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« on: April 30, 2012, 01:45:54 am »
That's one of the benefits of being able to move the thing up and down. By moving it up, I can reduce the angle needed to reach the edges of whatever I'm aiming at. I'm pulling these numbers mostly out of nowhere, but let's say I have a 30x30 cm base that I want to be able to aim at. If I have the laser sitting at 10 cm above this, then I'm going to need to hit angles up to the order of 65 degrees, which gives a pretty bad amount of spreading, by a factor of 2.4 or so. But If I raise it up to 50 cm, that cuts it down to about 25 degrees maximum, which is a much more manageable number (the spot increases by a factor of about 1.09). Over smaller distances, say a 10 cm radius circle with the apparatus centered on it, the size increase at the nearest distance is by about 1.23, with the increase at the largest being negligible. The only reason to move that close would be to do very detailed small-scale stuff.
So using the same laser you mentioned, we have a spot of about 3.6 mm in the absolute worst case, about 1.7 mm in the case with max height and greatest angle, with a range between about 1.5-1.9 in the small-area case with minimum distance. I'd say this is acceptable, though I'm not sure I actually know what I'm talking about.
For what it's worth, I wouldn't let this thing go at angles higher than 45 degrees in actual use. Too much of a risk that it would get jostled or something and end up shooting the laser across the room.