2021年经济学人 间谍活动--中科大再造"穿墙术"(1)

Espionage¹ (2)

间谍活动（2）

Round the bend

视线转弯

How to see what is hidden from view

如何看见视线外的隐藏物

In a locked room in a busy city, some terrorists are holding a hostage. The curtains are mostly drawn², cutting off any direct line of sight for those outside. In a building across the street, a team of engineers are set a task: they can have whatever equipment they need, but they must paint as clear a picture as possible of what is happening inside the room.

在一个繁忙的城市中的一间上了锁的房间里，一帮恐怖分子劫持了一名人质。窗帘被拉上了一大半，从外面无法直视其中。在街对面的一栋楼里，一队工程师接到了一项任务：他们可以拿到任何他们需要的设备，但必须尽可能清晰地描绘出房间内正在发生的事情。

This was the challenge given in 2015 to Daniele Faccio, then at Heriot-Watt University, in Edinburgh, by Dstl, a British government defence laboratory. He and his team eventually found a way to see around corners from a distance of 50 metres— which was reckoned impressive at the time, even though the system they devised could detect only the motion and position of hidden objects, rather than taking pictures of them. Now, however, Xu Feihu and Pan Jianwei of the University of Science and Technology of China, in Hefei, have blown that record out of the water. As they describe in the Proceedings³ of the National Academy of Sciences, they have managed to look around corners from a distance of well over a kilometre.

这是2015年英国政府的国防科技实验室Dstl给丹尼尔法乔（Daniele Faccio）的任务。当时供职于爱丁堡的赫瑞瓦特大学（Heriot-Watt-University）的法乔和他的团队最后找到了从50米开外隔墙观物的方法—这在当时被认为非常了不起，尽管他们设计的系统只能检测到隐藏物体的动作和位置而无法给它们拍照。然而现在，位于合肥的中国科学技术大学的徐飞虎和潘建伟已彻底击败了这项纪录。正如他们在《美国国家科学院院刊》中描述的那样，他们已经能够从一公里多外进行隔墙透视。

Non-line-of-sight imaging of this sort relies on two principles. One is that objects are visible to an observer if light bouncing off them makes its way to that observer's eyes or instruments. The other is that at least some light reflects off all but the blackest, most absorbing surfaces. The upshot is that something hidden from an observer's line of sight might nevertheless be visible if it is sufficiently⁴ near a wall which can serve as a reflecting surface. In this case, the observer can illuminate⁵ the wall with a tightly focused beam of light (in practice, probably a laser), knowing that some of the beam's light will bounce off the wall to illuminate the concealed⁶ object, and that some of this illumination will, in turn, be reflected back whence it came via the wall. The fraction of the original beam returned by this trilogy of reflections may be minuscule⁷, and the information it contains may appear hopelessly jumbled⁸. But sufficiently smart mathematics can turn it into an image of the thing it bounced off.

这种非视域成像技术（non-line-of-sight imaging）依赖两个原理。一是如果从物体上反射的光线进入观察者眼中或被仪器捕捉到，那么该物体便对观察者可见。二是除了最黑暗、吸收力最强的表面外，至少有部分光会反射出去。其结果是，隐藏在观察者视线之外的某物如果足够靠近可作为反射面的墙体，那它还是有可能被看见。在这种情况下，观察者可以用高度聚焦的光束（在现实中很可能是用激光）照亮这面墙，墙面会反射部分光束而照亮隐藏的物体，从该物体上又会反射一部分光通过墙面原路返回。经过这三重漫反射后，原始光束只返回了一小部分，可能非常微弱，所包含的信息也可能显得极度混乱。但只要经过足够智能的运算，就能将它变成该物体的成像。

1 espionage   

n.间谍行为，谍报活动

参考例句：

• The authorities have arrested several people suspected of espionage.官方已经逮捕了几个涉嫌从事间谍活动的人。
• Neither was there any hint of espionage in Hanley's early life.汉利的早期生活也毫无进行间谍活动的迹象。

2 drawn   

v.拖，拉，拔出；adj.憔悴的，紧张的

参考例句：

• All the characters in the story are drawn from life.故事中的所有人物都取材于生活。
• Her gaze was drawn irresistibly to the scene outside.她的目光禁不住被外面的风景所吸引。

3 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

4 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

5 illuminate   

vt.照亮，照明；用灯光装饰；说明，阐释

参考例句：

• Dreams kindle a flame to illuminate our dark roads.梦想点燃火炬照亮我们黑暗的道路。
• They use games and drawings to illuminate their subject.他们用游戏和图画来阐明他们的主题。

6 concealed   

a.隐藏的，隐蔽的

参考例句：

• The paintings were concealed beneath a thick layer of plaster. 那些画被隐藏在厚厚的灰泥层下面。
• I think he had a gun concealed about his person. 我认为他当时身上藏有一支枪。

7 minuscule   

adj.非常小的；极不重要的

参考例句：

• The human race only a minuscule portion of the earth's history.人类只有占有极小部分地球历史。
• As things stand,Hong Kong's renminbi banking system is minuscule.就目前的情况而言，香港的人民币银行体系可谓微不足道。

8 jumbled   

adj.混乱的；杂乱的

参考例句：

• Books, shoes and clothes were jumbled together on the floor. 书、鞋子和衣服胡乱堆放在地板上。
• The details of the accident were all jumbled together in his mind. 他把事故细节记得颠三倒四。