US Patent 10488921 Pellicle beamsplitter for eye tracking

A head-mounted display includes an electronic display configured to output image light, an optics assembly configured to direct image light in a first band from the electronic display to an eye box, an eye tracking unit configured to generate eye tracking information, and a pellicle beamsplitter configured to redirect light in a second band reflected from the eye box toward the eye tracking unit and transmit the image light in the first band. The pellicle beamsplitter is positioned along the optical axis between the optics assembly and the electronic display. The pellicle beamsplitter includes a front surface and a back surface. Each of the front surface and the back surface comprising a first radius curvature in a first plane and a second radius curvature in a second plane that is perpendicular to the first plane.