Light-based devices may be provided that emit light. The light-based devices may be incorporated into systems such as vehicles. The light-based devices may include light sources such as light-emitting diodes and lasers. Mirrors may be used to collimate light from the light sources. Light modulators may be used to pattern light from the light sources. The light sources may include light sources of different colors. Arrays of pixels may be used to provide dynamically varying patterns of emitted light. A light source may produce light that is diffracted by an array of diffractive elements on a window. Mechanical and electrical shutters may obscure light sources, mirrors, and light-emitting components mounted on windows.