Holographic HUD

A holographic head-up display (HUD) including: a picture generation unit (PGU) including at least one laser light source to generate an optical image to be projected on a HUD; a first mirror to reflect the optical image from the PGU; a second mirror to reflect the optical image reflected by the first mirror; and a holographic optical element (HOE) to diffract the optical image reflected by the second mirror at a first diffraction angle to provide an output optical image in a target direction. The first mirror includes a reflective compensatory HOE to diffract the optical image from the PGU at a second diffraction angle, and in response to change of a wavelength of the optical image from the PGU, the reflective compensatory HOE is configured to diffract the optical image from the PGU at a third diffraction angle different from the second diffraction angle such that the HOE provides the output optical image in the target direction.