Are laser safety glasses ALWAYS needed?

[LEDbeam]

I've read the many postings where it is said that laser goggles are mandatory if you don't want to suffer any damage. But then I always read posts where people say something like, "Wow, this laser's beam is so incredibly bright!" But if the safety goggles filter out the laser's light, then they wouldn't be able to eat see the beam at all.
If someone wanted to buy a laser mainly to view the beam by aiming at at a safe location in the sky, or at a distant tree or something like that, could a person still receive eye damage from simply viewing the beam?
I'm thinking seriously of getting a Jlasers 700mw Green. Just don't want to lose my eyesight as a result.

 

[Unown (WILD)]

Well no you aren't going to go blind looking at the beam. The issue is getting hit by reflections. We over press the issue for safety because of the nature of accidents (you never know when they will happen). But if you're just aiming at the night sky (making sure there's no planes and helicopters) then sure you don't need protection. Just be smart. Think of it as a gun or weapon and you'll be okay.

 

[Encap]

Not wearing laser goggles or glasses just means that you have no ocular/eye protection if a laser accident situation occurs.
An accident is by definition not a planned event and they do happen in less time than the human blink reflex on 0.25 seconds,which means no time/not possible to correct once an accident is in progress, so use caution and be sure you know the functional behavior of the laser and all circumstances of use when taking your chances and using the laser without goggles/glasses.

It may be useful for you to understand why you see a laser "beam" at all/ever.

The fundamental reality of "beam" visibility as follows:
It is not a matter of output power or wavelength.
A "laser beam" is invisible in a vacuum regardless of wavelength or power.

Beam visibility to an observer is complicated real world phenomenon of light, eye sensitivity, and reflection from particle/aerosols in the air the details of which are not intuitively obvious.

At sea-level, one cubic inch (1 inch x 1 inch x 1 inch) (16.39 cm3) of "air" contains approximately 400 billion billion (4*1020) air molecules, each moving at about 1600 km/hr (1000 miles/hr), and colliding with other molecules and anything else they come into contact with about 5 billion times per second. This is the reason for "air pressure". The amount of particles in that air that can reflect a portion of a laser beam's light back to your eye determines if you can see it or not.

It all depends upon atmospheric conditions--a beam you can see extremely well in fog or area with high concentration of particulate matter in the air can be almost invisible in clean clear air

Laser beam visibility is highly dependent on ever changing atmospheric conditions and aerosols in the air.
You never actually see the laser beam --what you see is the reflections from particles in the air.

"It is extremely small airborne particles called aerosols having a diameter significantly less than the wavelength of the light that causes the beam to become visible.

The effect of minute particles scattering light is called Rayleigh scattering and it's most noticeable effect is to turn the daytime sky blue. Rayleigh scattering causes photons to be scattered in a roughly spherical manner around these particles. Some of the light is scattered forward (in the direction of the beam), a lesser amount is scattered to the sides and about the same amount that is scattered forward is scattered backwards towards the light source. This backwards scattering is why the beam is more visible to people standing near the astronomer using it, than people standing some distance to the side. The more of these minute particles there are in the atmosphere, the more Rayleigh scattering there is."
From :RASC Calgary Centre - The Atmosphere, Astronomy and Green Lasers http://calgary.rasc.ca/atmosphere.htm

 

[LEDbeam]

Not wearing laser goggles or glasses just means that you have no ocular/eye protection if a laser accident situation occurs.
An accident is by definition not a planned event and they do happen in less time than the human blink reflex on 0.25 seconds,which mean no time/not possible to correct once an accident is in progress, so use caution and be sure you know the functional behavior of the laser and all circumstances of use when taking your chances and using the laser without goggles/glasses.

It may be useful for you to understand why you see a laser "beam" at all/ever.

The fundamental reality of "beam" visibility as follows:
It is not a matter of output power or wavelength.
A "laser beam" is invisible in a vacuum regardless of wavelength or power.

Beam visibility to an observer is complicated real world phenomenon of light, eye sensitivity, and reflection from particle/aerosols in the air the details of which are not intuitively obvious.

At sea-level, one cubic inch (1 inch x 1 inch x 1 inch) (16.39 cm3) of "air" contains approximately 400 billion billion (4*1020) air molecules, each moving at about 1600 km/hr (1000 miles/hr), and colliding with other molecules and anything else they come into contact with about 5 billion times per second. This is the reason for "air pressure". The amount of particles in that air that can reflect a portion of a laser beam's light back to your eye determines if you can see it or not.

It all depends upon atmospheric conditions--a beam you can see extremely well in fog or area with high concentration of particulate matter in the air can be almost invisible in clean clear air

Laser beam visibility is highly dependent on ever changing atmospheric conditions and aerosols in the air.
You never actually see the laser beam --what you see is the reflections from particles in the air.

"It is extremely small airborne particles called aerosols having a diameter significantly less than the wavelength of the light that causes the beam to become visible.

