The science of laser eye injury?

I figured while I was here, I may as well ask if someone could explain the science of laser eye injury? The Googler only returns generic answers like "Yes, it can cause eye injury" but it doesn't go into the science of how?

Also, is the science exactly (or nearly exactly) the same for say , blue lasers vs red laser, vs, violet? Different wavelengths.

Also, the assumption will be "if a laser hits you *DIRECTLY* in the eye" - but my question is more geared toward the question I really want answered: Is the science of eye injury the same if you're just looking at the "Dot" of a blue, red, green laser on the wall...

I understand keeping the "Dot" on the same spot of the wall (or whatever) and just mindlessly staring at it from say, 3 ft away may be one thing..... (and dumb without eye protection) - but how does the same logic apply if the "Dot" is say, 10 ft away? And not perfectly still or if you're just casually glancing at the "Dot" while it moves around, but not necessarily following it's exact location for minutes (or seconds) on end?

Welders flash, but permanently. Our eyes can't physically close fast enough to stop the irreversible damage.

Ricker said:

Welders flash, but permanently. Our eyes can't physically close fast enough to stop the irreversible damage.

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Unown, Ricker, where is that thread were the member got hit in the eye with a 1W laser and the aftermath.

You permanently damage your eye if the point hits you directly, it only takes a fraction of a second, being made of soft tissue, the eye is very delicate, I believe that before consulting science what it says in relation to this topic, it is always worth the attention that the person places, when he has a pointer in his hand, regardless of the power, always wear protective glasses, unless it is broad daylight and sunny, the beam is not visible, you only see the point of where the light is going to point, on the other hand, if you are at home and want to do some tests, there, glasses full, when it reflects on white especially, there is an exaggerated return of the beam.

But certainly you will have much more targeted responses from people or members who have been handling them for several years.

GSS said:

Unown, Ricker, where is that thread were the member got hit in the eye with a 1W laser and the aftermath.

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Oh I forgot but I know who you're talking about.

GSS said:

Unown, Ricker, where is that thread were the member got hit in the eye with a 1W laser and the aftermath.

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I'd like to see that...it's making me feel uneasy even thinking about it.

Question is, how do you enjoy your laser when wearing glasses in which you can't see it yourself? I know the con of being blind is obviously the motivator, but then how do you enjoy beamshots, etc?

I ended up ordering some laserglow glasses (in the correct spectrum) for the 7W blue JLaser I just picked up. I'm hoping it'll still be enjoyable to safely play around with it while wearing them.

brainst said:

I'd like to see that...it's making me feel uneasy even thinking about it.

Question is, how do you enjoy your laser when wearing glasses in which you can't see it yourself? I know the con of being blind is obviously the motivator, but then how do you enjoy beamshots, etc?

I ended up ordering some laserglow glasses (in the correct spectrum) for the 7W blue JLaser I just picked up. I'm hoping it'll still be enjoyable to safely play around with it while wearing them.

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I'll chip in here with some relevant links that I found..... a 1W 445nm blue laser has a "visual hazard distance" of 4.8 nautical miles.
A 1W 533nm Green laser on the other hand has a visual hazard distance of 25.5 nautical miles. https://www.laserpointersafety.com/page52/laser-hazard_diagram/different-lasers-compared.html

Insane difference, right?? (Wear your glasses)

And the link I think everyone *MIGHT* be referring to is this one I found: https://laserpointerforums.com/threads/hit-in-eye-with-1000mw-445nm-blue-laser.69469/

Guy was goofing around (if you ask me) - and paid the price. Permanent damage. Although the brain does correct for injuries....just avoid it. (Wear your glasses)

I still haven't found an reasonable explanation as to why watching the "dot" on , say, a rug on the floor at 5 ft, ish, while it moves around is harmful. If it's 1 inch away from your eyeballs - and you're just staring at the dot continuously, I would understand it.

But 5 ft away while it's "moving" around on the floor and you just occasionaly glance at the "dot" .....while being *extremely careful* not to hit anything reflective.....I just don't understand the science of *THAT* scenario and how it damages. Or even looking at the beam *FROM THE SIDE* - not head on into the eyeball.

I'm positive the W rating of the various lasers comes into play there.

Must be something just a bit above my pay grade as a laymen. (Wear your glasses anyway) (We both might get answers but that's going to be the bottom line anyway)

Avoiding eye damage from laser use is all about energy to the eye per unit of surface area.
The maximum permissible exposure to a visible laser, such as a pointer or handheld, is 2.54mW/cm2. The eye can intensify the energy of a laser beam by up to 100,000 times i.e.if the irradiance entering the eye is 1 mW/cm2, the irradiance at the retina will be 100 W/cm2, so even a low-powered laser can cause a burn if it's focused by the eye's lens directly on the retina.

For a more detailed explanation see: https://en.wikipedia.org/wiki/Laser_safety

Study the best web site on laser safety and related see: https://www.laserpointersafety.com/

See also: https://www.lasersafetyfacts.com/classes-menu.html

The type of damage that can happen depends on the type of light and the exposure.

