(光电信息工程专业英语)专英复习.ppt

If we direct light into one end of a long rod of glass or plastic, the light is totally internally reflected by the walls, bouncing back and forth until it emerges at the far end. 如果我们引导光进入长的玻璃棒或塑料棒的一端，光会被长棒的内壁来回全反射，直到它在另一端出现。 Because their fibers are so flexible, fiber optics light guides and coherent bundles are used in instruments designed to permit direct visual observation of otherwise inaccessible objects. Prime examples are endoscopes, which are used by physicians examine the interior of a patient’s body. 由于光纤的柔韧性好，光纤光导和相干光纤束被用在某些仪器设备，（这些设备）被设计用于对其它不可接触目标的直接可视化观察。 The fibers are less expensive to produce than are copper wires, and they are resistant to noise caused by stray electromagnetic signals. 光纤比铜线便宜，而且它们对杂散电磁信号所产生的噪声有抵抗力。 Thus, we can say that any ray incident on a converging lens and parallel to its optical axis(that is, the symmetry axis of the lens) passes through the focal point upon leaving the lens. 　　因此，我们可以说，任何入射于会聚透镜并平行于光轴的光线在离开透镜后立即通过焦点。 Any light ray entering the converging lens from the left parallel to the optical axis passes through the focal point F on the right after if leaves 　　任何从左侧平行进入会聚透镜的光线，在离开透镜后，通过焦点F。An ordinary piece of flat glass, such as a window with parallel faces, passes light without changing its direction. Although the direction of the ray does not changes, the ray is displaced laterally. 　 A virtual image is formed at a point where the light appears to converge, or from which it appears to come. 虚像在光线看起来会聚的点形成，或者是从这一点发出来的光形成。 虚像在两种位置形成：一种位置是光线看起来要会聚的点（入射光线延长线的交点），另外一种位置是光线看起来是由这一点发出的（出射光线的反向延长线交点） Graphical 图解的，绘画的 Algebraical 代数的 Principal axis　主轴 Lateral or linear magnification 横向或线性放大倍数 一个普通的平面玻璃，例如带有两个平行面的玻璃窗，透过光线而不改变它的方向。虽然方向不改变，但光线会发生侧移。 In either case, an image of the object is formed where light rays that come from points on the object intersect or at the points from which the rays appear to originate. 任何一种情况下，在来自物的光线相交的位置形成图像（实），或在看起来发出光线的点形成图像（虚） We see that what we said earlier about thin lenses is strictl