Multifunctional dual-view head-up display with both privacy protection and information sharing based on holographic optical elements

Considering the different needs of the driver and passengers for image information when a vehicle equipped with a head-up display (HUD) is driving, we propose a multi-functional dual-view compact HUD with both privacy protection and information sharing. The dual viewing angle display is achieved by stacking two layers of holographic optical elements (HOEs) with different diffraction angles due to the excellent angular selectivity of HOEs. Red-green multiplexing HOE1 and red-blue multiplexing HOE2 correspond to viewing angle 1 and viewing angle 2, respectively. The different diffraction angles of the green and blue images ensure the privacy of the driver and passengers, allowing for customizable displays. Moreover, the two diffraction angles of the red image ensure the sharing of warning information between the driver and the passenger, and improve the driving safety. Furthermore, the proposed HUD requires only one picture generation unit (PGU) and one holographic combiner and thus has a compact structure. The experimental results verify the feasibility of this method. The size of the fabricated HOEs was 20 cm×15 cm. The field of view (FOV) and eye-box (EB) of the two viewing zones are 10°×5° and 8°×4°, 147mm×81mm and 105mm×87mm, respectively.