One of the most stubborn engineering failures in augmented reality has never made headlines the way display resolution or field-of-view debates have — but it may be the single biggest reason AR glasses aren't on more faces today. The problem is brightness, and more specifically, the catastrophic light loss that comes with building true occlusion into optical see-through displays. Now a research team spanning Shanghai Jiao Tong University, Graz University of Technology, Nara I