Did I damage my retina by looking at a "DJ" laser projector?

Throckmorton

Lifer
Aug 23, 2007
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I went to an "intergalactic masquerade" last night and at the entrance they had a laser projector shooting at people coming in. On the way out we were taking pictures and I accidentally looked at the emitter. It was only for a split second and I looked away immediately. The after image was about the same that you'd get from looking at headlights and only lasted a second-- much less than from a camera flash. Is that any indication of the radiation intensity that hits your retina?

The light coming out wasn't just straight laser beams, but was going through some kind of prisms to create a star effect, and the projections were moving. The unit was about the size of an external hard drive... I should have thought to look at the model. But I assume these things come in standardized wattages.

Should I be worried?
 
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CycloWizard

Lifer
Sep 10, 2001
12,348
1
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It's probably low-intensity, and it's visible light rather than IR, so you're probably OK. Such devices are pretty heavily regulated, so anything other than relatively long exposure won't hurt you. The temporary loss of vision is exactly like looking into headlights as your photoreceptors are all temporarily saturated, but it comes back quickly as the isomerization process is reversed.
 

Murloc

Diamond Member
Jun 24, 2008
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it would be forbidden to use in such manner if it was dangerous. I mean, they were pointing it at people.
 

Rubycon

Madame President
Aug 10, 2005
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Nope. Those beams move very fast and most DJ units aren't even Class IV (>499mW TOTAL) power. Even still scanning the audience as it's called isn't wise and in some areas is against the rules.

More than likely it was a bright flash that can cause a temporary shift in your dark adaption not much different than say a flash from sunlight bouncing off a window temporarily.

If real damage was apparent you may have "holes" or spots in your vision but this takes a much higher power single beam moving much slower. Fans and tunnels won't do this and the larger displays using 10-50W+ power should NEVER come near the heads of patrons!
 

Throckmorton

Lifer
Aug 23, 2007
16,830
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I went to the optometrist and got retina photos. I've needed to get it done anyway since I skipped it when I did my last eye exam. No inflammation or damage at all on my macules
 

Modelworks

Lifer
Feb 22, 2007
16,240
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Good to hear you are okay. People tend to not realize the damage lasers can do. I see kids playing with laser pointers often and some of them are getting pretty high in the power range. There are also some LED out now that are narrow beam, under 15 degrees and output 15000mcd. I glanced at one of them and saw spots for about 15 seconds after, can't imagine the harm from someone staring into one.

The EU places LED in with lasers on determining eye damage but the USA considers all LED safe.
 

Throckmorton

Lifer
Aug 23, 2007
16,830
3
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0.5W and higher LED flashlights usually have a warning not to stare at the beam.

I'm guessing the difference between an LED and an incandescent is that all the light comes from the emitter directly, while with an incandescent most of it is coming off the reflector, so your eye sees the same amount of light from a much larger spot
 
May 11, 2008
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0.5W and higher LED flashlights usually have a warning not to stare at the beam.

I'm guessing the difference between an LED and an incandescent is that all the light comes from the emitter directly, while with an incandescent most of it is coming off the reflector, so your eye sees the same amount of light from a much larger spot

It has also to do with phase coherency of light.
Light from an incandescent has a wider spectrum. Light from a led is a lot more narrow spectrum, almost one frequency or wavelength. And if i remember correctly, when seen as particles for simplification, the photons come out of the led at a regular pace. At the right situation this could cause some resonance effect. Similar as when a group of soldiers walk over a bridge at the same pace. Those electrons keep getting excited, long enough to do damage to the overall molecular structure.
I do not know what happens into detail, though.


For those interested, here is a pdf that explains the history and the accidental discovery of leds.

http://assets.cambridge.org/97805218/23302/excerpt/9780521823302_excerpt.pdf


Good to hear you are okay. People tend to not realize the damage lasers can do. I see kids playing with laser pointers often and some of them are getting pretty high in the power range. There are also some LED out now that are narrow beam, under 15 degrees and output 15000mcd. I glanced at one of them and saw spots for about 15 seconds after, can't imagine the harm from someone staring into one.

The EU places LED in with lasers on determining eye damage but the USA considers all LED safe.

That has to do with the same phase coherency aspect i think.

I have looked at a wall when a LED light panel for a stadium was shining on a sort of non reflective gypsum plaster wall. Even the reflective light was to bright to look into without wearing sunglasses.
 

