The Characteristics Study Of Bessel Beams And Its Imaging Applications

Academic dissertation firstly studied the characteristics of Bessel beams, taking the high-order Bessel beams as sample, to comparatively study the periodic Bottle beams produced by the focusing of ideal axicon and vaulted axicon to Bessel beams with the use of stereo microscope and CCD imaging system to measure the spot separately. In addition to this, based on the characteristics of the Bessel beams, this paper analyzed the impact of line focusing characteristics of axicon to the focal depth of imaging system, and designed a non-coherent light of Bessel beams imaging system to apply the Bessel beams in the imaging system. The main contents include:(1)To analyze the application of optical measurement instrument stereoscopic microscope and CCD imaging system in the measurement of high order Bessel beams of luminous. By taking the high order Bessel beams produced by incoherent LED green luminous passing through spiral phase plate and axicon as example, simulate the luminous intensity distribution of section along different distance of axis and compare with the corresponding experimental parameters(such as: Maximum non-diffracted distance, the diameter of central dark spot, etc.). The numerical simulation and experiment results show that both the stereo microscope and CCD imaging system can measure the spot of the Bessel beams, and the measurement results are the same. But the larger faculae error by using stereo microscope to measure will affect the accuracy of measurement results.(2)To infer the luminous intensity expression of Bessel beams luminous through ideal axicon and vaulted axicon based on the generalized Huygens-Fresnel diffraction integral theory, and to describe the propagation characteristics of Bessel beams of ideal axicon and vaulted axicon, numerically simulate the luminous intensity distribution and radial luminous intensity distribution of different sections. The results of numerical simulation show that both ideal axicon and vaulted axicon can produce Bottle beams, but compared to the ideal axicon, the period of the Bottle beams produced by the vaulted axicon is shorter, the central luminous intensity is stronger and the dark spot is smaller.(3)To analyze the axicon line focusing and lens point focusing two imaging system on the basis of Fourier optics theory and the lens imaging theory, and discuss their impact on the depth of focus of the imaging system. To simulate the cross-sectional optical intensity distribution in different axial distance by using ZEMAX optical design software. With blue LED as the luminous source, experiencing these two imaging system and shooting the cross-sectional optical intensity distribution in different axial distance. The results show that the line focus features axicon has, can converge the luminous continuously on the different positions along the axis. With high-definition images, there is a greater depth of focus without focusing diffraction-free, the theoretical analysis, simulation and experimental results coincide with each other.(4)Designed an imaging system of Bessel beams with non-coherent luminous, derived from diffraction integral theory of the luminous distribution after the parallel luminous entering into axicon, analyzed the point spread function of imaging system after adding axicon with the incoherent illumination, then exported the resolution of imaging system according to Rayleigh criterion. Carrying out analogue simulation to the initial structural model of Bessel beams imaging system by using the design of ZEMAM software to stimulate the cross-sectional view of imaging, the distribution diagram of radial luminous and the modulation transfer function(MTF) curve. Finally, to validate the experimentation. Taking the blue LED as a luminous source and adding collimating beam expanding system and axicon optics to shoot imaging picture by using stereo microscope(including digital cameras).The theoretical analysis, simulation and experimental results all demonstrate the use of Bessel beams imaging system can improve the resolution of imaging system.