Sensitivity threshold of various laser wavelengths

Here's a question for anyone with several reasonably high-powered lasers in the red and near-IR wavelengths: What is the mw threshold for being able to detect heat from the laser beam on your skin?

For instance, I have a 660nm laser doing about 170mw, and I can't feel the beam at all, even when focused. I have a med-fair typical caucasian skin tone, BTW. I can easily feel the beam of my 125mw green pointer (and REALLY feel the beam of my 405mw greenie!), and also my 131mw blue laser (but not my argon - I think it's doing a little under 100mw).

How much power would it take for a person with average med-fair skin tone to feel a 660, 635, 808, or even 1.064nm laser beam? Let's assume the beam is unfocused and has the divergence of a typical green laser (unrealistic for the IR, but for the sake of argument....).
I know there are lots of variables here, but how much power do you need to be able to get a "sting" from a red or near IR laser?

Re: Sensitivity threshold of various laser wavelen

Just because you dont feel the laser, dont mean its not burning something(maybe your muscle or bone).

Its just like a worm in your head, you dont feel, no pain.

Re: Sensitivity threshold of various laser wavelen

No , it's actually getting reflected and scattered through the skin layers so the energy density is very low on nerve endigs.Don't worry about your bones being burnt. :

I am usually white as a ghost, but being summer I have a bit of a tan.My red laser(which is doing bellow 170mW right now because of drained batteries) can be felt when focused after 1 or 2 seconds on my arm, but not on my "white parts" .So I guess your skin tone matters a lot.

Aseras has a video of him pointing a crystalless RPL doing 2.9W at his hand with no effect.

To sumarize, I guess it's really hard to tell because it depends a lot on your skintone and how focused the laser is.

Re: Sensitivity threshold of various laser wavelen

I've found skin does a wonderful job reflecting IR light. I've had a few high power c-mount diodes at 808nm that I couldn't feel at all, and we're talking a couple watts here. I'm sure this is also why no one is really worried about IR light as far as skin goes. UV can cause cancer because it is readily absorbed by the skin. IR bounces right off as if we were mirrors. I'm sure this has to do with the fact that IR photons themselves carry less energy due to the longer wavelength, thus they cant penetrate.

Re: Sensitivity threshold of various laser wavelen

Actually they penetrate more than the green.They just don't get absorbed. and don't mess with DNA either.
Btw, do you happen to have any of those c-mount diodes for sale by any chance?

Re: Sensitivity threshold of various laser wavelen

check out snoctony's auctions on ebay. I think you can get a 2W 808nm for around $100

Re: Sensitivity threshold of various laser wavelen

GooeyGus said:

check out snoctony's auctions on ebay. I think you can get a 2W 808nm for around $100  

Click to expand...

Oh yea I know, they're the ones I was going for.I just thought that maybe you have a used one that you don't need anymore and willing to sell it even cheaper.I'm a cheap @ss

Re: Sensitivity threshold of various laser wavelen

Relatively light skin here. Red and NIR wavelengths rarely have any effect other than burning up some hair. I've had 10Watts of 808nm on my skin and not felt more than a mild heat. Stuck my arm in the focus of a 1.2W 808nm module yesterday though, and I could feel that about as well as a normal 80-100mW greenie.

Re: Sensitivity threshold of various laser wavelen

It's just funny how if you get a slight tan you're far more sensitive.

Re: Sensitivity threshold of various laser wavelen

My DX200 Red has always been able to burn my skin, I think skin tone is the real factor here. I'm not very tan either, but now that it is summer here and I'm outside a lot, my ~150mW red labby scorches my skin. In winter it would sting my skin, but not as easy as it does now. I'm guessing why I get burned easier is maybe because I have some Arabic in me, so it might give me that little extra bit of tan in winter to keep my skin laser-burnable. I'm not sure about that cause I do get pretty pasty without those yummy damaging UV rays. :

Re: Sensitivity threshold of various laser wavelen

It must have a lot to do with skin tone and maybe other things....I've "hammered" my finger tips with the focused beam of my 173mw 660nm pointer and felt nothing....not even warmth. I've got a bit of a tan, at least in summer, but I've never felt the beam on the top of my hand or anywhere darker.