Posted: 9/2/2012 10:53:48 PM EDT
| I want a green laser pointer, what power level should I get for just messing around with it? |
| Be a little wary of the greenies. We got one in at work from some Hong Kong vendor. Supposed to be ~5 mW. Well, it was, in the green. But the factory had neglected to install the IR filter. We measured something like >100 mW IR coming out of this baby. Not Cool. My numbers might be a little off, but that's the gist of it. |
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If you are going to use it for regular old pointing in a classroom or something in regular light, a 1mw laser is PLENTY. 5mw is BRIGHT. Uncomfortably so, viewing diffuse reflection off of a light surface nearby. Above 5mw, two problems. One, you are entering into the "potential damage before blink reflex kicks in" territory, and two, unless you know the provenance of the laser it is hard to know whether it has adequate IR shielding. The problem with that is that green lasers are DPSS type, which means they use an infrared laser to 'pump' a second infrared laser, which is then frequency-doubled to emit green light. A lot of that high-milliwatt IR light leaking out the end of the laser is not a good thing. It is both invisible, and potentially harmful. |
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Quoted: I also saw a video of them lighting paper on fire. Wonder what power level that would require and what distance. First, that requires WAY above the minimum power to permanently lose part of your vision instantly if you even get a partial reflection accidentally sweeping your eye. Now, if you want to light paper on fire from any significant distance, I'd say look at a minimum of 500 milliwatts (1/2 watt). I have a 200 mw red laser that can pop a black balloon at a short distance and do a little very light burning/engraving on paper, cardboard, wood, and similar items. Beware, some unscrupulous sellers will rate a laser up close and without an IR filter, so it SAYS xyz milliwatts, but only a fraction of that is useable collimated laser light. The rest (in IR) spreads out rapidly, becoming useless (but still potentially harmful) after exiting the aperture. If you aren't spending as much money or more on your eye protection, and spending at least a few hours of your time reading about laser safety and how to protect yourself and others from accidental exposure, you are probably not prepared to responsibly use a higher powered laser. |