"Capt. Rob" wrote in message
oups.com...
The Celestron
had special optical coatings to maintain the same focal length
regardless of
wavelength. The multispectral imaging is superb!



Coatings? To maintain the FL????

Yes, it's been used in spacecraft optics for years. As you must well know IR
has a different focal point than visible light through optical glass,
because of the difference in indices of refraction. Coatings can compensate
for this.

Don't believe me?

Here's a design of a hyperspectral imaging space based telescope, over 10
years old. See for yourself:

http://techdigest.jhuapl.edu/td1702/hefernan.pdf