Display devices with wavelength-dependent reflectors for eye tracking

An eye-tracking system includes two mirrors. A first mirror is positioned to transmit light, received at a first incident angle, reflected off an eye of a user toward a second mirror. The first mirror is also positioned to reflect the light, reflected from the second mirror, at a second incident angle. The second mirror is inclined from the first mirror so that the light transmitted through the first mirror is reflected by the second mirror toward the first mirror at a first reflection angle. The light reflected by the second mirror is reflected by the first mirror toward the second mirror at a second reflection angle greater than the first reflection angle. The eye-tracking system also includes one or more sensors positioned to detect the light reflected by the first mirror and the second mirror for determining a gaze direction of the eye of the user.