A Research Of Aperiodic Zone Plate And Its Axial Diffraction Characteristics

A zone plate is a kind of special optical diffractive elements,which has a similar focusing way with a traditional refraction lens.Its appearance is a new development in the field of optical imaging,and its unique focusing characteristics have important applications in the fields of spectroscopy,X-ray,near-field and far-field optical microscopy.In recent years,the design and fabricated methods of zone plates have been rapidly developed.Many methods have been proposed to produce zone plates for beam focusing.Some zone plates which can produce multiple focal points along the axis and have high diffraction efficiency have been proposed.In this thesis,three kinds of aperiodic zone plates based on Thue-Morse sequences are proposed,and we study the axial diffraction characteristics of these zone plates.The main contents of this thesis are as follows:Firstly,the development of aperiodic zone plates and the research status at home and abroad are introduced.Then,the design principles,diffraction properties and application fields of several typical zone plates are introduced,and then several fabricated methods of zone plates are introduced.Subsequently,the theoretical support part,which is needed for the research of this article and named as the Scalar Diffraction Theory,is introduced in detail.A generalized Thue-Morse zone plate is proposed.The construction method of the generalized Thue-Morse zone plate is introduced,and its axial diffraction characteristics are analyzed by numerical simulation.The simulation results show that this type of zone plate has two main focal points of equal intensity and multiple secondary focal points along the axial direction,and has the larger focal depth and smaller imaging chromatic aberration,and it also proves that its beam has self-reconstructing property.The composite Thue-Morse-like zone plate and the composite Thue-Morse-like zone plate with superimposed spiral phases are proposed based on the extended sequence of the third-order Thue-Morse sequence.The design principle of the composite ThueMorse-like zone plate is introduced.The axial irradiance of the composite Thue-Morselike zone plate and the transverse irradiance of the composite Thue-Morse-like zone plate with superimposed spiral phases are simulated by MATLAB.The results prove that the composite Thue-Morse-like zone plate can produce two pairs of equal-intensity main foci and the secondary foci,which can produce images with the lower chromatic aberration.the composite Thue-Morse-like zone plate with superimposed spiral phases produces a series of focused vortex beams at the corresponding focal position,which can be widely used in the capture and rotation of particles.A new type of zone plate is proposed based on the three-component Thue-Morse sequence,namely the three-component Thue-Morse zone plate.First,the design principle of the three-component Thue-Morse zone plate is introduced,and the axial intensity distribution,self-reconstructing property and polychromatic behavior of the threecomponent Thue-Morse zone plate are analyzed in simulation and experimental verification.The results show that the three-component Thue-Morse zone plate can produce multiple pairs of focal points with equal intensity,and has self-similarity and self-reconstructing property.Compared with the Thue-Morse zone plate of the same resolution,the three-component Thue Morse zone plate has lower imaging chromatic aberration.