Re: [ATM] Infrared Scope Design II

[Dominic-Luc Webb <dlwebb@canit.se>]

Hi Vlad!

Well OK, now that you brought this up.... the thought of using PIRs
is not new to me. We actually do have public restrooms up here,
and I have had the opportunity to make use of these. They seem to
work, although admittedly I do not spend much time investigating
the operations of public toilets. A used toilet would certainly
make for an interesting astrophotometer you could tell your
grandkids about, and for naming this device, several descriptive
acronyms come to mind. I'll leave that as an exercise for the
original poster. PIRs are dirt cheap, and come in an assortment
of packages.

I considered parts from an old IR spectrophotometer, but in my
own lab it is about the only type of photometer we do not possess.
Few labs have these, so they are a bit scarce. New ones are
very expensive. However, I once asked about the photodiode arrays
used in one commercial UV/Vis spectrophotometer and it turned
out that the company actually offered a source for their arrays.
You could maybe ask a few companies about purchasing the detectors
or maybe even a project board. I once inquired about a kind of
specialty IR photodiode, and received 10 at no charge.


Now some of the IR specs have "DLATGS detectors". For instance:
http://www.labequip.com/itemcatalog/stkno/N610/Buck-Scientific-M500/Infrared-Spectrophotometer.html

Models of IR specs that cover a broad range of IR are equipped
with detectors something like this:

DLATGS - Middle/Far IR
MCT(Hg-Cd-Te) - Middle IR
InGaAs detector - Near IR

Options are many these days. ATMs by tradition build their own, so
we need to keep tabs on the latest detectors. I would not build one
now the way I might have 5 years ago.

Dominic


On Mon, 15 Oct 2007, Vladimir Galogaza wrote:

> Dominic,
>
> There is another type of IR sensor,  used in motion
> detecting devices like those for front door lights or surveillance.
> Sensors are piroelectric devices (PIR). They are inherently AC because
> there is output only if there is change in input radiation intensity.
> Output is proportional to first derivative of the input signal.
> Some simple references are here:
> http://www.glolab.com/pirparts/pirparts.html
>
> http://www.glolab.com/pirparts/pirmanual.PDF
>
> but there must be plenty at all levels from popular to scientific.
>
> Modern IR spectrophotometers  almost exclusively use PIR detectors,
> (single though, not imaging arrays)
> Depending on wavelength range they are available with different
> windows like KBr or CsI and different prices accordingly.
>
> Regards
> Vladimir.
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>


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