Optical System Design for Three Virtual Plane Augmented Reality in Vehicle Head-Up Display

The automotive head-up display (HUD) system is a type of driving assistance technology that visually projects vehicle information into the driver's frontal field of vision. To meet the diverse needs of drivers for accessing information at various distances-ranging from far to near-during driving, we employ a dual free face-off three-reflection system to design an AR-HUD light path. This design facilitates virtual image distances of 10, 7. 5, and 3. 5 m, accompanied by corresponding field-of-view angles of 15 degrees 5 degrees, 12 degrees x3 degrees, and 6 degrees x1 degrees, respectively. In this setup, the optical path's image plane at the 3. 5 m projection distance shows only essential driving information like speed and fuel level; it is a static image plane. At distances of 7. 5 and 10 m, the image planes show additional information such as road conditions, navigation, and other auxiliary driving information. The image plane at a 10-m projection distance can seamlessly integrate virtual imagery with the actual road, with the two image planes dynamically switching based on the proximity to obstacles ahead, effectively alleviating visual fatigue in drivers. Notably, all three light spots at the eye point's center fall within Airy spots while achieving a modulation transfer function closely approaching the diffraction limit. Furthermore, the mesh distortion value is < 5%, and the dynamic distortion value is < 5 '.