Throckmorton

Lifer
Aug 23, 2007
16,830
3
0
Bumping this thread because I was wondering about other lasers-- the IR ones on mouse like the Logitech G9. What kind of power do they put out, and can the IR be focused by your eye? Logitech used to say their mice were eye safe Class I lasers, I remember this from the packaging for my MX610. But they don't say anything about their current mice.

The reason I wonder about the IR mouse lasers is that I was cleaning the underside of my G9 and saw the laser flash red for a split second, like you sometimes see IR camera lamps. I don't think I was looking directly at it though.
 

oynaz

Platinum Member
May 14, 2003
2,448
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Consumer lasers are safe. You have to delibately stare at them for a long time to do any kind of damage.
 

Throckmorton

Lifer
Aug 23, 2007
16,830
3
0
Consumer lasers are safe. You have to delibately stare at them for a long time to do any kind of damage.

That's not true. Laser pointers are considered safe because the blink response is supposed to close your eye in about 0.25 seconds. Would you consider 0.5 or 1.0 seconds staring for a long time?
 

oynaz

Platinum Member
May 14, 2003
2,448
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Yes. Bright light hurts your eyes, and you need to force yourself to keep them open. Considering this, 1 second is a long time.

And I doubt you damage your eyes by staring at a laser pointer for a single second anyway. Source?
 

Joseph F

Diamond Member
Jul 12, 2010
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Nope. Those beams move very fast and most DJ units aren't even Class IV (>499mW TOTAL) power. Even still scanning the audience as it's called isn't wise and in some areas is against the rules.

More than likely it was a bright flash that can cause a temporary shift in your dark adaption not much different than say a flash from sunlight bouncing off a window temporarily.

If real damage was apparent you may have "holes" or spots in your vision but this takes a much higher power single beam moving much slower. Fans and tunnels won't do this and the larger displays using 10-50W+ power should NEVER come near the heads of patrons!

Dude, if you're talking about a straight beam then even an entry level class IV would burn the living #@$ out of anything in its path, wouldn't it?
 

Rubycon

Madame President
Aug 10, 2005
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Dude, if you're talking about a straight beam then even an entry level class IV would burn the living #@$ out of anything in its path, wouldn't it?

Class IV begins at 1/2W. Yes this is high enough to do damage but certainly no death ray. I've had my back to a 60W DPSS system scanning and could feel its warmth on my neck similar to sunlight at low latitudes. If the beam (it was about 20cm thick) were to stop, that would probably hurt like getting poked with a copper pipe that was just taken away from a torch. 60W sounds like a lot of power but when you fan it out with hundreds of "threads" over a stage it's needed in order to create the "beam show" that everyone loves.

There are people building 2W 445nm diode lasers from parts extracted from projectors. I have one myself. :) Focused down infinitely its power is stunning at the beam's waist. Despite having 1.5 watts (verified) out the front it's no death ray. Of course that's no excuse to NOT treat it like a real weapon either. At that power a reflection into the eye even briefly can cause non healing damage.

There's plenty of videos showing these (portable lasers) doing various things on youtube.
 

WhoBeDaPlaya

Diamond Member
Sep 15, 2000
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Glad to hear you're alright OP. I work in a lab with both fiber and free-space optics; retina snapshots are mandatory.
 

Specop 007

Diamond Member
Jan 31, 2005
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Good to hear you are okay. People tend to not realize the damage lasers can do. I see kids playing with laser pointers often and some of them are getting pretty high in the power range. There are also some LED out now that are narrow beam, under 15 degrees and output 15000mcd. I glanced at one of them and saw spots for about 15 seconds after, can't imagine the harm from someone staring into one.

The EU places LED in with lasers on determining eye damage but the USA considers all LED safe.

The really dangerous ones are the IR lasers. No blink reaction, you burn up your eyes and dont even know it.
 

Rubycon

Madame President
Aug 10, 2005
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The really dangerous ones are the IR lasers. No blink reaction, you burn up your eyes and dont even know it.

Blink reaction will only protect your vision at powers under 5mW. This is the threshold of Class IIIb lasers. In reality the actual laser power is probably closer to 50mW or even higher as rarely if ever does 100% of the collimated beam energy enter the eye. If it does, it's intentional.

In the entertainment industry no IR lasers are used however DPSS lasers if used incorrectly can have a mix of dangerous IR (808 and 1064nm) within the primary beam. (532nm).