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  • 激光激光

    A scientist in military attire operates a laser system in a controlled research setting.

    A US Air Force scientist operates a laser in a test environment. The United States Air Force Research Laboratory (AFRL) conducts research on a variety of solid-state and chemical lasers. Most types of laser are an inherently pure source of light; they emit near- monochromatic light with a very well defined range of . By careful design of the laser components, the purity of the laser light can be improved more than the purity of any other light source. Lasers are used in spectroscopy, range finding, photochemistry, and microscopy. The m ilitary uses lasers for target designation, communications, and directed weapons.
    ::美国空军科学家在试验环境中操作激光,美国空军研究实验室(AFRL)对各种固态和化学激光进行研究,大多数类型的激光本质上是纯粹的光源;它们发射的光线范围非常明确。通过仔细设计激光部件,激光光的纯度可以比任何其他光源的纯度更高。激光用于光谱、测距、光化学和显微镜。军方使用激光进行目标指定、通信和定向武器。

    Laser
    ::激光激光

    Light is emitted by atoms that have been excited by thermal excitation, electron collision, or collisions with photons of exactly the right frequency. Light is emitted by an incandescent source at many different wavelengths and in all directions. Light produced by an atomic gas consists of only a few different wavelengths but still in all directions.  Both of these light sources produce light waves that are not in step or at the same point in their cycle . Groups of light waves that are not at the same point in their cycle are called incoherent light .
    ::光是由原子释放的,这些原子因热振动、电子碰撞或与极右频率的光子碰撞而激动。光是由不同波长和各个方向的白光源释放的。原子气体产生的光只由几个不同的波长组成,但始终是各个方向。这两种光源产生的光波都不在它们的周期中步态或同一点。循环中不同点的光波群被称为不连贯的光。

    Einstein considered what would happen to an atom already in an excited state that is struck by another photon of the same energy as the original photon that put the atom in the excited state. He showed that the atom will emit a photon of the same energy and go to a lower state. This process is called stimulated emission . The two photons leaving the atom will not only have the same wavelength, they will also be in step (at the same point in their cycle). Either of the two photons can now strike other excited atoms and produce additional photons that are also in step. This group of light rays are called coherent light . A device that produces such light was invented in 1959 and is called a laser .  The word laser is an acronym. It stands for L ight A mplification by S timulated E mission of R adiation.
    ::爱因斯坦考虑过一个已经处于兴奋状态的原子将会发生什么事情,这个原子被另一个将原子置于兴奋状态的原始光子的同一能量光子击中,这与最初的光子将原子置于兴奋状态相同。他显示原子将释放出一个同一能量的光子,然后进入较低状态。这一过程被称为刺激性排放。离开原子的两颗光子不仅具有相同的波长,而且将处于同一周期的同一点。两颗光子中的任何一个现在都可以击中其他振动原子,并产生其他也处于步态的光子。这组光线被称作连贯光线。产生这种光的装置是1959年发明的,被称作激光。激光是一个缩写词。它代表了辐射感应的光度增光。

    A continuous electric discharge like that in a neon sign can be used to put atoms in the excited state. The laser light resulting from this process is continuous rather than pulsed. The helium-neon lasers often seen in science classrooms and used as laser pointers are continuous lasers. The photons emitted by the atoms are collected by placing the glass tube containing the atoms between two parallel . One mirror reflects all the light striking it while the other mirror allows some small percentage of the light to pass through. The light which passes out of the tube produces the laser beam.
    ::连续的电放电,如射线标志中的连续电放电,可以用来将原子置入兴奋状态。由这一过程产生的激光光线是连续的,而不是脉冲的。科学教室中经常看到并作为激光指示器使用的氦-纳米激光是连续的激光。原子释放的光子是通过在两个平行的原子之间放置装有原子的玻璃管收集的。一个镜子反映所有照射的光线,而另一个镜子则允许一小部分的光线通过。射出管的光线产生激光光束。

    Laser light is highly directional because of the parallel mirrors. The laser beam is very small, typically around  1 2 mm in diameter. The light is monochromatic , coherent, and very intense. The concentrated power of laser light is used in a variety of ways. In medicine, lasers can be used to repair the retina in an eye. Lasers can also be used in surgery in place of a knife to cut flesh with little loss of blood (the laser cauterizes as it cuts). In industry, lasers are used to cut steel and to weld materials together. Lasers may, in the future, be used to start nuclear fusion reactions.
    ::激光光因平行镜像而具有高度方向性。激光束非常小,直径一般约为12毫米。光是单色的、连贯的和非常密集的。激光光的集中力量被以多种方式使用。在医学上,激光可以用来修复眼睛的视网膜。激光也可以用在手术中,用刀来切除肉部,略微丧失血迹(激光阴化)。在工业中,激光用来切割钢和焊接材料。激光今后可能用来引发核聚变反应。

    Summary
    ::摘要

    • The word laser is an acronym. It stands for L ight A mplification by S timulated E mission of R adiation.
      ::激光一词是一个缩略语,代表辐射辐射刺激释放的光放大。
    • A continuous electric discharge like that in a neon sign can be used to put atoms in the excited state.
      ::持续电流释放,如在电线符号中的电流释放 可以用来把原子放在兴奋状态中。
    • The helium-neon lasers often seen in science classrooms and used as laser pointers are continuous lasers.
      ::在科学教室中经常看到并用作激光指示器的激光是连续激光。
    • The photons emitted by the atoms are collected by placing the glass tube containing the atoms between two parallel mirrors. One mirror reflects all the light striking it while the other mirror allows some small percentage of the light to pass through. The light which passes out of the tube produces the laser beam.
      ::原子释放的光子是通过将装有原子的玻璃管放在两面平行镜像之间来收集的。一面镜子反映所有撞击它的光线,另一面镜子则允许一小部分光线通过。通过管外的光线产生激光束。
    • The light from a laser is monochromatic, coherent, and very intense.
      ::激光发出的光是单色的、连贯的和非常强烈的。

    Review
    ::回顾

    1. A laboratory laser has a power of only 0.0008 watts. Such a laser seems more powerful to us than a regular 100 watt light bulb. Suggest a reason for this.
      ::实验室激光只有0.008瓦的功率。对我们来说,这种激光比正常的100瓦的灯泡更强大。这说明原因。
    2. A device like a laser, that emits microwave radiation is called a maser . What words are likely to make up this acronym?
      ::发射微波辐射的像激光一样的装置被称为磁铁。 这个缩略语的缩略语可能包括什么词?
    3. What do you call an atom whose electrons have reached a higher energy state?
      ::你说一个电子达到更高能量状态的原子叫什么?
    4. When an electron moves from a higher energy level to a lower energy level, what is emitted by the atom?
      ::当电子从更高的能源水平升至较低的能源水平时,原子会释放出什么?

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

     

      

    1. What substance was used to make the first laser?
      ::用什么物质制造第一枚激光?
    2. What additions are needed on the ruby tube to get a narrow beam of light?
      ::红宝石管需要增加什么来获得狭窄的光束?
    3. What medical procedure using lasers is mentioned in the video?
      ::视频中提到了什么使用激光的医学程序?