章节大纲

  • 常规

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  • 光学仪器

    Close-up of colorful optical fibers transmitting light, illustrating modern communication technology.

    This colorful burst of “spaghetti” is really a bundle of optical fibers. These are hair-thin threads of glass that transmit laser light that has been encoded with messages. Optical fibers are a crucial component of modern communications. The use of light in devices such as these is possible because of optics .
    ::光纤是光纤的结合。 光纤是用电文编码的激光光传递激光光的玻璃发光线。 光纤是现代通信的重要组成部分。 在光学设备中使用光是可能的。

    Optics and Optical Instruments
    ::光学和光学仪器

    Optics is the study of visible light and the ways it can be used to extend human vision and do other tasks. Knowledge of light was needed for the invention of optical instruments such as microscopes, telescopes, and cameras, in addition to optical fibers. These instruments use and to reflect and refract light and form images.
    ::光学是对可见光的研究,是利用光来扩展人类视线和完成其他任务的方法,除了光纤之外,光学仪器,如显微镜、望远镜和照相机的发明也需要有光学知识,这些仪器用于反射和折射光和成形图象。

    Q: What is an image?
    ::问题:什么是图像?

    A: An image is a copy of an object created by the or of visible light.
    ::A:图像是由可见光创造或可见光产生的物体的复制件。

    Light Microscope
    ::轻型显微镜

    A light microscope is an instrument that uses lenses to make enlarged images of objects that are too small for the unaided eye to see. A common type of light microscope is a microscope, like the one shown in the Figure . A compound microscope has at least two convex lenses: one or more objective lenses and one or more eyepiece lenses. The objective lenses are close to the object being viewed. They form an enlarged image of the object inside the microscope. The eyepiece lenses are close to the viewer’s eyes. They form an enlarged image of the first image. The magnifications of all the lenses are multiplied together to yield the overall magnification of the microscope. Some light microscopes can magnify objects more than 1000 times! 
    ::光显微镜是一种工具,它使用透镜来制作无辅助眼睛无法看见的物体的放大图像。光显微镜的常见类型是显微镜,如图中所示。复合显微镜至少有两个锥形镜:一个或两个以上的客观镜片和一个或多个眼镜片。客观镜片接近所观察的物体。它们形成显微镜内物体的放大图像。眼镜眼部接近观察者的眼睛。它们形成第一个图像的放大图像。所有镜片的放大作用都结合在一起,产生显微镜的总体放大作用。一些光显微镜可以放大超过1000倍的物体。

    A compound light microscope, showing lens arrangement and main components.

    Q: How has the microscope advanced scientific knowledge?
    ::问题:显微镜先进的科学知识如何?

    A: The microscope has revealed secrets of the natural world like no other single invention. The microscope let scientists see entire new worlds, leading to many discoveries—especially in biology and medicine—that could not have been made without it. Some examples include the discovery of cells and the identification of bacteria and other single-celled organisms. With the development of more powerful microscopes, viruses were discovered and even atoms finally became visible. These discoveries changed our ideas about the human body and the nature of life itself.
    ::A:显微镜揭示了自然世界的秘密,不像其他任何单一发明那样。显微镜让科学家们看到整个新的世界,导致许多发现——特别是在生物学和医学方面——没有它就无法发现。一些例子包括发现细胞和辨别细菌和其他单细胞生物。随着更强大的显微镜的开发,病毒被发现,甚至原子最终变得可见。这些发现改变了我们对人体和生命本身的性质的看法。

    Launch the PLIX Interactive below to further explore the parts of a microscope:
    ::启动下面的PLIX互动 以进一步探索显微镜的部分:

    Telescope
    ::望远镜

    Like microscopes, telescopes use convex lenses to make enlarged images. However, telescopes make enlarged images of objects—such as distant stars—that only appear tiny because they are very far away. There are two basic types of telescopes: reflecting telescopes and refracting telescopes. The two types are compared in the Figure . They differ in how they collect light, but both use convex lenses to form enlarged images.  
    ::望远镜与显微镜一样,使用显微镜制作放大图像。然而,望远镜制作物体(如遥远的恒星)的放大图像,这些物体看起来很小,因为它们非常遥远。望远镜有两种基本类型:反射望远镜和反射望远镜。图中比较了这两种类型。两种类型在收集光方面有所不同,但两者都使用显微镜形成放大图像。

     

    Comparison of Cassegrain and Newtonian telescopes, highlighting their mirror configurations and light paths.

    Play around with a Cassegrain Telescope in the simulation below and see if you can adjust the sliders to  create a clear view of Jupiter in the eyepiece:
    ::在下面的模拟中与 Cassegrain 望远镜一起玩耍, 看看是否可以调整滑动器, 在眼镜中清晰可见木星 :

    Camera
    ::相机相机

    A camera is an optical instrument that forms and records an image of an object. The image may be recorded on film or it may be detected by an electronic sensor that stores the image digitally. Regardless of how the image is recorded, all cameras form images in the same basic way, as shown in the Figure .
    ::相机是一种光学仪器,它形成并记录物体的图像。图像可以录制在胶片上,也可以通过电子传感器通过数字存储图像而探测到。无论如何记录图像,所有相机都以与图所示的相同的基本方式形成图像。

    • Light passes through the lens at the front of the camera and enters the camera through an opening called the aperture.
      ::光从镜头前的镜头中穿过镜头,通过一个称为孔径的开口进入相机。
    • As light passes through the lens, it forms a reduced real image. The image focuses on film (or a sensor) at the back of the camera. The lens may be moved back and forth to bring the image into focus.
      ::当光穿过镜头时, 它会形成一个被缩小的真实图像。 图像的焦点是相机后部的胶片( 或传感器) 。 镜片可能会被回移来回移动, 使图像聚焦 。
    • The shutter controls the amount of light that actually strikes the film (or sensor). It stays open longer in dim light to let more light in.
      ::百叶窗控制着实际击中胶片( 或感应器) 的光量。 它在暗光中保持更长的开放时间, 以便让更多光进入 。

    Diagram explaining how a camera forms an image, showing lens, aperture, and film.

