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<p>[QUOTE=&quot;-jeffB, post: 1356280, member: 27832&quot;]I&#039;m going to dig in my heels as long as I can here -- a 500mW or higher laser is no longer a &quot;laser pointer&quot;. Yes, it&#039;s a laser; yes, you can hold it in your hand; yes, you can use it to point at things. But calling it a &quot;laser pointer&quot; is like calling an AK-47 a &quot;hole punch&quot;. (Yes, it can punch holes. But if you bring it into your office or classroom and use it for that, you can and should be subdued and prosecuted.)</p><p><br /></p><p>It&#039;s considered a war crime to use blinding weapons on personnel. A one-watt-range laser is a blinding weapon. As these things get cheaper and more readily available, there&#039;s going to be a rash of blindings, and there&#039;s going to be a huge backlash.</p><p><br /></p><p>But I digress. Yes, if you focus one watt of energy onto a tiny enough spot on a coin, it will affect the surface. It&#039;s going to be a challenge, though, because the coin reflects most of the light that hits it, and it rapidly conducts and disperses the heat away from the spot. With a darkly toned coin, reflectance would be reduced, and you&#039;d get more heat (and more results) with less power.</p><p><br /></p><p>If I had a one-watt laser, and hadn&#039;t yet managed to blind myself, I&#039;d surely try the experiment.</p><p><br /></p><p>I will say that a 50mW laser can sting your fingertip if you focus it down to a pinpoint, but I don&#039;t think it could cause actual burns (except to your retina). No way, no how, would it cause physical changes to a metal coin. And that&#039;s ten times the legal limit of power for a &quot;laser pointer&quot;.[/QUOTE]</p><p><br /></p>

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