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Bug #78

Use Frequency from VisiCut

Added by peteruithoven over 8 years ago. Updated about 7 years ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Category:
-
Target version:
-
Start date:
2013-03-15
Due date:
% Done:

0%


Description

What's the reason we don't use the frequency from Visicut?
If there is a good reason I'm going to request it can be removed from the ui of VisiCut, just like purge is hidden now when it's not supported by a lasercutter.

History

#1 Updated by parag0n over 8 years ago

Visicut definitely puts it in the simplecode file that is sent through (with a "7 102 5000") to LAOS, but I think nobody has written the LAOS side yet?

I can have a look at implementing frequency later, and send a pull request.

#2 Updated by peteruithoven over 8 years ago

That would be great.
Seeing the following topic there is a big change people need to experiment a bit with frequency, having support for changing that in the file means that people can test this in minutes instead of hours.
http://redmine.laoslaser.org/boards/2/topics/322

(I would try to use VisiCuts Laserscript functionality and write a test pattern)

#3 Updated by peter over 8 years ago

Adding the ability to modify frequency is easy in firmware.

But: It will not help if your laser (power supply) is not capable of pulsed operation.

Most DC gas lasers are CW (Continous Wave) lasers and not pulsed (like the more expensive RF (Radio Frequency) lasers in Epilog, Trotec and Universal laser systems).

If the PWM is used to modulate the laser power via the analog input of the power supply, changing the PWM has most likely no effect (apart from bad PWM to power linearity if the frequency is too high or too low).

If the laser power supply is capable of quickly switching the laser on and off, frequency modifications make sense. In this case the PWM signal has to be routed to the laser ON input.

I am not sure if switching the laser ON input quickly (at 5 to 10khz) kan damage power supplies that are not prepared for this, and I also do not know if would give improvements in peak power or beam quality.

We would need to do some measurements.

#4 Updated by peteruithoven over 8 years ago

Peter, you mean that the PWM isn't actually used as PWM but it's translated into a analog value because you hook it up to the analog input of the power supply? And so just changing the frequency of the PWM won't really allow you to control the beam? Control like you can't make it laser dots at a specific interval?

Well, this means it's interesting to have a optional frequency support anyway in VisiCut I guess.

#5 Updated by peter over 8 years ago

Peter, correct. The PWM is turned into an analog signal by the laser power supply (it has a low-pass filter on this input) to control the laser current.

If you want a specific DOT interval, you can use the raster mode (the LAOS board allows arbitrary angles for raster lines, but Visicut does not support this).

OR: Hook up the PWM output to the "LASER ON" input of your power supply. (needs a small firmware patch to switch PWM to "0" if the beam should be OFF").

I cannot guarantee that your chinese laser power supply is capable of handling high speed pulses on the input.

#6 Updated by peteruithoven about 7 years ago

  • Status changed from New to Closed

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