| Augmented reality head-mounted display is a near-eye display used to overlay virtual images onto ambient scenery.It has been applied to military and civil operations in recent years.Now the development tendency of head-mounted display is miniaturization,light weight and full-color.Therefore,some improvement should be made in system size,weight,image quality and display brightness.The study is concerned with holographic waveguide system and micro-display of head-mounted display.The modulation mechanism of micro/nanostructures on electromagnetic waves,the diffraction characteristics of novel gratings,the frequency selectivity property and polarization conversion mechanism of metasurfaces are investigated based on Grating Theory,General Snell’s Law and Surface Plasmon Theory.The optical characteristics of micro/nanostructures and their applications in head-mounted display are explored though Rigorous Coupled-wave Analysis and Finite Element Method.The diffraction,spectra and stray light characteristics of monochromatic and multiplexing volume holographic grating is studied,and the refractive index equation of multiplexing volume holographic grating is derived.Then,the diffraction efficiency is improved and the stray light is suppressed by optimizing structure parameters.Finally,a novel full-color hologhraphic waveguide system based on multiplexing volume grating is proposed with high out-coupling diffraction efficiency,little stray light,and uniform red,green and blue light.The diffraction performances,spectra characteristics and luminance efficiency of double-layer coupled grating is studied,and its Bragg condition is derived.Then,the diffraction and luminance efficiency is improved by optimizing metal grating geometry.Finally,a novel monochromatic hologhraphic waveguide system based on double-layer coupled grating is proposed with high luminance efficiency.The resonance principle of metasurface cavity and the polarization conversion mechanism is studied.Then,the optical characteristics and electrical modulation method of metasurface cavity is investigated.Also,the filter band and efficiency is optimized.Finally,a novel metasurface color filter with continuously electro-optical modulation is proposed,which realizes dynamic filtering with high reflectivity and narrow band.Based on the above metasurface color filter,the display principle and driving method of the super-high resolution full-color micro-display is studied.Dynamic color images can be displayed using a pulse pulse width modulation voltage.Voltage crosstalk is suppressed and reflectivity of pixel unit is increased by optimizing pixel gaps and size.Finally,a novel full-color micro-display with super-high resolution is proposed.The work in this thesis expands the application area of the diffraction elements and metasurface,which could guide for the next generation of head-mounted display. |
