 mm input beam aperture; across the range, moment of inertia rises from 0.01 to 40.47 g·cm², torque constant from 0.9 to 86 N·mm/A, 1% angle response time from 0.1–0.2 ms to 1.0 ms and weight from 12 g to 1,040 g, with a maximum mechanical scan angle of ±20°. [2]

Editorial note: the larger the aperture, the larger and heavier the mirror and rotor and the slower the step response in these tables; choose the smallest aperture that passes your beam (with margin for the scan angle) and compare step times at the same angle and settling criterion.

Give the supplier the laser wavelength and power, beam diameter at the scanner, mirror coating and substrate, required scan angle, small-step and full-scale response times with the settling criterion, repeatability, drift limits and warm-up time, position sensor resolution, driver type (analog or digital, protocol), supply voltage, cooling, operating temperature and mounting.

02

Check repeatability, resolution and drift

Thorlabs lists motor and position sensor linearity of 99.9%, scale drift of 40 ppm/°C maximum, zero drift of 10 µrad/°C maximum and repeatability of 15 µrad, with mechanical resolution of 15 µrad on its linear power supply and 70 µrad on a standard switch-mode supply. [1] Scanner Optics lists nonlinearity below 0.4%, repeatability below 2 µrad, offset drift below 15 µrad/K, gain drift below 40 ppm/K and 18-bit position resolution, noting that 18 bits over 25° corresponds to 1.7 µrad and that its higher-end series offers up to 23 bits. [2]

Editorial calculation: 25° is 0.436 rad, and 0.436 / 2¹⁸ ≈ 1.66 µrad, consistent with the stated 1.7 µrad. A zero drift of 10 µrad/°C over a 10 °C warm-up adds up to 100 µrad of offset, more than six times the 15 µrad repeatability, so allow warm-up or use drift compensation where position must hold. The temperature change is an assumed example.

A third maker separates standard and low-drift motors. Novanta's data sheet for Cambridge Technology 62xxK and 83xxK moving-magnet galvanometers (2022) covers recommended apertures from 3–7 mm up to 30–100 mm, a 40° maximum scan angle, position-detector linearity of 99.9% minimum over 20° (99.5% over 40°), short-term repeatability of 8 µrad, and maximum drift of 50 ppm/°C scale and 15 µrad/°C zero for the 62xxK against 15 ppm/°C and 5 µrad/°C for the lower-drift 83xxK, with a 110 °C maximum rotor temperature. Its smallest 6200K/8300K motor lists 0.013 g·cm² rotor inertia, a torque constant of 1.20 × 10⁴ dyne·cm/A, 2.14 Ω and 52 µH coil, 2.3 A RMS and 6 A peak current, 3.8 °C/W rotor-to-case thermal resistance and 13.3 g weight. [3]

Editorial calculation: over a 10 °C warm-up a 62xxK's 15 µrad/°C zero drift can add 150 µrad, against 50 µrad for an 83xxK, while both repeat to 8 µrad; and 1.20 × 10⁴ dyne·cm/A is 1.2 N·mm/A, so the 6200K's 6 A peak gives about 7.2 N·mm of torque. Specify drift if the scanner must hold position through temperature changes. [3]

03

Pick the scanner family by aperture before comparing speed

SCANLAB describes its dynAXIS galvanometer scanners as rotary motors "based on moving magnet technology and a high-accuracy position detector", with motors matched to the deflection mirror's inertial load. It offers them with mirrors for apertures from 6 mm to 30 mm; the dynAXIS 3 series, with an improved position detector for low drift, highest linearity and optional extended deflection angles, covers apertures from 10 mm to 30 mm; and the dynAXIS 421 covers apertures from 3 mm to 6 mm for biomedical and ophthalmic imaging, confocal microscopy and laser-assisted medical treatments. [4]

SCANLAB states that its motors are matched to the deflection mirror's inertial load [4]. Thorlabs reduces its ±12.5° scan angle for larger beams and gives a 300 µs small-angle step response for its small-beam GVS series [1], while Scanner Optics publishes inertia from 0.01 to 40.47 g·cm² across its range [2]. Fix the aperture from your beam diameter first, then compare step response, repeatability and drift only between scanners of that aperture.

Both SCANLAB and Thorlabs describe moving-magnet motors with a position detector feeding back the mirror angle [4] [1], and Novanta lists standard and low-drift versions of its scanners with different gain and offset drift [3]. SCANLAB's 3 series is its low-drift option; ask any supplier for the drift values of the exact family and aperture quoted, with the test temperature range.

Editorial calculation: SCANLAB's apertures span a factor of 10 from 3 mm to 30 mm; the dynAXIS 421 and the other dynAXIS models meet at 6 mm, and the 3 series starts at 10 mm. [4]

Values are from SCANLAB's galvanometer scanners overview page; model data sheets were not reviewed.

04

Compare what suppliers offer

Suppliers linked to this page list galvo motors or scanners; each card links to the page reviewed.

The listing reviewed covers galvo scanners in more than one series with analog and digital drivers, scan heads, dynamic focusing modules and optical encoders for galvo motors. Ask for step response with its settling criterion, drift figures and the test conditions.

05

Trace the galvo components

This is a functional reference built from the sources cited; it is not one maker's specification.

06

Fill the specification fields with values for your scanner

A galvo motor quotation needs values for your scanner. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the beam, motion and accuracy data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Beam: [wavelength; power; diameter]
Mirror: [aperture; coating]
Motion: [scan angle; step and full-scale response]
Accuracy: [repeatability; drift; resolution]
Driver: [analog/digital; protocol; supply]
Environment: [temperature; cooling; mounting]

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