Spectral samples at a distance- how do you tell what you're sampling?

[Shannon Dosemagen]

In Louisiana we're interested in using the spectrometer to look at smokestacks from chemical plants/refineries and other potential "samples" that are at a distance, such as an oil slick in the water from an airplane. Thus far, I've only used the spectrometer to look at close-up samples, but when talking to Scott Eustis, the question came up how we would actually know what we are sampling from a distance? Thoughts?

[Eyal Saiet]

Hello,

This idea is applied today in instruments e.g DOAS (Deferential Optical Absorption spectroscopy).

What is done is choosing  a window of interest say 335-345nm  acounting for the absortion cross section for the specices likely to be present. 

This is described in the  following paper:

http://hal-insu.archives-ouvertes.fr/hal-00295394/

This technique is great for molecules like not aerosols that have various absorption cross sections based on the conglomeration stuff..

Eyal  

On Mon, Apr 30, 2012 at 1:26 PM, Shannon Dosemagen <shannon....@gmail.com> wrote:

In Louisiana we're interested in using the spectrometer to look at smokestacks from chemical plants/refineries and other potential "samples" that are at a distance, such as an oil slick in the water from an airplane. Thus far, I've only used the spectrometer to look at close-up samples, but when talking to Scott Eustis, the question came up how we would actually know what we are sampling from a distance? Thoughts?

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Eyal Saiet

[Adam Griffith]

That's great info, Eyal.  Do you know what sort of spectral resolution in required?  That is a fairly narrow window there of only 10 nm.

Adam

Adam Griffith
Director of Science and Coastal Environments
publiclaboratory.org
828.321.2326

[Jeffrey Warren]

I think this may be a more basic question than Eyal is reading into it -- basically, it's like a gun sight -- how do you know you're aiming at the right spot if you're 200 yards away? or a mile away?

I put up some sketches and ideas here: http://publiclaboratory.org/notes/warren/5-1-2012/spectrometer-alignment-ideas

based on looking through a drinking straw, carefully watching the overall brightness in the Spectral Workbench client software, and noting when you pass the spectrometer across a distant bright light.

i think we just have to try it out and see if something like this can work!

jeff