Lab Reflects Mirror Technology

[Robb]

...and, of course, we're talking about the kind that point down....

http://www.af.mil/stories/story.asp?storyID=123005444

8/18/2003Ê-ÊKIRTLAND AIR FORCE BASE, N.M. (AFPN)Ê--ÊA milestone in telescope-mirror technology, completed recently by Air Force scientists here, is leading to lightweight, space-based telescopes much larger than NASA's Hubble Space Telescope.

Rather than use a heavy, glass mirror, researchers at the Air Force Research LaboratoryÕs directed energy directorate were able to produce a 1-meter-diameter (about 3.25-feet) mirror, made of a thin-film membrane material....

(snip)

ÒOur goal is to produce a telescope mirror with a diameter of 10 meters, or nearly 33 feet,Ó said 2nd Lt. Ethan Holt, the film mirror project officer in the directorateÕs surveillance technologies branch. ÒA surveillance telescope that size in orbit 124 miles over the earth would really improve our ability to image enemy and friendly assets and capabilities.Ó

(snip)

Large space-based telescopes could also be used to focus the energy from lasers, another potential application for this technology, officials said.
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Robb's comments:

a) Thinking about the CORONA satellite, the objective was about five inches, and could resolve (IIRC) 80 cm at orbital altitude. This is, obviously, what we call "a damn sight bigger".

b) The Directed Energy Directorate funds the thing, and calls focusing energy from lasers a "potential application"? Gimme a break. :eyes:

[Salviati]

1. Yikes!

So, the formula for determining the diffraction limit for a mirror or lens is theta = 1.22 Lambda/diameter, where theta is the angular resolution, lambda is the observed wavelength, and the diameter is the size of the mirror/lens.

Plugging your numbers from above into the formula, you can predict an orbital altitude of 150 km for the CORONA satellite, which is in the ballpark of what it is reported to have been, so it seems as if the numbers work out...

Plugging in the 10 meter mirror, along with 550 nanometer light (smack dab in the middle of the visible range), along with the 150 km orbit, we get a diffraction limit on the resolution of 0.01 m. That's 1 centemeter! Now, there are a lot of other things that are going to make the resolution worse than this limit, air turbulance, thermal fluctuations in the atmosphere, and such, but this still gives a pretty telling ballpark figure for the resolution of this mirror...

[librechik]

2. let's boost it into orbit and see what it does

we'll be watching tv screens in the living rooms of Epsilon Eridani! Damn, it's another Lucy repeat.

[TreasonousBastard]

3. A theoretical resolution of 1cm...

and computer enhancement to possibly even exceed that.

Why not an array of these things to make a microscope? Shit, it's only money, and who cares about that when "security' is at stake?

Focusing laser or other energy beams that tightly does have some interesting possibilites...

Damn, I want one!

[LifeDuringWartime]

4. i wish theyd use this kind of stuff for useful technology

like taking cool pictures of deep space..... not us :(