Re: ATM amateur infrared imaging?

[Stan Kaufman <sekfmn@pacbell.net>]

> From: Frank Henriquez <frank@ucla.edu>
>
> Assuming that you have an excellent machine shop and a diffusion pump
> handy, you're looking at maybe $60K - $75K (or higher) so the dewar,
> detector and electronics.

Frank, thanks for the reality check. Now I see why this remains the realm of the professionals!

Dominic-Luc Webb molmed wrote:

> By contrast, photomultipliers can be had relatively
> cheap that can 1) do high speed pulse counting
> photometry and 2) be obtained for UV through infrared
> by use of dual PMT heads.
>
> <snip>
>
> The CCD idustry has thus far not offered any high speed
> and hi-res solution to PMT imaging and I have heard of
> physical limitations that may prevent CCDs from ever
> attaining these goals. I am sure such a CCD would not
> be cheap either. My PMT photometer is home made and
> dirt cheap.
>
> One possible future alternative may well be the
> avalanche photodiode (APD). We are presently
> investigating arrays of APD for high speed imaging
> of longer wavelengths. The ones I am familiar with
> use visible wavelengths, around 650 nm. I am not
> aware of any IR APDs. I think you could check with
> Advanced Photonics about this.
>
> Finally, I know of no one using photodiode arrays for
> spectral analysis. These are very impressive. The
> ones from the newer HP spectrophotometers can fetch
> a spectrum from 200 to 1300 nm with a 2 nm bandwidth,
> in parallel!!!! I am doubtful you ever find a CCD than
> can do this.

Dominic, thanks for the interesting ideas about use of photomultipliers and photodiodes. Don't the issues Frank raises about cooling system requirements pertain to your devices?

Perhaps the best way for amateurs to explore the IR universe will be to sit in front of their computers with a fast Internet connection and use the "Virtual Observatory" (May S&T p 20) into which the 2MASS data will go. Though is appears that one could grind lots of mirrors before it comes online...

Stan