| Head-up display (HUD) is an important display device in airplane, it presents additionalinformation data without requiring the pilots to look away from the real scenes. Thus, thepilot can observe the flight information with his/her head positioned "up" and lookingforward, instead of angled down looking at lower instruments. In recent years, HUD has beenwidely used in civil aircrafts because it can effectively reduce the risk of take-off and landing,besides, the performance of the HUD has been greatly improved. However, as compared withthe developed countries, our technology lags fairly far behind.This paper is aiming to improve the luminance, resolution and reliability of HUD, ahigh-resolution and high-brightness liquid crystal displays (LCD), rather than a cathode raytube (CRT), is used as the display source. Meanwhile, holographic technology is applied inthe optical combiner to improve the diffraction and transmission efficiency of HUD. Afterthe design and development of the opto-mechanical structure, holographic combiner, finallya holographic head-up display (HHUD) that can be used to airliner, transportation aircraft,and helicopter is designed and fabricated. The main works of this paper are described asfollows:1. The design and analysis of an off-axis HHUD optical system with a wide field of view(FOV) is accomplished. In the design, the vertical FOV of the HHUD system is tilted downwith an angle of7°to match with the actual view of the pilot. The asymmetry of the FOVand big tilt angle of the holographic combiner induce large amount off-axis aberrations.Therefore, the rear lenses in relay system are decentered and tilted to compensate the off-axisaberration.2. The opto-mechanical structure for the HHUD system is designed by using the conceptof modularity, two neighbor components are connect with a transition plate, thus simplify thedesign process, reduce the difficulty of fabrication and assembly. Virtual assembly is carriedout after mechanical design to simulate the assembly process and verify the correctness ofthe design, thus greatly reduce the cost and development time.3. The assembly and test experiment of the HHUD prototype are implemented accordingto the virtual assembly process. The experimental results demonstrate that the HHUDprototype achieves a diffraction efficiency higher than80%, a resolution of1280×1024, and a5%distortion, that meets all the system requirements. |
