Researchers slow light to a crawl with liquid crystal
Light traveling in a vacuum is the universe’s ultimate speed demon, racing at approximately 186,000 miles per second. Now scientists have an effective new way to put a speed bump in light’s path. Reported last week in The Optical Society’s open-access journal Optics Express, researchers from France and China embedded dye molecules in a liquid crystal matrix to throttle the group velocity of light back to less than one-billionth of its top speed. The team says the ability to slow light in this manner may one day lead to new technologies in remote sensing and measurement science.
The new approach to manipulating light, conducted by a group from France’s Université de Nice-Sophia Antipolis and China’s Xiamen University, uses little power, does not require an external electrical field, and operates at room temperature, making it more practical than many other slow-light experiments. OSA
Ecosystems’ communities change before species lost
Communities in nature are likely to be a lot more sensitive to change than previously thought, according to a new study at Rice University that appeared last week in Nature Communications. It shows that human influence on the biosphere – for example, by removing large members of a species through overfishing – can have measurable consequences, said Rice ecologist Volker Rudolf.
“That’s the last thing that happens after you mess up the entire ecosystem for a long period of time,” he said. By then, changes forced upon the structure of a population – such as the ratio of young to old in a species – have already been felt up and down the food chain.
Rudolf suspected species play various roles and their effects on the environment change as they progress through their lifecycles, to the degree that altering these life “stages” within a species could have a significant impact.
Rudolf’s team chose dragonflies and water-diving beetles to represent species that have major impact on their respective communities – in this case, fishless ponds – and then created dozens of miniature environments to analyze that impact. Manipulating the presence of different developmental stages within a predator species in each pond helped researchers determine that such changes did alter the dynamics of complex ecosystems in a measurable way. news.rice.edu
Camera captures images at 10× speed of sound
Researchers at MetroLaser Inc., have developed a new design for a digital streak camera that captures full-color images of projectiles traveling up to 10 times the speed of sound. This system was designed to replace the film-based streak cameras that are still in use at high-speed test tracks.
Film-based streak photography records the motion of an object as it passes in front of a camera lens, while the film moves behind a vertical slit aperture during the exposure. The result is a long, continuous composite image of the object.
But the transition from film to digital has changed the photography industry, and the specialized film required for streak photography is no longer being manufactured. The Air Force asked Benjamin Buckner and Drew L’Esperance to design a system that could produce high-quality magazine-type images at the high speeds they require.
The new digital technology relies on a precisely controlled mirror to follow the object and freeze the image on the camera. spie.org
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