Lightguide with Butterfly Eye-Pupil Expander

In the design process of lightguide devices for augmented and mixed reality (AR & MR) applications, the field of view (FOV) that the device makes available for the digital image is a parameter of particular interest. In order to push the limits of the maximum FOV achievable, various approaches have been investigated, such as systems that split the FOV during the propagation from incoupler to outcoupler. One very popular approach is the so-called “butterfly pupil expansion”, where two separate expansion grating regions are used for the positive and negative parts of the FOV. This is the approach taken in Microsoft’s Hololens 2. In this document, we show the realization of such an eye pupil expansion (EPE) concept in VirtualLab Fusion, based on patent US9791703B1 by Microsoft.