Old 02-22-2011, 03:30 AM #1
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Default If you look at a laser dot from over 50 feet away it can still damage vision?

Just curious, I decided that having a laser that can burn rubber or pop a balloon is not really that important to me. I found some rather cheap but working laser pointers on amazon.com for roughly $25. Its a so called "100mw" laser pointer, although by an overwhelming amount of reviews I have seen on it it performs much much much less than what is advertised. One individual went as far as saying it runs like a 30mw laser. Some have said less. It is practically very false advertisement. But like I said all I want is a super long range, laser pointer that uses AAA batteries at less than $55 price.


Amazon.com: 100mW 532nm High Power Fixed Focus Green Laser Pointer Pen: Electronics



Anyways, I guess my question is if I were to use this laser to point to lets say...the side of a building that needs to get repaired, or a tree at about 3 blocks distance, and I look at where the dot is, without protective eye wear, can it still permanently damage my vision?

I have read reviews saying professors use it in lecture halls...wouldn't this mean that these students could sue the professors for permanently blinding them for looking where he is pointing?

Or am I not really getting this "danger at looking at where the dot is" to well?

If anyone can explain that would be great, Thanks.


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Old 02-22-2011, 04:17 AM #2
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Default Re: If you look at a laser dot from over 50 feet away it can still damage vision?

Hello, alazar14. The first question you need to ask is 'why do you need a pointer'? if you need it for pointing something far (a building that needs repair) you don't need a VERY strong one. 100mW can burn and is somehow dangerous to the eye..

What you are going to use the laser pointer?
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Old 02-22-2011, 05:24 AM #3
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Default Re: If you look at a laser dot from over 50 feet away it can still damage vision?

With most average handheld lasers, after about 5 meters, the laser dot is not much of a vision safety issue BUT it can still be quite bright and will become dangerous if viewed at closer ranges. The main issue with lasers and especially handhelds is a beam reflected off something back at the eye or worst yet, a direct hit in the eye. You'd be amazed at how much light a powerful laser will bounce off a white surface. Outside and used at range this is less of an issue, reflecting surfaces are usually further away. Most pointers made for actual pointer use (lecture) are <5mW. These are relatively safe when it comes to reflections but would still be very dangerous in a direct eye hit situation.

If your looking for a bright beam, go with green. Green is near the peak of human eye sensitivity. If your looking for distance, IIRC red light scatters less and will travel further.
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Old 02-22-2011, 05:41 AM #4
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Default Re: If you look at a laser dot from over 50 feet away it can still damage vision?

Somewhere was safe distance calculator. It calculating from power and divergenece.
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Old 02-22-2011, 05:46 AM #5
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Default Re: If you look at a laser dot from over 50 feet away it can still damage vision?

Always remember someone may be down range, and also, if you hit a mirror or high reflective surface, it's a whole other issue, but No, the dot at a distance will not hurt your eyes when the output is typical such as <500mW and the distance is >50 feet and nothing is more reflective than say an eggshell white painted surface that is not glassy smooth...
Beware the glass sphere coated signs, street signs , painted street lines and car license plates these can reflect a lot of light -Glenn
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Old 02-22-2011, 01:38 PM #6
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Default Re: If you look at a laser dot from over 50 feet away it can still damage vision?

IT DEPENDS ON THE CLASS AND ON THE WAVELENGTH of the laser. You will not get the same results with a Class IV 532nm and with a Class IIIB 660nm.
Oh well, what glenn said. Just beware with mirrors, signs, etc, everything that can reflect the light back at you. Try with a flashlight;
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