can an IR dot cause afterimage or damage

Hi guys, obviously if you stare at a bright visible light source you will get after image. That is, if you stare at the dot of a 445 or 532nm laser on a wall your eyes won't feel well. What happens if you do the same with an IR laser. I don't want to find out but I'm curious; does it cause damage even though there is no after image. Also, what would happen if an IR laser struck an eye. Would you feel it? Does it effect the retina?

I looked through some kids type IR nightvision goggles at the 980nm laser and was surprised to find how bright this laser is. The beam is clearly visible at night through these goggles.

Sometimes I might shine a visible laser at a wall briefly but not stare at it and find I see a slight spot after, but no lasting effects. Will the invisible laser cause more damage?

Crazlaser said:

Hi guys, obviously if you stare at a bright visible light source you will get after image. That is, if you stare at the dot of a 445 or 532nm laser on a wall your eyes won't feel well. What happens if you do the same with an IR laser. I don't want to find out but I'm curious; does it cause damage even though there is no after image. Also, what would happen if an IR laser struck an eye. Would you feel it? Does it effect the retina?

I looked through some kids type IR nightvision goggles at the 980nm laser and was surprised to find how bright this laser is. The beam is clearly visible at night through these goggles.

Sometimes I might shine a visible laser at a wall briefly but not stare at it and find I see a slight spot after, but no lasting effects. Will the invisible laser cause more damage?

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This is not good, sometimes called a "floater" and after to many of those, permanent damage WILL(not CAN) be done.. Also, I personally feel everytime that happens it IS causing damage, but the brain is correcting it for the time being; the effects will come with age.

Symptoms of a laser burn in the eye include a headache shortly after exposure, excessive watering of the eyes, and sudden appearance of floaters in your vision. Floaters are those swirling distortions that occur randomly in normal vision most often after a blink or when eyes have been closed for a couple of seconds. Floaters are caused by dead cell tissues that detach from the retina and choroid and float in the vitreous humor. Ophthalmologists often dismiss minor laser injuries as floaters due to the very difficult task of detecting minor retinal injuries. Minor corneal burns cause a gritty feeling, like sand in the eye.
The exposure to a visible laser beam can be detected by a bright color flash of the emitted wavelength and an after-image of its complementary color (e.g., a green 532 nm laser light would produce a green flash followed by a red after-image). When the retina is affected, there may be difficulty in detecting blue or green colors secondary to cone damage and pigmentation of the retina may be detected.

Exposure to the Q-switched Nd:YAG laser beam (1064 nm) is especially hazardous and may initially go undetected because the beam is invisible and the retina lacks pain sensory nerves. Photoacoustic retinal damage may be associated with an audible "pop" at the time of exposure. Visual disorientation due to retinal damage may not be apparent to the operator until considerable thermal damage has occurred.


The cornea, lens and vitreous fluid are transparent to wavelengths. Damage to the retinal tissue occurs by absorption of light and its conversion to heat by the melanin granules in the pigmented epithelium or by photochemical action to the photoreceptor. The focusing effects of the cornea and lens will increase the irradiance on the retina by up to 100,000 times. For visible light 400 to 700 nm the aversion reflex which takes 0.25 seconds may reduce exposure causing the subject to turn away from a bright light source. However, this will not occur if the intensity of the laser is great enough to produce damage in less than 0.25 sec. or when light of 700 - 1400 nm (near infrared) is used, as the human eye is insensitive to these wavelengths.
Source: Environment/Health/Safety (EHS): Laser Safety

Because of the way Near-IR, such as 800nm, does not cause a temporary flash blindness when hit with it, or viewing a high intensity spot at that wavelength my thought is that it might take more energy at IR to cause damage. If the retina is insensitive to the longer wavelengths, I would think it has a higher tolerance to IR compared to visible wavelengths, of course, enough power at IR and you will fry those same cells which are insensitive to the longer wavelengths.

