Laser galvanometers in action
Tesladownunder, Sat Jul 01 2006, 01:53PMI arranged two mirror galvanometers to give two dimensional control of a laser beam. These have a response to about 100Hz but can still be used to about 200Hz. I fed one with 50Hz and the other from a frequency generator. This gives smoothly rotating complex patterns that vary with the ratios of the two frequencies.
So 50Hz + 50Hz gives a circle, 50 + 100Hz gives a figure 8 etc.
These are some examples. I will show and explain the setup in a later post.
Peter
Re: Laser galvanometers in action
Hazmatt_(The Underdog), Sat Jul 01 2006, 11:51PM
That's really great TDU. Now if you can get a really fast response you can sweep one at a concert A and demonstrate modulation, overtones, and all sorts of neat stuff with the two generators, an audio amp, and the laser setup.
Hazmatt_(The Underdog), Sat Jul 01 2006, 11:51PM
That's really great TDU. Now if you can get a really fast response you can sweep one at a concert A and demonstrate modulation, overtones, and all sorts of neat stuff with the two generators, an audio amp, and the laser setup.
Re: Laser galvanometers in action
Tesladownunder, Sun Jul 02 2006, 12:17AM
Here are some pics of the setup with the two miror galvos at right angles and as close together as possible. Power is from a 5mW red diode laser. I have made up an "optical table" with a 3cm beam height to accomodate this sort of stuff and some power so I can put all my mirrors and lenses etc on acrylic blocks.
Peter
Tesladownunder, Sun Jul 02 2006, 12:17AM
Hazmatt_(The Underdog) wrote ...
... Now if you can get a really fast response you can sweep one at a concert A and demonstrate modulation, overtones, and all sorts of neat stuff with the two generators, an audio amp, and the laser setup.
A concert requires big lasers (and a license). These galvos came with a diagram of how to passively run them from a stereo. Simply just a series resistor, 100 ohm WW pot and filter cap. This goes to one coil of the 10 pole motor and the other coil goes to 5-10V DC to provide a "spring" to hold it centered on one of the poles.... Now if you can get a really fast response you can sweep one at a concert A and demonstrate modulation, overtones, and all sorts of neat stuff with the two generators, an audio amp, and the laser setup.
Here are some pics of the setup with the two miror galvos at right angles and as close together as possible. Power is from a 5mW red diode laser. I have made up an "optical table" with a 3cm beam height to accomodate this sort of stuff and some power so I can put all my mirrors and lenses etc on acrylic blocks.
Peter
Re: Laser galvanometers in action
Hazmatt_(The Underdog), Sun Jul 02 2006, 05:34AM
I think you misunderstood a concert A is 440Hz.
I am simply stating that you could demonstrate Lissajou patterns to an audience and let them experience the AV. Its on my to-do list.
Hazmatt_(The Underdog), Sun Jul 02 2006, 05:34AM
I think you misunderstood a concert A is 440Hz.
I am simply stating that you could demonstrate Lissajou patterns to an audience and let them experience the AV. Its on my to-do list.
Re: Laser galvanometers in action
cjk2, Sun Jul 02 2006, 05:47AM
I did something similar like a year ago. I used 3 mirrors and didn't have as sophisticated of a way to control motor speed. If there is any interest, I'll post more pictures and a better description of what i did.
cjk2, Sun Jul 02 2006, 05:47AM
I did something similar like a year ago. I used 3 mirrors and didn't have as sophisticated of a way to control motor speed. If there is any interest, I'll post more pictures and a better description of what i did.
Re: Laser galvanometers in action
Carbon_Rod, Sun Jul 02 2006, 06:13AM
TDU,
Nice response time – the unit I built made use of Stylus galvo-motors out of an old unit. The unit used a 250-watt Car audio power Amp and shorted the secondary stabilization coils with a shunt resister to break the oscillations. I only managed around 70Hz for a decent complete sweep.
However, the colour bands had a special shutter system with small relays. The 45’ angled mirrors glued onto the arms to reflected to a light trap (they work pretty fast.) As yours is a diode unit it should be easy to key -- so this is not an issue.
For laser plotting pictures most use a PWM based system with an optical based feedback loop for high speed absolute positioning (calibration is easier this way.)
Here are some links to test files and stuff:
AVR project with driver software from ELM:
Norms stuff:
Clip Art (and test patterns):
Cheers,
Carbon_Rod, Sun Jul 02 2006, 06:13AM
TDU,
Nice response time – the unit I built made use of Stylus galvo-motors out of an old unit. The unit used a 250-watt Car audio power Amp and shorted the secondary stabilization coils with a shunt resister to break the oscillations. I only managed around 70Hz for a decent complete sweep.
