我们可以把惠更斯原理扩展到二维波以外，以包含三维波，像声波和光波。 The points of constant phase define a surface called the wave surface or wavefront. （空）
The law of reflection applies to both flat and curved surfaces. For a curved surface, the angle of reflection is determined by the angle of incidence between the incident ray and the surface normal at the point where the incident ray strikes the surface.
像差可以通过组合具有适当的曲率半径的不同球面而被减小，但却不能完 全消除。
However, to reduce aberrations of this kind to an acceptable level for optical instruments such as microscopes, binoculars, or cameras, each lens must be made of several thin lenses in combination. （选择）
Chapter 3. Optical Instruments
1.2 Reflection and Refraction(定义、选择）
The normal, the incident ray, and the reflected ray all lie in a plane perpendicular to the reflecting surface, known as the plane of incidence. The light ray does not “turn” out of the plane of incidence as it is reflected.
1.8 Spherical Mirrors Many optical instruments use curved mirrors as
image-forming devices. Curved mirrors, like lenses, are used to focus light and create images.(翻译）
然而，镜子是靠反射光工作，而不是靠折射光，所以 它们的应用是不同的。
光电信息技术专业英语
Chapter 3. Optical Instruments
1.9 Lens Aberrations
Up to now, our discussion of lenses has not taken into account some of the optical imperfections that are inherent in single lenses
当波遇到障碍物，波将被反射；但是如果障碍物有一个缺口，部分波将可 以穿过。 We can extend Huygens’s Principle beyond two-dimensional waves to include three-dimensional waves, such as sound and light.（填空）
geometry of image formation. （翻译）
这些透镜成像的不完美性被称为像差。它们与一个透镜的构成成分或表面 的光滑程度没有任何关系，而是自然地产生于像形成的几何关系。
光电信息技术专业英语
Chapter 3. Optical Instruments
1.9 Lens Aberrations
In optics it is an established convention to measure angles with respect to the normal, which is a line perpendicular to the surface, as indicated in Figure 1.4. The angle between the incoming ray and the normal is called the angle of incidence, θi. The angle between the outgoing ray and the normal is the angle of reflection , θr. Both angles are measured positive from the nomal. When these angles are measured, the angle of reflection is always found to equal the angle of incidence. Thus, the observed law of reflection is that the angle of reflection is equal to the angle of incidence, or θi= θr
As we watch the wavefront expand, we are actually following a series of points of constant phase. Every point along the wave crest all around
the circle has the same phase, and as the wave expands, this circle of constant phase expands. （选择）
当我们看到波阵面伸展的时候，我们实际是在关注着一系列的等位相点。 环周围沿着波峰的每一个点都具有相同位相，并且当波伸展时，等位相圆环 跟着伸展。
光电信息技术专业英语
Chapter 3. Optical Instruments
2.1 Huygens’ Principle（填空）
If the wave encounters a barrier, the wave is reflected; but if the barrier has an opening, part of the wave passes through. （选择）
They may be reduced to an acceptable level, but in general, the reduction of one type of aberration tends to increase another. （翻译）
它们可以被降低至可接受的水平，但是一般而 言，一种像差的降低会使另外一种像差趋向于增 加。
如图1.4所示，在光学上有一个确定的惯例就是说要根据法线来测定角度， 法线是一条垂直于镜面的直线。入射线和法线之间的角叫做入射角θi。出射光 线和法线之间的夹角叫做反射角θr。从法线起这两个角都是正角。测量时，反 射角总是等于入射角。因此，遵循反射定律：反射角等于入射角，即θi= θr
光电信息技术专业英语
法线、入射角、反射角位于一个与反射面垂直的平面，即入射面内。当光 线反射时，它不能偏出这一入射面。
反射定律对于平面和曲面都是适用的。对于一个曲面，反射角的大小由入 射线达到反射面时该点处法线与入射线所成的入射角的大小决定。
光电信息技术专业英语
Chapter 3. Optical Instruments
图1.22所示是为相机设计的镜头。这些透镜 的设计在实际工程中是相当复杂的，但是运用 的基本原理仍然是由斯涅尔公式所决定的折射 定律。
光电信息技术专业英语
Chapter 3. Optical Instruments
2.1 Huygens’ Principle（填空）
We can understand his principle in terms of simple water waves. Suppose we toss a rock into a pond. When the rock hits the water, it generates circular waves that spread out from the point of impact [Fig. 2.1]. （选择） 我们可以从简单的水波来理解他的原理。 假设我们向一个池塘抛一个石块。 当石块击中水面，它将产生从撞击点向外分散的圆形波。
Chapter 3. Optical Instruments
1.2 Reflection and Refraction(定义、选择）
Suppose we shine a beam of light at a mirror. The light strikes the mirror at a point P and is then reflected. What is the direction of the reflected beam? You may know the answer even if you have not formulated it mathematically: The incident and reflected beams make equal angles with the mirror.
然而，为了减小这种由于光学仪器所带来的在允许之内的像差，例如显 微镜，双筒望远镜，或者照相机，每一个镜头必须有几个薄透镜组合而成。
光电信息技术专业英语
Chapter 3. Optical Instruments
1.9 Lens Aberrations
Figure 1.22 shows such a lens designed for a camera. The design of these lenses is quite complicated in practice, but the basic principle used is still that of refraction as determined by Snell’s law. （选择）