DIY Changing 808 pump From Greenie

[mauswiesel]

Hello all !  
I fried my 50 mw newish type when i was trying to high the current flowing to the diode  with a ddl driver . So i bought some Stenkat's Ir diode to replace the fried diode ( which worked at 400ma). To dismantle the laser, see http://www.laserpointerforums.com/forums/YaBB.pl?num=1213312210

First you need A IR diode from Stenkat http://stonetek.org/shop/index.php?main_page=product_info&cPath=65&products_id=220

Stenkat[ch8217]s Ir [ch8217]s diode
These diodes are standard size but have no window and SenKat says they are rated at 200 mW.  I mounted the first one in an Aixiz style module for testing through a plastic lens assembly.  Testing is made here with no TEC cooling, regulated power supply and a Scientech 365 power meter.  Current increments are made at 20 mA intervals and the diode gave me about 15 mW per 20 mA step right to the top.  
I stopped my testing at 0.500 AMPS !!!!  Reading 374 mW !!!!
Now the bad news ---- As you all recall from the modding days, go over 300 mA and you're risking your diode.  I ran this diode later at 400 mA (270 mW) for a life test.  It was fun burning stuff for about 25 minutes    
The second diode has been run for over 4 hours at 200 mW (320 mA) showing no degredation in power out.  
This is a good little diode for those of you wanting to experiment with IR or give life to that poor old greenie you toasted. StoneTek tells me he has a limited qualtity of these and for a price far less than ebay.

The initial pump was an open can diode. You will need to remove the can from the Stenkat's diode, it's a bit easy with a knife, juste take a lens to see when there is a breach, then you can "pop" the can

then, place the diode, screw a little to allow the diode to move and find the max output ! then srew the diode  
See the vid, there is a defined position of the diode which provide max output   :

 

[Andresc4]

wow.... exelent!!!
i have a dx30 ... how many mw is the diode  ?
if i get a 5mw green and i remplace the diode and driver, can i get the same output ?
i meen the cristals are the same ?
can you get the same output as the original ?
how far did you push the original before it died?

 

[mauswiesel]

I have no powermeter that can check if i loss power. With senkat diode, i can go to 300/350 ma max. The initial open can was at 400 ma, so im losing a bit of pump power.
But the output is not linear ! for example if u increase the current, the output of green willl not increasing linearly, i see that the ouput obey to a step law, depending also on temperature of cristal, but i can have much output at lower current ! its strange  
edit : when i use a tec to regulate the temperature, the output is more linear !
Remenber that the diode is a little warm, thus we can't go in higher current, with low duty cycle, not a problem in fact.

For a common greenie (30 mw, 300ma), an optical-to-optical conversion efficiency is equal to ~35 %(ND:Yag) for 808@1064 and ~40% (KTP) 1064@532 nm, thus according to Mike's graph i think that your diode pump is nearly a 200mw

I see also that when i high powered my first diode pump at 500 ma (fried with some driver error i think), the glue or something on the surface of Nd:yag was melting. I see many post about overdriving a 5mw into a high powered greenie, but don't want to tell something wrong, their is some limit that the cristal can tolerate

i will see with more test if i recover my full power.  
edit : it seems that a given current corespond to a value of power. for example, i have 2 value of current wich i have max output : 264 ma and 320 ma. between this value, i have less power, even at 450 ma ! but its a litlle more stable with Tec cooling. I found also something interesting. Near 270 ma, my greenie was pulsed ! (almost 1 pulse per second) i take a vid of that.
In conclusion i think i have loss power, at now i can't recover it (i compared to a 5mw newwish)
vid : the second dot is not pulsed (normal dot)

 

[Andresc4]

try to open the bean with a magnifin glass,,, probably that oscilations it because mode hoping ?
you are not using the feedback ld rigth ?

i dont think they use diferent cristal for 5mw 10mw 30mw and 50mw ,,, probably in the hi end ( viper and so ) but on the pointer less than 30$uss,,, mmm....

