Why doesn't intense infrared radiation from a fire harm your eyes?

  • #26
Drakkith
Staff Emeritus
Science Advisor
21,078
4,902
What exactly causes eye damage when staring at the Sun? Is the retina heated to a high temperature?
 
  • #29
803
9
So this implies that if the sun had no UV light, we could stare directly at it? This somehow doesn't seem right. Just from experience, the natural tendency for you to not stare at the sun seems to be down to its brightness, not its UV output.

I'm not arguing, just bringing up a point (which I brought up on the previous page) that I wished someone would address.

Isn't the visible light damaging to the eyes (in the short term) simply because the eyes are sensitive to it? Just like loud noise will damage the ears...but won't affect the eyes. Likewise, no matter how bright you make the light, it won't damage the ears (within reason)?
 
  • #30
Drakkith
Staff Emeritus
Science Advisor
21,078
4,902
I'm not sure Lsos. Unless the cells are getting killed, then I'm not sure what the problem would be.
 
  • #31
russ_watters
Mentor
20,120
6,632
I'm not sure Lsos. Unless the cells are getting killed, then I'm not sure what the problem would be.
Cells don't need to die for you to feel pain/discomfort. I have sensitive eyes and if I'm not wearing sunglasses on a bright day I feel discomfort even if I'm facing away from the sun!
 
  • #32
Drakkith
Staff Emeritus
Science Advisor
21,078
4,902
Cells don't need to die for you to feel pain/discomfort. I have sensitive eyes and if I'm not wearing sunglasses on a bright day I feel discomfort even if I'm facing away from the sun!
Sure, but acute damage to your eyes via sunlight would only result from dead cells right?
 
  • #33
Andy Resnick
Science Advisor
Education Advisor
Insights Author
7,525
2,114
<snip>Just from experience, the natural tendency for you to not stare at the sun seems to be down to its brightness, not its UV output.
You are referring to the aversion reflex- that is generated by light hitting the retina, and so is not generated by UV light. Nonetheless- sunlight, in the 400-1400nm spectral region, is of insufficient brightness to physically damage your retina according to experiments on rabbit retinas.
 
  • #34
The other night I was watching a campfire and the infrared light from it was intense enough that it warmed my face quite a bit, almost uncomfortably. I must have been receiving quite a bit of invisible light in my eyes, but there was no damage (and I've never heard any warning about watching campfires being dangerous to eyes).

On the other hand, light from the Sun would not warm my skin as much as the fire did, yet looking directly at the Sun would damage my eyes. Also, I know that infrared lasers can be quite an eye hazard because your eyes don't respond to limit the light at all.

This leads me to believe the following conclusions: A. Infrared light can damage your eyes. B. The intensity of light received from a campfire can be higher than from the Sun. C. Even if there is more intense light from a campfire, it is safer than light from the Sun.

Why isn't light from a campfire a danger to your eyes?
Infrared radiations are radiations with wavelength about 1nm -3000nm, and with different divisions like Near(.75-1.4), Short(1.4-3), Mid(3-8), Long(8-15) and Far(15-1000) all values are in nm. Now if you are talking about radiations coming from sun, then first of all they are about 2500nm +, secondly radiations are of extremely high intensity, last but not the least they are coming from a source having area larger then area of earth. Further infrared radiations coming from a camp fire is not completely harm less they will harm your eyes but because they are coming from a small source in cool surroundings with less wavelength it will not look like harming instantly.

And about Infrared radiations even we release infrared radiations, then it doesn’t mean if you are looking at someone continually then your eyes will get damaged due to infrared radiations releasing by that person.
 

Related Threads on Why doesn't intense infrared radiation from a fire harm your eyes?

Replies
4
Views
964
  • Last Post
Replies
4
Views
2K
Replies
11
Views
830
  • Last Post
Replies
8
Views
1K
Replies
4
Views
3K
  • Last Post
Replies
9
Views
5K
Replies
17
Views
8K
Replies
9
Views
3K
  • Last Post
Replies
5
Views
23K
Top