an "invisible" artifical star?

Since a webcam without the IR filter is sensitive to IR, why couldn't I use
an IR light source to illuminate an artificial star. Such a system wouldn't
disturb the neighbors as the beam would be invisible to the eye, and I could
continue collimation as I always do with the webcam/ barlow combo.
Thoughts?

JJ

On Tue, 12 Apr 2005 16:02:14 GMT, "John J Brown"
wrote:

Since a webcam without the IR filter is sensitive to IR, why couldn't I use
an IR light source to illuminate an artificial star. Such a system wouldn't
disturb the neighbors as the beam would be invisible to the eye, and I could
continue collimation as I always do with the webcam/ barlow combo.
Thoughts?

You could do that. But I can't see how any artificial star system should
bother your neighbors, visible or otherwise. An advantage of the visible
system is that you can still aim and focus through an eyepiece if you
want. And if you are doing this at night, you are better off using a
real star.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

An artificial star is more used to test optics than to collimate them.
In addition, if you do the artificial star right, the light from it only
goes out in a small beam from the source to the telescope. Finally, the
light level will be on the order of a neon indicator light (uW of power)
such as used for nightlights that shouldn't affect anybody in the area.

--
Why isn't there an Ozone Hole at the NORTH Pole?