[ATM] Re: ATM Spectroscopy and fiber optic info needed

[jsgrmfg at gracemfg.com (jsgrmfg@gracemfg.com)]

    Thanks, Matt.  Fiber collimator, eh.  That's a wrinkle I hadn't
run into before.  More research needed. (sigh)

Jim Sturtevant

>Jim,
> Your first problem will be in getting the light into the fiber.  You'll
>need a lens for the fiber which will efficiently couple the light into the
>pipe.  Think in terms of trying to use a garden hose to spray water into
>the top of a distant 2 liter soda bottle.  Without a funnel, only a little
>water will get in.  With the right funnel, a lot will go in.  The coupling
>lens is that funnel.  In general such coupling lenses are extremely short
>focal lengths and are placed with micron level accuracy with respect to
the
>end of the fiber.  You can purchase collimator lens+fiber assemblies
>commercially.  Google on "fiber collimator".  Collimated correctly, your
>fiber will show a high angular sensitivity, which, I'd think, is what you
>want to be sure you are looking at just one star.

>=Matt



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