Laser Use with Goggles

[tomcat017]

Hey Everyone,

Well--I'm really new to the lasers section here. But I've been reading tons of threads, trying to learn as much as I can. I'm a bit confused about one thing, and wanted to ask how everyone here works it. I read several threads noting that you should wear laser goggles with anything > 10mw. On the other hand, I've seen videos and pictures with the people in them not wearing any goggles (even with lasers at 200mW+). I know that certian situations (like pointing in the sky) are far less dangerous than others (say, pointing in a room). But when should you wear goggles, and when can you not? I'm thinking about possibly looking into buying a 300mW laser on of these days (maybe a year or some from now, once I know more about them)--but can you enjoy using it if you can't see it, b/c you have the goggles on? Anyway...sorry for the long newbish question. Just curious to hear everyones responses.

 

[Aseras]

goggles are a safety precaution. as such there's a risk involved that you mitigate when you wear them. with the correct safety goggles on, there's NO risk at all with a laser ( unless you have some monster laser that would probably burn a hole through your head just as fast as your eye ). Goggles also have the downside of making your laser not look like anything. you wont even know it's on until you can find the dot. the bad side of this is once you are wearing goggles and are invincible, everyone else who might stumble onto you isn't, so you have to make sure noone else can do that without proper protections. That means signs, locked doors etc.

Now without glasses, lasers look cool. with the right precautions you can use a laser without protection, provided you control the laser ( fixed mount ) it's beam path and environment. That means keeping yourself and anyone else out of direct contract with the beam or reflections.

The other thing to keep in mind is that the higher the power, the greater the chance from damage from an accident. generally your dot or reflections are diffuse and scattered and those are usually safe to look at provided you are far enough ( several feet ) away. The closer you get or the brighter you are, the more light is going into your eye. if the surface is highly reflective, there's a chance that the beam won't scatter and instead could come right back at full power, or even become focused and do some real damage.. at the speed of light. the flick of the wrist, a flash, and with a high enough powered laser, you just got a blind spot quicker than you can blink.

 

[tomcat017]

Thanks for the reply aseras--I'll keep reading posts, and will try to get a feeling about when it is a reasonable situation to use your laser without goggles, and when they should be on (I imagine, most situations), as well as what power lasers present which level of risk. If anyone has any input to share, I'd love to know. Otherwise, I'll keep my eye on new threads, like I said. Thanks again for the info!

 

[nc987]

Can someone tell me about the damages of bouncing a laser off the ceiling. Is it dangerous if your not looking at the beam just the general green glow that covers the room? What i mean is your not looking at the source or the spot on the wall, just using it to light up a room?

 

[Aseras]

if it's a diffuse reflection ( the light is being scattered, like a dot on drywall or some other rough surface ) it's safe to look at, provided you are not too close ( the light needs to scatter, the further away you are the safer it is )

Once the light is no longer a beam, it's not concentrated and not dangerous. a Laser's power is in it's coherency. once you let it "splash" into something the light scatters and it's not longer coherent ( a beam ) and then it just becomes monchromatic light( one color).

what you worry about is smooth surfaces or anything that can cast a reflection, liquids, metals, highly polished anything- wood, plastic, glass, cermaics etc.. those are dangerous because they can reflect the beam.

 

[tomcat017]

So viewing the dot on a white wall from >10 feet away would be OK? Or having it diffuse from a balloon surface or match head? What about some of the pictures that people post here, of the "tunnel effect" etc. I'm not sure how that is created, but is that a safe thing to view?

 

[Kenom]

it is as long as there is no large amounts of IR leakage and you don't shoot the thing in your eye as you pass into the circle

 

[allthatwhichis]

What about some of the pictures that people post here, of the "tunnel effect" etc. I'm not sure how that is created, but is that a safe thing to view?

A tunnel effect is usually created with a spinning mirror causing the laser to "draw" a circle. The picture is done by placing a camera inside the circle and pointing it towards the "start" of the tunnel or at the mirror which is reflecting the laser. When "I" take a tunnel picture, I only set the camera in the circle and take the picture, not me and the camera. I do not hold the camera up to my face while "in" the tunnel to take the picture.

Now, being inside the tunnel is the best place to view the tunnel, but it is also the most dangerous and is not suggested, hence the pictures. Getting in and out of it are the real dangerous spots, but also if you happen to stick your head inside it and the fan with your mirror on it stops... you will probably end up in the beam's path...

 

[SenKat]

The first tunnel video I did had it aimed right at the camera, and since I was holding the spinning mirror, I was in complete control of it.

There is a real need for goggles at powers abouve 5mw - Although it is uber bright, as long as you don't stare into the beam, you will most likely be okay - no IR is a valid point, too - you gotta do your homework, and ensure you are get as pure a source of green as possible !

 

[Aseras]

So viewing the dot on a white wall from >10 feet away would be OK? Or having it diffuse from a balloon surface or match head? What about some of the pictures that people post here, of the "tunnel effect" etc. I'm not sure how that is created, but is that a safe thing to view?

As long as it's a diffuse reflection, you should know if it's too bright or not. If you see spots afterwards, it's too bright, if it hurts or you blink, it's too bright. it's totally dependent on the brightness of your laser and the surface reflectivity. gloss paint would be a danger in my opinion. flat paint, and the darker is better. the color of the surface also matters, white reflects very well, darker color absorb more. i can look at the dot of my rpl 260 on a black pice of foam all day, but i can't look at it at all against white drywall, even 100feet away the "dot" is still very bright.

 

[flashlightpoor]

the simple answer is high power lasers require goggles. But goggles either reduce the intensity of light or block it completely. no fun if your intent is to see your beam. everything that everyone has said is essentially true. staring at a bright spot isn't good and a direct hit or even a reflection (from a high power source) is bad. here's the thing though. You pick a spot on the wall you want to shine your laser at. it is a matte surface with nothing that can reflect a beam back at you. it is fine. but if you try to set up a special effect or you go looking for something to shine your beam on, you are going to accidentally shine on something reflective or make a mistake and get a reflection. it happens to everyone and is why people who use lasers wear goggle. the odds are you won't catch this in the eye and most reflections are only a fraction of the incident power. but, if you are unlucky and you catch a high power bounce you will put your eye kid.
as an example in my lab we wear goggles with anything over 10mWs. but how do you align a long set of optics if you can't see the laser? it is a catch 22. if we can, such as the case with a yag we run it at very low power and do not wear goggles. if we can't run it at low power we use an alignment beam which is usually a 5 mw red laser.
also, you mention a 300mW laser. that's serious business.