Re: Help with Infrered images fron a plane

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 15 Nov 00 at 0:24, Willem-Jan Markerink wrote:

> On  6 Nov 00 at 21:06, Ing. Jose Plano wrote:
> 
> > Hi to all,
> > My name is Jose, and I planinig to take photos from an air-plane to the
> > crops, but my problem is... that I dont know how I can do it.
> > 
> > 1.- May I use a digital camera? 
> 
> Sure, compared to analog IR-film, digital is an alternative....but:
> 
> > 2.- wich is the best for it?
> > 3.- The range in IR that I wont to cover are from 0,4 to 2,8 um, there are
> > any     filters for this range?
> 
> um is micrometer, 10^-6m, while photographers mostly talk about 
> nanometers, 10^-9....and 0.4-2.8um translates to 400-2800nm....from 
> which 400-780nm isn't IR at all, only the part above 780nm....
> [as a reference, 380-780nm is the visible spectrum, 380nm on the border 
> of UV/Violet, 780nm on the border of red/IR]
> 
> However, IR-film only covers the invisible range 780-940nm (plus a 
> significant part visible below that btw), so with film you cannot solve your 
> entire problem....digital cameras go a little big higher, 
> 1000-1100nm, but you still need a thermal-camera for the spectrum 
> above that....and if my memory is correct, most thermal cameras can 
> be devided in two types, one type covering 3000-5000nm, and one 
> type covering 7000-12000nm....so you would still not see below your 
> 2800nm....I assume sensors exist for your application, but they are 
> probably much less common.

I must correct myself on most of the above words, apparently broad-band 
IR-sensors *do* exist, see a recently created text file on my homepage:

http://www.a1.nl/phomepag/markerink/thermcam.txt 
(not linked from and to /mainpage.htm yet)

--                 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand

<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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