The Huygens-Fresnel principle is the main postulate of wave theory , which describes and explains the mechanism of wave propagation, in particular, light .
Description
The Huygens principle is a development of the principle introduced by Christian Huygens in 1678 : each front point (surface reached by a wave) is a secondary (that is, new) source of spherical waves . The envelope of the wave fronts of all secondary sources becomes the wave front at the next time instant.
The Huygens principle in this form explains the propagation of waves, which is consistent with the laws of geometric optics , but it cannot fully, and even more quantitatively, explain the phenomena of diffraction . In 1815, Fresnel supplemented the Huygens principle by introducing the concepts of coherence and interference of elementary waves, which made it possible to consider diffraction phenomena on the basis of the Huygens-Fresnel principle.
The principle of Huygens - Fresnel is formulated as follows:
Each element of the wave front can be considered as the center of the secondary perturbation, generating secondary spherical waves, and the resulting light field at each point in space will be determined by the interference of these waves. |
Gustav Kirchhoff gave Huygens a rigorous mathematical form, showing that he can be considered an approximate form of the theorem, called the Kirchhoff integral theorem .
The front of a point source wave in a homogeneous isotropic space is a sphere . The amplitude of the perturbation at all points of the spherical wave front propagating from a point source is the same.
A further generalization and development of the Huygens principle is the formulation through path integrals , which is the basis of modern quantum mechanics.
See also
- Reflection (physics) / Reradiation
- Farm principle
- Hamilton - Jacobi equation
- Formulation via path integrals
Notes
Links
- Huygens - Fresnel principle // The Great Soviet Encyclopedia : [in 30 t.] / Ch. ed. A. M. Prokhorov . - 3rd ed. - M .: Soviet Encyclopedia, 1969-1978.
- Huygens - Fresnel principle - an article from the Physical Encyclopedia .
- Video, vividly describing the principle of Huygens - Fresnel // Central cinema laboratory of the school film of the RSFSR, Ministry of Education, Moscow.