每一个 DLP® 投影系统的核心部分都是称作 DLP® 芯片的光学半导体，该芯片在 1987 年由德州仪器 (TI) 的 Dr.Larry Hornbeck 发明。

全数字显示芯片

DLP® 技术是革命性的显示解决方案，它采用光学半导体以数字方式对光进行利用。它是一款高度可靠、全数字显示芯片，为多种系列产品提供最佳图片，这些产品包括大屏幕数字电视，用于公司、家庭、专业需要的投影仪，以及数码电影 (DLP Cinema®)。它也是全球领先的显示类电子公司使用的可靠技术，自 1996 年以来已向超过 75 家制造商交付 1000 多万个系统。

哪里需要视觉享受，哪里就采用了 DLP® 技术。它还是高度灵活的显示技术。它是市场上唯一可使世界上最小的投影仪重量低于 2 磅、照亮电影屏幕最高达 75 英尺的显示技术。

结果是实现了最高的保真度：图片的清晰度、亮度和色彩如亲眼所见。

半导体改变了一切

每个 DLP® 投影系统的核心部分都是称作数字微镜器件或 DLP® 芯片的光学半导体，该芯片在 1987 年由德州仪器 (TI) 的 Dr.Larry Hornbeck 发明。

DLP® 芯片可能是世界上最精密的光开关。它包含一个多达 200 万个安装在铰链上的微镜的矩阵；每个微镜尺寸小于人头发丝直径的五分之一。

当 DLP® 芯片与数字视频或图形信号协调起来，光源微镜和投影透镜可以将全数字图像反射到屏幕或其它表面。DLP® 芯片及其周围精密的电子元件就是所谓的 Digital Light Processing™ 技术。

数据光源处理 I：灰度级图像

DLP® 芯片的微镜安装在微型铰链上，从而使其可以在 DLP® 投影系统中倾向光源（打开）或偏离光源（关闭）- 在投影表面造成像素的或明或暗。

输入半导体的比特流图像代码指引每个微镜每秒开关多达数千次。当微镜打开频率高于关闭时，将反射浅灰像素；当微镜关闭频率高于打开时将反射深灰像素。

这样，DLP® 投影系统中的微镜可反射多达 1,024 个灰度梯度的像素，将进入 DLP® 芯片的视频或图形信号转换成灰度级非常详细的图像。

数字光源处理 II：增添色彩

由 DLP® 投影系统中的灯生成的白光在传播到 DLP® 芯片的表面时穿过色轮。“色轮”将光过滤成红色、绿色和蓝色，单芯片 DLP® 投影系统可从中至少创建 1670 万 种颜色。而 DLP Cinema® 投影系统中发现的 3 芯片系统能够产生超过 35 兆种颜色。

每个微镜的开关状态与这三个基本的颜色构建块协调。例如，负责投射紫色像素的微镜只会将红色光和蓝色光反射到投影表面；然后我们的眼睛混合这些快速交替的闪光，以看到投影图像中的预期色彩。

• 访问 DLP.com

他们提出了一种新的方法，可以用来解决量子力学中一个极富吸引力的问题：在更大更复杂的系统中的量子叠加和纠缠的性质。

量子叠加是指粒子，如光子或原子，同时存在于两个位置的一种状态。而量子纠缠使得粒子之间可以共享信息，即使他们在物理上是分开的，也就是爱因斯坦所说的“幽灵般的超距作用（spooky action at a distance）”。

观察一个小的力学系统中的量子行为的主要挑战是系统和其噪声环境——也就是支撑该系统的周围物质或任何其他外部联系——之间的相互抑制作用。例如，该系统所处环境的随机热振动可能会转移到系统中的对象上，从而破坏其脆弱的量子特性。为了解决这个问题，全世界不少研究机构都开始使用低温冷却设备，将直接环境冷却到非常低的温度，以减少这些随机振动的幅度低温设置。

