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445nm bad diode?

mitbrown

mitbrown

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I bought this A130 diode from Modwerx.

I know it's not the lens because the defect is obvious even when the lens is off.:yabbmad:

It still fires up, and burns okay, seems to be about half as potent at burning, and beam is AWFUL
This is hard to describe (so bear with me), When I try to focus it to infinity, the middle section will come to a focus, but more than half of the outer part of the beam spreads out away from the dot. :thinking:

2TfPW6CJ.jpeg
 





Gryphon

Gryphon

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Is the pic you posted showing the output of the raw diode without a lens? If so, the
problem might be as simple as crap on the window. If anything were to fall onto the
window during assembly, it would be baked on when the laser is powered up and cause
the ouput to look dirty.
 
mitbrown

mitbrown

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No, this is with the lens on, but out of focus.
It looks very similar without the lens.

doesn't look like anything got on the window, and i've tried wiping it off with a q-tip, with no result
 
lasersbee

lasersbee

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You say you have a Laser Diode...
You don't say...
1) what it is mounted in
2) what is driving it and at what current
3) what lens you are using
4) what distance from the aperture the Laser Beam profile
is being looked at.... etc.

Jerry
 
H

heruursciences

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This seems to be a major problem with these diodes. Tiny motes of dust get on the window and it fries so bad that the window actually melts- the only real cure is decanning it.
 
Gryphon

Gryphon

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^ then the best thing it would seem it is to make absoluetly sure the window if clear of
any debris before powering it on the first time., i don't want to try and decan a 445nm

mitbrown, could you post a macro shot of the diode's window
 
mitbrown

mitbrown

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It's in the lab style heatsink from Modwerx with a glass lens from Stonetek. I'm using a homemade DDL driver, the current was about 600ma for the picture.

Here's a pic of the raw output at 400mA, 1 foot away from the wall.
(just now took this pic with my phone)

hzCOyaU3.jpeg
 
DTR

DTR

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Do you have a pic with it in focus. I burnt one of my a140's using an acrylic lens and it left an aura around the dot when focused. I was hoping it was just the lens but changed out several with the same effect and ended up having to change out the diode. No aura now.

Did not try it but Daguin did suggest this for cleaning the diode

Daguin said:
Try lens cleaner and then PURE acetone. Be gentle and DO NOT use nail polish remover type acetone.
Click to expand...
 
Gryphon

Gryphon

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The problem is either on the diode window or with the laser diodes die,
could you take a pic of the diodes window, to see if it has anything baked on it,
or if the diode window is warped in anyway, skewing the ouput pattern
 
mitbrown

mitbrown

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Gryphon said:
mitbrown, could you post a macro shot of the diode's window
Click to expand...

I don't have anything that can take good close up photos :(

After a closer look, I can see a small mark on the window. You must be right...

I'll be sure not to let the same thing happen to the next one.
 
Last edited:
hakzaw1

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these doides all have a bit of thermal paste on them when they come out of the 'array'-- I put a piece of scotch tape over the windows is keep everything out as soon as I remove the array from the bottom of the C*sio--- they sell a small handheld microscope at RatShack for cheap-- it really lets you see what is there. I keep mine handy all the time. If you see anything on there that cannot be removed with a swab and a little high % alcohol may be time to move on to a new diode--

-I seriuosly doubt that Andrew got anything in your diode window--but if you got some on your fingers from the can it could have easily gotten there inadvertantly. hope this helps

hak
 
mitbrown

mitbrown

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Is it safe to try to clean it with 70% isopropyl alcohol? It's the only thing I could find..
 
C

CrazyMonkey

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If your next option is to replace it, then what can it hurt.
99% iso is better though, or better yet, lens cleaner that's safe for AR coatings.

I would try it without hesitation.
 
Scottyzedinosaur

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Also, a classic trick is to put a magnifying glass in front of your camera, it lets you get fairly good macro shots. try that.:)
 
jander6442

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I can say also that in the event of you using a metal barreled lens please wipe the threads and maybe use it a couple of turns in a module without a diode in it.

The new threads still have some minuscule amounts of machining particles on them.
Just passing some knowledge, not life changing just a little ditty.
 
rkcstr

rkcstr

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I use 91% isopropyl alcohol ("rubbing alcohol) with a cotton swab. Make sure you have one that is tightly wound so you don't leave stray fibers and just dip the end of the swab in a little alcohol (you just want it damp, not dripping!) and VERY lightly touch the window and run it across. Let the alcohol evaporate, do not dry it. Then look at the window very closely under a lamp so you can use the reflection to look for any defects. If there is, then repeat as necessary.

If you push down, make a grinding motion (twirl it on the window), rub, push too hard, etc, you risk breaking or pushing the window in or scratching it. From that point, your only option is to de-can, which is not easy in comparison. Plus, you risk breaking the wires connecting to the die on the inside, which are extremely fine gold wires and not feasibly repairable.
 
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