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I am working on prototyping a product and the ideal solution, from similar designs, seems to be using galvanometers, specifically mirror galvanometers. In doing my research the majority of Galvanometers that I found were extremely expensive. I understand that more precision in any device will generally increase the price.

The theory behind galvanometers seems really simple. So what makes them so expensive? Is it something in the manufacturing that is inherently costly?

Are there less costly alternatives to the mirror galvanometer besides a stepper motor? A stepper motor might need quite a bit of design time to get accuracy to where I want it. If it is even possible.

Nick Alexeev
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mkrinblk
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  • Welcome to EE.SE. The tone of your question is not quite right for EE.SE. It may invite opinion-based discussion, or recommendations for products, both of which are off-topic on EE.SE. (1) Keep the last paragraph. (2) Reduce the rant about the high cost of optical galvanometers to 3 sentences max. (3) Adjust the title accordingly. – Nick Alexeev Apr 19 '15 at 00:57
  • I'm not looking for opinions. If there is something **specific** in the manufacture that is what I want to know. – mkrinblk Apr 19 '15 at 01:05
  • [Peachy Printer](http://www.peachyprinter.com/). These folks are making an additive 3D printer that uses galvos and a laser to harden resin. They have spent months learning how to make accurate but inexpensive galvos for their product. Have a chat with them. They may be amenable to working with you. As far as I know, everything will eventually be released as open-source. – Dwayne Reid Apr 19 '15 at 00:56
  • Welcome to the site! I think I agree with Nick here: you have a good question (what is it about galvanometers that makes them expensive, and what alternatives exist?), but the title looks like you're asking a different question (find me a cheaper galvanometer!). – Greg d'Eon Apr 19 '15 at 02:55
  • Stepper motors are not the best control mechanism for achieving smooth point to point motion with a mirror galvo. Particularly of you are trying to scan something like a laser beam. You will also find that some galvo positioners have DC Motor type drivers in them that require a closed loop server system to drive them. – Michael Karas Apr 19 '15 at 03:26
  • Helmoltz coils and mirror with attached magnet on a string (ballistic galvano) didn't work? – GR Tech Apr 19 '15 at 03:45
  • There is not much that dictates a high price- precision electromechanical bits in smallish quantities tend to be expensive. Good electric motors can be hundreds of dollars too. Cheaper galvos are made for laser light shows, but again that's a smallish market. – Spehro Pefhany Apr 19 '15 at 11:55
  • @NickAlexeev: So if a querent asks for help with something and the solution turns out to be a shift register which someone identifies with a part number, the question shouldn't have been asked and the answer shouldn't have been given if the question managed to, somehow, slip past the Query Kops? – EM Fields May 31 '15 at 21:26
  • Might you be able to get by with a voice coil motor driving a mirror? – EM Fields May 31 '15 at 21:31

2 Answers2

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The voice coil/galvanometer acting as the head actuator of a hard disk drive could be a solution. They are ubiquitous, can be scavenged at zero cost from old drives and have an insanely fast response for a mechanical part (as they are optimized for low seek time). head actuator][1

In order to use one, I would remove any encumbering area of the aluminum case, get rid of the magnetic R/W head and associated wiring, mount a reflector/prism to the pivot of the arm and wire the coil directly to a driver: either an audio amplifier for testing, or if better control (closed loop position control and/or asymmetrical movement) is necessary, a H bridge circuit (could be implemented with discrete transistors, a ready-made chip such as the SN754410, or even the arduino motor shield) pulse width modulated with a microcontroller.

schematic

simulate this circuit – Schematic created using CircuitLab

For mass production using scavenged parts from random e-waste is not really an option, but you could probably source something similar from china, or even make your own design.

Community
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jms
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If your application can use a continually rotating mirror driven by a small motor, with a pulsed light source, the pointing accuracy is ensured by the timing of the pulse (by a counter synchronised to the rotation) and nothing expensive is involved. Commercial galvanometers contain delicate precision suspended coils which are not easily mass produced, hence the high price.

cuddlyable3
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