Why is my laser weeker in the cold?

goa2000 · Oct 18, 2010

Why is my laser weeker in the cold? i noticed this a few days ago when im indoors at around 25 Celsius the laser burns a my finger no problem ...however
if im in a climate of around 15 Celsius it wont burn skin ? is it the sensitivity of hands issue or is the cold temperature really making it lazy...

ps if i turn the rayfoss on for 45 seconds to warm it up and then try stinging my skin the same thing.... in a cold room ....nothing....

i have an overspec rayfoss 100 focusable

Psychopatic · Oct 18, 2010

It's depends on the batteries. I also had a laser at about 200 mW. I had it in my car, before my work, and it was very cold outside. Then after about 8 hours, the laser only shined very weak. And that was almost new batteries.

goa2000 · Oct 18, 2010

But when i get back into a warm place it burns like a freak ...
ps the batteries are 18650 and are topped up

Petacat · Oct 18, 2010

In Alaska I would be out doing Astronomy with my scopes at -30 F. That was my cut off point for doing astronomy, any colder and the focuser would freeze up. To keep my laser pointer working for pointing the scopes, I would keep the pointer stuck up my artic parka sleeve. That would give me a few good moments to get the scope pointed at the star before it would get dim. Then back up the sleeve with the cold little

sucker.

goa2000 · Oct 18, 2010

****UPDATE****

Just found the answer by myself so i wanted to share it with everyone...
Apparently batteries dont like the cold Li-ion is no exception ... when they warm up they give much better performance but if the host is heat conductive it will get cold again verry fast and again the same issue will arise again , some lasers are also sensitive to the cold and have an optimum operating temperature for my laser that is 20-30 degrees celsius
so there you have it ...q and a

RA_pierce · Oct 18, 2010

The KTP and Nd:YVO4 crystals are very temperature sensitive.
Read up on DPSS lasers.

Lithium batteries tend to work better in colder conditions than Alkalines - or so I've heard.

jedirock · Oct 28, 2010

Yeah, I find it's just the crystals. I had the same thing happen to a 50mW greenie outside in around 10C weather, and thought it was the batteries at first. Swapped them out with a pair I had brought with me in my pocket, so they were toasty warm. Didn't fix it. Figured it out based on what I've read on here, that they're temperature sensitive. Held my hand on the head for about 20 seconds, and it was back up to full power.

Also, this was with Ni-MH AAA batteries, so that's another reason why it's not the battery chemistry.

Hemlock_Mike · Oct 28, 2010

I have a S-ky Laser 150 which is real temperature sensative. When cool, ~ 16 Deg C, it puts out 140 to 200 mW as it warms. Then it takes a dive to 50 mW. It got too warm.
Now the trick --- I heat the head with a butane lighter (or a torch) and the power really comes back to over 200 mW. This laser has a cold and hot peak but is crap at normal ambient temps :-(

HMike

Meatball · Oct 28, 2010

RA_pierce said:
The KTP and Nd:YVO4 crystals are very temperature sensitive.
Read up on DPSS lasers.

Lithium batteries tend to work better in colder conditions than Alkalines - or so I've heard.

^^^^There's your answer right there. Such non-linear optics inside your green laser require a very precise alignment. Not to mention if the speeds (temperature) of the atoms of the optical materials is too low or too high, they'll behave differently... typically with negative results.

Hemlock_Mike · Oct 28, 2010

If I preheat the head on my S-ky 150 to ~ 36 Deg C, It works pretty good -- near 180 mW!!! It runs for a while hot or cold but not ambient.
This is the nuttiest laser I own...........
HMike

Why is my laser weeker in the cold?

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RA_pierce

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