加州理工学院的研究者提出了一个完全不同的方法——利用强光束产生的作用力使整个力学对象“漂浮”起来，从而将系统从外部联系和物质支持上隔离开来。研究人员发现的这种方法可以大大减小环境噪音，即使是在室温下都有可能观察到量子行为的各种表现。

参与这项工作的科学家有Darrick Chang，美国加州理工学院量子信息研究所博士后；Oskar Painter，应用物理学副教授；H. Jeff Kimble，加州理工学院William L. Valentine教授和物理学教授。

利用光学力俘获或悬浮小粒子的想法是现实可行的。它由贝尔实验室的Arthur Ashkin在二十世纪七八十年代始创，并为科学进步奠定了基础。如经常被用来控制微小生物物体的运动的“光镊”的出现，以及使用激光来冷却和俘获原子。这些技术提供了非常灵活而多样的操纵原子的方法，并且已经被用来演示原子尺度上的各种量子现象。

在这项新的工作中Chang和他的同事们证明，理论上来说，只要是在纳米尺度上，即使用一个更大规模的力学系统来取代一个单独的原子也有可能取得类似的成功。与此同时，德国Garching，Max Planck量子光学研究所的一个研究组已经提出了一个相关的研究方案（来进行实践探索，译者注）。

由加州理工学院的研究小组提出的系统由一个高透明材料，如熔融石英，制成的微小球体构成。当球体与激光光束接触，光学力很自然地将它推向光强度最大的方向，在这一点将其捕获。该球体的直径约为100纳米，相当于人的头发丝直径的千分之一。由于其体积小，该球体与外部环境之间的剩余相互作用足够微弱，量子行为应该很容易出现。这里的剩余相互作用指的是除与另一种物质直接接触之外的其它任何作用，因为小球是“悬浮”的。

然而，为了让类似的现象能够出现，还必须将该球体置于一个光学谐振腔内。光学谐振腔是由两个安置在该系统两边的镜子组成的。在镜子之间来回反射的光束能够探测该球体的运动，从而可以被用于在量子力学的水平上对其运动进行控制。

研究人员描述了这种作用是如何减小机械运动的能量（或者说冷却）直到系统达到量子基态（量子力学所允许的最低能量状态）的。这一过程的根本性限制在于光学冷却（效果）与热量在环境和系统之间双向传导的速率的相对优势。

原则上来说，可以将这个近似孤立的球体从室温冷却到1000万分之一那么低；在这样过冷的状态下，限定区域中的物质仅在固有的量子涨落所允许的最小（能量）范围内运动。

研究人员还提出一项计划来观察“量子纠缠”的特性。量子纠缠是量子力学的核心内容之一。两个远离的系统通过量子纠缠所共享的信息比经典物理所允许的要多。在某些情况下，纠缠态可能是一个非常宝贵的资源；它是使先进的计量学和速度更快的量子计算机成为现实的基础。

该提计包括将一对初始纠缠的光束（该成果由加州理工学院的Kimble领导的研究小组于1992年首次完成）分别发射到两个谐振腔中，每一束都包含一个悬浮的球体。通过量子态转移过程，光的所有属性——尤其是纠缠态及其相关性——都可以映射到两个球体的运动上。

虽然这些纳米级的力学对象的大小与我们日常生活中见到的物体相去甚远，加州理工学院的研究人员仍然坚信，他们的研究结果显示出在前所未有的大尺度——大约包含1000万个原子——的物体上实现和控制量子现象的可能性。

该项目的研究人员还包括加州理工学院研究生Dalziel Wilson和博士后学者Cindy Regal and Scott Papp；Jun Ye，JILA（位于Boulder的Colorado大学与美国国家标准与技术研究所的联合研究机构）的研究员；Peter Zoller，Innsbruck大学教授。这项工作是在Gordon and Betty Moore的著名学者，Ye和Zoller在加州理工学院做访问学者的时候展开的。

该项目得到Gordon and Betty Moore Foundation, the National Science Foundation, the Army Research Office, Northrop Grumman Space Technology, the Austrian Science Fund and European Union Projects共同支持。

要想了解更多信息，请访问 www.caltech.edu

Translate from Quantum Entanglement Realized

The technology could have applications in the design of microelectromechanical systems (MEMS) – nanoscale devices with moving parts – and micro-optomechanical systems, which combine moving parts with photonic circuits, said Michal Lipson, associate professor of electrical and computer engineering. Others involved in the study include postdoctoral researcher Gustavo Wiederhecker, and doctoral students Long Chen and Alexander Gondarenko.

silicon_nitride.jpg

“The challenge is that large optical forces are required to change the geometry of photonic structures,” Lipson explained.