Visible light goes through the eye with negligible absorption, which makes sense since you need it to get to the retina to see it, The spots on the retina that get hit with the laser beam can get burned and get destroyed and turn into blind spots where you don't have any vision. But the brain is good at compensating for these types of defects so depending on the severity it could be hard to notice the damage, like we have a blind spot in each eye where the optic nerve exits, but the brain fills in the spot so we don't notice that we have an area where we have no vision in normal day to day life.

Near-infrared light still mostly goes through the eye, but our visual perception of it is incredibly weak, meaning the blink reflex will not get triggered as easily, or not at all, and the damage will get caused by burning/overheating an area, destroying the tissue there.

Further into the infrared spectrum the light will start to get absorbed in some of the structures that lie between the surface of the eye and the back and can cause defects in these structures leading to cloudy or blurry vision as a result.

Ultraviolet light gets absorbed by the cornea and lens and can similarly lead to cloudy or blurry vision in the eye.

As for your other question, looking at a laser dot on a wall is not particularly dangerous, the light gets dispersed and what you see is a tiny fraction of the light, the pupil in your eye is only a few millimeters wide and you can imagine you would be able to fit it many many times tiled on a hemisphere around the laser dot and the dot would be visible from all these positions, the closer to the dot you are the greater the intensity obviously, it will eventually start to cause damage, but it will also be extremely uncomfortable, like looking directly at the sun is uncomfortable and will result in damage if done too long.

The risk you take when looking at the dot without protection is that whatever you're pointing at could have little bits of reflective material that could redirect a much larger portion of the beam into your eye, imagine sweeping a laser pointer across the ground and you hit a shiny facet of a grain of sand at just the wrong angle to reflect the beam towards your eye, suddenly the laser dot gets a thousand times brighter briefly. It might not be very likely to happen, but permanent vision damage is a hell of a risk to run in my opinion, my eyes are far more important to me than the cost of a pair of laser safety goggles.

No one has said this yet, but your eye also focuses the light coming in to a specific part of the retina. That is also why this is so dangerous.

brainst said:

I'd like to see that...it's making me feel uneasy even thinking about it.

Question is, how do you enjoy your laser when wearing glasses in which you can't see it yourself? I know the con of being blind is obviously the motivator, but then how do you enjoy beamshots, etc?

I ended up ordering some laserglow glasses (in the correct spectrum) for the 7W blue JLaser I just picked up. I'm hoping it'll still be enjoyable to safely play around with it while wearing them.

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You can watch the beam without glasses in your house or outside.
You can point the beam around but being super careful to not hit a reflective object. You can point the beam in the air again being super careful that there is no aircraft of any kind or point it around lower as long as there is no people or animals.
If your all about safety you can enjoy your laser.

The more powerful the laser the dot will be brighter and more tiring on your eyes if pointed inside on a wall but the eyes will recover kinda fast.
A green laser at 1W or more or a blue laser at 3W will put dot so bright I wouldn't look at it inside the house. Just to much.

If your burning something then safety glasses are a must!!
With glasses the dot wont show the color of the laser, it will be like a fluorescent color. You will see a flash when something catches fire and the fire shadow but thats about it. Thats the price we have to pay to save are eyes.

Good companys and strongly recommended like the Eagle brand glasses have a 30% VTL which lets you see the dot and burning better but still have a high OD5 or OD6 rating for protection..

Your eyes lens not only focuses the light onto a small area, but all our detailed vision stems from a tiny area called the fovea where nerves are tightly packed, it's also the center of our vision, so any damage there would have a harsh impact of quality of vision.

Mistakes happen when we least expect them, so make it a habit to wear your laser safety glasses.

@RedCowboy
I thought I had lost you, I didn't read you anymore, had you gone into politics? I consider you a very knowledgeable person, god of laser collimations and not only, I'm not sure you remember me.

I'm just a hobbyist with a thirst for knowledge..... Your Flavio, right ?

Yes it's me, I'm glad you remember me

GSS said:

You can watch the beam without glasses in your house or outside.
You can point the beam around but being super careful to not hit a reflective object. You can point the beam in the air again being super careful that there is no aircraft of any kind or point it around lower as long as there is no people or animals.
If your all about safety you can enjoy your laser.

The more powerful the laser the dot will be brighter and more tiring on your eyes if pointed inside on a wall but the eyes will recover kinda fast.
A green laser at 1W or more or a blue laser at 3W will put dot so bright I wouldn't look at it inside the house. Just to much.

If your burning something then safety glasses are a must!!
With glasses the dot wont show the color of the laser, it will be like a fluorescent color. You will see a flash when something catches fire and the fire shadow but thats about it. Thats the price we have to pay to save are eyes.

Good companys and strongly recommended like the Eagle brand glasses have a 30% VTL which lets you see the dot and burning better but still have a high OD5 or OD6 rating for protection..

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Thanks for the tips! I picked up a pair of OD 7+ at 190-532 nm rated goggles from Laserglow. (They allow me to fit my eye glasses underneath as well. These specifically: https:// alignment . laserglow . com / product/safety-goggles-fit-over-13/ - I'm hoping these will do the job well. (can't post links)

As far as lasers - I ended up ordering the C3 Razor 450nm 1.6W + the Titan Cerberus 445nm 7W from JL. I have all of the batteries, goggles, etc in, just awaiting the lasers to be shipped.

Looking forward to the burning fun for sure! and beamshots