Micro-projection System Design Based On Planar Optical Waveguide

The head-mounted display is a near-eye visual optical system with a combination of micro-display device and image transmission system. It is widely used in the fields of virtual reality and augmented reality as it can directly present image information at the viewer eye pupil witch is displayed through micro-display. Initially, the head-mounted display were mainly used in the military field, with the rapid development of information technology, head-mounted display has shown great values in many fields,and their application has extended to all aspects of our social life. Adapt to the requirement of light weight and small size, while improving systems efficiency as well as uniformity of illumination distribution, we designed two head-mounted display structure based on planar holographic wave-guide and semi-transparent filmed wave-guide, witch are called holographic semi-transparent filmed wave-guide and planar wave-guide based on micro-structure. Firstly, we described the basic principles and optical path of the two structures, in-depth analysis of constraints among the parameters within the systems were conducted, then we simulated the overall systems,and experimental verification at the same time.In order to enhance the optical efficiency of the traditional grating structure,semi-transparent filmed element and holographic gratings are used to expand the exit pupil. After simulation with optical design software, the proposed structure has a field of view of 2015??? and an exit pupil of 2020 ?mmmm. Though simulation, the systems has uniform illumination distribution with an optical efficiency of 17%.Limited by experimental conditions, only part of the experiment was carried out to verify the imaging effect.In accordance with the light guide plate design, as well as semi-transparent filmed wave-guide structure, we designed a head-mounted display, which is based on a planar wave-guide with micro-structure. The proposed design is extremely compact compared to the conventional head-mounted display systems, and could eliminate the ghost images in traditional structure. In this paper, we designed a planar wave-guide structure with a triangular micro-structure, to solve the problems in this structure, a improved micro-structure system was proposed. In the improved system, both triangular micro-structure and trapezoidal micro-structure are used to expend the exit pupil. Basedon simulation, the head-mounted display has a field of view of 30°, and an exit pupil of 2015 ?mmmm. Since the rays are trapped in the planar wave-guide by total internal reflection and extracted by micro-structure, there is almost no loss of energy within the whole system, the energy efficiency will be much higher than the traditional transparent filmed wave-guide structure, and achieve uniform illumination distribution.