things

i just ordered a 20mw green laser pointer for deal extreme and was wondering if it was normal that the laser starts out dull and eventually gets brighter by flickering a little bit. and also it starts out with two dots at the output.
is this normal?if anyone has this laser does yours do it as well?

thanks

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arunb

What kind of a power supply have you used a constant voltage source or a constant current source.

thanks
a

jbeng

Sounds like your pointer is operating in a "mode" different to what you're used to, at least until it warms up. Look up transverse mode on Wikipedia. Partway down the page it shows a pic of the various "modes" (TEMxx) a laser can operate in.
Jeff

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things

well actually it's a laser pointer running off 2 aaa battery's. thanks for the link and all the help

__________________
The 3 laws of science....
1. If it smells bad, It's chemistry.
2. If it's mushy, It's biology.
3. If it doesn't work, It's physics.
www.laserpointerforums.com A forum for disscusion of lasers and laser shows!
www.laserchat.org IRC chat for laser and electronic related stuff.

Sceadwian

Green lasers aren't directly modulated like red ones, they're actually a laser diode that's used to pump a solid state frequency doubler, the frequency doubler was probably still settling into it's normal mode when it was first turned on, didn't know they did that. They make blue ones which I think are directly modulated, but they make green one's look cheap, and are lower power.

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proteusII

I think you'll find that dealextreme laser pointers don't come with IR filters. A big difference from the laser pointers sold by Dragonlasers (www.dragonlasers.com) that do.

At 20mW you will probably not get a dangerous level of IR but it is hard to tell

things

well i have heard somewhere that they do. not sure though and if they do it's probably a bad ir filter. although someone had tested for ir in a 20 mw dx laser and only 1-2mw of ir came out

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The 3 laws of science....
1. If it smells bad, It's chemistry.
2. If it's mushy, It's biology.
3. If it doesn't work, It's physics.
www.laserpointerforums.com A forum for disscusion of lasers and laser shows!
www.laserchat.org IRC chat for laser and electronic related stuff.

ThermalRunaway

I was thinking of getting this green laser from ThinkGeek. Why? Just for the sake of it really!

Brian

Oznog

This is a much better place to ask:
http://www.candlepowerforums.com/vb/...splay.php?f=53

But the quick answer is, no, it's not supposed to. That's a sign of a crappy pointer.

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I thought what I'd do was I'd pretend I was one of those deaf-mutes.

jbeng

Personally, I'd be much less concerned about the 1-2mW of IR than I would the 20+mW @ 532nm coming out of the aperture. I guarantee that I wouldn't want to get hit in the eye with that at close range. I doubt anyone else would either. Be real careful.
Jeff

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Oznog

No, the IR's significant because it may not be coincident with the beam. So you could be pointing the IR beam at someone beside the beam without actually putting the green part in their eyes. Or you catch a reflection without catching the reflected green. The pupil won't contract for IR so yeah it's dangerous esp in the dark with your pupil fill open.

The other factor is that the mW reading comes from a black thermistor or solar cell that responds to IR. Vendors who do not use an IR filter have falsely high mW ratings. Someone choosing the higher mW green laser from a cheaper vendor at the same price as a lower power from a better vendor may get the same power of green, just more unless and potentially dangerous IR bumping up the mW rating.

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I thought what I'd do was I'd pretend I was one of those deaf-mutes.

proteusII

Very accurate and well written, i agree entirely.

Sure i'd buy from Dragonlasers, the laser pointers are much better quality (http://www.dragonlasers.com/viper).

I would not completely discret dealextreme. To their credit, they acknowledge (http://www.dealextreme.com/details.dx/sku.1998) their lasers don't have IR filters and they are honest/foolish enough to admit they can't verify the power of their lasers.

Sceadwian

Even the every day red laser pointers (recent ones at least) will leave spots in your eyes from even a brief viewing. The higher end green ones will most definitly temporarily blind you even from short exposure and any lengthy exposure will likley be permenent, they are fun, but they are not toys.
Radioshack used to sell special paper that would change color if exposed to bright IR light. Was basically used to test TV remotes. The IR portion should show up on a CMOS camera as well.

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