![]() This same factor leads to many technical difficulties in studying the wave properties of other objects. Therefore, the diffraction of sound, seismic, and radio waves for which this condition is almost always satisfied (X extends from approximately a meter to a kilometer) can be easily observed, while it is much more difficult to observe the diffraction of light (λ ~ 400-750 nanometers) without special devices. Diffraction is observed most distinctly in those cases when the size of the obstacles being rounded is commensurate with the wavelength. When the number of equally spaced slits (the diffraction grating) is large, sharply separated directions of mutual wave amplification result.ĭiffraction depends significantly on the ratio between the wavelength λ and the size of the object that causes diffraction. As the number of slits increases, the maxima become narrower. If the screen has two small apertures or slits, the diffracting waves are superimposed on one another and, as a result of wave interference, produce a spatially alternating distribution of the amplitude maxima and minima of the resultant wave with smooth transitions from one to the other. Therefore, by placing a screen with a small aperture (having a diameter on the order of the wavelength) in the path of the waves, we will obtain in the aperture of the screen a source of secondary waves from which a spherical wave is propagated, also entering the region of the geometric shadow. According to this principle, in considering the propagation of a wave, every point of the medium that this wave has traversed may be considered a source of secondary waves. Diffraction can be explained in the first approximation by using the Huygens-Fresnel principle. The reception of radio signals in the long-wave and medium-wave bands far beyond the limits of direct visibility of the radiating antenna is due to the diffraction of radio waves around the surface of the earth.ĭiffraction is a characteristic feature of the propagation of waves regardless of their nature. The possibility of hearing the voice of a person around the corner of a house is due to the diffraction of sound waves. Because of diffraction, waves bend around obstacles, penetrating into the region of the geometric shadow. As acoustic wave frequency exceeded 10 MHz most of the liquids reached Bragg regime before these crystals.Phenomena observed when waves pass by the edge of an obstacle and which are associated with a deviation of the waves from rectilinear propagation upon interaction with the obstacle. ![]() For acusto-optic diffractions in liquids, sound velocity plays an important role in Bragg regime with Q increasing with increasing acoustic frequency. ![]() Klein Cook parameter with the change of acoustic wave frequency was investigated for liquids with refractive index in the range1.3-1.7 and their diffraction patterns were compared with practically applicable acusto-optic crystals. ![]() A slight variation of the incident angle from Bragg angle had a considerable effect on Bragg diffraction pattern. Higher value of Klein Cook parameter gave Bragg diffraction and ideal Bragg diffraction was obtained for Q ~100. The ideal Raman-Nath diffraction slightly deviated when the Klein Cook parameter was increased from 0 to 1 for low phase delay values and for large phase delay, the characteristics of the Bessel function disappeared. With optimized parameters for Q, incident light wave length of λ = 633 nm, sound wave length of Λ = 0.1 mm, acusto-optic interaction length L=0.1 m, and refractive index of the liquid in the range of 1 to 2, the existence of ideal Raman-Nath and Bragg diffractions were investigated in terms of phase delay and incident angle. For the acusto-optic interactions in liquids, an equation for the diffraction light intensity was obtained in terms of Klein Cook parameter Q. ![]()
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