i open my dx30 http://www.laserpointerforums.com/forums/YaBB.pl?num=1218341484
i dont know how did you take the barrel out, it was imposible for me to do it!
and i was tying to change the focus and accidentaly i damadge the lens,,, do you know if is the same as the lens on the axis lens ?

if the inical was 400mw for 50mw output,,,
with 350mw for sure you will get more than 5mw,,, maybe near my 30mw! nice to know that
how log did it take to arrive your hose ? i will probably order a few.

i realize that my dx30 on warm condicion works much better than cold, if its cold i have 2 beams,,, and if i leave it on my poket i have one clear beam on the firs second without any mode hop,,, try to check if you have the same problem. i left this one over a heater for 20 seconds to have all the cristals warm to take a few pictures,,, the problem its that i forgot the laser there for a few minutes,,, it was REALY hot... so i star crying ^... but after i left if get cold,,, i try it and it still working fine,,, i take a litle bit more to get to the max output,,, i dont know i i damadge the cristals of the diode...

 

[mauswiesel]

nice pic ! here a photo to dismantle the diode
Im using a ddl style driver with a lm317 + potentiometer.
im agree with you concerning their cristal : i dismantle my 5m newish type and compared to my 50 mw newish 's crystal : its exactly the same so its possible to remove their weak diode, place a powerful diode with an other driver to have more power
Green laser are already focused, they have much lens that the one used in our module
The initial diode was supplyng with 400mA, so according to Mike graph, if the curve is linear for these diode too, my old diode was a 300 mw
I received my diode in one week, to France, thanks to Stenkat
For your observation about temperature, your probably right, but i need some other experience to know more about greenie
You can fit an aixiz/dx lense to remplace your, no problem at all
Im using a solar cell to evaluate the power of my laser : when i power on, i got a pulse of 800mV, but rapidly decreasing to 400mV (not stable) when it reach the lower limit, it start to increase mv per mv to 800 or 900 ! the crystal is more and more warmer, and the output is linear, after reaching the upper limite (800 and few) it decrease again. Interesting.

 

[Benm]

it seems that a given current corespond to a value of power. for example, i have 2 value of current wich i have max output : 264 ma and 320 ma. between this value, i have less power, even at 450 ma !

I've seen the same thing, i guess the lower maximum is at the best match in wavelength between the diode and solid state laser, and at the higher one is the inefficiency is overcome by more pump power.

Btw, adjusting it by turning it around looks pretty easy, the maximum is quite broad. I have the same experience with other green lasers, so diode swapping seems feasible.
You should be careful when adjusting it like that though: if you can freely rotate the pump diode, it will have very little thermal contact for cooling and could be fried.

Oh.. and removing the can with a breadknife? Priceless

 

[Hemlock_Mike]

Mausw ---

Thanks for cleaning up the printing on my graph ;D I'm still "old school" on that. This is a great post for anyone planning to rebuild a "loved" greenie. It is touchy but you learn a bunch doing it.

Mike

 

[Andresc4]

offtopic: i was going to post it,,, but as you already said that here,,,,
why dont we ( all members of the forum ) find the same solar cell, o photodiode resistence, or ir reciver, i donw know, there are a lot of eletronic componets that shoud be the same in any part of the world and that are realy unexpensive, an we make like a "standard" laser measuring device ?

for example we all find the same solar cell + digital voltmeter, and with the ones who have a real laser power meter can help us to create a graph so the ones who dont have those devices can have a small idea of the power that we are geting from our  lasers ?

on: yes, i can se the 2 gaps to remove the diode,,, but bur there i wont change the focus,,, i will only remove the diode,,, i just want to leave this pointer under 1.5 mrad ... as you can see on the pictures i post before on that thread,,, the metal part its damadge,,, i place the barrel on a vince and i get a scredriver and "eat" the midle of the screew driver so it can fit on the diode, and i made A LOT of force holding the screwdriver with another tool and it dint move!, i only brake the bronce barrel and it didt move!

you are 100% sure that the diameter of that glass its the same of the axis lens , and the lens "focus distance" its the same ? if it is,, i will completly destroy the actual lens and order a glass lens from here http://stonetek.org/shop/index.php?main_page=product_info&cPath=77&products_id=219

i have you word ? :-/

 

[GooeyGus]

I just wanted to point out that in your picture it says: IR Diode (Greenie, CD/DVD, Senkats).

