On Mon, 13 Jan 2003, Bob Ammerman wrote:

*>What you want to do is not to *focus* the beam, but rather to "collimate
*>it". A focused beam comes together at a single point because all the 'rays'
*>are angled together. The rays in a collimated beam are all parallel to one
*>another.
*>
*>With a collimated beam you could have multiple apertures to get different
*>line widths/pad shapes, very much like the old photoplotters.

I think that for that you want to focus the image of the aperture on the
target. You also want to iris the beam in the optics so there is enough
depth of field to avoid focus problems. This will use up some light (so
you get to use a bigger lamp). I do not know what you mean by collimation.

Peter

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