Optimal Design of Optical Modules for Double Free-Form Surface Head-Up Display Systems

To ensure high quality of virtual images in augmented reality head- up display (AR-HUD) systems, the size of the AR-HUD should be reduced as much as possible to achieve a longer distance and a larger field of view. Using an off-axis dual-reflection system with a free-form surface, a virtual image display optical path with a virtual image distance of 10 m and a field of view angle of 10 degrees x5 degrees is designed. Furthermore, the Eyebox (aperture diaphragm offset range) is divided into the moving range of a driver's field of view. The system has nine structures, and multiple structures can be used for the optimization simulation. The light spot from each field of view falls within the Airy disk. The modulation transfer function of the image is close to the diffraction limit, and both the distortion and dynamic aberration values are less than the industry standard values. Once the imaging requirements are satisfied, the dust-proof film of the head-up display (HUD) system is drawn, and the light damage simulation is performed; based on the results, sunlight can be prevented from entering the eyes. Finally, the AR-HUD shell is drawn, and the measured volume is 10 L. The display effect is simulated through a user interface (UI) image to verify the correctness and feasibility of the design.