Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers rely on Newton's interference for new experiment

13.08.2007
Most people think of Sir Isaac Newton as the father of gravity.

But for Lawrence Livermore National Laboratory physicist Henry Chapman and his colleagues, Newton's “dusty mirror” experiment served as a launching pad for them to keenly watch the X-ray induced explosion of microscopic objects.

Using the FLASH soft-X-ray free-electron laser (FEL) in Hamburg, Germany, the team blew up a plastic sphere, but used that same laser pulse to look at the sphere a split second later by placing an X-ray mirror right behind the object. A hologram (three-dimensional image of the object) formed through interference, which was caused when the light scattered through the sphere the first time combined with the light scattered through the sphere the second time (the light bounced back through the object from the mirror).

“We know from previous work we did at FLASH that the object did not explode during the initial 25-femtosecond pulse, and that forms the known reference wave of the hologram,” Chapman said. “The reference wave can be used to determine the unknown object wave, which is actually the same object, but a split second later.”

So where does Newton come in?

Newton created one of the earliest observations of interference in his “dusty mirror” experiment. In a darkened room, he used a prism and a small hole in a screen to form a quasi-monochromatic beam from sunlight, which he shone onto a back-quick silvered mirror. The mirror was angled to return the beam back through the hole and on the screen. Newton observed dark and light rings of light, which he found “strange and surprising.” It was 100 years later when the British scientist Thomas Young determined the rings were caused by interference at the screen between two paths of light scattering from dust particles on the mirror's front surface.

The research appears in the Aug. 9 edition of the journal, Nature.

Chapman designed the experiment after visiting the Chabot Space and Science Center with his wife (Sa_a Bajt, another author on the paper) and daughter. There was an optics exhibit that would let you see interference by looking down a long tube, which had a mirror at the bottom. When you held a small penlight close to the eye, you saw colored curved fringes in the mirror's reflection. The exhibit was described as the dusty mirror experiment. “It suddenly struck me that you could do the same thing with short pulses and X-ray mirrors, and it would be really interesting if the X- ray pulse was shorter than the time it takes for it to travel from the dust particle to the back of the mirror and back,” Chapman said.

And so the experiment was born.

The experiment is part of LLNL's Laboratory Directed Research and Development project: “Biological Imaging with Fourth-generation Light Sources” to develop the technique and determine the feasibility for single-molecule imaging experiments to be carried out at the Linac Coherent Light Source (LCLS) at Stanford when it comes on line.

Unlike the static conditions of Newton's experiment, in the recent experiment the object is ultimately vaporized by the X-ray pulse and the object size changes in the brief interval that the pulse takes to reflect back to the particle. The time it takes the pulse to return is encoded in the fringe pattern of the X-ray hologram, and this can be “read out” from the hologram to an accuracy of about 1 femtosecond. Coupled with the short wavelength of X-rays, the measurements give information simultaneously at the highest spatial resolution and time resolution for general noncrystalline materials.

“This experiment allows us to study the dynamics of material in the extreme conditions of intense FEL pulses, both during the pulse and as it turns into plasma,” Chapman said.

Plasma is considered to be a fourth state of matter, an ionized gas that has distinct properties. Until the recent experiment, there had been no structural methods to follow the early steps in plasma formation. Understanding these initial processes is crucial to future near atomic-resolution imaging experiments at LCLS. The key is to use short pulses to beam the damage and get a high-resolution image of the object before it explodes.

Anne Stark | EurekAlert!
Further information:
http://www.llnl.gov/PAO

More articles from Physics and Astronomy:

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

nachricht Airborne thermometer to measure Arctic temperatures
11.01.2017 | Moscow Institute of Physics and Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

New technology enables 5-D imaging in live animals, humans

16.01.2017 | Information Technology

Researchers develop environmentally friendly soy air filter

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>