    Lasers
    ::激光激光

    Did you ever see a cat chase after a laser light, like the one in Figure ? A laser is a device that produces a very focused beam of visible light of just one and color. Waves of laser light are synchronized so the crests and troughs of the waves line up. The diagram in Figure shows why a beam of laser light is so focused compared with ordinary light from a flashlight.
    ::你曾经见过像图中那样的激光光之后的猫追逐吗?激光是产生一个非常有焦点的光束的光束的装置,光束只有一个和颜色。激光光线波是同步的,因此是波的柱子和槽。图中的图示显示了激光光束为什么与手电筒的普通光束相比如此集中。

    A cat reaching for a laser light beam, illustrating focused light compared to normal light.

    The following Figure provides a closer look at the tube where laser light is created. Electrons in a material such as a ruby crystal are stimulated to radiate photons of light of one wavelength. At each end of the tube is a concave mirror. The photons of light reflect back and forth in the tube off these mirrors. This focuses the light. The mirror at one end of the tube is partly transparent . A constant stream of photons passes through the transparent part, forming the laser beam. 
    ::下图更仔细地查看产生激光光的管。 象红宝石晶体这样的材料中的电被刺激为辐射一个波长光的光。 管的每个端都是一个凝固镜。 光的光反射成份会回反射到这些镜面的管中。 这让光线集中。 管的一端的镜片部分是透明的。 光子的源源不断流通过透明部分, 形成激光光束 。

    The structure and components of a laser.

    Optical Fibers
    ::光纤

    Besides entertaining a cat, laser light has many other uses. One use is carrying communication signals in optical fibers. Sounds or pictures are encoded in pulses of laser light, which are then sent through an optical fiber. All of the light reflects off the inside of the fiber, so none of it escapes. As a result, the signal remains strong even over long distances. More than one signal can travel through an optical fiber at the same time, as you can see in the Figure . Optical fibers are used to carry telephone, cable TV, and Internet signals.
    ::除了娱乐猫以外,激光光还有其他许多用途。 一种用途是携带光纤中的通信信号。 声音或图片在激光光脉冲中编码, 然后通过光纤发送。 所有光线都从纤维内部反射, 因此都无法逃脱。 因此, 信号即使长距离仍然很强。 正如图中所示, 不止一个信号可以同时通过光纤传递。 光纤被用来携带电话、有线电视和互联网信号。

    Light reflection in an optical fiber's core, illustrating communication signal transmission.

    The optical fiber in the diagram is much larger than a real optical fiber, which is only about as wide as a human hair.
    ::图表中的光纤比真的光纤大得多, 光纤和人的头发一样宽。

    Q: When lasers were invented in 1960, they were called "a solution looking for a problem.” Since then, they have been put to thousands of different uses. Can you name other ways that lasers are used?
    ::问:当激光于1960年发明时,它们被称为“寻找问题的解决方案 ” 。 从那时起,它们被投入了数千种不同的用途。 你能说出激光的其他使用方式吗?

    A: The first widespread use of lasers was the supermarket barcode scanner, introduced in 1974. The compact disc (CD) player was the first laser-equipped device commonly used by consumers, starting in 1982. The CD player was quickly followed by the laser printer. Some other uses of lasers include bloodless surgery, cutting and welding of , guiding missiles, thermometers, laser light shows, and acne treatments.
    ::A:首次广泛使用激光器是1974年推出的超市条形码扫描仪,光盘机是消费者自1982年起常用的第一台激光装置,光碟机很快被激光打印机跟踪,激光器的其他一些用途包括无血外科手术、切割和焊接、制导导弹、温度计、激光光学显示和肛门治疗。

    Summary
    ::摘要

    • Optics is the study of visible light and the ways it can be used to extend human vision and do other tasks. Optical instruments are based on optics. They use mirrors and lenses to reflect and refract light and form images.
      ::光学仪器以光学仪器为基础,使用镜子和镜头反射和折射光和成形图像。
    • The light microscope and telescope use convex lenses and mirrors to make enlarged images of very tiny or distant objects. A camera uses a convex lens to make a reduced image of an object.
      ::光显微镜和望远镜使用显微镜和镜像制作非常微小或遥远物体的放大图像。相机使用显微镜制作一个物体的缩小图像。
    • A laser is a device that produces a very focused beam of visible light of just one wavelength and color. Pulses of laser light carry communication signals through optical fibers.
      ::激光是一种设备,它产生一个非常集中的光束,其可见光光束只有一个波长和颜色,激光光脉冲通过光纤传递通信信号。

    Review
    ::回顾

    1. Define optics.
      ::定义光学。
    2. Explain how a compound microscope uses convex lenses to make an enlarged image of a tiny object.
      ::解释一个复合显微镜如何使用显微镜来放大一个微小物体的图像。
    3. Compare and contrast reflecting and refracting telescopes.
      ::比较和对比反射和折射望远镜。
    4. Write a paragraph explaining how a camera works. Assume you are explaining it to a much younger student. Draw a sketch as a visual aid.
      ::撰写一段解释相机如何工作的段落。 假设您正在向年轻得多的学生解释。 绘制草图作为视觉帮助 。
    5. Explain how reflection is involved in the production of laser light.
      ::解释激光光的产生是如何涉及反射的。
    6. How are optical fibers used?
      ::如何使用光纤?