G'day Roy, Vikki, et al.
Laser beams being coherent light will diffract around thin objects;
yes light bends. A thicker a long pinhole would be needed preferably
with non specular reflecting sides. As I Read Vikki's post this
morning I experimented with a laser pointer and a business card with
a pin hole in it. Having the laser a little way away from the card
allowed me to direct a thin beam on to the curtains about 400mm (16")
away. Laser pointers need a larger diameter beam so they can be seen
on a screen; contradictory to what we require for edge and centre
finding.
Thanks to Vikki's post I looked up the MicroMark link and purchased a
LC/EF on the spot; USD19.95; it will cost me AUD40 by the time it
gets to me in Oz. Thanks Vikki!
One good turn deserves another.
Regards.
Ian
--- In 7x12minilathe@..., viajoaquin@... wrote:
I recall something about the material through which a pinhole is
made as having to be at least the same thickness as the diameter, in
order to properly "funnel" the lazer down a cylindrical hole. Maybe
drilling a precise, tiny hole through something thick, rather than
using foil, would be worth a try to clean up the dot.
Roy
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