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Beam has suddenly become divergent

ChukiDori

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I still have this ole 50mW greenie I bought a while back.

its been sitting for a while but I fired it up again and the beam has become much more divergent than it used to be, very thick dot (2 inches at 20 feet) and less visible beam. its a "production" laser, not one I made..i can shake the housing and hear a rattle.

What causes this to happen "suddenly". theres not a strange pattern that would indicate a smudge ...somehow it has "unfocused" itself.

Maybe this would be a good first project? swap it into a new housing with better optics?

or could the diode itself be failing
 
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Eudaimonium

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If the diode would be failing, your laser would flicker and/or just dim down to no light.

About the laser having bad divergence after a while, it's the first time I heard of that, but in any case, it would really help if you would, you know, provide any sort of information about your laser, other than "50mW bought a while back".

Pictures preferable, website where you bought it, and stuff like that.

*Mumbles to self* I have a black computer bought a while back, what's wrong with it? Meh.
 

LaZeRz

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It could be that your collimating lense fell off...

Another possibility is that the crystals which convert the IR light to green are loose or damaged. This could mean that your laser is going from tem00 (= 1 round dot) to tem01 (= 2 dots)



You might want to post pictures :) They tend to help quite a bit.
 

ChukiDori

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Its a 50mW pointer from ledshoppe.com They also have a 50mW violet now for 24$ which ill probly pick up next the same time I put my dvd diode together.
 

ChukiDori

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I cant really get a good picture to show either. I only have a camera phone and the laser does wiierd things to it. I can get an image of the dot but its highly distorted..and no real way to scale it
 
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LaZeRz

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Firstly, do you have laser safety goggles?

If you do (I hope you do) you can shine the laser through them and it will dim down the dot so you can get a clear picture of it.
 

ChukiDori

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Phone camera lens clearly has its own issues. The light is scattering off the camera, nothing I can do about it. The rays you are seeing are a result of the camera, those "rays" are not present to my eye.
 
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ChukiDori

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the beam is also noticably less visible , probably because its spreading out more.. its got fresh energizers in it (not that those are the best batteries by far...but they r new ^_^) It used to be a nice bright hot spot. Now its just a big round glob. Intense of course...
 
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Looks to me like you have dust/dirt on the lens. I would see about carefully cleaning the lens
 
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ChukiDori

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Oh good. Now I can put my vice to use. ^_^. The lens is so far in there I get to take the host to pieces :)
 
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InfinitusEquitas

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Could be the crystals are slightly misaligned, but I'm leaning toward a dirty, possibly damaged lens.

If the laser has been sitting for a long while there is a fair chance that dusk has collected on the lens. Try compressed air.

After that, if you happen to have a lens cleaning kit that would work well... but if not you can use a microfiber towel (depending on the towel - must be lint free) and a bit of rubbing alcohol.

Acetone is also a good option.

No guarantee that it will help too much... but it should help somewhat.
 

Opentoe

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Please, for all cleaning glass, LCD screen, plasma TV, etc...please use
Purosol cleaner. It really is amazing stuff and is SAFE, unlike most chemicals people use.
 
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I'd say so too. If a big line appears on the projection, its probably lens damage, or crystal displacement.
 

ChukiDori

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The line is again, not visible to my eye. It is a refractive issue with the camera.
 
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Oh sorry. Thinking about the divergence again, the colliminating lens could be offset... thats what usually gathers the light up
 

jost4318

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I think your de-collimation lens has come loose it is inside the module behind the collimating lens and in front of the DPSS crystals the horrible divergence is due to running a partially collimated beam through a collimating lens without it being de-collimated first the loose lens would also evplain the rattling if it were one of the dpss crystals he would not have green light being emitted due to the crystals being mis-aligned if i hold a collimation lens in front of my nexus's collimaed beam it does the same thing so im pretty sure this is your problem.
 




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