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FrozenGate by Avery

250mW red laser diode Death in a week

I know, Thats why I added the *could*
I know how this goes. Its not working, then you look into it for a little surprise to "Oh it works, and I have lost an eye"
Ya, I have had things like that happen to be before... The little surprises when something fails. Very common with my hobby of high voltage. "why isn't it arcing? *grabs the flyback wire*... OWWWWW" =D
 





I know what you mean about HV. I was once neutralizing the PA section of a ham radio and grabbed a tuning stick that was supposedly anti-static.
OUCH!! Anti-static means slightly conductive. I just grabbed the first tuning tool I could and didn't realize what happened until the zap was over.
Oh well, live and hopefully learn.:banghead:
 
Juniortore1 said:
Well, Not that tricky. All I need is a crystal and the diode. I want to try the crystal from my 5mW green just to test it. Then I will get a real crystal for the build. The only really tricky part is to align the crystal with the beam.
Click to expand...

There's more to DPSS than a single crystal.

You'll need a ND:YVO4 crystal with one side HR coated for 532nm and 1064nm and AR coated for 808nm This face forms the rear of the optical cavity. The other side will need to be the opposite. AR coated for 532nm and 1064nm, and HR coated for 808nm.

Then you'll need a KTP crystal with both sides AR coated for 532nm and 1064nm.

You'll also need an output coupler to form the front of the cavity. The inner face should be concave if you want any real hope of 'finding the beam' and coated HR for 1064nm and have an OC coating for 532nm, with the outside face AR coated for 532nm.

If you want any real power you need at least one.. probably more, TEC's to keep the various components at their optimum temperatures. Both the pump diode and the ND:YVO4 will want to be cooled, and the KTP likes being warm. The exact temperatures will have to be tuned to your particular crystals though.

Everything in this assembly needs to be precisely aligned as well for peak power output and stability.

Even the cheap green pointers use two crystals and an OC. The crystals are just usually optically bonded together into one chunk.

If you do everything *perfectly*, you can get maybe a little over 30% conversion efficiency. Meaning from your 1W 808nm pump, you'll get a little over 300mW of green.

By all intents try to build a green. I plan to. And I really think everyone should heh. But I'll caution against going into it thinking you can build a 500mW green for $100 and show everybody up. It's just not possible. High power DPSS lasers are expensive for a reason. They're hard to make and keep stable. The cheap 5mW pens are cheap and work because their efficiency is generally sub 10%. Sometimes they use up to 200mW of IR to get 5 - 10mW of green. It's a 'brute force' approach that's just not doable when dealing with higher powers.
 
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Damn a 1W IR for only 300mW of green! Wow. Yes, I will need to research this a bit more when I plan to make one. I will try it someday, just nor right now since I need to understand it a lot better.
Thanks for the information, I will need it!
 
Ya, I plan to use the O-like crystals. I plan to make one soon. I will either have a giant heatsink OR have a water pumped system for stability and warmth.
But first, to make me want green lasers and convince me to make a nice stable DPSS one, I will be getting a 300mW green from Rayfoss this Christmas, there are 2 kinds of 300mW there, I will look into which one I will get. I might want waterproof, or the one with a higher driven diode, or one i can run for slightly longer periods.
 
I think I saw DPSS kits (crystals, OC, mounts) for sale on ebay before that were claimed to be good for high power green with sufficient pump input. They were $250ish but I can't seem to find it now.
 
Congrats on your first build.

If you are using a DVD diode I don't know of many that are going to have a long life when you push 300 mA through them.. Some might last a few hours, most wont. If you want the diode to last try less than 200mA of current. Yeah I know it will not burn as well.

I've got a DIY red that I set to 125mA and its lasted years. The few other high powered reds I made did not live long.

And if you are going to run it that hard you need good heatsinking. Try arctic silver epoxy, or thermal grease. JB weld wont work.
 
No, different diodes handle different powers. Example: LPC-815 from the 22x sled can handle 400ma but 380 is recogmended. a PHR-803t sled can handle about 90-120ma

Mine had a recogmended 300ma input, but I put in 295 for a "long life" But I think it died from soldering it for too long and heat damaging it.

The heatsink is decent for a LPC run at 400mA, my friends with the same heatsink lasted for 6 minutes before it died. And... the JBweld was to stop the aixiz from moving in the hatsink since it seemed to be small (deformed) and there was thermal paste in there.

Thanks. and sorry if there are any spelling mistakes
 
FYI I have a LPC-815 build that accidentally got set to around 500mA when I sealed up the pill. It started out doing 330mW but has dropped down to about 280mW now.. though amazingly it seems to be holding there. I left it on for half an hour straight to see how fast it was degrading the other day. It started at 280mW and as normal, output dropped as it heated. It dropped to about 250mW after half an hour, though surprisingly after cooling off it was back up to 280mW.
 
I think it would be good if you checked your solder connections.
looking at the drive when you made the solder connection to short
some circuit pads to increase the output of the driver it looks like you
have connected 4 points together where there should only be two points connected.
I am refering to the one in the center of the board not the one on the edge.
I can't get the picture any larger to look at here.
2jexocn.jpg
 
I remember a debate on whether or not the microboost could be used for LOC or not because of the fact that it's case negative. I can't recall exactly what the problem was, but some were saying that because the LOC is case negative by default and the layout of the microboost makes it so that there is a direct path from the battery to the diode, thus it bypasses the driver and the diode gets the batteries entire current.

I don't remember the outcome of this debate, but if it turned out to be true then the death would be from using a microboost on a LOC diode.

Isn't this the same reason we use a jumper wire to go from the case pin to the - input on 445nm diodes, instead of bending it over and soldering the case pin to the - pin on 445nm diodes?
 
A lot depends on the driver/diode combination you use. If the driver pcb is common "+", regulating the "-", you have a red diode(case "-") and the host body is battery "-" you have an instant full battery situation to the LD unless the heat sink is isolated from the host.
 
I saw some misinformation in this thread that needed some correction, so just a quick note:

Juniortore1 said:
yes, that is a micro boost, but it is fine for red, because no matter what, the diode will get whatever current that I set it to. I could prob run my diode on a rectified and smoothed NST if its a 30ma NST. Volts dont really matter, what kills it is the current.
Click to expand...

In this case, you are incorrect. The microboost will regulate the current as long as the battery voltage is equal to or less than the diode voltage. This means that yes it's OK to use with a red diode and 2 AA batteries, but not with a red diode and an 18650! The manual states this specification.


jbtm said:
A driver is a driver. It does not matter, if its a flex or a microboost. The only difference is the microboost can handle more current, and more voltage. Flex drive is limited to 5V peak, microboost, last i recall, can do 12V. Either way, it still DROPS voltage to make it run at 300mA. I had my red 20X on a microboost for 3 months. It died because I left it on for over 5 minutes once!!
Click to expand...

It depends on the batteries you were using and a lot of things.. But if you had put a fully charged 18650 in there at 4.2V then you were driving it with more than 300mA.

As other have said, the FlexDrive can buck AND boost the voltage, so it works great for reds, but it can only boost to about 5V, while the MicroBoost can boost to 12V.
 
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