Dont need Glasses?

[denodan]

I understood that you need Glasses more so with the green lasers due to many don't have IR filters, as the green laser puts out IR, which is unseen and damages the eye.

If you have an IR filter on you green laser it's fine. Heat will damage the eye, if it is to bright, like the sun you cannot look at it to long, so your reaction is you will not be able to stand looking at the dot to long.

This is why you cannot look at the sun to long unaided, to bright so the automatic reaction is you cannot see it for anymore then a split second. So the heat, IR damage the eye.

My understanding is red lasers are much safer the green as they don't put out the IR like green lasers, and the eye is less sensitve then the green.

A 200 mv red laser will still burn like any green 200Mw, but much safer as it appears much less bright. I did see on You tube, I think it was looked not much brighter then a grren 30Mw.

I allready have an Astro aimer, 5Mw and hooked, now getting a 50Mw green and looking at a 200Mw red burning laser.

I know any laser,even a 5Mw will harm the eye if directly looking at it, but a green with no IR filter is a no no without glasses, even not looking at the beam the IR is there.

But remove the IR with filter on laser is fine as long as your not looking at the beam your fine.

Red lasers are much safer then green. Green lasers over 5Mw without IR filter built in should not be sold. The IR filter is the make it safer for the eye.

But I do know direct contact with the eye will damage it, even from a mirror into the eye, but on a white wall with something over 5 Mw will do no permant eye damage but do to reflex action you may not find the dot comftable to see and will not end up looking directly at it.

To sell green lasers with no IR filter should be illegal to sell.

The idea of wearing glasses takes away the purpose of owning a laser,the light show and WOWfactor.

if you got to dull the beam down so it's brighness is cut right down then what's the point, you may as well buy a 5Mw one.

for burning your better off with red laser as are safer and not putting out the IR that green are, and appears much less brighter then a green one of the same power.

I think it boils down to using a laser with common sense.

 

[Murudai]

Okay, uh...

Firsly, IR filters aren't really all that big a deal. Generally, it's only a few mW of IR. And plus it diverges so fast from the laser that it quickly goes to safe levels. Unless you're staring along the beam just next to it and looking towards the laser aperture for long periods, it should be okay.

Mainly problem with IR is that some sellers include the IR in the power output. So a 100mW laser might be outputting 80mW of green and 20mW IR, so you're not getting what you're paid for.

IR certainly isn't a good thing for a laser to have, but going out to buy goggles just for the IR is a bit extreme.


Now, you said red lasers are much safer than green. No way, green would be more dangerous in my opinion Your skin and eyes and stuff are generally red, because of red blood and stuff. This means it reflects red light, and absorbs green. This is why it's hard to burn your skin with red and easy with green, so getting green in your eyes will do lots of damage

 

[denodan]

Well that is what I said, red is much safer then green, so for burning using a red laser is much safer then using a green laser, which carries far more risk.

I am getting a 50mw laser which has been measured to be within +/- 5mw, and intend to use it for astronomy and will try it inside. I know the beam will be bright, but I would not see the dot being damaging to the eye unless I got the beam reflected off a mirror. Relected off glass your looking at 10%-15% while the rest goes outside, so should be ok, but not recommeded to always do.

I would imagine it being very bright in a dark room and uncomfable to view the dot, but not damaging to the eye unless relfected of a mirrored surface.

 

[Murudai]

Oh yeah, you did say that. I totally misread it, lol. All those one line paragraphs, so hard to follow...

 

[diachi]

200mW of red is just as dangerous as 200mW of Green, green is just brighter because the eye is more sensitive to it, its still 200mW of focused light, so if you get a hit from either your still screwed without laser goggles.

Diachi

 

[Murudai]

200mW of red is just as dangerous as 200mW of Green, green is just brighter because the eye is more sensitive to it, its still 200mW of focused light, so if you get a hit from either your still screwed without laser goggles.

Diachi

They're both seriously dangerous and will screw you up badly. But green will be worse because it burns better, and your skin (eyes) absorb green better than red. They aren't equal

 

[diachi]

Still at those powers they will burn your retina instantaneously no matter what the colour is.

 

[erdabyz]

Yes, but in less powered lasers red is more thangerous than green, because the eye is less sensitive to it and blink reflex and other protective mechanisms of the eye don't work like with a green laser.

But in that powers (200mW) eye protection mechanisms are too slow to avoid damage, in both colors.

 

[Murudai]

Still at those powers they will burn your retina instantaneously no matter what the colour is.

No duh, which is why I said exactly that

They're both seriously dangerous and will screw you up badly.

erdabyz, brighter light won't make you blink faster (or if it does it's negligible). It's just with IR where you won't blink at all.

