3 ms·

If it's bright enough to be visible, it's bright enough to cause damage.

by maaku 15y ago

Natsu 15y ago
Not true. Lasers are just light. They can be dangerous because they can focus a lot of energy on a small area, and are actually more dangerous when you cannot see them, but if they're weak enough, you can, in fact, stare directly into the laser with no eye damage. I have done this as a demonstration. Granted, I was using a weak laser pointer I knew to be safe and I'd never do that for a powerful or unknown laser, but that particular one I used wasn't any worse than staring at an ordinary light bulb. I should mention that there are "laser pointers" strong enough to be dangerous (e.g. the ones that can pop balloons or be seen from X miles away and whatnot). The one I used was not one of those and I knew that the wattage was low enough to be safe. And I have the eye doctor take pictures of my (very healthy) retinas during screenings, so I'm reasonably sure there was no hidden damage.
- Klinky 15y ago
  Like you alluded to, but I think it's good to be specific, dim != weak[1]. There could be a lot of infrared coming out of a cheap laser device you cannot see. Obviously no one should do your demonstration unless they have the laser device fully vetted by someone who knows what they're doing. What was the milliwattage of the laser in your demo? I imagine 5 - 10mw is too dangerous, so it must have been really low power. [1] http://www.wired.com/wiredscience/2010/08/laser-pointer-hazard/ http://www.wired.com/wiredscience/2010/08/laser-pointer-haza...
  - Natsu 15y ago
    That's a very good point. It was a long time ago, so they used the old system back then and labeled it as a class IIa: https://en.wikipedia.org/wiki/Laser_safety https://en.wikipedia.org/wiki/Laser_safety I don't remember a wattage offhand and I no longer have that laser pointer, but I think it was under 1 mw. But there are other safety factors that can come into play, too. Mostly, it's a matter of how much energy is focused onto how small of an area for how long, not to mention how much of that energy is visible, which is why it's good to know the safety classifications. There are dangerous lasers, after all and it's a bad idea to be cavalier about eye safety around those. In fact, I saw some just the other day in operation at MakerBench, where they were cutting plastic. The paper covering the plastic was getting set on fire... not something you want shining into your eyes. EDIT: Reading your article scares me a little. I had a laser from a reputable supplier with an accurate classification. If they're selling crap with no filters like that nowadays, that's a lot more worrisome. People might own a laser that's a lot more dangerous than it's marked as being. Some lasers, especially cheap, "dim" green ones may not be what they're marked as. If it's cheap and not red, it's probably frequency doubled IR, so, yeah, beware....

If it's bright enough to be visible, it's bright enough to cause damage.

by maaku 15y ago

If it's bright enough to be visible, it's bright enough to cause damage.

Natsu 15y ago

Not true. Lasers are just light. They can be dangerous because they can focus a lot of energy on a small area, and are actually more dangerous when you cannot see them, but if they're weak enough, you can, in fact, stare directly into the laser with no eye damage. I have done this as a demonstration. Granted, I was using a weak laser pointer I knew to be safe and I'd never do that for a powerful or unknown laser, but that particular one I used wasn't any worse than staring at an ordinary light bulb. I should mention that there are "laser pointers" strong enough to be dangerous (e.g. the ones that can pop balloons or be seen from X miles away and whatnot). The one I used was not one of those and I knew that the wattage was low enough to be safe. And I have the eye doctor take pictures of my (very healthy) retinas during screenings, so I'm reasonably sure there was no hidden damage.

Klinky 15y ago
Like you alluded to, but I think it's good to be specific, dim != weak[1]. There could be a lot of infrared coming out of a cheap laser device you cannot see. Obviously no one should do your demonstration unless they have the laser device fully vetted by someone who knows what they're doing. What was the milliwattage of the laser in your demo? I imagine 5 - 10mw is too dangerous, so it must have been really low power. [1] http://www.wired.com/wiredscience/2010/08/laser-pointer-hazard/ http://www.wired.com/wiredscience/2010/08/laser-pointer-haza...
- Natsu 15y ago
  That's a very good point. It was a long time ago, so they used the old system back then and labeled it as a class IIa: https://en.wikipedia.org/wiki/Laser_safety https://en.wikipedia.org/wiki/Laser_safety I don't remember a wattage offhand and I no longer have that laser pointer, but I think it was under 1 mw. But there are other safety factors that can come into play, too. Mostly, it's a matter of how much energy is focused onto how small of an area for how long, not to mention how much of that energy is visible, which is why it's good to know the safety classifications. There are dangerous lasers, after all and it's a bad idea to be cavalier about eye safety around those. In fact, I saw some just the other day in operation at MakerBench, where they were cutting plastic. The paper covering the plastic was getting set on fire... not something you want shining into your eyes. EDIT: Reading your article scares me a little. I had a laser from a reputable supplier with an accurate classification. If they're selling crap with no filters like that nowadays, that's a lot more worrisome. People might own a laser that's a lot more dangerous than it's marked as being. Some lasers, especially cheap, "dim" green ones may not be what they're marked as. If it's cheap and not red, it's probably frequency doubled IR, so, yeah, beware....