冒牌自然老師

Special Seminar

Speaker: Professor Che Ting Chan陳子亭( Hong Kong University of Science and Technology)

Title: A Metamaterial Slab as a Lens, a Cloak and Something in Between

Time: 10:30am, 12 July, 2010

Venue: R833, New Physics Building , NTU

Abstract:

A metamaterial slab with ε=μ= -1 is a perfect lens. If the thickness of the lens is d, the source to image distance would be 2d. However, it is has also been shown that a collection of dipoles cannot be excited by external sources when it is placed within a distance of d/2 from a slab with ε= -1 + δi as δ approaches zero in the quasi-static limit. If a dipole cannot be excited by external sources, it is just another way of saying that it is cloaked. This result can be generalized to a metamaterial slab with ε=μ=-1 and to finite frequencies. So, a metamaterial slab is a perfect lens and also a perfect cloak. This seems contradictory as a cloak makes an object invisible, and a perfect lens make an object perfectly visible. To resolve the puzzle, we will examine the issue of image formation of an object placed in front of a metamaterial slab, and see under what circumstances should we see a image as predicted by the complimentary media concept and under what circumstances would the object become invisible and thus no image is formed.

陳子亭教授經歷
Professor Che Ting Chan received his BSc degree from the University of Hong Kong in 1980. He completed his PhD degree at the University of California at Berkeley in 1985. He joined the Physics Department of HKUST in 1995. Before coming to HKUST, Professor Chan worked at Ames Laboratory in the United States.

Professor Chan was a co-winner of an Outstanding Scientific Accomplishment Award (Solid State Physics) in the U.S. Department of Energy Materials Science Research Competition. He has been a Fellow of the American Physical Society since 1996. In 1999, he was awarded the Michael Gale Medal for Distinguished Teaching, HKUST. In 2000, he was awarded the Achievement in Asia Award by the Overseas Chinese Physics Association.

Professor Chan's main research interests include application of first principles and related methods to study the electronic, structural and other physical properties of matter; surface physics; photonic band gaps; and material physics.

陳教授的演講功力確實不錯, 陳述的過程有趣而且清楚. 雖然國語充滿濃濃廣東腔, 但是陳教授堅持在華人世界還是應該講中文.

大家都期待有一個隱形斗篷, 所以拼命在做一個結構來讓物體消失, 但是如此一來人躲在當中, 雖然別人見不到, 自己同時也看不到外面.....所以陳教授發展了一些計算方法來讓被隱身的對象可以看到外面, 成為哈利波特真正的隱形斗篷...