Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have displays that produce images. Positioners may be used to move the displays relative to the eye positions of a user's eyes. An adjustable optical system may include tunable lenses such as tunable cylindrical liquid crystal lenses. The displays may be viewed through the lenses when the user's eyes are at the eye positions. A sensor may be incorporated into the head-mounted display to measure refractive errors in the user's eyes. The sensor may include waveguides and volume holograms, and a camera for gathering light that has reflected from the retinas of the user's eyes. Viewing comfort may be enhanced by adjusting display positions relative to the eye positions and/or by adjusting lens settings based on the content being presented on the display and/or measured refractive errors.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have displays that produce images. Positioners may be used to move the displays relative to the eye positions of a user's eyes. An adjustable optical system may include tunable lenses such as tunable cylindrical liquid crystal lenses. The displays may be viewed through the lenses when the user's eyes are at the eye positions. A sensor may be incorporated into the head-mounted display to measure refractive errors in the user's eyes. The sensor may include waveguides and volume holograms, and a camera for gathering light that has reflected from the retinas of the user's eyes. Viewing comfort may be enhanced by adjusting display positions relative to the eye positions and/or by adjusting lens settings based on the content being presented on the display and/or measured refractive errors.

Abstract: A head-mounted device may have optical modules that present images to a user's left and right eyes. Each optical module may have a lens support structure that supports a display and a fixed lens. Vision correction lenses may be removably coupled to the fixed lenses to help customize the head-mounted device to the vision of a particular user. A user may view images on the displays through the removable and fixed lenses from eye boxes. The optical modules may include infrared light sources that supply infrared light to the eye boxes and infrared light sensors such as infrared cameras for gaze tracking and authentication. The lenses may have optical surfaces covered with coating that enhance optical performance and may have edge surfaces that are provided with structures to help reduce stray light reflections. The lenses may be configured to pass visible and infrared light.

Abstract: An electronic device may have a support structure that supports a display and lenses. Each lens may be a reflective lens such as a catadioptric lens that receives polarized image light from the display and provides a corresponding image to an eye box. The display may be an emissive display with pixels that include light-emitting diodes. The light-emitting diodes may be overlapped by a light recycling layer such as a reflective polarizer or cholesteric liquid crystal layer. The light recycling layer recycles emitted light to enhance display efficiency.

Abstract: An electronic device such as a head mounted device may have a display that displays an image for a user. Head-mounted support structures may be used to support the display and to support lenses. The image on the display is visible through the lenses from eye boxes. The presence of the user's nose and the presence of opaque lens holder structures presents a risk that some of the image will be obscured by undesired black regions. To reduce or eliminate these black regions, facial illumination may be generated using a light source in the electronic device. The facial illumination may be provided by a light source such as a light-emitting diode die or laser or may be provided by a corner region of the display that contains pixels that do not supply any part of the image.

Abstract: An electronic device may have a support structure that supports a display and lenses. Each lens may be a reflective lens such as a catadioptric lens that receives polarized image light from the display and provides a corresponding image to an eye box. The display may be an emissive display with pixels that include light-emitting diodes. The light-emitting diodes may be overlapped by a light recycling layer such as a reflective polarizer or cholesteric liquid crystal layer. The light recycling layer recycles emitted light to enhance display efficiency.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have displays that produce images. Positioners may be used to move the displays relative to the eye positions of a user's eyes. An adjustable optical system may include tunable lenses such as tunable cylindrical liquid crystal lenses. The displays may be viewed through the lenses when the user's eyes are at the eye positions. A sensor may be incorporated into the head-mounted display to measure refractive errors in the user's eyes. The sensor may include waveguides and volume holograms, and a camera for gathering light that has reflected from the retinas of the user's eyes. Viewing comfort may be enhanced by adjusting display positions relative to the eye positions and/or by adjusting lens settings based on the content being presented on the display and/or measured refractive errors.