No Diffraction Bessel Beam Transmission And Transformation

"Non-diffraction beam"was first proposed by J. Durnin in 1987, it is a specific solution of the free-space wave equation, and its field distribution has a Bessel-like form. When it propagates in the free-space, its intensity and patterns behind the axicon will keep constant, so J. Durnin name it as"non-diffraction beam". It was confirmed by many experiments and used in many different aspects.In this thesis, the properties of the free-space propagation and focus were studied when a beam propagates through an axicon. Based on Huygens-Fresnel diffraction integral theory, the propagation properties of Bessel beam were studied in this paper. By using the analyses of geometrical optics, hollow beam are found and the formula of the starting point,the end point and the bottle length can be got. In the experiment, we use the He-Ne laser and the semiconductor laser as the source, record the Bessel beam patterns behind the axicon by using a digital camera and a microscope, measure the radius of the Bessel beam central spot by film-scanning and measure the effect of both the radius of the aperture and the open angle of the axicon on the maximum non-diffraction distance. The experiments show that a specific propagating range has constant power and the beam has a Bessel-like distribution in this range. The results agree with the beam corresponding to a diffraction free beam. As the diffraction-free beam were focused by a lens, it became a bottle...