The Facts about Eye damages - or What is (not) safe ?

[fricek12]

Hi, I have read many posts and articles about laser pointers (up to 200mW). I d like to ask you few questions because I am not sure if I understad to lasers enaught yet. (sorry about my English, I am from Czech)

1. IR and power in mW

Can be said that laser beam is consisted of 2 different rays (beams) ?

1.1 From IR ray which can be reduced to 0% by IR filter which is installed inside laser pointer (the quality ones). So If there is IR filter, I dont have to afraid of this ray.

1.2 From "laser ray" at certain power in Watts (mili W) which can be reduced by special goggles (glasses) ?

Q1: Are goggles 100% safe for my eyes? (let say for lasers up to 200 mW) Can I look into laser beam with theese goggles withou risking eye retina damage (just hypotethycaly)?

Q2: Is IR beam dangerous too (I know it is, but how much)? If laser has built-in filter, my eyes will be safe?



2. Power and your eyes

I have read that 5mW is the limit. Over 5mW your eyes could be damaged.

Q3. Can anyone write here his own experiences with this? Has anyone got hit his eye? Please write in this thread:

Laser type (color or/and nm)
If you got hit by reflection or got direct hit
Time how long it lasts

This will help not just me, but all other people (newbies included).


3. Are Eye damages permanent?
Somebody wrote that got hit but after few hours/days his eyes went good (they healed). One user (Xoul) wrote he got direct hit by 1W laser and had to go to surgery. Anyone knows how is he now? Is he OK?

Q4. Can be said that green lasers up to 30mW will not damage your eyes permanently?

Q5. If you damages your eye retina permanently (can it be by reflection of 100mW green laser?), is it for all your life? Cannot be fixed by doctor?






Please dont "spam" here. If you wanna say me something like: "U are noob" or "use google" , please use PM. I have already read FAQs too

I would like if most experienced laser fans / scientists ;-) reply in this thread. Hope this thread will be usefull for everyone.

Thank You all very much.

 

[Bluefan]

1.1 You're probably refering to green DPSS laser pointers. these lasers are diode pumped solid state frequency doubled lasers. The infrared used in this proces can leak out and needs to be filtered. It won't be reduced to exactly 0%, but a good IR filters reduces the IR down to a very low and safe level.
This infrared is like the green light laser light, it's just not visible or almost invisible.

1.2 The green laser light can be attenuated by appropriate goggles or glasses (IR by the way too). The glasses need to have a strong enough attenuation so that you don't have the risk of eye damage in case of an accident.

Q1 Hypothetically laser safety goggles should protect you in case of a direct hit. Of course it's stupid to look into a laser on purpose, but proper goggles will protect you in that case. In case they get damaged by a direct hit they shouldn't be used anymore, but that's unlikely.

Also, be sure that you have the right safety goggles. The wavelength coverage and the rating needs to be right for the laser that you use or you may not be protected at all.

Q2 The IR beam is dangerous too, that's why decent lasers have an IR filter that atenuates the IR to a safe level. Laser safety goggles also covering IR work too, but that is more expensive.

Q3 I only got hit by 2mW a few times, nothing higher. From 1mW to 5mW the chance of eye damage is very small because your blink reflex will protect you. Over 5mW will be dangerous. A 6mW laser may not be that devastating as it's close to the 5mW line that separated class 3A and 3B, but i wouldn't take any chances and take good safety precautions with anything above 5mW.

The laser color will matter but not that much. Green and blue lasers are probably more dangerous as the veins in the retina absorb it better, but for safety considerations red lasers shouldn't be considered safer. In the UV a cumulative exposure is dangerous, in the IR (>1400nm) your eyes can take a bit more.

In my case it was a mirror that tipped over and swept a 2mW 532nm green laser fast across one eye. I did not see afterimages or something like that, just a small green flash.

Q4 no, 30mW can definately cause (severe) permanent eyedamage. Be carefull and wear you safety glasses.

Q5 Retina damage is permanent. Over time your brain will compensate and it will heal a bit but not back to normal.

 

[fricek12]

Bluefan, Thank You for many answers, realy useful for me...


Please anyone... write here Your own experiences with your "eye hits"... Has anyone got hit his eye? Please post here:

1. Laser type (color or/and nm)
2. If you got hit by reflection or got direct hit
3. roughly Time how long it lasts (e.g. just a flash; few seconds; for hours and nothing happens)

 

[Sigurthr]

405nm <1mW (dying diode) - direct hit - no flash, no vision disturbance. Diode probably was putting out nW (nano watts).

5mW 670nm - direct hit - flash, after image for about 30sec. I was a kid, happened about 20 years ago.

5mW 650nm - specular reflection - flash , no after image or disturbances.

5mW 532nm - specular reflection - flash, after image, no permanent damage.

95mW 532nm - specular reflection - WITH WL GOGGLES ON - flash, after image, headache, and bleached sense of green for about an hour. The laser reflection came at such an angle that it went between the nose cutout and my skin. No permanent damage. This was about four years ago, after it happend I got REAL careful with my lasers.

Just for kicks;

"Flashed" while welding - ~350A SMAW (Stick) Welding DCEP - corneal and skin UV burns, intense burning and pain, swelling, blurred vision for 48hours, bleached vision (both eyes) for 4 days. Felt like I had acid poured on my face and in my eyes.

"Flashed" while welding - ~190A GTAW (TIG) DCEN Scratch-Start - failed arc - flash, after images, bleached center of vision, no UV burns, recovered in about 8 hours.

"Flashed" while welding - ~200A GTAW (TIG) AC w/ HF/HV start - full arc - auto-helm battery died, default lens rating of 3 instead of 11 - flash, after images, bleached center of vision, no burns, lasted about 24hours, maybe a tad longer.

 

[magmabeam]

hi fricek12, you should look through threads in this sub-forum, there are plenty of stories of people describing accidents with lasers

 

[Benm]

Its also very important understand what a safe limit means.

There is a minimum exposure level that is guaranteed not to cause any damage (like 1 mW for less than 1000 seconds), but that does -not- mean any exposure OVER this level is guaranteed to do any damage at all.

The margin between what is surely safe and likely dangerous is rather broad. The safe exposure area ends at about 5 mW into the eye for visible lasers, but the point where brief exposure is certain to cause damage starts in the 100s of mW range.

The entire area in between is problematic: you could probably take a 50 mW green hit to the eye, but there is just no guarantee if there will be any lasting effects. The best thing is erring on the side of caution whenever you can though... bear in mind that people have actually suffered lasting visual defects from medium powered lasers, even if they knew exactly what they were doing.

 

[Bluefan]

... (like 1 mW/cm^-2 for less than 1000 seconds)...

fixed according to MPE.