Mitigating chromatic aberration in wide-field pancake VR optics through the integration of diffractive optical elements

With the rise of the metaverse, the development of virtual reality headsets has gained significant attention in recent years. The optical architecture of VR head-mounted devices has undergone numerous transformations, with pancake optics becoming the mainstream configuration. Compared to traditional refractive designs, Pancake optics offer advantages such as compact size, high resolution, and wide viewing angle. Its catadioptric layout significantly reduces module thickness, while reflective surfaces provide greater optical power, achieving high resolution and a broad field of view. However, full-color VR headsets typically suffer from severe chromatic aberration at large viewing angles. This study adopts a two-element aspheric pancake design, incorporating a kinoform-type diffractive optical element. Due to the strong negative dispersion of the DOE, our hybrid diffractive-refractive pancake system with an FOV of 106° significantly improves lateral color shift. In the 450 to 650 nm wavelength, the multicolor root-mean-square spot radius is reduced from 142 to 30 µm. This result demonstrates that the DOE-enhanced design successfully improves full-color resolution across the entire FOV. We present simulation results for both designs with and without DOE, validating the effectiveness of our approach. This paper proposes an optical design method that includes first-order calculations and DOE principles, detailing generating the DOE profile. This innovative design not only achieves a technical breakthrough but also shows significant performance improvements in quantitative data, providing a crucial reference for the future optical design of VR headsets and laying a solid foundation for the further development of VR technology.