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Educational series: Galvanometer scanners vs. stepper motors

Here’s our third post in our series of educational content. For the first two posts, check out our Facebook page (click here).

With laser projectors, there are two main methods of scanning a laser beam: stepper motors and galvanometer scanners. Here, we’re going to get into the basics of these systems and how they stand apart from one another.


Stepper motors are inexpensive and powerful, but slow and inaccurate when compared to galvanometers. Stepper motors are frequently used in situations where costs need to be kept down and/or a large mirror is better suited to capture larger beams like those in X-Laser’s Aurora series laser projectors. Because stepper motors more slowly and are and less accurate than galvanometer scanners, they don’t lend themselves well to complex aerials or text and graphics projections, so steppers are best used for “liquid sky” and hot beam effects, where the slow-moving beams can be a real asset to the effect and ambiance created.

Steppers

An example of stepper motors in X-Laser’s Caliente projector.

Galvanometers are used much more commonly than stepper motors in laser projectors, and are much smaller, faster, more precise and more expensive than stepper motors. Galvanometers require a sophisticated driver system to constantly monitor the position of the mirrors and make tiny corrections. This galvanometer driver system allows the scanners to be incredibly accurate, which makes them excellent for the creation of complex graphics projections like text or logos. Galvanometers typically cannot provide as much torque as a stepper motor can, but through the use of smaller mirrors, galvanometers can move at much higher speeds than steppers and can produce smoother effects and sharp corners in projected images.

An example of galvanometer scanners in X-Laser's Skywriter HPX projector. The HPX has galvanometers rated at 30K PPS (points per second) for graphics and animations.

An example of galvanometer scanners in X-Laser’s Skywriter HPX projector. The HPX has galvanometers rated at 30K PPS (points per second) for graphics and animations.

These two scanning systems are very much two different tools for two different jobs. Generally speaking, stepper motors are used in entry-level products like laser systems for clubs where there is not someone dedicated to programming laser content. Alternatively, galvanometers are used in laser projectors where someone is going to spend some time programming a custom show for the best effects. Because galvanometers are capable of much more sophisticated effects than stepper motors, it takes a skilled programmer using PC-based control software to unlock the full potential of galvanometers.

To learn more about how stepper motors actually work, check out this article by the folks at the always-excellent Adafruit: https://learn.adafruit.com/all-about-stepper-motors/what-is-a-stepper-motor

If you’d like to learn more about the technology behind galvanometer systems and what they’re used for other than laser light show systems, you can find a great article by Laser Focus World that’s from 2010, but still accurate as an overview: http://www.laserfocusworld.com/articles/2010/09/product-focus-galvanometer.html

American Disc Jockey AssociationCanadian Disc Jockey AssociationU.S. Food and Drug AdministrationInternational Association of Amusement Parks and AttractionsInternational Laser Display AssociationNAMMSPIE