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Need advice on 50mW 589nm spartan issue.

CynicalBrad

CynicalBrad

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I finally managed to save up and get myself a 50mW rated spartan which arrived on 2/14/17 and from the beginning noticed it dims VERY quickly. Most runs have it dimming at around 30 seconds into the run.

I am wondering whether this is completely normal for these when rated 50mW or whether I should contact Gary at DL and try to work something out.
This is a very nice wavelength but at the same time is very pricey for a unit that won't hold it's rated power for more than half it's rated duty cycle. Especially bothers me seeing most of these units tended to peak much higher than rated then settle at or above the rated power for the remaining duty cycle.

Attached is a power graph.
Ambient temp for this was 65F laser temp was 75F. Battery is an IMR unprotected cell fresh off the charger. Temperature was measured with an IR thermometer.

589_AMBIENT_65F_LASER_75F_zpscetlv0c5.png
 





HydroSean

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It can't hurt to send a polite email to customer service. Just ask them nicely if what you're experiencing is expected.
 
CynicalBrad

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HydroSean said:
It can't hurt to send a polite email to customer service. Just ask them nicely if what you're experiencing is expected.
Click to expand...

Email sent. I knew going into this that they were unstable but did kind of expect it to stay at or near it's rated output for it's rated duty cycle. Now just to wait on the reply.
 
ultimatekaiser

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might be a minor alignment issue. is it mode hopping? Mine I can run for a fair bit of time, but their quoted duty cycle by CNI is 45sec las I was told.
 
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CynicalBrad

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ultimatekaiser said:
might be a minor alignment issue. is it mode hopping? Mine I can run for a fair bit of time, but their quoted duty cycle by CNI is 45sec las I was told. average running diode temp, and thus case temp in the case of these lasers, is typically 20-25C. does sound like it needs some attention.
Click to expand...

Does not appear to be mode hopping however I would need to grab a lens to expand it to see. I did bring up a potential misalignment caused in shipping in the email I sent them. Give me just a few minutes and I can set up to see if it is mode hopping.
 
ultimatekaiser

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sure, another thing you might check is the current draw and make sure that it is stable, not likely, but could be an electrical issue.
 
CynicalBrad

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ultimatekaiser said:
might be a minor alignment issue. is it mode hopping? Mine I can run for a fair bit of time, but their quoted duty cycle by CNI is 45sec las I was told.
Click to expand...

ultimatekaiser said:
sure, another thing you might check is the current draw and make sure that it is stable, not likely, but could be an electrical issue.
Click to expand...


Mode hopping like crazy. Pretty much stays TEM01 and even glimpsed TEM02 for a moment. Only snaps into TEM00 momentarily then back to TEM01

Current draw starts at 1.730 amps for a few seconds then drops to 1.723 and holds steady there so nothing really unusual there.

Let me see if I can get some video of these modes. Seems to be a LOT more going on that simple TEM 01/Tem 00 hopping.
 
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ultimatekaiser

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yeah, sounds like a minor alignment issue. the KTP may have been jostled a bit in shipping, or the alignment temperature was warmer/colder than when you ran it. try lightly chilling it and running again. It may improve.
 
CynicalBrad

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ultimatekaiser said:
yeah, sounds like a minor alignment issue. the KTP may have been jostled a bit in shipping, or the alignment temperature was warmer/colder than when you ran it. try lightly chilling it and running again. It may improve.
Click to expand...

About to work on uploading the videos. Also about to stick the laser in the fridge @38F for a few while these upload to see if it changes.

Pretty cold in my house though at 63F right now as that is how I prefer it.
 
ultimatekaiser

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yeah, these lasers do like it chilled, but some prefer it warm too. might try doing several short runs and see how it copes. but it does sound like a minor alignment issue to me just going off the raw info i'm being given.
 
CynicalBrad

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Comparison shot with LG-Aries through exact same lens moments after these videos were taken.
0218170326_zpshubrvcqx.jpg

Added a chilled video as-well. Saw a complete mainline shift to that 583 line during it as it warmed back up which was neat.

I promise that was a very squeaky floorboard @ 00:31
 
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HydroSean

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That has got to be one of the weirder things I've seen with a laser. Very interesting, looks like the wave equation is moving between eigenstates. Idk how that would happen for a semiconductor diode though....hmm
 
CynicalBrad

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HydroSean said:
That has got to be one of the weirder things I've seen with a laser. Very interesting, looks like the wave equation is moving between eigenstates. Idk how that would happen for a semiconductor diode though....hmm
Click to expand...

You lost me..

EDIT:Just did some googling. I can see the resemblance.
 
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HydroSean

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HydroSean

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CynicalBrad said:
That is one of the image I found in my brief search.

UltimateKaiser: I'm warming the laser up now to see what happens to it as far as power output and this crazy mode hopping.
Click to expand...

I'm hypothesizing that this "mode hopping" (which I need to read more up on) is basically the population inversion electrons switching between eigenstates.
 
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