Zap!
激光歼蚊
Jun 4th 2009
From The Economist print edition

Medical technology: Researchers are devising laser-defence systems to shoot down mosquitoes and prevent the spread of malaria. No, really
医学技术：研究者正在设计激光防御系统，用来歼灭蚊子，防止疟疾扩散。不会吧，这是真的吗？



TOWARDS the end of the cold war Ronald Reagan announced plans to use powerful lasers to shoot down any incoming intercontinental ballistic missiles that the Soviet Union aimed at America. The lasers were real but the plan was fanciful. Scientists now propose a more modest system, aimed at insects rather than nuclear warheads. They think lasers could be used to zap the mosquitoes that carry malaria, a disease which kills more than a million people each year, most of them children, and debilitates hundreds of millions more.
冷战末期，罗纳德·里根宣布了用强力激光击落苏联射向美国的洲际弹道导弹的计划。激光是真实的，但计划却是虚构的。目前科学家建议设计一个不那么暴力的激光系统，用来对付昆虫而不是核弹头。他们认为可以用激光来歼灭携带疟疾病毒的蚊子，疟疾每年害死了一百多万人，绝大多数都是儿童，此外还使几亿人病弱不堪。

Researchers at Intellectual Ventures, an innovations company established by former Microsoft executives in Bellevue, Washington, have developed what they call a photonic mosquito fence. It has a series of posts, each of which is equipped with a cheap camera and a light bulb (which will be swapped for a light-emitting diode in future versions). The cameras are connected to a central computer. When a camera detects movement, the computer analyses it to see whether it is consistent with the behaviour of a mosquito. If it is, then the computer trains a laser onto the insect and blasts it into oblivion.
前微软总裁在华盛顿贝尔维尤建立了一家创新企业“高智发明”。该公司的研究员已经研发出一种他们称为光子蚊子围篱的新发明。它有一系列柱子组成，每个柱子上都装有一个廉价摄像机和一个灯泡（未来版本中可能会换成发光二极管）。摄像机与中央计算机相连。当摄像机探测到物体移动，计算机会进行分析，判断这是不是蚊子的行为。如果是的话，计算机就会把激光对准蚊虫，将它彻底歼灭。

Jordin Kare, an astrophysicist and a former scientist on the missile-defence programme, leads the effort. He says it is possible to detect different species of mosquito because their wings beat with a distinctive frequency. He is aiming for Anopheles gambiae, the species most effective at spreading plasmodium, the parasite that causes malaria, when it bites people to feed on their blood.
曾经参与导弹防御计划的天体物理学家Jordin Kare领导这一研究。他说探测不同种类的蚊子是可能的，因为每种蚊子以不同频率扇动翅膀。他的目标是冈比亚疟蚊，这种蚊子叮人吸血时，最容易传播引起疟疾的寄生虫疟原虫。

Dr Kare imagines that the mosquito fence will be set up around a hospital or a village in a malarial area. His experiments with prototypes have shown that posts spaced 100 metres apart work best. The lasers would target only mosquitoes, although Dr Kare says some work still needs to be done to ensure that the laser is safe for people and animals. Although he will not give an exact figure, Dr Kare says he built his prototype from parts bought at surplus stores and on eBay, and has calculated that the cost will be comparable to that of supplying all the inhabitants of a medium-sized village with bed nets.
Kare博士设想围绕疟疾肆虐地区的医院和村庄建立蚊子围篱。他用样机进行实验，发现柱子间的距离为100米时效果最佳。激光将只把蚊子当做目标，但是Kare博士说，为保证激光对人和动物的安全性，还有许多工作要做。虽然他不会给出确切数字，但他说他制作样机的零件是从eBay上出售剩余物品的商店购买，并推算其成本与向一中等大小村庄的全体居民提供蚊帐的费用相当。

Another, somewhat simpler, approach is being developed by Szabolcs Marka, an astrophysicist, and his colleagues at Columbia University in New York. Dr Marka has created a curtain of invisible light that mosquitoes cannot penetrate. He uses a common diode laser, a simple lens and a power supply to generate an infra-red barrier that can cover a door or window. Mosquitoes are very sensitive to heat and light (indeed, their sensitivity to infra-red radiation helps them sense the presence of food, in the form of people). The idea is that when a mosquito encounters the infra-red curtain, its senses are overwhelmed and it flies away. Tests have shown that the curtain kills some mosquitoes that fly into it.
天问物理学家Szabolcs Marka及其纽约哥伦比亚大学的同事研发出另一种更为简单的方式。Marka博士发明了一种蚊子无法穿透的不可见光光幕。他使用普通的二极管激光、一简单镜片以及产生红外线屏障覆盖门窗的电源。蚊子对光和热非常敏感（事实上，它们对红外辐射的敏感帮助它们感应其食物——人的存在）。其构想是当蚊子遇到红外线光幕时，它的感官无法承受，便飞离此处。试验显示光幕杀死了一些飞入的蚊子。

Even if a mosquito somehow managed to penetrate such a barrier, a second light curtain set up around a bed, for example, would provide further protection. Dr Marka envisages two or three light curtains in a home: one at the door, one around a sleeping person and one surrounding the area in which mosquitoes typically hide (under the thatched roof of a hut, for example). Dr Marka calculates that if there is a 6% chance that a mosquito will penetrate a light curtain, and a hut contains four curtains, then only one in 100,000 mosquitoes will be able to spread malaria. Dr Marka, whose research is funded by the Gates Foundation, says that a prototype of his machine costs a little over $100.
即使蚊子能穿过一道此类屏障，第二道光幕，比如说设立在床周围，会提供进一步的保护。Marka博士设想在一家安装两到三道光幕：一道在房门处，一道环绕睡觉的地方，还有一道围绕蚊子通常隐藏处（例如茅草房的屋顶）。Marka博士预测，如果蚊子穿过一道光幕的概率6%，那么对一所安装了四道光幕的茅草屋来说，蚊子能传播疟疾的概率仅为十万分之一。Marka博士的研究由盖茨基金会资助，他说他的样机成本略高于100美元。