AR/VR light engines: perspectives and challenges

Augmented reality (AR) and virtual reality (VR) have the potential to revolutionize the interface between our physical and digital worlds. Recent advances in digital processing, data transmission, optics, and display technologies offer new opportunities for ubiquitous AR/VR applications. The foundation of this revolution is based on AR/VR display systems with high image fidelity, compact formfactor, and high optical efficiency. In this review paper, we start by analyzing the human vision system and the architectures of AR/VR display systems and then manifest the main requirements for the light engines. Next, the working principles of six display light engines, namely transmissive liquid crystal display, reflective liquid-crystal-on-silicon microdisplay, digital light processing microdisplay, micro light-emitting-diode microdisplay, organic light-emitting-diode microdisplay, and laser beam scanning displays, are introduced. According to the characteristics of these light engines, the perspectives and challenges of each display technology are analyzed through five performance metrics, namely resolution density, response time, efficiency/brightness/lifetime, dynamic range, and compactness. Finally, potential solutions to overcoming these challenges are discussed.