A head-mounted display (HMD) includes a pancake lens block, an eye tracking system, and an electronic display. The electronic display is coated with a dichroic film that transmits visible light and reflects infrared light (IR). An IR emitter illuminates an eye of the user, and infrared light is reflected from an eye through the pancake lens block and is incident on the dichroic film. The reflected light is captured by an image capturing element of the eye tracking system that is positioned at a periphery of HMD located off-axis relative to an optical axis of the pancake lens block.