500mw 808nm diode question....

Okay - does anyone know what is the highest power of 532nm I could expect out of a 500mw 808nm diode if conditions are optimal ?

My plan - (please check for serious folly prior to me buying a few diodes to screw around with !)

replace the low powered diode in a Leadlight, or Fleabay pointer with the 500mw one....

Yup - that's all there is to my plan !!

So - I KNOW some of you have more experience than I, and probably know the formulas and all - what do you think ? Somebody - anybody please answer !!! I am DYING to try this - I DO have adequate eye protection, and I do have some IR filters to use if the leadlight or fleabay pointer is not equiped to block the IR.....

SKAt --

Again, it's luck of the draw. I've modded a couple Leadlights to 50 mW. Super BUT something has gone wrong and I think I have over heated the MCA. Power dropped in half and mA input almost doubled after a couple weeks. There are some high power MCA assemblies out there but kinda $$$$.

If you do it, heat will be your enemy. I've heard that the bond between the Nd portion of the crystal assembly and the KTP darkens with too much heat.

Mike

Hemlock Mike said:

SKAt --

Again, it's luck of the draw.  I've modded a couple Leadlights to 50 mW.  Super BUT something has gone wrong and I think I have over heated the MCA.  Power dropped in half and mA input almost doubled after a couple weeks.  There are some high power MCA assemblies out there but kinda  $$$$.

If you do it, heat will be your enemy.  I've heard that the bond between the Nd portion of the crystal assembly and the KTP darkens with too much heat.

Mike

Click to expand...

If you got a leadlight up to 50mW the symptoms you describe sound like you burned up the diode. When you completely overpower of them, you can kill the diode, but when you just put them under that type of stress they often drop to lower power, and may eventually fade to nothing. I believe this is due to the damage done to the end facets of the diode from such heat. Feel lucky though, my leadlight died after a mod to 8mW    

Psuedo --

Thanks for the reply. I thought myself it was the diode fading out but others told me about the MCA. I will have to set up an IR power level meter to see what has happened. Your ideas agree with mine

Mike

Pseudo --

More info looking like you are right !! I lowered the range on one of my "sick" pointers and found something.

If I slowly turn the current up, I can get back to about 4 mW output at 230 mA. As I slowly go over that setting, it suddenly drops to about .5 mW output at 240 mA. I don't think the MCA can fall off that fast. This would look like a diode problem.

Thanks --

Mike

Yep, I had a nice Aries laser that used to do 170mW and fell to only around 20-30 after the diode got messed up. I turned up the power to where I was getting >30mW and then anything after that it drops to nearly nothing. It was going to be RMAed anyway, so I just gave up and ran 7V through and killed the diode completely. Now I have another "black laser"

I just got my DL95 today -- too cold from outside to try until it warms up.
Will the diode hold up in this ?? I usually don't stay on for more than 10 seconds.

Mike

Alright, now this question is right along what I want to know, but no one answered SenKat's question!!!

I want to do the same thing, except maybe with a 2, 3, or even a 5 watt 808NM diode...

Also, if the diode was replaced in a green cheapy laser by one of these units, SenKat's 500mw, or a 5W 808NM diode, would it be green that came out...?

Correct me if I am wrong, but I was under impression that you used a 1064NM diode and then that wavelength got cut in half to 532NM, making it green.

Thanks Guys!

Enigmafied

Enigmafied. In theory you are correct if you were to frequency double a 1064 nm diode you could indeed achieve 532nm green light.

However this is not the way that 532nm light is actually produced. Relativly cheap 808nm IR diodes pump a crystal of Nd:YVO4, This emits light at the further IR of 1064nm which is then passed into a KTP crystal which frequency doubles the light to the 532nm which is the green.
I would hazard a guess that 1064nm diodes are available but I guess their cost is probably why 532nm light is produced This way

Jason.

Thanks tallaxo,

Now... could I throw a 2-5 watt diode in there...? Or would that cook everything inside of the cheapo green laser?

Do these things need to be focused or are they good just straight off the diode?

Last question this post does an IR laser beam travel the same as say a green laser? I thought I read somewhere that an IR laser spread out quicker or easier or something?

Thanks again,

Enigmafied

I'm not sure, but I think that leadlights might come with 500mW diodes...

All of this really depends on crystal efficiency. You can pump more power into the crystal, but at a certain point, called the saturation point if i remember right, the crystal will not take in any more IR and the remaining IR just sits there burning the crystal (might be why it turns brown Mike ) 5W in a leadlight case would not go over very well, you would break something and get nothing back. If you really want power search ebay for 808nm diodes then search for ND:YV04 and KTP crystals or hybrid crystals, which is just the two put into one. Or theoretically you could just use a 1064nm diode and KTP crystals, but i'm sure there is a reason they don't use them, especially in higher powered labbys where price doesn't really matter. That would be a cool experiment though!

Here is a hybrid ND/KTP crystal
http://cgi.ebay.com/LASER-CRYSTAL-S...yZ105818QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Green kinda got boreing to me for a while, I forgot how complicated it really is!

I have learned MUCH since posting that question !

If you attempt this, you are in line for some aggravation....let me explain.
The leadlights, etc are PERFECTLY aligned all the way through the process - the diode is at a certain angle to shine on the NdYv04 crystal, then the ktp is at the precise angle it needs to be in order to lase. The alignment process is a PAIN - it was fun to try for the first 12 hours or so, but after that, my nerves were shot :-/

If the owner agrees, I could sell you a 500mw (IR) RPL laser from Optotronics that has the crystals mis-aligned and you can beat yourself up trying to get it to work perfectly, and you would end up with (in this case) a 120mw green laser. Everything it intact - but the laser has issues with the alignment...The owner has $200.00 invested in it - and I am certain he would sell given the chance. It IS really frustrating to get these things properly set up, and in less than optimal circumstances, you will be in for one hell of a ride ! I am NOT discounting the involvement of luck in this process - I just know I have had his laser for a while now, trying to get it to act right, and have been unable to do so.

Good luck with your experiments...they can be rewarding, offering a major learning experience, and frustrating at the same time !