I think the take away point is that though red and green will burn differently at the same power output, the difference between them would be too small compared to the overall effect anyway. If 200mW red burns like 160mW green... well... you've still screwed up your eyes either way, lol

 

[Petrovski]

Red lasers are in no way "much safer" then green lasers. The fact that your eyes are more sensitive to red light has nothing to do with the fact your retina is red, it has to do with the way the optical cells in your eye (cones) work. I've posted a graph about the sensitivity of the cone cells before:

http://www.laserpointerforums.com/forums/YaBB.pl?num=1214080814/8#8

It's true however green will burn your skin easier than red. One can assume that a green also will burn your eye more easily than a red (shorter wavelength = more energy), but I highly doubt the difference is in the category "much safer". For a 200mW red you NEED safety eyewear, especially if you intend to burn stuff with it.

 

[lazerguy]

That greens are more dangerous than red ones because the green looks brighter is a common misunderstanding. Yes, reds are a bit less eye damgerous than green ones, but NOT safer only because it looks less bright. lets say you have a NIR laser at 808nm with 500mw power. You can hardly see the dot, but it is still 500mw! It may look like a 5mw keychain red, but it is WAY more dangerous to the eye.

Reds are actually a bit less dangerous, but as mentioned above it depends on that green photons carry more energy than red ones, but it's hardly noticeable. The skin is a lil red coloured, isn't it? How about the retina? Also a lil red coloured! Thus, it reflects red better than green, decreasing the damage.

And you are not wearing goggles because of the IR. You are wearing it to decrease the actual power level of the laser, regardless the color. And if you have glasses for lets say a 100mw laser, you don't have to wear them always. Only when burning or looking at the dot up close. For just showing it for some friends outdoors, you will not need goggles (at least if you are careful). So it doesn't decrease the WOW factor at all. IMO it even increases it, because I think it's cool that you have a laser so powerful you will need eye protection.

If you are looking for a 200mw red laser, get the focusable 200mw one from DX for only $43. Really cheap, but it is a very nice and stable laser. Get goggles for it, and use them when you are burning. If you are not using goggles, you may in a couple of years or so start to experience blurry vision. No "dark spots" as with a direct hit, but the exposure of the light all the time will slowly make your vision worse. And I assume you want to have nice and fresh eyes all your life.

Hope all this straightened things out a bit.

 

[FrothyChimp]

To the eye, 200mW of red is the same as 200mW of green, or 200mW of near IR. Green sensitivity is an evolutionary neuro-chemical response due to the prevalence of blue-green and green in the composition of sunlight. It has nothing to do with the ability to resist focused laser light. It is also my contention, in other fields of endeavor, that green sensitivity in vision developed as it was not used for photosynthesis. As light sensitive organs developed in plant like creatures it would only make sense to favor light not being used for photosynthetic processes.

Anyway back on topic. In the eye the number of cones responsive to the red spectrum (>60%) outstrips those responsive to the green or blue end of the spectrum. What this means is that more cones of the eye absorb the red spectrum than other wavelengths. You can expect those cones and associated neural connections to be ablated on a direct shot to the eye. The other cones although not as sensitive to red can still be affected by red due to the sheer light intensity and can be ablated.

According to the FDA if you have a Class IIIb or Class IV laser you need protective eyewear. That means if your laser outputs 6mW or a 100W you need glasses. Of course, it's your vision. Just remember that a laser is not benevolent nor is it malevolent. It's happy to burn whatever gets in it's way with equal fervor.

 

[pseudolobster]

The time required to blink is some 10ms, FAR TOO LONG TO PROTECT YOU FROM LASERS.

Regardless of the color, you will not be able to blink in time to save your vision... With lasers it usually doesn't matter if you blink or not, the damage is done as soon as the light enters your eye... That light is traveling some 16 million miles per hour, I doubt your eyelids can travel that fast.

Incidentally we never really hear back from most of these anti-goggle people... it seems this forum doesn't translate well into braille.

Anyways, to steer this post firmly back off topic, I was under the impression that most IR is absorbed by the cornea and never reaches the retina... In a way I thought IR was safer since it gives you cataracts rather than blinding you.

 

[FrothyChimp]

Near IR focuses just as well as visible light. Long IR such as 10,600nm from a CO2 is not focused by a lens and all clear structure of the eye are opaque. It thus begins burning from the surface towards the back. If the beam of a CO2 is 6mm then the damage is 6mm wide though the cornea then to the lens eventually vaporizing the vitreous humor and the back of the eye.

 

[diachi]

I thought the same thing Psuedolobster, so the IR doesnt really hit the back of your eye unless it burns its way through the cornea ?

 

[FrothyChimp]

For IR light there is a continuum. The closer the light is to visible the better it is focused by the cornea and lens of your eye so near IR will do retinal damage. As the wavelength gets longer you see effects of optical refraction and retinal damage as well as surface ablation. At far infrared you only see surface ablation. So in theory you could get retinal damage and a nice cataract from lower to mid IR laser exposure.