A picture generation unit emits a light field. A mirror reflects the light field toward a windshield of a motor vehicle such that the light field is reflected off of the windshield and is visible to the driver as a virtual image. An infrared emitter transmits infrared energy through the mirror such that the infrared energy is substantially co-axial with the light field, and such that the infrared energy is reflected off of the windshield toward the human driver. An infrared camera captures infrared images based on the transmitted infrared energy reflected off of the human driver and received by the infrared camera. Eye tracking is performed based on the captured infrared images. The infrared energy is transmitted at a higher power level at a beginning of the eye tracking than after the beginning of the eye tracking.