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It's late, pitch dark, and a self-driving car winds down a narrow country road.
天已晚，黑夜中一辆自动驾驶汽车沿狭窄的乡村公路蜿蜒行驶而来。
Suddenly, three hazards appear at the same time. What happens next?
突然间，同时出现了三个危险警示。接下来会发生什么呢？
Before it can navigate this onslaught of obstacles, the car has to detect them
在驾驶通过突然出现的障碍物前，汽车必须先发现障碍物，
gleaning enough information about their size, shape, and position, so that its control algorithms can plot the safest course.
收集有关大小、形状和位置信息，以便用算法规划出最安全的路线。
With no human at the wheel, the car needs smart eyes, sensors that'll resolve these details
因为无人驾驶，汽车需要智能眼，也就是解决问题的探测器，
no matter the environment, weather, or how dark it is -- all in a split-second.
无论周围环境、天气如何，或者天有多黑，问题要在眨眼间解决。
That's a tall order, but there's a solution that partners two things:
要求虽高，但有解决方案，该方案由两样东西组成：
a special kind of laser-based probe called LIDAR,
特殊激光探测技术LIDAR
and a miniature version of the communications technology that keeps the internet humming, called integrated photonics.
以及集成光电技术，即实时联网的微通信技术。
To understand LIDAR, it helps to start with a related technology -- radar.
要了解光达LIDAR，需要先了解与此相关的技术--雷达。
In aviation, radar antennas launch pulses of radio or microwaves at planes to learn their locations by timing how long the beams take to bounce back.
在航空领域，雷达天线向飞机发射无线电脉冲或微波，通过计算波束返回时长来确定飞机位置。
That's a limited way of seeing, though, because the large beam-size can't visualize fine details.
但这一种观察方式很有限，因为大光束脉冲或微波无法显示微小的细节。
In contrast, a self-driving car's LIDAR system, which stands for Light Detection and Ranging, uses a narrow invisible infrared laser.
相反，自动驾驶汽车的LIDAR系统使用窄带不可见红外激光，LIDAR是光探测和测距的缩写。
It can image features as small as the button on a pedestrian's shirt across the street.
它可以将极其微小物件成像，如街对面行人衬衫上的扣子。
But how do we determine the shape, or depth, of these features?
但是，我们如何确定这些物件的形状或距离呢？
LIDAR fires a train of super-short laser pulses to give depth resolution. Take the moose on the country road.
LIDAR发射一系列超短激光脉冲去测距离。以乡间小路上的驼鹿为例。
As the car drives by, one LIDAR pulse scatters off the base of its antlers,
汽车驶过时，一个LIDAR脉冲遇到鹿角的根部后散开，
while the next may travel to the tip of one antler before bouncing back.
它反弹回来前，下一个脉冲可能已到达一个鹿角的顶端。
Measuring how much longer the second pulse takes to return provides data about the antler's shape.
测量这两个脉冲返回的时长差，可得到有关鹿角形状的数据。
With a lot of short pulses, a LIDAR system quickly renders a detailed profile.
通过发射大量短脉冲，LIDAR系统可快速得出物体详细轮廓。
The most obvious way to create a pulse of light is to switch a laser on and off.
打开再关上激光器是产生光脉冲最简便的方法。
But this makes a laser unstable and affects the precise timing of its pulses, which limits depth resolution.
但这会造成激光束不稳定，并影响发射脉冲的精确频率，影响距离测量准确性。
Better to leave it on, and use something else to periodically block the light reliably and rapidly.
更好的办法是让激光器开着，用其他东西定期、快速地阻挡光线。
That's where integrated photonics come in.
这就是集成光子技术。
The digital data of the internet is carried by precision-timed pulses of light, some as short as a hundred picoseconds.
互联网的数字数据是由精确定时的光脉冲承载的，有的脉冲短至一百皮秒。
One way to create these pulses is with a Mach-Zehnder modulator.
一种产生光脉冲的方法是使用马赫-曾德尔干涉仪。
This device takes advantage of a particular wave property, called interference.
该设备利用特定的波特性，称为干扰特性。
Imagine dropping pebbles into a pond: as the ripples spread and overlap, a pattern forms.
想一下将一些鹅卵石扔进池塘的情景：涟漪扩散和交叠构成了一种花纹。
In some places, wave peaks add up to become very large; in other places, they completely cancel out.
某些地方的波峰叠加，变得非常大；而其他地方，则完全抵消了。
The Mach-Zehnder modulator does something similar.
马赫-曾德尔干涉仪的原理与此类似。
It splits waves of light along two parallel arms and eventually rejoins them.
先将光波沿2个平行臂分为2束，然后合二为一。
If the light is slowed down and delayed in one arm, the waves recombine out of sync and cancel, blocking the light.
如果一束光减慢而延迟，因为2束光不同步，合并后的抵消现象就阻挡了光线。
By toggling this delay in one arm, the modulator acts like an on/off switch, emitting pulses of light.
通过切换一束光的延迟，干扰器就像一个开合的开关，发射出光脉冲。
A light pulse lasting a hundred picoseconds leads to a depth resolution of a few centimeters,
持续一百皮秒的光脉冲可以探测到小至几厘米厚的物体，
but tomorrow's cars will need to see better than that.
但未来的汽车需要更高的分辨率。
By pairing the modulator with a super-sensitive, fast-acting light detector, the resolution can be refined to a millimeter.
将干扰器与超灵敏、反应快的光探测器配对，可将分辨率提高到毫米级。
That's more than a hundred times better than what we can make out with 20/20 vision, from across a street.
比我们以正常视力看街对面的物体，要好一百倍以上。
The first generation of automobile LIDAR has relied on complex spinning assemblies that scan from rooftops or hoods.
第一代自动驾驶汽车的LIDAR，依赖车顶或发动机盖上的复杂旋转组件进行扫描。
With integrated photonics, modulators and detectors are being shrunk to less than a tenth of a millimeter,
借助集成光子技术，干扰器和探测器可缩小至不到十分之一毫米，
and packed into tiny chips that'll one day fit inside a car's lights.
装在小巧的芯片中，将来可以放在车灯里。
These chips will also include a clever variation on the modulator to help do away with moving parts and scan at rapid speeds.
这些芯片还将包括干扰器智能调节器，可消除移动物体，并快速扫描。
By slowing the light in a modulator arm only a tiny bit, this additional device will act more like a dimmer than an on/off switch.
通过减慢干扰器一个平行臂发出的光，这个额外设备的作用不像开关，更像一个调光器。
If an array of many such arms, each with a tiny controlled delay, is stacked in parallel, something novel can be designed: a steerable laser beam.
如果许多带微型控制延时的平行臂并列排放的话，就设计出了新的特性：可操纵的激光束。
From their new vantage, these smart eyes will probe and see more thoroughly than anything nature could've imagined
有了这些新优势，这些智能眼的探测和观察比能想到的任何自然的东西更彻底，
and help navigate any number of obstacles.
帮助导航通过任何数量的障碍物。
All without anyone breaking a sweat -- except for maybe one disoriented moose.
不费吹灰之力--或许一头没有方向感的驼鹿除外。
