Scientific American magazine says huge lasers turn only about twenty to thirty percent of the energy they use into a laser beam.

VOA: special.2010.09.01

So this gives you a little bit of an idea of just how many individual photons there are in a laser beam of light. This is a huge number of photons.

这个给你们一点思路关于,一个激光束有多少独立的光子,这是一个巨大的光子数目。

麻省理工公开课 - 化学原理课程节选

Also, what's the energy per photon of this red laser pointer, and then it's also worth trying a calculation dealing with intensity. So let's also try calculating the numbers of photons that would be emitted by this laser pointer, if, for example, we were to use it for 60 seconds and this were a one milliwatt laser.

同样，红色激光笔的,每个光子能量是多少，这也值得用处理强度的方法计算一下,让我们也计算一下,有多少光子会从这个激光笔射出，举个例子，如果我们使用它持续60秒,这里会有一毫瓦的激光。

麻省理工公开课 - 化学原理课程节选

A special needle is inserted directly into the tumor and light energy is passed through a laser.

VOA: special.2010.11.23

Doctors Charles Campbell and Charles Koester used a laser to remove a tumor from a patient's eye at Columbia-Presbyterian Hospital in New York City.

VOA: special.2010.09.01

(Speaking) With LASIK,doctors use a laser to permanently change the shape of the cornea to improve vision.

VOA: standard.2010.03.03

When a Marine gets hit by a laser beam, his weapon gets de-activated.

VOA: standard.2010.04.06

Lang lives in the San Francisco bay area. He is a laser physicist and graduate of the California Institute of Technology, and has nearly 50 U.S.patents to his name.

VOA: standard.2010.03.17

Before the laser, scientists developed a similar device: a maser which stands for Microwave Amplification by Stimulated Emission of Radiation.

VOA: special.2010.09.01

Laser disc players use lasers to accurately read or write marks on a reflective,coated plastic disc.

VOA: special.2010.09.01

In Theodore Maiman's first laser, a rod of man-made ruby supplied the electrons.

VOA: special.2010.09.01

Their guns are equipped with a special device that emits laser beams each time a Marine pulls a trigger.

VOA: standard.2010.04.06

An Australian company, Electro Optic Systems, has received a $3.5 million government grant to develop the world's first automated, high-precision, laser tracking technology.

VOA: standard.2010.07.24

Its ultimate aim is to build a series of laser tracking stations in various countries to provide a defensive shield for activity in space.

VOA: standard.2010.07.24