Anyone have thoughts on this? I can get flash blindness from the visible wavelengths, but it doesn't happen for IR... Perhaps at that wavelength the cones and rods of our eyes are more resistant to problems at IR, unless the power density is enough to burn the cells? As I write this I am thinking the question or comment isn't being stated quite right, but I really do think it might take more power at IR to harm us. Would that make a difference regarding safety or being darn careful, even more careful at IR because you can't see when it is too high? Nope, still more dangerous.

Crazlaser said:

Hi guys, obviously if you stare at a bright visible light source you will get after image. That is, if you stare at the dot of a 445 or 532nm laser on a wall your eyes won't feel well. What happens if you do the same with an IR laser. I don't want to find out but I'm curious; does it cause damage even though there is no after image. Also, what would happen if an IR laser struck an eye. Would you feel it? Does it effect the retina?

I looked through some kids type IR nightvision goggles at the 980nm laser and was surprised to find how bright this laser is. The beam is clearly visible at night through these goggles.

Sometimes I might shine a visible laser at a wall briefly but not stare at it and find I see a slight spot after, but no lasting effects. Will the invisible laser cause more damage?

Click to expand...

This may answer your questions. Laser Safety Program: Biological Effects of Laser Radiation This link may be a repeat of the other reply. https://www.phys.ksu.edu/personal/macf/safety-training/jrml-web-training.htm

Alaskan said:

Because of the way Near-IR, such as 800nm, does not cause a temporary flash blindness when hit with it, or viewing a high intensity spot at that wavelength my thought is that it might take more energy at IR to cause damage. If the retina is insensitive to the longer wavelengths, I would think it has a higher tolerance to IR compared to visible wavelengths, of course, enough power at IR and you will fry those same cells which are insensitive to the longer wavelengths.

Anyone have thoughts on this? I can get flash blindness from the visible wavelengths, but it doesn't happen for IR... Perhaps at that wavelength the cones and rods of our eyes are more resistant to problems at IR, unless the power density is enough to burn the cells? As I write this I am thinking the question or comment isn't being stated quite right, but I really do think it might take more power at IR to harm us. Would that make a difference regarding safety or being darn careful, even more careful at IR because you can't see when it is too high? Nope, still more dangerous.

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Flash blindness is caused by over-saturation of the retinal pigment. Seeing as your eye isn't sensitive to IR it doesn't get over-saturated. Damage threshold should be similar to visible depending on wavelength, but it'd be best just to stick to the prescribed limits for invisible laser radiation.

Flash blindness caused by visible light isn't really harming you (Think camera flash etc), it's not burning the tissue (There may be issues associated with intense blue light).

The issue comes when you've got enough power to actually burn the retina and at that point it doesn't matter if it's IR (To an extent, go deep enough into the IR and the cornea/vitreous gel will absorb the light before it reaches the retina) or Visible. Although, SWIR-LWIR can still cause eye damage with enough power, just not necessarily retinal damage.

Fun fact, our retinas are actually sensitive to UV to an extent and some people with artificial cornea implants can see a little UV.

Anyway ... hope that answers your questions. That wasn't so concise, haven't had my coffee yet.

That makes complete sense, except with IR, you don't get the warning some of the time of being flashed with too much light before the damage happens, that is, if you only get a little and immediately close your eyes, at some levels that could save your vision, with IR no chance.

Alaskan said:

That makes complete sense, except with IR, you don't get the warning some of the time of being flashed with too much light before the damage happens, that is, if you only get a little and immediately close your eyes, at some levels that could save your vision, with IR no chance.

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Yep, no blink reflex with IR! Hopefully the power is low enough and/or the exposure is short enough that no damage occurs. If the power is high enough it's not going to make a difference anyway, blink or not.

This one always creeps me out when I read it:

For example, some people exposed to high power Nd:YAG laser emitting invisible 1064 nm radiation may not feel pain or notice immediate damage to their eyesight. A pop or click noise emanating from the eyeball may be the only indication that retinal damage has occurred i.e. the retina was heated to over 100 °C resulting in localized explosive boiling accompanied by the immediate creation of a permanent blind spot.

