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Why are my laser not "stable"?

prometheus

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I have bought a relatively cheap 50 mW green laser (bought it in Denmark, but it looks very much like the ones from DX).

But it's quite unstable.

Often, at least when indoor, when I push the button it lights up very bright, but instantly gets dimmer. And within a second or so it's noticably less bright. Then it seems to stabilize. If I release the button and press again the same thing happends, even after just a second or so.

Often, when outdoor, it's very dim. To the extend that I might not even be able to see the beam in air outside in the night. But within a bit of time (perhaps 10 seconds) it's quite strong. And the beam is very visible.

Now, why is it so unstable? It seems to be that it might very well be because of temperature.
1) But what is unstable? The 808nm laser? The first wavelength/frequency converter (to 1064 nm) or the second conversion (to 532 nm)?

And perhaps much more interesting
2) Can I do anything to stabilize it?

And
3) Will a better quality small (pen-shaped?) 532 nm laser be much better?
 

prometheus

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Thanks ElektroFreak.
I have seen the FAQ.
But I don't really think it answers my questions though.

It does however tell me that what I see is quite normal which is off course always nice to know. :)
But actually I was assuming this already.
 
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To more precisely answer your questions:

It is the combination of all the parts of your laser's cavity reacting to heat buildup that is causing your instability.

Most likely there is nothing you can do. Dark_Horse (see ad at bottom of the page below the reply box) does make a heatsink assembly that will fit your pen, and may help, but it is doubtful this would cure the problem completely. Most manufacturers will accept an unstable laser as a return and send you a different one, which may be better or worse. With cheap greens you just never know.
In your case it sounds like a normal warmup, that's all. I wouldn't worry.

The answer to your last question is in my previous post.
 
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Another thing I've found with a LOT of the cheap chinese pens is the quality of the electrical contact (open it and take the batteries out, then replace them (the same batteries) and see if you get better performance, at least temporarily...)

I always make sure to clean the threads with a little alcohol and a scotch-brite scrubbie as well as use the same scotch-brite (a little piece) and a stick to scrub the battery terminals clean on both ends, just be careful if your pointer has the black rubberized coating as the alcohol will mess it up if you get too much (even a little is too much) on there.

Just an observation - BTW, not to thread jump, but the BEST plan would be to wait until you get back from Israel, THEN clean it ;)
 




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