Visual artifacts caused by pulse width modulation in AR/VR displays: a case study on Magic Leap 2 head-mounted display (HMD)

With the rapid development and widespread application of Virtual Reality (VR) and Augmented Reality (AR) technologies, microdisplay technologies used in AR/VR applications have garnered significant attention from both the industrial and academic communities. Many of these displays are modulated digitally using pulse width modulation (PWM) methods. Examples include micro-LED, Liquid Crystal on Silicon (LCOS), and Digital Micromirror Device (DMD) display. In HMD applications, due to the frequent and rapid movements of the eyeball during device usage, the retina and screen exhibit corresponding displacement. The temporal light emission profile, i.e., the PWM scheme, could result in various visual artifacts, such as motion blur, flicker, double image, color breakup, dynamic false contour, and so on. These visual artifacts significantly impact the user experience and need to be addressed. In this paper, we analyzed the root cause of these artifacts by space-time diagram method, using Magic Leap 2 display as an example. We also proposed corresponding mitigation approach for each artifact to enhance the application of various micro-display technologies in AR/VR devices, thereby providing an improved user experience.