But the researchers reduced the force required by creating two ring resonators – circular waveguides whose circumference is matched to a multiple of the wavelength of the light used – and by exploiting the coupling between beams of light traveling through the two rings.

A beam of light consists of oscillating electric and magnetic fields, and these fields can pull in nearby objects, a microscopic equivalent of the way static electricity on clothes attracts lint. This phenomenon is exploited in “optical tweezers” used by physicists to trap tiny objects.

The forces tend to pull anything at the edge of the beam toward the center.

When light travels through a waveguide whose cross section is smaller than its wavelength, some of the light spills over, and with it the attractive force. So parallel waveguides close together, each carrying a light beam, are drawn even closer, much like two streams of rainwater on a windowpane that touch and are pulled together by surface tension.

The researchers created a structure consisting of two thin, flat silicon nitride rings about 30 µm (millionths of a meter) in diameter mounted one above the other and connected to a pedestal by thin spokes. Think of two bicycle wheels on a vertical shaft, but each with only four thin, flexible spokes. The ring waveguides are three microns wide and 190 nm thick, and the rings are spaced 1 µm apart.
When light at a resonant frequency of the rings, in this case infrared light at 1533.5 nm, is fed into the rings, the force between the rings is enough to deform the rings by up to 12 nm, which the researchers showed was enough to change other resonances and switch other light beams traveling through the rings on and off. When light in both rings is in phase – the peaks and valleys of the waves match – the two rings are pulled together.

When it is out of phase, they are repelled. The latter phenomenon might be useful in MEMS, where an ongoing problem is that silicon parts tend to stick together, Lipson said.

An application in photonic circuits might be to create a tunable filter to pass one particular optical wavelength, Wiederhecker suggested.

The work is supported by the National Science Foundation (NSF) and the Cornell Center for Nanoscale Systems. Devices were fabricated at the Cornell Nanoscale Science and Technology Facility, also supported by NSF.

The research appears in the online edition of the journal Nature.

For more information, visit: www.cornell.edu

via Light Moves Nanostructures (photonics.com | Nov 2009 | News and Features).

The Oxford University research team, funded by the UK Medical Research Council, genetically engineered the fruit flies so that a small set of nerve cells in the brains would “fire” in response to a flash of laser light. This showed which cells are involved in how a fruit fly learns and remembers what to avoid, and offers an exciting new opportunity to investigate how memories are formed.

The Oxford scientists, with colleagues at the University of Virginia, Charlottesville, demonstrated that they could use flashes of laser light to train flies to dislike a certain odor.

“We tracked the flies using a video camera as they moved around a small chamber while two different odors were fed into the chamber from either end. We found that we could implant a lasting preference for one odor over the other by remotely activating a specific set of brain cells each time a fly strayed into a particular odor,” said Dr. Adam Claridge-Chang, who is now at the Wellcome Trust Centre for Human Genetics at Oxford University.

Using this method, the researchers were able to pinpoint the precise nerve cells that are responsible for telling the flies that they’ve done wrong, narrowing down the search from the 100,000 cells in the brain of a fruit fly to a set of just 12 neurons.

“Surprisingly, the source of these signals is in a limited number of cells – just twelve,” said professor Miesenböck. “These cells send the signals that train the fly to associate the odor with something bad, so wherever their signals go must be the seat of memory. We can now follow this up and start to characterize the process by which memories are formed and organized.”

The results of the study are published in the journal Cell. While this work has been done in fruit flies, general lessons about how actions are learned and memories are stored should hold true for humans.

