Ultra-simplified and low-cost head-up display system enabled by freeform holographic element

Head-up display (HUD) systems play an important role in the fields of navigation prompts in aircraft/vehicle, entertainment display, exhibition, etc., In this paper, we propose the design and fabrication of novel ultra-simplified and low-cost HUD systems that only comprise the picture generating unit (PGU) and the optical combiner (OC), where OC is a holographic optical element (HOE) fabricated using freeform wave. OC possesses an equivalent degrees of design freedom compared with optical freeform surface, and it simultaneously performs the optical functions of correcting the off-axis system aberrations and combining the see-through beams. Based on the proposed structure, an off-axis reflective HUD system prototype is designed and fabricated. In addition, a HUD system with a simplified structure applied for the vehicle fields is designed. The proposed ultra-simplified system structure opens a new gateway for developing the next generation HUD systems as well as other AR displays systems in the fields of industry, entertainment, exhibition, vehicle, etc.