Proposed Telescope Focuses Light Without Mirror Or Lens 165
A team of scientists from Observatoire Midi Pyrénées in Toulouse, France have been working with an unusual technique for focusing light. It takes advantage of diffraction - the bending of waves when they encounter an obstacle in their path - to focus light as it passes through a foil sheet with precise holes in it. The scientists suggest that an orbital 30-meter imager could resolve planets the size of Earth within 30 light-years. In addition, the foil is much lighter than traditional materials, and thus easier to transport.
"A Fresnel imager with a sheet of a given size has vision just as sharp as a traditional telescope with a mirror of the same size, though it collects just 10% or so of the light. It can also observe in the ultraviolet and infrared, in addition to visible light. The imager can take very detailed images with high contrast, which is great for 'being able to see a very faint object in the close vicinity of a bright one.'"
Will they build it. (Score:2, Insightful)
ok... (Score:5, Insightful)
Make a sphere with a central axis. Place the fresnel lens on the surface of the sphere. Rotate the sphere about the center (where the focal point is.) No more formation flying, etc. Since you don't need any part of the sphere but the place where the fresnel lens is, just create a radius - lens at one end, focal point at the other end. Use a track to adjust the focal point distance from the foil. Rotate the entire assembly to re-point. No formation flying. Precision alignment all the time. Slow adjustment means good fuel economy.
It seems to me that this is a great excuse for a foil-making plant in space. Imagine a veewwwwy large foil sheet. Then think of the available resolution. This is better than a dispersed array.
Well, one can hope. :-)
Much more fragile than a sail (Score:2, Insightful)
Re:Will they build it. (Score:2, Insightful)
Re:Not for amateurs... (Score:3, Insightful)
I don't know how this would be dealt with, but it's a bit of a potential stumbling block. (well, that and getting a thin, light, high precision piece of anything into orbit without damaging it)
Re:Not for amateurs... (Score:3, Insightful)
Not an astronomer... yet.
-l