Improved systems ensuring an accuracy of eye gaze measurements in an augmented reality head-mounted wearable device include a radiation direction rerouter (e.g., a partial retroreflector) configured to adjust an angle of incidence of the radiation in the waveguide at a first surface of a waveguide to produce radiation directed at an adjusted angle of incidence at an outcoupler such that the output direction is essentially parallel to the gaze angle of the user's eye. For example, a partial retroreflector may be disposed on a surface of the waveguide opposite the outcoupler provides an additional reflection so that the gaze angle of the user's eye is matched to an angle of an image of the eye pupil onto a world-facing radiation detector (e.g., a camera).