[GRLUG] OFF TOPIC - Speaking of Infrared...

[john-thomas richards]

On Thu, Jan 28, 2010 at 06:03:26PM -0500, Michael Mol wrote:
> On 1/28/2010 4:18 PM, Benjamin Flanders wrote:
> > I think there are different wavelengths for IR.  What this simple
> > camera trick will show is hi-frequency IR not the low frequency IR
> > emanating from warm objects.  You would be able to see in the dark
> > with this and an ir l.e.d. but you wouldn't have predator vision.
> 
> Warm objects emit some energy on a large range of wavelengths, 
> approximating* the blackbody curve, including both near-IR and far-IR 
> frequencies.
> 
> The chief problem with "darkvision" as it applies to passive near-IR is 
> that there is a lot of ambient near-IR radiation that's not related to 
> warm bodies.
> 
> In short, your warm body radiation in the near-IR will be there, but 
> largely drowned out by the ambient near-IR radiation.**
> 
> * I'll avoid going into a discussion of emissivity changing things away 
> from the ideal curve.
> 
> ** I'll also avoid going into a discussion of how thermovision cameras 
> work, unless people actually want to hear...

Seriously?  Wow.  You are conversant in more technical fields than I
could *list*.
-- 
john-thomas
------
How much easier it is to be generous than just! Men are sometimes
bountiful who are not honest.
Junius, pseudonym of the unknown author of a series of letters published
in a London newspaper during 1769-1772