ABSTRACT
The Huygens–Fresnel principle provides a good basis for understanding and predicting the propagation of light. Although there are some limitations and different views as to whether it accurately represents reality, this principle is consistent with many experimental observations and can explain diffraction effects fairly well. A diffraction grating is an optical element that splits and diffracts light into several beams traveling in different directions. A repetitive array of diffracting elements has the effect of producing periodic alterations in the amplitude, phase, or both of the light. X-ray diffraction is a very powerful, nondestructive tool for analyzing crystalline materials. The diffraction pattern, characterized by the direction and intensity of the diffracted beams, is characteristic of the matter and its internal structure. Electron diffraction is most frequently used to study the crystal structure and phase of solids. The periodic structure of a crystalline solid acts as a diffraction grating, scattering the electrons in a predictable manner.
