Looking at 1 or 2 watt beams from the side

1234username · Mar 13, 2016

I want to know if safety glasses are needed if you only point a 1 watt 532 nm green laser into the sky? If you are holding the laser and then point it into the sky away from you and you only look at the beam going through the air is there danger of eye damage? how about red or blue 1 or 2 watt lasers looking at the beam from the side?

Before you respond please understand I already know to never allow the laser to go across the flight path of any possible plane. I will certainly be very careful about that.

Razako · Mar 13, 2016

Theoretically no. Only danger would be in rain/snow or if a highly reflective bug flew through the beam right in front of your face.

Isaac Clarke · Mar 13, 2016

welcome to the forum.

NightExplorer96 · Mar 13, 2016

1234username said:
I want to know if safety glasses are needed if you only point a 1 watt 532 nm green laser into the sky? If you are holding the laser and then point it into the sky away from you and you only look at the beam going through the air is there danger of eye damage? how about red or blue 1 or 2 watt lasers looking at the beam from the side?

Before you respond please understand I already know to never allow the laser to go across the flight path of any possible plane. I will certainly be very careful about that.

Wow, finally some common sense. Good on you man

-Alex

Benm · Mar 14, 2016

There is no danger with looking at beams in air, regardless of laser power really.

One issue is that with really large power you will actually break down air causing sparks in mid air to appear. This doesn't happen with continous output lasers like the diode handhelds we often use here, but a modestly sized 1064nm q-switched pulsed laser can be used to demonstrate this quite easily.

Isaac Clarke · Mar 14, 2016

that would be cool.

Pi R Squared · Mar 14, 2016

You haven't said where you're located. I would be careful about pointing lasers of that power in the sky, especially a green one, you don't want to attract unwanted attention to yourself and location. Lasers that powerful can be seen from very far away.

Alan

Eudaimonium · Mar 14, 2016

Razako said:
Theoretically no. Only danger would be in rain/snow or if a highly reflective bug flew through the beam right in front of your face.

This forum is quite obsessed with overexaggeration of safety.

Existance of this thread proves it, and annoys me.

And no, that is false. If rain or snow is falling or a bug does fly by (it never flies into the beam anyway but whatever), you are in NO danger from 2 W laser being pointed outside in the sky.

LEDbeam · Mar 14, 2016

Benm said:
There is no danger with looking at beams in air, regardless of laser power really.

One issue is that with really large power you will actually break down air causing sparks in mid air to appear. This doesn't happen with continous output lasers like the diode handhelds we often use here, but a modestly sized 1064nm q-switched pulsed laser can be used to demonstrate this quite easily.

What are those little sparks then in all the videos people have posted on youtube? I've been told that those are dust particles. But if that's what they are, and a 1W or 2W laser burns things like electrical tape so quickly, then why wouldn't a dust particle turn into a little spark?

diachi · Mar 14, 2016

LEDbeam said:
What are those little sparks then in all the videos people have posted on youtube? I've been told that those are dust particles. But if that's what they are, and a 1W or 2W laser burns things like electrical tape so quickly, then why wouldn't a dust particle turn into a little spark?

Yes, they are dust particles. Dust particles are too small/too reflective to burn though. Keep in mind the size of a dust particle relative to the beam, they are only going to be absorbing a small fraction of the power in the beam at any one time due to having such a small surface area.

With enough power and a small enough beam you could achieve the power densities required to burn dust.

I've heard stories of Laser Scopes and other such high powered YAGs zapping literally thousands of bugs - apparently you end up with a big line of dead bugs under the beam if it's buggy out.

H2Oxide · Mar 14, 2016

LEDbeam said:
What are those little sparks then in all the videos people have posted on youtube? I've been told that those are dust particles. But if that's what they are, and a 1W or 2W laser burns things like electrical tape so quickly, then why wouldn't a dust particle turn into a little spark?

Depends what you mean by sparks. If you mean the tiny reflections in a CW laser beam, then yes that's dust.

If you mean the sparks in those "hologram" videos then no, that's the air itself having its electrons stripped off and turned into plasma.

Pi R Squared · Mar 14, 2016

Yes a laser with a visible beam is a good indication of how clean your air is, try running an air cleaner with a HEPA filter in a room for awhile and then see the difference in how visible the beam is.

Many bugs are attracted to light, white light at least, I suspect that may vary with light of a single wave length, it may depend on where you are and what type of bugs, I don't believe bugs/rain/snow could be a safety hazard.

Alan

Pman · Mar 15, 2016

I'm not concerned with the reflection off of dust or snowflakes etc. either. I like beams and not dots and know my surroundings very well. Unless I am messing around trying to burn something which is not very often I don't wear my safety glasses. I wear them when appropriate. If I couldn't see beams I wouldn't be interested in this hobby.

Benm · Mar 15, 2016

Zapped bugs, dust or such and actual air breakdown are different things.

If a dust particle large enough passed through a high energy density laser beam it could catch fire, evaporate, etc. with a visible effect.

Dielectric breakdown of air does not require any of this - it will happen in totally clean, dry air just as well. It works just like a spark gap does: at some voltage differential you will get a spark between electrodes regardless of how clean the air is.

This is comparable to the limitation on how much power you can transmit from an antenna of given size before it arcs over and shorts out. For practical transmitter stations this rarely is a fundamental problem because the wavelength is, compared to light, enormous, but the fundamental limitation is still there.

LEDbeam · Mar 15, 2016

diachi said:
I've heard stories of Laser Scopes and other such high powered YAGs zapping literally thousands of bugs - apparently you end up with a big line of dead bugs under the beam if it's buggy out.

That would be cool to see!

diachi · Mar 15, 2016

LEDbeam said:
That would be cool to see!

Yeah! Unfortunately (Or fortunately?) it wasn't buggy outside the last time I was around a scope so never got the chance to experience it that part of it! Still an absolutely awesome laser to see.

Looking at 1 or 2 watt beams from the side

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