The effect of minute particles scattering light is called Rayleigh scattering and it's most noticeable effect is to turn the daytime sky blue. Rayleigh scattering causes photons to be scattered in a roughly spherical manner around these particles. Some of the light is scattered forward (in the direction of the beam), a lesser amount is scattered to the sides and about the same amount that is scattered forward is scattered backwards towards the light source. This backwards scattering is why the beam is more visible to people standing near the astronomer using it, than people standing some distance to the side. The more of these minute particles there are in the atmosphere, the more Rayleigh scattering there is."
From :RASC Calgary Centre - The Atmosphere, Astronomy and Green Lasers http://calgary.rasc.ca/atmosphere.htm

I'll try to explain my understanding of this in layman's terms.
The light we see from a laser beam is light that isn't staying inside the beam and directed forward since we are seeing it off to the side, and therefore it is laser energy that is actually "escaping" the directed beam, and therefore is a danger (?)
If that's the case, then is it dangerous to view the beam from the back or sides? I'm starting to think so since particles in the air are actually reflections of the beam to our eyes? Otherwise, we wouldn't see the beam at all, correct?

 

[Blarg King]

The light you see as the "beam" is light that has been redirected out of the collimated beam by scattering off small particles in the air. AFAIK pretty much any laser you can easily get your hands on, that scattered light that you see as the beam isnt a hazard, its a tiny amount of the total energy and it isnt being focused into your eye directly.

For higher power stuff like CO2, fiber, YAG, etc, then perhaps the energy is high enough that even this scattered light could pose a hazard.

As for needing safety glasses on at all times, technically no, but in that same vein, you don't need to wear a helmet to ride a motorcycle, and if you never have an accident you'll be fine, but the one time you do get into an accident you'll probably regret not having that extra safety.

 

[kecked]

Looking at scattered light in air or fog from a handheld laser say under 1w has zero chance of harming you. Now you hit your neighbors bumper and it’s chrome and it comes back on you as a direct reflection is game over possibly. It would depend on distance and how concentrated the beam is on return. It’s like getting hit by a ricochet from a gun. That said. Back reflection from a surface like white painted wall could cause an issue in higher power laser. Stick to under 20-50mw lasers and this should be ok. Make sense? Your eye is focusing the dot it sees on your eye and if it can focus enough energy your in trouble. Hence the dot on the wall. Now if that dot is moving it is safer as the dot energy is spread out. You can and should calculate this. However just flashing your laser around outside is pure stupidity. You might accidentally hit a kid on a bike on the next street and not even know or piss offa neighbor who see the beam in their house, they are not toys.

 

[LEDbeam]

Looking at scattered light in air or fog from a handheld laser say under 1w has zero chance of harming you. Now you hit your neighbors bumper and it’s chrome and it comes back on you as a direct reflection is game over possibly. It would depend on distance and how concentrated the beam is on return. It’s like getting hit by a ricochet from a gun. That said. Back reflection from a surface like white painted wall could cause an issue in higher power laser. Stick to under 20-50mw lasers and this should be ok. Make sense? Your eye is focusing the dot it sees on your eye and if it can focus enough energy your in trouble. Hence the dot on the wall. Now if that dot is moving it is safer as the dot energy is spread out. You can and should calculate this. However just flashing your laser around outside is pure stupidity. You might accidentally hit a kid on a bike on the next street and not even know or piss offa neighbor who see the beam in their house, they are not toys.

I hear what you're saying about them not being toys. I do wonder what they're meant to be though. Not really a practical tool accept as a pointer, but then only 5mw is needed to point to things (or play with your cat) using the dot. Maybe around 50mw for pointing out astronomical objects in the sky. But beyond that, they seem to be purely recreational devices.
Either way though, I wouldn't be shining it around carelessly. Think of it like a gun; know what's beyond what you're pointing at and make sure there's a safe backstop. That way the beam stops at a known point and doesn't continue on to cause harm.

 

[LEDbeam]

The light you see as the "beam" is light that has been redirected out of the collimated beam by scattering off small particles in the air. AFAIK pretty much any laser you can easily get your hands on, that scattered light that you see as the beam isnt a hazard, its a tiny amount of the total energy and it isnt being focused into your eye directly.

For higher power stuff like CO2, fiber, YAG, etc, then perhaps the energy is high enough that even this scattered light could pose a hazard.

As for needing safety glasses on at all times, technically no, but in that same vein, you don't need to wear a helmet to ride a motorcycle, and if you never have an accident you'll be fine, but the one time you do get into an accident you'll probably regret not having that extra safety.

Makes sense. I figure that the biggest lure a laser has is the visible beam. Those who like science fiction movies featuring laser weapons are usually the ones who gravitate toward a hobby like this.

 

[Cressa]

For the most part, a rule of thumb I go by is that you should keep eyes at least 1ft away from the dot per 100mw, if not wearing protection, if shining on typical white surfaces, not mirrors. In other words, 700mw means to keep that dot like 7ft away from any eyes. The beam itself is safe to see as long as your laser isn't in the kilowatt range or more.

Shining that thing in eyes from less than like 50-100ft away can instantly cause eye damage, so don't point near humans or very reflective surfaces.

 

[RedCowboy]

Remember, mistakes happen when you least expect them and wearing your safety glasses builds a good habit that can save your eyesight.

 

[Alien Laser]

I remember once when i was testing a laser build M140 and i drop it by accident and the beam hit me in the face i was lucky i was wearing safety googles this is why i like push button hosts in case you drop it the turn off, Still it’s a Laser safety is important, Also when i shine the laser outside i check the sky for 1min making sure the are no planes around i live around mountains so at night i have a nice view i use the laser for 5/10sec and check again