Patent attributes
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 barrel with a low-reflectance coating, a display coupled to the lens barrel that generates a visible-light image, a lens mounted to the lens barrel through which the image is viewable from an eye box, an infrared light-emitting diode that emits infrared light that illuminates an eye box at an infrared wavelength through the lens, and an infrared camera that captures an image from the eye box at the infrared wavelength. The low-reflectance coating may be a low-visible-reflectance-and-low-infrared-reflectance coating that exhibits low-reflectance for visible light from the display and for infrared light at the infrared wavelength that is generated by the light-emitting diode.