Re: [ATM] Spectroscopy and fiber optic info needed

["Bob May" <bobmay@nethere.com>]

Fiber optics is used for a lot of different things and thus, there are a lot
of different versions of the stuff.
Pretty much you can leave the plastic fibers alone as they are more intended
for consumer stuff where the light loss isn't important but price really is.
The multiple strand stuff is more to get a large area source than anythign
else.
The rest of the field goes into whether it is broadband or not.
Since you are doing spectroscopy, that means that you want a wideband fiber.
As to the light coming out, it will be modified by the transmission
attenuation of the fiber but at a few yards, this won't be much except at
the edge of the transmission band of the fiber.
I'll note that the fibers are available in a lot of diameters and this can
deal with the resolution of the instrument to pick up any particular spot in
the image of the telescope.  The position information is, of course,
scrambled at the output as there is no focusing and refocusing of the image
as it goes down the fiber thus you can use a large fiber and capture a
single star with that fiber in just a small part of the input side and yet
the output side will be a fairly even illumination of the fiber exit beam.
As to telling where the star is on the fiber, the only thing that you can do
is to observe the output of the fiber and when the light is max, the star is
best aligned on the end of the fiber.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net