[hackspacebristol] Contact: Laser Cutter

Tom Gardner tggzzz+hs at gmail.com
Sun Apr 14 15:22:18 UTC 2013

Dominic Morrow wrote:

The window in the top of the laser is more than adequate for defusing the
very week and focused beam of our 40w laser.

That statement worries me.

Firstly, the 35W (or 40W) beam most certainly is *not* "very weak" [1].
Whatever gave you that idea?

Any laser over 500mW (i.e. *only 1.5%* of that beam's strength) is a Class
4 laser that "may be hazardous to the eye and skin *even after diffuse
reflection*". My emphasis, from wackypedia entry on laser safety.

Secondly, what makes you think that the window would significantly diffuse
the beam?

If you can see an image through the window then the window is demonstrably *
not* diffusing light!

 Operating it with the lid up is a no no and not possible anyway without
defeating the magnetic safety switch.

I would be gobsmacked if that was a possibility.

[1] Although only indirectly relevant to this discussion, an illustration
of the differences between laser and ordinary light is shown by the recent
cases of people shining laser pointers at aircraft from several kilometres
away and temporarily blinding pilots. In one case in which the perp was
jailed for 2 years, the pointer power output was 3mW (and that's not mega
watts! :)
Our laser is 10000 times stronger and at 1/1000th the range
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