> I would expect this sort of approach to work for you unless the spectral
> lines are extremely close together.

I haven't got the wavelengths handy at the moment but I dont think they are
_that_ close
together so maybe CCD would be an option after all.

Probably have to use something more powerful than a (current) PIC to do
spectral analysis though :)

> As an after thought, have you considered trying to pass the emitted light
> through a prism, and then using a linear CCD to look at the resulting
> spectral line image?

Clever ******* :-) Thats definately worth looking into.

> The only problem I see with this approach is that you
> seem to think the light output will be that low, that filter losses will
be
> too great. If that is the case you are probably going to have to cool what
> ever detector you use to minimise the internal detector noise. The
> "standard" method on spacecraft is to use a helium pump to get close to
> absolute 0.
>  ;)

I may have to cool the detector and I am 'familiar' with helium cryogenic
pumps as featured on
shall we say .. satellites used for watching other peoples activity :)

Maybe I'll give the M.O.D research department a call and ask them if they
have a spare lying around :-) They probably
wouldn't be too obliging though. Last time I 'heard' anything they were
trying to use ultrasonic not-quite-so standing waves
to pump the helium around. Be interesting to know if they got anywhere with
that.

Thanks for the insights.

--
Jon Baker

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