Reviewed by Lexie CornerFeb 19 2025
Researchers from the University of Washington and MIT have developed a meta-optic eyepiece using a doublet system. One layer functions as an aperture and corrector plate, while the other serves as a focusing lens. The study was published in Light: Science & Applications.
The challenge for near-eye display optics is to project the image on a display that is placed near the eye to a comfortable viewing distance to avoid visual fatigue and discomfort. By collimating light from the display into the pupil of the eye, the wearer perceives the projected image to be located at infinity despite the screen being physically located much closer to the eye. In order to achieve a realistic and immersive experience, exceptional optical performance over a wide field of view is required. In this work, the eyepiece optics are composed of two layers of meta-optics. As illustrated in the inset, the meta-optics consist of arrays of nanoscale pillars or meta-atoms. Image Credit: Anna Wirth-Singh, Johannes E. Fröch et al.
The demand for augmented and virtual reality (AR/VR) near-eye displays has increased alongside advancements in artificial intelligence and the widespread availability of digital content. In addition to applications in national security and defense, including night vision and enhanced vision technologies, there is commercial interest in their use for social interaction, education, and gaming.
Near-eye displays require high optical performance to enable effective user interaction, as the human eye is a highly optimized optical system. Additionally, these displays must be lightweight and compact for user comfort and safety. The need for both a compact form factor and high optical performance presents engineering challenges.
A wide field of view is essential for an immersive experience in near-eye displays. The human visual field spans approximately 120 °, which exceeds the capture capability of most wide-angle lenses.
The conventional approach to correcting aberrations at large field angles involves stacking multiple refractive lenses in series, which increases system size and weight. This is particularly restrictive for head-mounted displays, where excessive weight can cause discomfort and fatigue, while sufficient eye relief is necessary for usability.
Meta-optics have shown potential for compact near-eye display systems by improving and miniaturizing imaging components. In meta-optics, quasi-periodic arrays of sub-wavelength pillars are arranged across a surface to impart localized phase shifts, enabling global optical functions such as steering or lensing.
Advancements in nanoscale lithography have enabled the fabrication of meta-optics for visible and near-infrared wavelengths. However, developing a meta-optics-based eyepiece with both a large aperture (approximately 1 inch) and a wide field of view (greater than 60 °) remains challenging.
Fabrication of large-aperture meta-optics for visible wavelengths requires high-resolution (sub-100 nm) lithography over a large surface area, making it a complex process. Additionally, achieving both a large aperture and a wide field of view simultaneously is fundamentally difficult due to increasing aberrations with aperture size and incidence angle, requiring careful optical design with multiple optical elements.
The study was led by Dr. Tian Gu of the Massachusetts Institute of Technology and Professor Arka Majumdar of the University of Washington. The meta-optics design considers practical constraints, including a 2.1 cm aperture, 5.4 mm pupil size, and 15 mm eye relief. A doublet system, consisting of two meta-optic layers, is used to achieve a large aperture and wide field of view simultaneously. The first layer is an aperture and corrector plate, while the second is a focusing lens.
When combined, the two meta-optic layers demonstrate high-quality imaging with a 60 ° full field of view. The researchers first validated optical performance with a 1 cm aperture prototype before scaling up to a 2.1 cm aperture eyepiece.
Theoretical models and experimental data show strong agreement for both optical configurations. Additionally, the meta-optic system outperforms a comparable commercial refractive lens eyepiece in terms of reduced total track length and improved image quality over a wide field of view at the design wavelength.
The study addresses both the fabrication challenges of large-area meta-optics at visible wavelengths and the correction of optical distortions and aberrations in large-aperture optics. Achieving sub-wavelength resolution in visible meta-optics requires lithography with a resolution of 100 nm or less. While electron beam lithography offers one of the highest-resolution nanofabrication methods, its cost and scalability make it unsuitable for commercial applications.
To address this limitation, the researchers developed a 2 cm eyepiece doublet compatible with deep ultraviolet (DUV) stepper lithography, a mass-production-friendly technique. This represents a step toward commercially viable large-aperture meta-optics fabrication.
The integration of meta-optics into full-scale near-eye display systems, including AR/VR and night vision, is a potential application of this work. However, the meta-optic doublet is designed for 633 nm single-wavelength illumination. While immediately applicable to monochromatic applications such as night vision, additional development is required for full-color applications.
This study advances nanofabrication and meta-optic design techniques. Given the increasing demand for AR/VR and the ongoing need for compact night vision systems, meta-optics will play a critical role in the development of these technologies.
Journal Reference:
Wirth-Singh, A., et al. (2025) Wide field of view large aperture meta-doublet eyepiece. Light: Science & Applications.doi.org/10.1038/s41377-024-01674-0