A billion suns: Bright light illuminates healthcare
Izzie Clarke
Author
07/25/2017
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36
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Interview with Donald Umstadter by the Naked Scientists.
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- [00:00:00.153]When light particles, called photons,
- [00:00:02.270]hit the electrons and the atoms that things are made of,
- [00:00:04.792]the light is scattered back.
- [00:00:06.059]This is the very reason that things
- [00:00:07.460]are actually visible in the first place.
- [00:00:09.724]Now scientists at the University of Nebraska-Lincoln
- [00:00:12.131]have created the brightest light on Earth
- [00:00:15.347]and they found that these sorts of energies,
- [00:00:16.855]when substances are illuminated,
- [00:00:18.968]something very exciting happens that could make
- [00:00:21.081]a massive contribution to both healthcare and security.
- [00:00:24.413]Izzy Clark spoke to Donald Umstadter
- [00:00:26.564]about the light source he's made
- [00:00:27.792]and what happens when it illuminates something.
- [00:00:30.374]It's about billion times brighter
- [00:00:32.752]than the surface of the sun.
- [00:00:35.170]In terms of power, it's got the power
- [00:00:37.611]of all the Earth's electrical grid
- [00:00:40.702]but it's only on for a very short time.
- [00:00:44.263]To make high brightness, you need to have
- [00:00:47.244]that power of light focused to a very small spot.
- [00:00:51.885]We focused it to an area that is only
- [00:00:54.606]about a millionth of a meter in diameter.
- [00:00:58.921]We're producing the most photons per unit area
- [00:01:03.774]that has ever been produced on Earth.
- [00:01:07.170]Donald and his team amplified short pulses of light
- [00:01:09.941]up to high energy in a laser system.
- [00:01:13.720]That makes this light of a high power,
- [00:01:16.130]which is equivalent to a trillion light bulbs,
- [00:01:19.505]but that only occurred for a very short amount of time.
- [00:01:23.168]By concentrating that power into a tiny spot
- [00:01:26.402]makes the light incredibly bright with high intensity.
- [00:01:30.360]Next step was to aim this extremely bright light
- [00:01:33.614]at a minute target, an electron.
- [00:01:37.057]But how?
- [00:01:38.186]What we're using is a mirror that has a curved surface,
- [00:01:43.004]so we call it a parabolic reflector,
- [00:01:46.310]that allows the rays to be focused at some distance away.
- [00:01:51.859]These parabolic mirrors are similar
- [00:01:54.141]to those used in radio telescopes.
- [00:01:56.944]Looking at how light interacts with matter
- [00:01:59.290]is a fundamental part of physics.
- [00:02:02.134]Under typical conditions,
- [00:02:03.873]when the light from a bulb or the sun strikes a surface,
- [00:02:07.610]it's scattered by an electron
- [00:02:10.010]and this is what makes vision possible.
- [00:02:12.775]With light of a standard brightness,
- [00:02:14.715]the electron will scatter the photon at the same angle
- [00:02:17.686]and energy it had before striking the electron,
- [00:02:20.672]regardless of how bright that light might be.
- [00:02:24.208]Yet, Donald's team found that, above a certain threshold,
- [00:02:28.169]the laser's brightness altered the properties
- [00:02:30.642]of the scattered light.
- [00:02:32.770]Well, the electron responded to this brighter light
- [00:02:36.029]by emitting a new light that had much more energy
- [00:02:40.000]than the original light.
- [00:02:41.547]The energy was high enough that we would call it an x-ray.
- [00:02:45.680]That phenomenon stemmed partly from a change
- [00:02:47.988]in the electron's movement, which abandoned it's usual
- [00:02:50.867]up and down motion in favor of a figure eight pattern.
- [00:02:55.218]It was found that the ejected photon had absorbed
- [00:02:58.112]the collective incoming photon energy,
- [00:03:01.127]granting it the energy and wavelength of an x-ray.
- [00:03:04.978]Whilst this theory had existed for decades,
- [00:03:08.215]this behavior in light had never been documented.
- [00:03:11.599]Let's break this down a bit more.
- [00:03:13.731]Imagine you had a dimmer switch in your kitchen.
- [00:03:16.725]At low brightness, your table would appear dark
- [00:03:19.802]but as you turn up the switch
- [00:03:21.651]it gets brighter and more visible.
- [00:03:24.078]This is what happens when we use standard light to see,
- [00:03:27.488]but hypothetically if your dimmer switch
- [00:03:30.556]was controlling this ultra bright light,
- [00:03:33.235]it's as though your table would've suddenly disappeared.
- [00:03:36.976]The light waves that are being scattered
- [00:03:38.662]back from the table have turned into x-rays,
- [00:03:41.591]which we cannot see, but an x-ray scanner can, of course.
- [00:03:47.195]The typical x-ray you get at a hospital
- [00:03:50.166]is more like a light bulb than it is a laser,
- [00:03:54.158]so produces all frequencies of x-rays
- [00:03:58.213]and it produces them over all different angles.
- [00:04:01.865]Most of those x-rays are wasted.
- [00:04:04.393]X-rays can also give you cancer,
- [00:04:06.973]so the dosage has to be kept below a certain level.
- [00:04:11.193]It turns out that the x-rays we produce
- [00:04:13.855]produce good quality images with ten times lower dose,
- [00:04:17.785]so they're much safer and better quality.
- [00:04:21.422]X-rays are also used within security.
- [00:04:23.799]Is there the possibility that we could
- [00:04:26.074]use x-rays to improve security as well?
- [00:04:30.393]We have shown that the x-rays we are producing this way
- [00:04:34.906]can penetrate through very thick steel
- [00:04:38.604]and still get a very good image
- [00:04:40.822]of what is hidden behind that steel.
- [00:04:43.909]There's a big concern that nuclear materials
- [00:04:47.974]could be transported through cargo containers,
- [00:04:51.396]so it's very important to be able
- [00:04:52.978]to inspect cargo containers for such threats
- [00:04:56.896]in a rapid and non-destructive way.
- [00:05:00.289]That's what we've demonstrated with our x-ray source.
- [00:05:04.765]Illuminating stuff.
- [00:05:05.965]That was Donald Umstadter and he was talking with Izzy Clark
- [00:05:08.545]about the work he's just published in Nature Photonics.
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