We know Huygens’ Principle from introductory physics. It tells us that a “new” wavefront of a traveling wave may be constructed at a later time by the envelope of many wavelets generated at the “old” wavefront. One assumes that a primary wave generates fictitious spherical waves at each point of the “old” wavefront. The fictitious spherical wave is called Huygens’wavelet and the superposition of all these wavelets results in the “new” wavefront. This is schematically shown in Figure 3.1. The distance between the generating source points is infinitely small and therefore, integration has to be applied for their superposition.
KeywordsOptical Path Difference Main Maximum Interference Factor Fresnel Diffraction Small Angle Approximation
Unable to display preview. Download preview PDF.