![]() ![]() Again, there is no actualĬhange in propagation for the light passing the aperture, including Principal waves and diffracted waves from within - will create a pattern ofĮnergy distribution behind the aperture. The portion passing through it is separated from the rest of the field,Īnd its energy - this time consisting from both, aperture-shaped Inset top right illustrates the (diffraction) effect of placing obstruction in the light path. ![]() wave interference produces zero amplitude. In terms of phase difference at P, varying cyclically from 0 to 1, the wavefront can be seen as consisting of concentric zones - Fresnel zones - between the circles for which the phase difference is λ/2, i.e. ![]() Wave amplitude at point P is a sum of all wave amplitude contributions from the wavefront containing point M, which are determined by the ray path length from each of these points. It is this second aspect that is relevant for image formation in a telescope. Likewise, the geometrically unobstructed field in the proximity of obstruction will change due to the absence of contribution from the blocked out portion of the field. In the space behind obstruction - the diffraction pattern. Remaining diffracted field creating some form of intensity distribution it merely took out energy of the blocked out principal waves, with the The obstruction did not change anything in the way the light propagates In the "emergence" of this energy in the space behind obstruction. However, these diffracted waves do interfere with both,Īs a consequence of the existence of diffracted waveĮnergy, placing obstruction of some form in the light path will result Preventing them from forming another effective Waves moving in other directions generate phase difference, Principal waves, or wavefronts, form in the direction determined byĮxtending straight lines from the point source. The direction of the wavefront, but also spreading out in other directions (Fresnel's modification to this principle is that intensity of wavelets drops as the angle of deviation from the direction of principal rays increases). Micro-structure of energy field propagation, with the energy advancing in Out in the direction of propagation ( FIG. Every wavefront point is a source of secondary spherical wavelets, which spread ![]()
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