#7 - The power of lasers 激光的力量

1.Laser light is a special kind of light.
Like ordinary light, it is made of waves, but it has three main differences. Ordinary white light is a mixture of colors, while laser light is one pure color. Ordinary light waves have peaks (highs) and troughs (lows), which do not line up - laser light waves line up perfectly. Lastly, ordinary light spreads and fades. A laser beam can travel thousands of kilometers as a strong, straight beam.

V The narrow horizontal beam from a laser spirit level can shine all the way across V

2.To make a laser beam, energy is fed in short bursts into a substance called the active medium.
The energy might be electricity, heat or ordinary light. In a red ruby laser, the active medium is a rod of ruby crystal. A strong lamp makes the particles in the crystal vibrate.

V Waves of light build up and bounce to and from inside a laser, then emerge at one end. V

V In a spectacular outdoor light show, different colored laser beams sweep to and from as they pierce the darkness, seemingly all the way into space. V

3.Lasers were invented in 1960.
They are used to play CDs and DVDs for music and movies and in computers. They cut through thick metal in factories, and carry out delicate eye operations. They carry phone calls and television programmes along cables. They even measure movements of the Earth to warn of volcanos or earthquakes.

V A CD laser detects tiny pits in the disc's underside. V

V An industrial laser has the power to melt metal into gas and cut a neat line. V

激光灯是一种特殊的光。
像普通的光一样，它由波组成，但它有三个主要的区别。普通白光是颜色的混合物，而激光是一种纯色。普通的光波有高峰和低谷，没有排列 - 激光波完美地排列起来。最后，普通的光线传播和消失。激光束可以传播数千公里，如同一条强而直的光束。

V来自激光水平仪的窄水平光束可以一路照射V

2.要制造激光束，能量以短脉冲的形式馈入到称为活性介质的物质中。
能量可能是电，热或普通光。在红宝石激光器中，活性介质是红宝石晶体棒。强光灯使水晶中的粒子振动。

V波的光在激光器内部聚积和反射，然后出现在一端。 V

V在壮观的室外灯光表演中，不同颜色的激光束在刺入黑暗中时扫过，似乎一路进入太空。 V

激光是在1960年发明的。
它们被用来播放音乐和电影的CD和DVD以及电脑。他们在工厂切割厚金属，并进行微妙的眼科手术。他们通过电话进行电话和电视节目。他们甚至测量地球的运动来警告火山或地震。

V CD激光器检测光盘底面的微小凹坑。 V

V工业激光有能力将金属熔化成气体并切割整齐的线条。 V