Is it possible to drive Laser Galvos via a PID with a PC soundcard?

Thread Starter

tangent-man

Joined Mar 26, 2022
3
I wonder if anyone can help (asking for a friend LoLz) ? I am looking at this page here: https://braintoblueprinttobuild.wordpress.com/2016/04/17/diy-laser-projector-part-5-building-it/ and wondering if rather than using an arduino to generate the signal if the output from a PC soundcard could be used in a similar way to this: https://www.youtube.com/channel/UCECl4aNz5hvuRzW5fgCOHKQ is that possible? My friend is interested in projecting Lisserjoos figures and that sort of thing using lasers. It would be great if it could be driven by a PC soundcard output as he could use the output from VCVrack.

Sorry if I am asking this in the wrong place? If so, sorry, is there another forum or another place that you know of that would be a better place to ask this question?
 

Ya’akov

Joined Jan 27, 2019
5,663
Welcome to AAC.

There is no reason why the left and right analog signals couldn’t be used to drive galvanometers the way the DAC of the Arduino does in that example.

By the way, it is “Lissajous” named after Jules Antoine Lissajous a French physicist from the 1800s.
 

Thread Starter

tangent-man

Joined Mar 26, 2022
3
Thanks for your reply. Would I need a circuit like this to get them to optimize the audio output to get the best results from the Galvos? : https://www.buildlog.net/blog/2018/02/laser-galvo-control-experiments/

Also is there not an issue with modulating/blanking the laser when required? To quote that website:

"
The catch

My intention was to switch off the laser beam at the end of each frame and switch it back on at the start of the next frame. This would have been achieved by switching on the transistor’s collector on and off as necessary. This is called ‘blanking’

Unfortunately, it turns out the laser has a ‘warm up’ time and can’t be switched on and off quickly enough. Instead, I had to live with the beam being on when it returned to the start position of every frame. Watching the video I posted in my previous laser projector post, you can sometimes see the return path beam. I generally tried to design the displayed images to hide the return path.

If I improve the projector for future use, I’ll use a third galvo to block the beam as it returns to the start of the frame."


Is this necessary? If so how would one go about blanking / modulating the beam using only an audio output?

Thank you for your time reading this...
 

Ya’akov

Joined Jan 27, 2019
5,663
Thanks for your reply. Would I need a circuit like this to get them to optimize the audio output to get the best results from the Galvos? : https://www.buildlog.net/blog/2018/02/laser-galvo-control-experiments/

Also is there not an issue with modulating/blanking the laser when required? To quote that website:

"
The catch

My intention was to switch off the laser beam at the end of each frame and switch it back on at the start of the next frame. This would have been achieved by switching on the transistor’s collector on and off as necessary. This is called ‘blanking’

Unfortunately, it turns out the laser has a ‘warm up’ time and can’t be switched on and off quickly enough. Instead, I had to live with the beam being on when it returned to the start position of every frame. Watching the video I posted in my previous laser projector post, you can sometimes see the return path beam. I generally tried to design the displayed images to hide the return path.

If I improve the projector for future use, I’ll use a third galvo to block the beam as it returns to the start of the frame."


Is this necessary? If so how would one go about blanking / modulating the beam using only an audio output?

Thank you for your time reading this...
The outputs of the sound card would have to be the same as the expected level of the galvanometer. This might require an amplifier or an attenuator depending on the actual requirements.

I don't know the context of that quote, but a blanking interval is only relevant for a raster scan, like a CRT television. For LIssajous curves there is no return of the beam to hide, it is a continuous image.
 

Thread Starter

tangent-man

Joined Mar 26, 2022
3
The outputs of the sound card would have to be the same as the expected level of the galvanometer. This might require an amplifier or an attenuator depending on the actual requirements.

I don't know the context of that quote, but a blanking interval is only relevant for a raster scan, like a CRT television. For LIssajous curves there is no return of the beam to hide, it is a continuous image.
The outputs of the sound card would have to be the same as the expected level of the galvanometer. This might require an amplifier or an attenuator depending on the actual requirements.

I don't know the context of that quote, but a blanking interval is only relevant for a raster scan, like a CRT television. For LIssajous curves there is no return of the beam to hide, it is a continuous image.

Thank you! That's awesome! :)
 
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