“Biology teaches us that fundamental mechanisms tend to be conserved. Learning about the storage of memories from brain cells in flies should tell us a lot about how they are stored in humans,” said Miesenböck.

He has pioneered this method of genetic engineering to remote control the action of specific cells within tissues, or whole organisms like worms, fruit flies, fish and mice, using light from the outside. These efforts have given rise to a new field sometimes called “optogenetics,” to indicate that sensitivity to light is encoded genetically.

A separate paper by Miesenböck summarizing the status of this new field has also been published in Science. As the ability to write memories directly to the brains of fruit flies demonstrates, optogenetic techniques have particular power in neuroscience.

“The great advantage is that we are no longer just passive observers of processes in the brain. In the past, neuroscientists had to be content with recording the chatter of brain cells and trying to infer what it all meant. The ability to talk back and influence behavior directly is proving quite valuable,” Miesenböck said.

via Lasers Twist Fly Memories (photonics.com | Oct 2009 | News and Features).

Optical discs have been a leading storage solution for decades

A disc that can store 500 gigabytes (GB) of data, equivalent to 100 DVDs, has been unveiled by General Electric.

The micro-holographic disc, which is the same size as existing DVD discs, is aimed at the archive industry.

But the company believes it can eventually be used in the consumer market place and home players.

Blu-ray discs, which are used to store high definition movies and games, can currently hold between 25GB and 50GB.

Micro-holographic discs can store more data than DVDs or Blu-ray because they store information on the disc in three dimensions, rather than just pits on the surface of the disc

A single GE disc could be used to package up a library of high definition movies but is there pent-up consumer demand for such an offering? News website Technology editor Darren Waters Read more on the Dot.Life blog

The challenge for this area of technology has been to increase the reflectivity of the holograms that are stored on the discs so that players can be used to both read and write to the discs.

Brian Lawrence, who leads GE’s Holographic Storage said on the GE Research blog: “Very recently, the team at GE has made dramatic improvements in the materials enabling significant increases in the amount of light that can be reflected by the holograms.”

More capacity

The higher reflectivity that can be achieved, the more capacity for the disc. While the technology is still in the laboratory stage, GE believes it will take off because players can be built which are backwards compatible with existing DVD and Blu-ray technologies.

In a statement the firm said: “The hardware and formats are so similar to current optical storage technology that the micro-holographic players will enable consumers to play back their CDs, DVDs and Blu-ray discs.”

”GE’s breakthrough is a huge step toward bringing our next generation holographic storage technology to the everyday consumer,” said Mr Lawrence in a statement.

He added: “The day when you can store your entire high definition movie collection on one disc and support high resolution formats like 3D television is closer than you think.”

Micro-holographic technology has been one of the leading areas of research for storage experts for decades. Discs are seen as a reliable and effective form of storage and are both consumer and retail friendly.

However, General Electric will need to work with hardware manufacturers if it is to bring the technology to the consumer market.

The relatively modest adoption of Blu-ray discs sales globally might be an issue with some companies who believe digital distribution and cloud computing is the long-term answer to content delivery and storage.

“This is truly a breakthrough in the development of the materials that are so critical to ultimately bringing holographic storage to the everyday consumer,” said Mr Lawrence.

via Optical disc offers 500GB storage

今年的诺贝尔物理学奖集中在光电子技术领域。其中，高锟的获奖理由为“在光学通信领域光在光纤中传输方面所取得的开创性成就”。另外两位美国科学家共同获得另一半奖金，获奖理由为“发明了一种成像半导体电路，即CCD（电荷耦合器件）传感器（用于数码成像的感光和传输器件）”。

早在1966年，高锟就在一篇论文中首次提出用玻璃纤维作为光波导用于通讯的理论。简单地说，就是提出以玻璃制造比头发丝更细的光纤，取代铜导线作为长距离的通讯线路。这个理论引起了世界通信技术的一次革命，为现代光纤通信技术的发展和应用做出了重要贡献。随着第一个光纤系统于1981年成功问世，高锟“光纤之父”的美誉传遍世界。