50mw 532nm Snoctony labby

[jnrpop]

[quote author=wannaburn link=1228783157/0#8 date=1231982905]Good to see you LPM arrived, yay, no more guessing!

Just be careful not to damage the thermopile with all that mad science going on ;D

You and Jerry have warned me about Thermopile damage.  I have read the manual (although it was a quick skim read, in all the excitemnet) and I recall it saying that the thermopile has been tested at 1.1w with a 1.0mm diameter beam for extended periods of time.

Should I worry about shining beams on it from lasers that have achieved a high degree of collimation?  With Blu-Ray I will make sure the beam is focused to infinity and *not* to a pin sized narrow waist (as in burning).  Is there something else I should be concerned about?  I know others have ruined their thermopile head.  I'll read over the manual again.  Thanks.

-Brett

PS:  Here's the Snoctony, after the pot has been turned up.  It now appears that the Aixiz is the most powerful of my "50mw" green labby lasers.  However, it would be more telling if I had two of these identical switching supplies and could warm them both up simultaneously for the same duration.  Sorry for the poor focus on this one.


[/quote]

Was this with the pot turned all the way??

 

[Brett]

Was this with the pot turned all the way??

Yeah, I ran the test again just for you (in fact it's on the laserbee right now as I write this). It ran right up to a 113mw peak this time, then settled down to around 105 or so. It will plateau at close to 110 for a while then trickle down to 100 or so. After doing this a couple times, it seems to settle close to 100mw (after a 10 minute period).

-Brett

 

[JLSE]

You havent hooked your laserbee up to your PC yet? :-? This is a must! ;D

The beauty of the datalogging option when using DPSS is watching the stability in the graph.
Measuring the peak and or average just wont give you the info needed to make changes. When you refference the graph after a 10 min run, you can see exactly when changes to power are occouring. If you make an adjustment, you may find a lower peak, but the graph can illustrate the overall performance and aid in finding the sweetspot for a higher average.

I will compile a short list of tricks ive learned for squeezing the max out of the crystals. There are certain things that I have found that can double your 532 output, without stressing the diode : via PM of course :-X


Now go hook up that datalogger

And welcome to a very exclusive club, club 532

 

[jnrpop]

WOW u ran it for 10min on with the pot turned all the way
This things stronger than i thought. :

Are you using additional heatsinking or cooling???

 

[Brett]

WOW u ran it for 10min on with the pot turned all the way  
This things stronger than i thought.   :

Are you using additional heatsinking or cooling???

I'm not using any additional cooling, however, the heatsink on the MOSFET gets pretty warm very fast with the pot maxed out on that switching driver. I would suggest (as others have) blowing a fan on that FET for extended runs. The laser head seems to stay cool at 10 minute runs, although I wouldn't necessarily recommend maxing out the pot for anyone wanting long life. The idea of a lab laser (I thought) was for higher duty cycles as would be seen in the laboratory. But in the lab they would run it at its rated power.

-Brett

 

[jnrpop]

I just turned the pot up to full, no really noticeable difference in brightness but after one minute the power supply gets considerably hot....prop wont leave it pot modded, will return it to original setting, but with alot of heatsinking it prop would be good.

 

[Brett]

I just turned the pot up to full, no really noticeable difference in brightness but after one minute the power supply gets considerably hot....prop wont leave it pot modded, will return it to original setting, but with alot of heatsinking it prop would be good.

Your results are concurrent with what I have found as well.  The first part to overheat in this Snoctony 50mw system is the MOSFET.  You could outfit it with a taller (preferably copper) heatsink and some thermal paste and you ought to be able to get away with longer runs with only passive cooling.  You could use a fan, or both, with even better results.  That module and heatsink however, are relatively small compared to other lab lasers I've seen, so that would eventually become an issue.  However, this is a great laser at its rated power as seen in my first Laserbee photo.

-Brett

 

[ElektroFreak]

I simply mounted a small fan directly above the MOSFET in question. That lowers the temp so that it never gets more than very slightly lukewarm. For the record, however, that MOSFET is rated up to 150C. Even at it's hottest without a fan it doesn't come close to that hot.. It should live a long life with only the installed heatsink.

 

[Brett]

For the record, however, that MOSFET is rated up to 150C. Even at it's hottest without a fan it doesn't come close to that hot.. It should live a long life with only the installed heatsink.

True.  Jnrpop, don't hesitate to look up the datasheet on parts like this when you have thermal concerns.  I had a good habit of doing that when I was building my own drivers for solid state tesla coils, but am still getting acquainted with current regulated supplies.  

You know, what we ought to try and do is to design a SMPS ourselves, which is good for up to 3 amps or more, and uses a half or full bridge of some beefy mosfets with good heatsinking.  We're getting into new thread territory now.

-Brett

 

[ElektroFreak]

[quote author=ElektroFreak link=1228783157/20#23 date=1232125115] For the record, however, that MOSFET is rated up to 150C. Even at it's hottest without a fan it doesn't come close to that hot.. It should live a long life with only the installed heatsink.

True.  Jnrpop, don't hesitate to look up the datasheet on parts like this when you have thermal concerns.  I had a good habit of doing that when I was building my own drivers for solid state tesla coils, but am still getting acquainted with current regulated supplies.  

[highlight]You know, what we ought to try and do is to design a SMPS ourselves, which is good for up to 3 amps or more, and uses a half or full bridge of some beefy mosfets with good heatsinking.  We're getting into new thread territory now.[/highlight]

-Brett[/quote]

That's a great idea! What would make the design truly awesome is if it were set up to be both variable voltage and current. That way it could be set up to power any diode no matter what the voltage/current requirements.. There are a lot of schematics out there for power supplies that fit this description, so I'll look around and see if I can't come up with any ideas..

 

[Brett]

That's a great idea! What would make the design truly awesome is if it were set up to be both variable voltage and current. That way it could be set up to power any diode no matter what the voltage/current requirements.. There are a lot of schematics out there for power supplies that fit this description, so I'll look around and see if I can't come up with any ideas..

Great! I'm glad you like the idea. I see that Meredith Instruments has a supply the sell regularly on ebay that does up to 1.5A, but it costs 50 USD. I've thought about buying that and reverse engineering it, but once I've paid that much, I expect to get a module and crystals along with it. Maybe I'm spoiled :-/

I will start looking around too. We should start a thread in the experiments section.

-Brett

 

[jnrpop]

Yer that would be great, adjustable voltage and current, so basically one LAb-Style power supply for all. There is another thread using simular ideas around mosfets so that may be worth having a look, it in the experiment section. But its a great idea.

Another thing is what do these green modules run at, so whats the spec voltage and current to the pump diode in these 50mw labbies, does any one know?

 

[Brett]

Yer that would be great, adjustable voltage and current, so basically one LAb-Style power supply for all. There is another thread using simular ideas around mosfets so that may be worth having a look, it in the experiment section. But its a great idea.

Another thing is what do these green modules run at, so whats the spec voltage and current to the pump diode in these 50mw labbies, does any one know?

You should be able to find spec sheets for IR pump diodes at Roithner laser, and also the ebay seller snoctony has specs for the 808nm diodes he sells as well. Sam's Laserfaq is where I developed my framework of understanding about DPSS.

-Brett