An eye-tracking system is provided that includes a light source configured to emit at least infrared (IR) light and a microelectromechanical system (MEMS) scanning mirror configured to direct the IR light. The system further includes a relay including at least one prism, and the relay is configured to receive the IR light directed by the MEMS scanning mirror and redirect the IR light. The system further includes a waveguide through which the IR light redirected by the relay passes to reach an eye, and at least one sensor configured to receive the IR light after being reflected by the eye.