Compact Optics System Delivers Multi-Depth AR Display
A research paper published in Opto-Electronic Science (DOI: 10.29026/oes.2026.250031) describes the development of an integrated metasurface and freeform optical system designed to support augmented reality displays with multiple focal planes.
Augmented reality technology has progressed from laboratory research towards early commercial use, supported by advances in artificial intelligence and computing capability. The technology is expected to underpin new categories of mobile devices and spatial computing applications. Most current real-time AR systems rely on single-focus displays, which can create accommodation-vergence conflict and reduce visual comfort during extended use.
Multi-focal display methods have been developed to address this issue by generating several virtual focal planes that reproduce depth cues similar to those experienced in natural vision. Existing solutions, however, face difficulties in achieving consistent optical performance across multiple depths while maintaining compact size and practical cost. The integration of three-dimensional digital imagery with real-world environments, therefore, remains an ongoing technical challenge.
Researchers from the Beijing Institute of Technology, in collaboration with Beijing NED+ AR Ltd., the Institute of Physics at the Chinese Academy of Sciences and the National University of Singapore, proposed a multi-focal AR display architecture that combines a non-orthogonal polarisation-multiplexing metasurface, freeform optical elements and an OLED display. The study, titled Integrated Metasurface-Freeform System Enabled Multi-Focal Planes Augmented Reality Display, was published in the first issue of the journal for 2026 and selected as the cover article.
The system employs a multiplexing metasurface capable of applying distinct phase modulation across different polarisation channels, enabling the generation of multiple focal planes within a compact optical structure. Freeform surfaces provide additional flexibility for system configuration and alignment. A joint optimisation approach based on ray tracing and diffraction theory was used to coordinate multi-depth image projection with the optical path for see-through viewing. The design maintains a slim form factor while supporting stable image quality and controlled distortion at each focal distance.
The research team developed a solid-state prototype measuring 9.3 cm by 4.5 cm by 4.9 cm. Experimental evaluation showed that the device could simultaneously render digital imagery across three focal planes located at distances of 0.7 metres, 1.5 metres and 3 metres, while maintaining alignment with the real-world scene.
When the viewer adjusts focus to a specific depth, the image at the corresponding focal plane remains sharp, while imagery at other depths becomes naturally defocused, reproducing depth perception effects observed in normal vision. The prototype operates at a high frame rate and uses a fully solid-state optical configuration within a compact housing.
The study indicates that the combination of multi-plane depth rendering, reduced system size and integrated optical design provides a technical approach for future AR display development. Potential application areas include mobile intelligent terminals, immersive interaction systems and industrial visualisation. The work outlines an alternative optical design pathway for next-generation augmented reality displays requiring both multi-depth imaging capability and compact form.
