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## Gamma-Ray Bending Opens New Door For Optics65

sciencehabit writes "Lenses are a part of everyday life—they help us focus on words on a page, the light from stars, and the tiniest details of microorganisms. But making a lens for highly energetic light known as gamma rays had been thought impossible. Now, physicists have created such a lens, and they believe it will open up a new field of gamma-ray optics for medical imaging, detecting illicit nuclear material, and getting rid of nuclear waste."
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## Gamma-Ray Bending Opens New Door For Optics

• #### Not impressive yet (Score:5, Insightful)

on Wednesday May 09, 2012 @03:55AM (#39938729)
While this is an interesting deveopment, it is important to note the caveats: The refractive index in silicon, the only material tested so far, is only 1.000000001. IF this theory of how this is accomplished is correct, this MIGHT be higher for heavier elements. That's a big IF.
• #### Re:Fogbank? (Score:4, Insightful)

by Anonymous Coward on Wednesday May 09, 2012 @04:21AM (#39938833)

when you think to yourself "I know, I'll mention something obscure that people will need to look up on Wikipedia to know wtf I'm talking about!", you might want to double-check that Wikipedia doesn't contradict your claim.

• #### Re:n = 1.000000001 (Score:5, Insightful)

on Wednesday May 09, 2012 @05:04AM (#39938977)

Agree. Even if you do it with depleted uranium, and you suppose the "virtual electron effect" increases in proportional to the square of the number of protons in the nucleus, you might get an index of refraction in the ballpark of n = 1.000000033. Applying the lensmaker's formula [mtsu.edu], a convex lens with radii of curvature of 1 cm will have a focal length of ....

150 kilometers.

So the gamma ray imaging camera you want to build for airport security will have to be roughly the same size as your flight. No, not the length of the plane, the mileage.

• #### shhhh... (Score:5, Insightful)

on Wednesday May 09, 2012 @06:41AM (#39939355)
don't tell TSA or they'll gamma nuke everybody until they glow.
• #### Re:n = 1.000000001 (Score:4, Insightful)

<.rgb. .at. .phy.duke.edu.> on Wednesday May 09, 2012 @12:16PM (#39942621) Homepage
Well, yeah, except that all of the bending occurs at the interface surface. So in principle, one could stack 150 lensing surfaces constructed Fresnel-style and bring that right down to a kilometer. Depending on what the "interface surface" is for gamma rays. Or, stack 1500 of them and bring it down to 100 meters. Or stack 15,000 of them, in a 3D structure created with e.g. molecular beam epitaxy, and bring it down to 10 meters (with a lens with a total length of perhaps a meter). At that point it is conceivable that it might be useful, although probably not as an optical grade lens (wouldn't it be uber cool to build a gamma ray telescope with an aperture lens a meter across? Sure it would!)

I think that a lot of these same principles are involved in building x-ray lenses -- the lens is less like a glass lens, more like building an interferometric scattering array that causes a single central primary peak. But not my specialty, just thinking out loud...

rgb

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