Study On Holographic Waveguide Technology For Helmet Display System

With the continuous development of display technology,helmet display technology has shown tremendous potential for development in many fields such as military,entertainment,and medical care.Nowadays helmet display is mostly based on goggles imaging.However,in the actual wearing process,due to its large and heavy internal optical system,it may cause serious head discomfort.In order to overcome these shortcomings,many new types of helmet display technologies have been proposed.Compared with the conventional helmet display,they have the advantages of light weight and small size.The holographic waveguide display technology is the latest helmet display technology.However,due to the lack of knowledge accumulation of related technologies,holographic waveguide display technology still has problems such as low utilization of light energy and inability to realize colorful display.In this dissertation,a grating structure is designed to solve the problem of low utilization of light energy,which can improve the diffraction efficiency of the grating at a lower cost,and improve the light efficiency and reduce the cost.In this dissertation,the related principles of holographic waveguide display technology and diffraction theory are described firstly,and the relationship among parameters such as spatial frequency,wavelength,waveguide refractive index and incident angle of holographic grating is analyzed.Then,using the design method of scalar diffraction theory,the microstructure of the surface of the grating is designed,which is then simulated using the vector diffraction theory.Based on the simulation results,the surface structure of the grating is optimized,and the latitude of the grating structure is analyzed using scalar theory.Finally,according to the final design results,the corresponding gratings were prepared by maskless direct-write lithography.The holographic waveguide system with such grating was tested.The test results show that the diffraction efficiency of the grating reaches 50% when the incident angle is 0°.The diffraction efficiency reaches 40% when the incident angle is 56°.The efficiency of the final system is more than 10% higher than that of a common holographic waveguide system.The designed grating can satisfy the initial requirements.