Axicon Novel Optical Element-based Design And Its Characteristics

In this thesis, several new optical elements are designed, including novel axicon,Step refractive index axicon,combined positive axicons and helical axicon, and their optical propagation properties are analyzed, The reconstructions of Bessel beam with an annular obstacle and focused high order Bessel-Gauss beams are studied either, the main results are summarized as following:1. A new type of optical element --- combined axicon was proposed for generating non-diffracting Bessel beams, this element is designed with gluing positive and negative axicon. Its property is the same as single positive axicon for beam transformation, and equivalent cone angle is decided by the cone angle difference of positive and negative axicon, therefore, we can get smaller cone angle by combining positive and negative axicon with comparatively large cone angle for each axicons, also get longer non-diffracting distance. The numerical calculation results show that the combined axicon can transform plane wave to Bessel beam. The optical field distribution behind combined axicon was also simulated by Zemax software, Research results open a new way for generating non diffracting Bessel beams with a longer non-diffracting distance.2. Step refractive index axicon and combined positive axicons for generating Bottle beam is designed, they have advantages of simple structure and easy processing. The optical field distribution and 2D light spot image in different propagation distance behind two kinds of axicons are numerical simulated by the diffraction integral theory. Research results show the significant guidance for the practical applications of the bottle beam.3. Based on Hankel waves theory and geometric optical theory, the reconstruction of Bessel beam disturbed by an annular obstacle is studied, non-diffracting beam disturbed by annular obstacle is simulated with Zemax software, the cross sections intensity distribution at different place on axis behind annular obstacle is stimulated, the experiment is designed, and the result agrees with the simulation. The theoretical analysis and experimental results both show that reconstruction of Bessel beam with an annular obstacle can generate Bottlte beam with zero central optical intensity.4. Reconstruction of focused high order Bessel-Gauss beams by using thin lens is proposed. Based on the diffraction theory, reconstruction behavior of focused high order Bessel-Gauss beams is analyzed. The three dimensional optical intensity distribution and the cross section optical intensity distribution of the high order Bessel-Gauss beam focused by first thin lens, and then reconstructed by the second thin lens are numerical simulated. Result shows that the high order Bessel-Gauss beams pass through the single thin lens can generate Bottle beam. To rectify the beam divergence after focus, another thin lens is introduced at suitable position. After that, the beam keeps the Bessel distribution.