The Bessel Beam Imaging System And The Characteristics Of Image Information Carried By The System

This thesis studied on long-distance Bessel beam,and designed two kinds of optical systems with long-distance non-diffracting Bessel beams,then introduced their advantages in detail.Studied the resolution and the characteristics of carrying the image information of the Bessel beam imaging system,either.The research content mainly includes:1?Based on traditional axicon method and geometric optical effects of concave lens,two new optical system improving the Bessel beam's diffraction-free distance were designed,the optical fields' formula of beam propagating through improved system was deduced,according to scalar diffraction theory.Due to the diverging characteristics for concave lens,placed the concave lens in front or in rear of the axicon,and simulated this program with Trace Pro,set up optical path to experiment in the laboratory,then compare with traditional axicon method,some conclusions were gotten: either the concave lens in front or in rear of the axicon,can achieve the effect of increasing the non-diffraction distance.Therefore,we can choose a certain curvature radius of the concave lens and the position according to actual requirements to obtain the Bessel beam with a longer diffraction free distance and higher quality.The results of the study has guiding significance in the application of optical imaging and barcode scanning.2?As coherent and incoherent light sources can produce approximately Bessel beam through the pyramid,this chapter studied the effect on the resolution of the imaging system by light sources during the process of non-diffracting beam imaging.Fraunhofer diffraction by a circular aperture with pupil,obtained different point spread function of imaging system,and simulating by MathCAD.Using coherent 632.8nm He-Ne laser and blue LED incoherent with center wavelength 458.5nm?half-peak bandwidth 24.5nm as sources,setting up an experimental device for experiment,and comparing the experimental results and the numerical simulation,the stripes image is more uniform?clearer and higher resolution in the incoherent source,it means the effect of incoherent light source is better than coherent one.3?With image information in the incident plane wave,the optical fields' formula of information propagating through the non-diffraction beam imaging system was deduced.Based on Kirchhoff diffraction formula and Fresnel diffraction formula's Angular Spectrum theory,the intensity distribution of receiving screen has been described in Fourier method.After adding Sellmeier formula and sampling,a discrete Fourier formula has been derived;set related parameters and simulated with MATLAB,the results show the intensity distribution indifferent propagation distances.Set up optical path to experiment,and observed results by CCD,then compared to simulation show that: the image in film can be observed clearly and fully after through axicon,when the transmission distance within 100 mm.The experimental results are in fair agreement with the numerical simulation?It is meaningful for optical imaging to study how the system carry information.This thesis has important significance for improving the quality and expanding the application of Bessel beam,also can help exploring high-resolution imaging system,and the study result will have important application value in imaging quality and the integrity of image information carried by system,after a special optical elementaxicon added to the system.