光的传播使用Geometry.docVIP

Propagation of Light using Geometry光的传播使用Geometry The treatment of light as wave motion allows for a region of approximation in which the wavelength is considered to be negligible compared with the dimensions of the relevant components of the optical system. Huygens Principle惠更斯原理 The Dutch physicist Christian Huygens imagined each point of a propagating disturbance as capable of originating new pulses that contributed to the disturbance an instant later. 荷兰物理学家惠更斯想象一个能够发起新的脉冲干扰瞬间后传播干扰的每一点。 To show how his model of light propagation implied the laws of geometrical optics, he formulated a principle which says that each point on the leading surface of a wave disturbance may be regarded as a secondary source of spherical waves, which themselves progress with the speed of light in the medium and whose envelope at later times constitutes the new wavefront . 为了显示他的光的传播模式如何暗示几何光学的法律，他制定了一个原则，说， 每个点上的龙头表面的波干扰，可作为辅助源的球面波，这本身进步的速度与光在介质和在以后的时间，其信封构成了新的波前 。 Notice that the new wavefront is tangent to each wavelet at a single point. 请注意，新的波前是相切的每一个单点的小波。 According to Huygens, the remainder of each wavelet is to be disregarded in the application of the principle. 根据惠更斯，其余各小波是被忽视的原理与应用。 In so disregarding the effectiveness of the overlapping wavelets, Huygens avoided the possibility of diffraction of the light into the region of geometric shadow. 在如此无视重叠小波的有效性，的惠更斯避免进入几何阴影区的光衍射的可能性。 Huygens also ignored the wavefront formed by the back half of the wavelets, since these wavefronts implied a light disturbance traveling in the opposite direction. 惠更斯也忽略了小波的后半期形成的波前，因为这些波前隐含了光的干扰，在相反的方向行驶。 Despite weaknesses in this model, remedied later by Fresnel and others, Huygens was able to apply his principle to prove the laws of both refection and refraction. 尽管在这种模式下，后由Fresnel和其他补救弱点，惠更斯是能够运用他的原则，以证明便餐和折射的法律。 Law of Reflection from Huygens Principle法惠更斯“原则的反思 The figure illustrates Huygens construction for a narrow, parallel beam of light to prove the law of reflection. 这个数字说明了惠更斯“建设一个狭窄