| In this paper,the theory and the design method of the phase type reticle of holographic sight has been studied,the purpose is to design the pure phase type diffractive optical element with surface relief structure to realize the function of the traditional holographic sight reticle.Based on the working principle of holographic sights,the theory of computer generated hologram and diffractive micro-optics,the imaging theory of the phase type holographic sight reticle has been analyzed,the mathematical model of the diffractive light field has been established,and the design method of the surface phase structure of the reticle has been studied.On the basis of theoretical research,the diffractive structures of the holographic sight reticle and the snowflake pattern have been designed respectively.Considering the characteristics of the lithography process,the quantitative structures with 2-steps and 4-steps have been given.The reconstruction image has been simulated by MATLAB software.The sample elements have been made,and the holographic reconstruction experiment have been carried out.Theoretical results show that the reconstruction image of the desired image could be obtained by controlling the height and width of micro-structures on the surface of recording medium material with a certain refractive index.The diffractive structure have been designed by using two different methods under the different principle of kinoform and hologram,the minimum feature size of the diffractive structures are 8μm and 16μm respectively.Also,the theoretical calculation results and the reconstruction simulation results show that the design method of the pure-phase type computer-generated-hologram is feasible in the case of un-considering fabrication errors.This method can also be used to design the pure-phase type computer-generated-hologram of other specific patterns.It can also be used to design diffractive optical elements for beam shaping.The phase type reticle with surface relief structure is convenient to replicate.It is suitable for mass production in the future.Also,to overcome the shortage of the traditional holographic element on quality stability and short service life.It provides a way to develop the new holographic elements with new applications widely. |
