High-performance Automotive Heads-up Display Using Single Freeform Mirror: An Inverse Design Approach

This paper introduces a groundbreaking optical architecture for automotive head-up displays (HUDs) based on an inverse design methodology with a single freeform mirror. Departing from conventional multi-element systems, our approach treats the virtual image plane as the object and the LCD as the image plane, enabling a fully reflective, monochromatic design that inherently eliminates chromatic aberrations. The system achieves an expansive 180×90 mm² eye-box while projecting a high-quality virtual image at 2.2 m, corresponding to a field of view of ± 85 mm (X) × ±51 mm (Y). Utilizing a 170×120 mm freeform mirror optimized via Radial Basis Functions (RBFs) for precise aberration control, the design attains exceptional optical performance. Ray-tracing analyses confirm spot RMS sizes consistently below 0.1 mm—significantly smaller than the LCD's 0.4 mm pixel pitch—and distortion stable at approximately 4% across the entire eye-box. This single-mirror solution represents a significant reduction in system complexity and volume compared to existing multi-mirror HUDs, while maintaining high image fidelity, making it a highly compact, cost-effective, and performance-competitive alternative for next-generation automotive applications.