I am assuming the part in parenthesis are 'sources' to obtain your IR diode to use for pumping. But, the CD/DVD IR diode will not work. It's more like 790nm, and the crystals can ONLY utilize 808nm light to function properly.

 

[mauswiesel]

i will spam image to provide you a response

so yes, no problem to remplace their lens to a glass lens, but beware, the glass lens are 650 nm coated inside it, so you will lose power by reflection !
There is not many difference between a glass lens and an acrylic (plastic) for red laser, so for your green, i suggest you to buy a Dx module (4.3$)
and take the lens http://www.dealextreme.com/details.dx/sku.5914 or this unit http://www.dealextreme.com/details.dx/sku.5900 (but you have no brass ring with sku 5900, dont need for your greenie infact^^ )

For the solar cell, yes it will be a great idea, but we need to define a experimental protocol (same solar cell (from Dx for example), luminosity, polarizer to reduce power of laser, size of the dot).. but its possible

 

[mauswiesel]

I just wanted to point out that in your picture it says: IR Diode (Greenie, CD/DVD, Senkats).

I am assuming the part in parenthesis are 'sources' to obtain your IR diode to use for pumping. But, the CD/DVD IR diode will not work. It's more like 790nm, and the crystals can ONLY utilize 808nm light to function properly.

Nice one GUs !
Plus the pinout for these diode are not the same as the 808 diode, i will fix this

 

[Andresc4]

Exelent!!! ;D ;D ;D
the problem its that it realiy stuck now,,, what shoud i do to take it out ?
i was thinking in placing the barrel in the vince pointin up, and makin one cut with a saw in the same direccion than the original marks (to unscrew the len ), of course this will destroy the len, but i will be able to stick the screwdriver there and uncrew the original one,,,
the problem its with the dust of the bronce fallind down between the cristal and the open can diode,,,
:S i realy dont like this,,, probably doing the same at 90º will be better ?
i have acrilic lens so i dont worry about the coating, and i rather to loos a few mw but to loos a few mrad will be better!

thanks for all the pics! in a few days i will post the results, firs i want to finis the 555 circuit to make it pulsed

 

[mauswiesel]

In fact the first lens is glued in the barrel, you need to force a lot (dont be wrong with the direction of unscrewing   look at this picture :

The dust will fall on the Ir filter, but u can clean it with some "coton tige" ,

so no problem in fact.

but don't destroy the "pas de vis" ("screwing"  ?) of the barrel, you will need it to screw the other lens. The only solution is the screwdriver :/

Your 555 circuit interest me ! tell us when it work ^^
good luck  

 

[mauswiesel]

i made some experiment with a 5 mw newish type, i dismantle it and removed the fried diode to place a Senkat's diode. The diode was press fit so i was obliged to filled off some metal.
During my experiment, i use a "filled off machine" llike this :

Don't do that,if u need a tynier green module for a project, use  abrasive paper instead of a machine, their is less vibration and Nd:Yag on metal will stay glued (otherwise u must glue it again)
During my experiment, i was running the diode to 0=> 300 mA (uncooled) and i can tell with no doubt that the power emited is linear in low current only.

After this linear output i reach the maximum output (there is always a step of few mA to have a high output) then the power start decreasing when current increase, and few mA later, output start increasing with a second step ect.
The 3 maximal output are exactly the same, so  i will run my diode at 190 mA to have max output at minimal current.
I notice also that when i cool the diode with heatsink, that is more linear with higher current
I'm thinking about mode emited after a linear output, like our lab's 4000nanometer infrared diode we were using :

808 diode could do the same; just an idea to explain the /\/\/\ output.