Green lasers and the cold

[jamied360]

My green laser is a 10mW (no make) and it doesn't work in the cold at all, anyone got any ideas what i can do about this?

 

[timelord]

Green lasers suffer greatly form unit to unit and the cold sometimes does this mate. Higher powered greens still do this but will still show a visible beam...

 

[Chris.]

Mine works in the cold, deffinitley, but I actually get 2 distinct dots which combine to form one in about 2-6 seconds ;D

 

[timelord]

That's called mode hopping.....

 

[Chris.]

Are you sure? I mean 2 dots with a gap between them e.g. 2 laser pointers from one unit momentarily?
I thought mode hopping was simply changes in output over time?

 

[timelord]

I'm sure.

 

[Chris.]

I expected no less, ~£20 ebayser

Thanks for clearing that up!

 

[charleytown55il]

its amasing how sensitive dpss lasers are to temperatures variations.

 

[ixfd64]

Isn't there an urban legend which states that lasers will output more power if they are cooled? ;D

 

[RA_pierce]

I live in California, so even in the coldest part of winter my laser runs at full power ;D. But the heat is what causes problems... My 5mW cooked in the sun.

 

[philguy]

Isn't there an urban legend which states that lasers will output more power if they are cooled? ;D

Depends. If you fire several tens of watts through a 5mm KTP cube, cooling it will increase efficiency and thus power. But that only applies to "removing excess heat" and not "chill close to freezing temperatures"

By the way, now when it's cold outside my DX is really dim, but when I keep on holding it in my hands and heat it up, I will get proper output again.

 

[SWestgard]

i just recieved a <5mw from nova and when it arrived via airmail it was frozen so cold i could hardly touch it. I let it warm up a bit be for putting batteris in, but now it does not work correctly. It starts very very dim, gets brighter, and fluctuates intensity every time i turn it on. Any ideas?....I think the frezzing of the electronics fried it. ???

 

[likewhat]

Isn't there an urban legend which states that lasers will output more power if they are cooled? ;D

Cooling diode lasers can change the frequency of them and usually allow you to run more current through them. With solid state lasers it is a bit different, the temperature of them affects the gain a lot. In some cases such as with YAG the small signal gain is dependent on temperature, this can have consequences for amplifiers. By letting the crystal get hot you reduce the small signal gain so the crystal will not be constantly losing energy to amplified spontaneous emission and thus it will hold more energy for you do extract when you send a pulse through it.

 

[Benm]

Isn't there an urban legend which states that lasers will output more power if they are cooled?

It's no legend at all, cooling the pump diode WILL make it put out more power for a given current. However, it also shifts its frequency a bit upwards which could cause a (further) mismatch with the input absorption range of the solid state laser. Add to that that doubling efficiency also depends on temperature, you end up with a DPSS laser that works best around room temperature as a whole.