Laser fails to saturate anode completely

Discussions on optics for laser cutter/engravers

Laser fails to saturate anode completely

Postby Zilvertail » Sat Mar 21, 2015 11:38 pm

I've had this problem ever since i put together my laser.

I don't know what's at fault here besides not the power supply, since that has been replaced and continues to show same problem.

When firing for alignment or running a job, the laser will light up as per usual, sometimes it will work normally for a while, other times even after longer periods of cooldown, it will then only partially saturate the metal ring at the beam exit, it will move around and fire the beam off course in a direction opposite the saturated area of the anode with a limited potential.

My guesses falls on the usual suspects in suspected order:

1. poor grounding
2. bad tube
3. poor cooling

I would love to get some input, suggestions for tests, and misc. feedback from anyone seeing the same problem, before i let loose the havoc beam.


Thanks in advance
Zilvertail
 
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Re: Laser fails to saturate anode completely

Postby sshwarts » Sun Mar 22, 2015 2:09 pm

A couple questions...

Are you pulsing the laser (using PPI?)?
What frequency is your controller set to?

What's the end result of this problem? Are you just lacking power?

Scott
sshwarts
 
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Re: Laser fails to saturate anode completely

Postby Zilvertail » Wed Mar 25, 2015 11:13 pm

Hi Scott


I am using a LAOS controller and from what i gather that would be with PPI, the pulsing doesn't seem to be the problem i'm afraid, but not ruling it out though, might be i'm just not familiar enough with it!

But the beam inside the tube does not collect on the anode, so it just flickers around the metal ring when i get the failures.

The end result from the failure is that the beam is off path completely, when it isn't and it fully saturates it passes the beam path and collects and emits a nice cut on whatever material is in focus of the focus lens, it's a 40w laser, and the cuts seem to match previous cuts.


P.s. i'm danish so i might not be explaining myself well enough :/
Zilvertail
 
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Re: Laser fails to saturate anode completely

Postby sshwarts » Thu Mar 26, 2015 1:02 am

I'm completely shooting in the dark here, but here are the things I would check:

-Is my laser power supply really digital PWM input or analog? From what I understand of the LAOS board, it's expecting a digital input. My understanding of these power supplies is that the digital input has a low pass filter on it to convert the digital PWM to a 0-5v signal and the analog input bypasses that filter.
-What is laser.pwm.freq in the LAOS firmware set to and can my laser power supply handle that? (while you're at it, whats pwm min & max?)

Just a few things I would check if I suspected by laser was not firing properly. Of course as you pointed out, grounding might be bad as well.
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