The Application Of Bessel Function In Beam Generation And Edge Enhancement Imaging

In recent years,with the theoretical development of laser optics has gradually matured,laser has been widely used in optical communication,information transmission,medical and health care and other fields.Bessel beam which is an exact solution of the Helmholtz equation,has attracted the attention of many researchers.Bessel function is an important mathematical tool in laser optics.Based on Bessel function's practical application and mature theoretical framework,this paper studies the application of Bessel function in the field of new beam generation and edge enhancement imaging.Firstly,a new beam is studied in detail by means of Fourier transform and angular spectrum transfer theory,which is two-index Bessel beams(TIBBs).Its light field distribution and transmission characteristics are analyzed,It is found that this beam is the linear superposition of multiple Bessel beams,and it also shows the propagation characteristics of periodic self-replication.In the experiment,because the ideal Bessel beam cannot be generated,we designed an experimental device to produce two-index Bessel-Gauss beams(TIGBGs).Such a beam is the result of TIBBs truncated by a Gaussian envelope.Therefore,the properties of TIBBs will be retained at a certain propagation distance.Experimental results also confirm our theoretical expectations.Secondly,due to the lack of theoretical guidance to design optimal filter,imaging results often appear diffraction noise in edge enhancement imaging.Therefore,by means of convolution theory,we propose a method to optimize the spatial filter of edge enhancement imaging system.It is found that when the real and imaginary parts of the point spread function of the filter have no superfluous side lobe and the width of the main lobe is as small as possible,the resolution and contrast of the image will be higher.The design principle of filter is described in detail,and an optimal filter is designed.Experimentally,both phase and amplitude objects are used to verify that the optimal filter can indeed achieve high contrast edge enhancement imaging with high resolution.Finally,the Bessel amplitude filter(BAP)is studied and it was found that there are two higher resolution edge images in the image.