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Especially me, because that is the direction I am going, into pulsed high peak power YAG's next. I am starting to run out of folk here who can help me with some of my questions now, because so few members have experience with them. Right now I am trying to figure out if I can AOM, EOM or Pockel switch some diode pumped 3mmX12mm YAG's mounted in copper holders which are set up to take side pump power from a single 20 watt 808nm diode array bar to produce high peak power 1064nm IR pulses. A lot of googling has turned up they can be EOM pulsed, and your remarks in PM to that question were helpful too, thanks.

As you suggested, pumping with three diode bars around the side was better, but I did find reference to others doing so with a single bar, just isn't as efficient.

By the way, I would be happy with even 1 mJ at 3 to 6ns pulse widths, even 10ns from one of those due to the small size.

Alaskan said:

Especially me, because that is the direction I am going, into pulsed high peak power YAG's next. I am starting to run out of folk here who can help me with some of my questions now, because so few members have experience with them. Right now I am trying to figure out if I can AOM, EOM or Pockel switch some diode pumped 3mmX12mm YAG's mounted in copper holders which are set up to take side pump power from a single 20 watt diode array bar. A lot of googling has turned up they can be EOM pulsed, and your remarks in PM to that question were helpful too, thanks.

By the way, I would be happy with even 1 mJ at 3 to 6ns, even 10ns from one of those due to the small size.

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Sounds like it's time to start digging into scientific papers and Sam's laser FAQ. The Wiki on RP Photonics has also been a great resource.

This website has been immensely useful: Sci-Hub: removing barriers in the way of science

Combine that with some good Google skills, Google Scholar and literature mentioned on the RP-Photonics articles (Which you can access from Sci-Hub for free!) and you'll have access to a whole world of information.

Yep, that's certainly possible with the right setup. Experimenting yourself will be incredibly useful, especially if you're a hands-on and book learner like me.

Thank you for the links, I've been digging into Sam's Laser Faq lately, as well as the RP-Photonics web site, thanks for the link to Sci-Hub, I wasn't aware of that one.

Alaskan said:

Thank you for the links, I've been digging into Sam's Laser Faq lately, as well as the RP-Photonics web site, thanks for the link to Sci-Hub, I wasn't aware of that one.

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I'll need to fire up my server, I'm sure I have a couple e-books on laser fundamentals/physics saved on there that I can give you access to, they'd likely be very useful too, although perhaps a little outdated now. Will fire it up after work and see what's what.

Thank, very appreciative. I am wondering off topic in this thread so badly but I found this on ebay for 100 bucks, a SHG for a YAG, this thing probably has a huge crystal in it but I won't be opening it, will be using it with a 1064nm YAG output to make 532nm green.

Alaskan said:

Thank, very appreciative. I am wondering off topic in this thread so badly but I found this on ebay for 100 bucks, a SHG for a YAG, this thing probably has a huge crystal in it but I won't be opening it, will be using it with a 1064nm YAG output to make 532nm green.

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You probably know Photonlexicon, but in case not... I just checked the news group alt.lasers, it appears to be active and current. See if it is helpful. That pre-dates Sam's Laser FAQ. It was the only laser info site in the early days of the web.

steve001 said:

You probably know Photonlexicon, but in case not... I just checked the news group alt.lasers, it appears to be active and current.

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Alt.lasers is still active? Huh... I haven't been on there in years.

Edit: Wouldn't really call 1-2 posts/month active. PL is certainly more active, although not as much as it used to be.

Still looking for a definite answer as to if damage can be caused by looking at the dot of an IR laser on a white wall close range.

I imagine the answer is simply how much power you are observing and how close you are to the spot. If you gave a specific amount of power, wavelength, the distance from the spot, as well as the specific reflectivity of the surface to that wavelength we could probably find an answer, after searching more and doing some calculations.

I observed the spot from a 50 watt 808nm FAP laser for a second on accident once just three feet away from it and saw a faint red spot on the wall, nothing happened to my vision I am aware of, but I would not do that purposely. I have heard stories of individuals having harm come to them just getting a little splash reflection from such a powerful IR wavelength.