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2010年9月11日星期六

激光成功移動物件 1.5米

Beam me up Scotty - Andrei Rhode Invention Means Tractor Beams get Real
光束射我蘇格籣人 - Andrei Rhode 發明意味拖拉機光束成真

西元2010年09月10日

激光成功移動物件 1.5米
2010年09月11日

科幻片中隔空吸物的牽引射線,離成真又邁進一步。科學家過去只能用激光移動微小粒子一段短距離,澳洲國立大學的研究員大躍進,移動的粒子大了百倍,而且移動距離長達 1.5米。
研究員羅德( Andrei Rhode)的做法,是用空心的激光束照射玻璃粒子(圖),由於包圍粒子的激光令周圍的空氣加熱,空氣粒子的碰撞形成一道無形的管狀牆壁,把玻璃粒子停留在溫度較低的空心部位。研究員用兩束空心激光,就可控制玻璃粒子向不同方向移動。
羅德指測試受實驗室器材所限,他估計用這方法移動玻璃粒子的最遠距離可達 10米,但他表明這方法需要借助於空氣粒子,不能像《星空奇遇記》那樣在太空的真空狀態下使用。
英國《每日郵報》
http://hk.apple.nextmedia.com/template/apple/art_main.php?iss_id=20100911&sec_id=15335&subsec_id=10943028&art_id=14438907

拖拉機光束成真
Tractor Beams Get Real

2010 09 15
By Mike Lucibella InsideScience.org

Tractor beams, energy rays that can move objects, are a science fiction mainstay. But now they are becoming a reality -- at least for moving very tiny objects.

Researchers from the Australian National University have announced that they have built a device that can move small particles a meter and a half using only the power of light.

Physicists have been able to manipulate tiny particles over miniscule distances by using lasers for years. Optical tweezers that can move particles a few millimeters are common.
The tractor beam in action suspends a small particle over an optics table.
Credit: Courtesy of the Australian National University

Andrei Rode, a researcher involved with the project, said that existing optical tweezers are able to move particles the size of a bacterium a few millimeters in a liquid. Their new technique can move objects one hundred times that size over a distance of a meter or more.

The device works by shining a hollow laser beam around tiny glass particles. The air surrounding the particle heats up, while the dark center of the beam stays cool. When the particle starts to drift out of the middle and into the bright laser beam, the force of heated air molecules bouncing around and hitting the particle’s surface is enough to nudge it back to the center.

A small amount of light also seeps into the darker middle part of the beam, heating the air on one side of the particle and pushing it along the length of the laser beam. If another such laser is lined up on the opposite side of the beam, the speed and direction the particle moves can be easily manipulated by changing the brightness of the beams.

Rode said that their technique could likely work over even longer distances than they tested.

"With the particles and the laser we use, I would guess up to 10 meters in air should not be a problem. The max distance we had was 1.5 meters, which was limited by the size of the optical table in the lab," Rode said.

Because this technique needs heated gas to push the particles around, it can’t work in the vacuum of outer space like the tractor beams in Star Trek. But on Earth there are many possible applications for the technology. The meter-long distances that the research team was able to move the particles could open up new avenues for laser tweezers in the transport of dangerous substances and microbes, and for sample taking and biomedical research.

"There is the possibility that one could use the hollow spheres as a means of chemical delivery agents, or microscopic containers of some kind, but some more work would need to be done here just to check what happens inside the spheres, in terms of sample heating," said David McGloin, a physicist at the University of Dundee in the U.K not connected with the Australian team.
Tractor Beam Team. Source: anu.edu

Article from: insidescience.org
http://www.redicecreations.com/article.php?id=12524

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