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Blue Laser "dirty" (or burned) diode ?

llcsm

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Hello. My name is Luiz and this is my first post.
First of all I´d like to thank for all the help I could find in this forum.

I bought a blue laser from china and it was working perfectly.
Today I realized that the light that comes directly from the diode is not uniform anymore. I don´t know what could have caused this.
It´s still able to focus with the lens and I didn´t notice any power loss when burning things.
I attached a picture that can clarify better the problem.

I appreciate any help.
Thanks !
 

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deadshadow

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as laserbee said please make a welcome post for a small introduction.

in your problem now,did you completely removed the lens and took the picture of the bare diode output?if so this look like you touched the diode window(or your lens in case the pic include the lens) with your fingers and left some "oil"-particulates that our skin always have even after washed out hands. the is a chance if you try to clean it without be an expert to make it worst or even burn and cook the whole diode instead.
 

WizardG

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Many noobs get their first burning blue laser and proceed to ...burn, this that and the other, all the while being oblivious to the way smoke gets cooked on to the lens. If you can remove your lens do so, and if the output (the unfocused splash of light on the wall) looks 'cleaner' then your best bet would probably be a new lens. Smoke that gets cooked onto the surface of the lens is almost impossible to remove without damaging the coatings on the lens.

Now go introduce yourself!
 

llcsm

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I already tried cleaning the diode with a smooth cloath and alcool but nothing changed.
I believed it was smoke that went into the diode. I'm just guessing. I'm a newbie in this area so a probably did something wrong. If it's smoke in the diode lens, is there a way to clean it? If not, which diode is a good replacement with output around 1,5mw?
By the way, the picture attached is the laser without the lens. Straight from the diode.
 
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Hi,

the picture looks like a dirty diode window. There is a chance that you can still clean it. How did you clean the window exactly and what kind of alcohol have you used?

Singlemode
 

paul1598419

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If you have cooked debris from your burning efforts onto the diode's window it may not be possible to clean it off. I have used 99% isopropanol w/v with a lint fee cloth to clean diodes and lenses with varied success. This may just have to be a learning experience for you. These cheap Chinese lasers are often put together with a great deal of glue and are cheaper and easier to replace than repair. I keep all my lasers out of the air when not in use and NEVER allow smoke or debris to come into contact with them. Dust can also settle on optical parts of a laser and get burned into them.
 
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Benm

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First of all it's important to find where the contamination is: if it's on the laser diode it will not rotate when you change the focus point, if it's on the lens it will rotate with the lens.

If it's actually on the diode window chances of really cleaning it are slim, though you could certainly try. The optical density on the window is so high it would melt/burn most materials right onto it though, and those don't rub off with a bit of alcohol.
 
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You can try finding and buying a new lens top for your laser, will probably come cheap for a cheap laser, also there are whole hosts available for cheap for these lasers.
 

llcsm

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I know that the problem is not in the lens because the picture is the beam without the lens. Anyway, I already ordered a G7 lens from sanwu to replace the plastic one that came in the laser.
How hard ( or easy ) and expensive is it to replace the diode ? The laser I bought is very easy to disassemble. I attached some pictures of it disassembled.
I paid around US 45,00 for it.
Honestly, I´m quite happy with the build quality and power of it.
 

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llcsm

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You are right Steve. I still don´t have the skills to replace the diode. But I believe anyone is capable of doing so after acquiring the proper knowledge.
I,ve been a hobbyst for almost 15 years building and programing every kind of RC stuff, cars, drones, 3d printers, helicopters, etc... . My soldering skills are good. But I know very little about lasers.
I asked about the difficulty and expense for replacing the diode because the one I have is still strong. It may be not worth replacing if it´s too hard.

I was looking at the diode type M140 on ebay. It´s not expensive and I read a review on this forum showing that it could output more than 2W.
Could I use this diode ?
Any help will be welcome.
Thanks in advance
 

WizardG

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You would be limited to a certain duty cycle. Say a minute or two on with not less than a minute of cool down time. That host is a little small but should handle the heat pretty well. Installing a new diode would be a good learning experience, even if you have to do it more than once ;-) Tools: you're gonna need a good soldering utensil and a diode press. If you're soldering skills are uncertain then practice a bit on a scrap circuit board. soldering an LED to the edge connections of an old dimm or something like that would be a decent analog for soldering a diode to a driver.
 

llcsm

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Thanks for the reply WizardG.
Which diode would you recommend as a replacement for that one ? The M140 I mentioned before is a good pick ?
How can I remove the diode host from the external housing ? The driver board is glued to the external housing.
Do you think the diode host is screwed inside the external housing or is it a pressure fit ?
I have a good soldering station with temp control.
 

WizardG

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The M140 I mentioned before is a good pick.--Yes, it's cheap, has decent power and relatively decent beam specs.

How can I remove the diode host from the external housing ? Carefully

The driver board is glued to the external housing. That may be a problem. If the driver can't be removed..... non-destructively you'll wind up needing to order a new driver as well.

Do you think the diode host is screwed inside the external housing or is it a pressure fit ? Can't tell from your photos. The diode itself is pressed in but I can't see if the piece it's pressed into is removable.

I have a good soldering station with temp control. Good.
Pro tip: flux is your friend.
 

llcsm

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I was looking into the "List of Diodes" thread and I saw that there are mainly 2 sizes of diodes: 9mm and 5.6mm
I measured mine from the outside and I´m pretty sure it´s a 5.6mm one.
In the DTR website there are some diodes with good prices. The M462 called my attention. Almost the same price as the M140.
Thanks for the tip. I already use flux and it really helps a lot. The solder sticks to the metal a lot easier.
Removing the glue from the driver board won´t be a problem. My main concern now is how to take the host out of the external housing.
I´m looking everywhere in the internet to have an idea of how it can be secured in there.
 

paul1598419

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Rosin, being a good solder flux, rosin core solder is your friend as well. I have a flux pen, but only use it when I need to apply solder to an area that won't normally take it well.
 




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