Abstract: A computing device comprises a device image display outputting device display light; an optical configuration for a viewer of the computing device to view external display images rendered with external display light from an external image display and device display images rendered with the device display light; a display light combiner to combine the external display light and the device display light to reach the viewer's vision field. The external display light and the device display light are of different light properties. The display light combiner selectively reflects the device display light toward the viewer's vision field and selectively transmits the external display light toward the viewer's vision field.

Abstract: A wearable device includes circuitry on substrate. The substrate is coupled to an optical element in an optical stack. A refractive index of the substrate perceptually matches a refractive index of the optical component. The circuitry is imperceptible to the viewer wearing the device, despite that the circuitry has a view of (or, as an example, an unobstructed line of sight to) the viewer's eye. The circuitry can include a camera or an emitter, or both. The camera captures one or more reflections of the emitter from the viewer's eye. In a specific embodiment, the substrate includes a waveguide, Fresnel lenses, or lens to bend light rays around from the circuitry to achieve the imperceptibility. In alternative embodiment, the circuitry can be a piezoelectric device, liquid crystal controller, or any electronic circuitry relevant for a wearable device.