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Help with fiber coupled pld 40 diode 30w

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Branson33

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Hi guys it’s been a while since I posted but I was wondering if you guys can help me? Alright so I’m about to buy a fiber couples 30w diode for 350 dollars and I was wondering how should I cook this? I was thinking maybe putting it straight on a peltier cooler with a piece of metal between it and the cooler maybe?
The item number is 262996281323 on eBay and the spec sheet is here http://www.ipgphotonics.com/641/Widget/PLD-40+Laser+Diode+Datasheet.pdf
My other question is it says forward voltage is 4.8 volts is that the max amount of volts? Or is that when the diode only starts to turn on? And the amp threshold is .7 what does that mean? Thanks guys! I don’t want to ruin a 350 diode.
 





DashApple

DashApple

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Threshold is the current that the laser diode starts lasing , so 700mA ( 0.7A )

Forward voltage is the drop across the diode when its running at its operating current , its less important to know than the operating current , you need to know this to run the diode within its specs .

I have a 20W similar version and mines just on a heat sink , but if you want temperature regulation then a TEC / controller is best .

This is mine on a camera without its IR filter

00300007 by TwirlyWhirly555, on Flickr
 
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Branson33

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Alright so it will start at 700ma. Also that looks very cool :) and but what is the max voltage though because I don’t want to ruin it or kill it by going above it’s max so I thought the 4.8 volts it said is max but I’m not sure, what do you run yours at? And what power supply are you using?
 
paul1598419

paul1598419

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I have a 1.3+ watt 532nm DPSS lab laser. It uses Peltier TEC temperature control on the IR diodes as well as the crystals. That is a very good way to keep the diodes running close to spec and gives unlimited duty cycles.
 
DashApple

DashApple

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Branson33 said:
Alright so it will start at 700ma. Also that looks very cool :) and but what is the max voltage though because I don’t want to ruin it or kill it by going above it’s max so I thought the 4.8 volts it said is max but I’m not sure, what do you run yours at? And what power supply are you using?
Click to expand...

Yes , I'm using three flexmod P3 as the driver each set to 4A for 12A , voltage drop is around 4V

4.8V isn't a max nor is there one , 4.8V is the expected voltage drop of the diode at 12A drive current . Just use a constant current driver that can supply 12A and a voltage above the diodes drop voltage .

The higher you go with the drive current the higher the drop voltage will be over the diode .
 
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Branson33

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Alright, so 5-5.5 volts isn’t going to hurt it? Because I’m going to be using a mean well 5v 12 amp power supply just one of those generic ones and when you turn it on it jumps to 5.3 volts and back down to the voltage it is set at but you are saying that the 5.3-5.5 volts won’t hurt it? And that as long as I go above 4.8 volts it should work fine and there is no voltage that can hurt it? Except like 6 volts or so of course ?
 
DashApple

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I'm trying not to confuse you but the 4.8V is the drop across the diode at 12A that's it , You NEED a constant current driver , anything other than that will kill the diode . Laser diodes are current driven devices

I may have no worded it very well but I'm not saying go over 4.8V , I'm saying 4.8V is the drop at 12A , running the diode at 14A may give a drop of 5V but that's above its rating

A 5V supply will be to low , you will have the diode drop at 12A of 4.8V Plus the drop of the driver of say 2 - 3V ( assuming its linear ) so you need 7V ish + .
 
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Branson33

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Alright, so could you recommend a constant current supply that you can find maybe like 20-30 dollars? Please I’m sorry I keep asking I just don’t want to hurt the diode I mean I have plenty of lasers just not that expensive and I run them with a bench power supply but it is only 0-30 volts and 0-5 amps so definitely not high enough but please could you find one and show me?
 
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Branson33

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So I have a constant current power supply that I use with other diodes, is the voltage drop how how much voltage it literally drops at 12a? So say I have my supply set at 4.8 volts and 5 amps you are saying it won’t turn on ? And say I set it up to 7 or so like you said so 7 volts at 5 amps would it be turned on?
 
DashApple

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Yes , Its what the diode should drop at 12A , If you set the voltage limit to 4.8V and the current to 5A the diode will lase fine , but the voltage drop across the diode will be less than 4.8V

Setting it to 7V limit and 5A will be the exact same at a 4.8V limit at 5A . The current determines the voltage drop and output power
 
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paul1598419

paul1598419

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Like DashApple has been telling you, the 12 amp current rating is what the diode is set to. You should never limit the voltage as it will change with the current and temperature. So, even a 12 volt supply set at 12 Amps will not hurt the diode as it will only drop whatever voltage is necessary to keep it at 12 amps. As long as the current is regulated, you don't need to concern yourself with the voltage drop as long as there is enough voltage to allow the diode to draw 12 amps.
 
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Branson33

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So how many what’s do you think it would be at 5 voltsand 5 amps because that’s the strongest supply I have as of right now, and also what would you recommend I don’t go over as far as voltage and current?
 
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Branson33

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And okay I’m starting to understand now I have troubles with these kind of things lol, so if I run it at a max of 5 amps how many volts should I limit it to? Or should I just limit it to 5 amps and keep twisting the voltage knob until it is drawing 5 amps?
 
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Branson33

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Branson33 said:
And okay I’m starting to understand now I have troubles with these kind of things lol, so if I run it at a max of 5 amps how many volts should I limit it to? Or should I just limit it to 5 amps and keep twisting the voltage knob until it is drawing 5 amps?
Click to expand...

And also would a pair of eagle pair laser goggles for 800-1700nm od5 be okay for this laser?
 
paul1598419

paul1598419

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Yes, the voltage will only drop what the diode's current allows it to. So set the voltage to at least a couple of volts more than you'll even need. A pair of OD6 would be better, but that should give you pretty good protection against accidents. Certainly don't ever look into the beam even with the googles on.
 
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Branson33

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Alright so say I’ll set it to 2 volts and current limit it to 5 amps, at 2 volts it probably won’t draw 5 amps correct? So I’ll crank up the voltage until it hits five amps and I should be good to go right?
 
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