Automated design of freeform imaging systems for automotive head-up display applications

Freeform imaging system is playing a significant role in developing an optical system for the automotive head-up display (HUD), which is a typical application of augmented reality (AR) technology. There exists a strong necessity to develop automated design algorithms for automotive HUDs due to its high complexity of multi-configuration caused by movable eyeballs as well as various drivers’ heights, correcting additional aberrations introduced by the windshield, variable structure constraints originated from automobile types, which, however, is lacking in current research community. In this paper, we propose an automated design method for the automotive AR-HUD optical systems with two freeform surfaces as well as an arbitrary type of windshield. With optical specifications of sagittal and tangential focal lengths, and required structure constraints, our given design method can generate an initial structure with high image quality automatically, and then the final system is realized by our proposed iterative optimization algorithms with superior performances due to the extraordinary starting point. Two examples of AR-HUD systems at different structures are realized automatically by our presented automated design algorithms. Both AR-HUD designs can have superior optical performance for an eye-box of 130mm×50mm and a field of view of 13°×5°, which demonstrates the feasibility and superiority of our proposed design framework.