However, the colour bands had a special shutter system with small relays. The 45’ angled mirrors glued onto the arms to reflected to a light trap (they work pretty fast.) As yours is a diode unit it should be easy to key -- so this is not an issue.
For laser plotting pictures most use a PWM based system with an optical based feedback loop for high speed absolute positioning (calibration is easier this way.)
Here are some links to test files and stuff:
AVR project with driver software from ELM:
Norms stuff:
Clip Art (and test patterns):
Cheers,
Re: Laser galvanometers in action
Tesladownunder, Sun Jul 02 2006, 09:48AM
Photos show stereo input. First one was the Dresden Dolls.
Peter
Tesladownunder, Sun Jul 02 2006, 09:48AM
Hazmatt_(The Underdog) wrote ...
I think you misunderstood a concert A is 440Hz.
After considerable investigation it has been conclusively demonstrated that I don't have a single musical bone in my body. So your comment fell flat (?A flat).I think you misunderstood a concert A is 440Hz.
cjk2 wrote ...
I did something similar like a year ago. I used 3 mirrors and didn't have as sophisticated of a way to control motor speed. If there is any interest, I'll post more pictures and a better description of what i did
I'm interested...I did something similar like a year ago. I used 3 mirrors and didn't have as sophisticated of a way to control motor speed. If there is any interest, I'll post more pictures and a better description of what i did
Carbon_Rod wrote ...
TDU,
..I only managed around 70Hz for a decent complete sweep.
..For laser plotting pictures most use a PWM based system with an optical based feedback loop for high speed absolute positioning (calibration is easier this way.)
Performance certainly drops off in mine over 50Hz. I am not looking to take this further apart from trying it on my argon laser. Of course, shooting down aliens will take some further refinement.TDU,
..I only managed around 70Hz for a decent complete sweep.
..For laser plotting pictures most use a PWM based system with an optical based feedback loop for high speed absolute positioning (calibration is easier this way.)
Photos show stereo input. First one was the Dresden Dolls.
Peter
Re: Laser galvanometers in action
Tesladownunder, Fri Aug 18 2006, 06:30PM
I have now made up a more compact unit with my 40 mW multiline argon laser which gives some great effects.
Some pics of the setup first, then of the output if any replies.
Peter
Tesladownunder, Fri Aug 18 2006, 06:30PM
I have now made up a more compact unit with my 40 mW multiline argon laser which gives some great effects.
Some pics of the setup first, then of the output if any replies.
Peter
Re: Laser galvanometers in action
Hazmatt_(The Underdog), Fri Aug 18 2006, 06:39PM
Now that's what I'm talking about! very nice.
I would want the demo for kids to have 2 large dials for them to change the frequency, or maybe 2 HP signal generators so they could read the dial.
I found a complete laser light show unit in the mall in a store called Spencers. I'm thinking of picking one up and just modifying it for my inputs because its only going to cost me $40.
Hazmatt_(The Underdog), Fri Aug 18 2006, 06:39PM
Now that's what I'm talking about! very nice.
I would want the demo for kids to have 2 large dials for them to change the frequency, or maybe 2 HP signal generators so they could read the dial.
I found a complete laser light show unit in the mall in a store called Spencers. I'm thinking of picking one up and just modifying it for my inputs because its only going to cost me $40.
Re: Laser galvanometers in action
Marko, Fri Aug 18 2006, 06:47PM
Very cool TDU! Holographic laces
I wonder if red and blue bemas could be crossed somehow..
Marko, Fri Aug 18 2006, 06:47PM
Very cool TDU! Holographic laces
I wonder if red and blue bemas could be crossed somehow..
Re: Laser galvanometers in action
Tesladownunder, Sat Aug 19 2006, 12:32AM
The multi line laser gives nice diffraction effects with the beam splitting in to beams from green to violet. The digital camera doesn't reproduce this well but the colours are much more intense in reality.
I did make up a little wein bridge sine wave oscillator from 15 - 150 Hz for the public to alter, but the amplitutde instability made it a bit hard to use. I gave up and will just use the function generator.
Just a few pics.
Peter
Tesladownunder, Sat Aug 19 2006, 12:32AM
The multi line laser gives nice diffraction effects with the beam splitting in to beams from green to violet. The digital camera doesn't reproduce this well but the colours are much more intense in reality.
I did make up a little wein bridge sine wave oscillator from 15 - 150 Hz for the public to alter, but the amplitutde instability made it a bit hard to use. I gave up and will just use the function generator.
Just a few pics.
Peter
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