In the project I'm working on I try to build a laser scanning module which allows to deflect a laser beam in a controlled manner.
The plan is to use a rotation stage which allows to precisely control the orientation of a mirror. The rotation stage should provide an as good angular resoultion as possible while scanning speed is not relevant at this point. That's why I first thought about stepper motors but I couldn't find a decent product which would allow for the desired angular resoultion of like 0.001°. Maybe it could be done with a servo motor together with high quality angular encoders but I'm not sure about that. What would you suggest?
In the project I'm working on I try to build a laser scanning module which allows to deflect a laser beam in a controlled manner.
The plan is to use a rotation stage which allows to precisely control the orientation of a mirror. The rotation stage should provide an as good angular resoultion as possible while scanning speed is not relevant at this point. That's why I first thought about stepper motors but I couldn't find a decent product which would allow for the desired angular resoultion of like 0.001°. Maybe it could be done with a servo motor together with high quality angular encoders but I'm not sure about that. What would you suggest?
Thanks a lot in advance!
Lets assume you are using a front surfaced mirror so you don't get TWO reflections. What is the useful angle the mirror will allow the laser beam to be used? Once that angle is known, you can then select a servo that will match.
Well the opening angle of the scanned region should be at least 20°, so that probably won't give us a huge limitation but what bothers me is that it's super hard to find a servo that can provide very precise movement of like 0.001°..., but you would then stick with servos rather than steppers?
Camee:
Well the opening angle of the scanned region should be at least 20°, so that probably won't give us a huge limitation but what bothers me is that it's super hard to find a servo that can provide very precise movement of like 0.001°..., but you would then stick with servos rather than steppers?
Unless you have a very expensive front surface mirror and a laser with colimating lenses, the exactness of the servo will not matter.
Have you considered using gears to reduce to rotation increments of the servo to something that will fit your project?
Yes exactly I intend to use expensive mirror and subsequently collimate the light so that the limiting factor should be the resolution of the motor.
Gears would be certainly a great idea. The problem I saw there was that one would need to assemble the gears very accurately and the gears themselves would need to be manufractured also with a high accuracy in order to maintain a high angular resolution.
That's why I would have prefered to use an off-the-shelf motor which provides the required accuracy but if that's not available I guess gearing would be the way to go...
Hmm yes you're right... So with this we could provide the minimum scan region of 20° in one dimension and we probably could extend this easily to a two-dimensional scan by using two galvos, but what if we would like to scan a full hemisphere. Then we would probably run into problems with the galvos whereas with two rotation-stages we could manage this, right?
Camee:
Yes exactly I intend to use expensive mirror and subsequently collimate the light so that the limiting factor should be the resolution of the motor.
Gears would be certainly a great idea. The problem I saw there was that one would need to assemble the gears very accurately and the gears themselves would need to be manufractured also with a high accuracy in order to maintain a high angular resolution.
That's why I would have prefered to use an off-the-shelf motor which provides the required accuracy but if that's not available I guess gearing would be the way to go...
A toothed belt with matching sprocket wheels will work better than gears.
