Research background
Augmented reality display technology is developing rapidly, but its core component, the near-eye display module, still faces many challenges, especially the "vergence adjustment conflict (VAC)" that limits the user experience. Retina projection display is regarded as an important direction to solve the VAC problem due to its unique principle of directly projecting images to the retina. However, the traditional retinal projection display structure is limited by passive modulation devices (such as MEMS, LCOS), and it is difficult to balance miniaturization, high image quality and environmental adaptability.
Technological innovation points
Innovation point one: μRPD optical architecture that breaks through structural limitations
This research proposed and implemented for the first time a retinal projection display (μRPD) architecture based on the integration of imaging optical fiber and Micro-LED, using pixel-level alignment of imaging optical fiber to accurately transmit images, and achieving the design of optoelectronic module separation and structural flexibility. Compared with the limitations of traditional retinal projection display architectures that require strong collimated light sources and fixed spatial positions of optical modules, the μRPD architecture can accurately shape the LED divergent beam by regulating the numerical aperture of the imaging fiber, achieving luminous angle control that is equivalent to or even better than that of traditional beam shaping devices. At the same time, based on the bending characteristics of the optical fiber itself, the overall design has greater freedom. This method significantly improves the imaging quality and freedom of the system.
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Innovation point two: building the first full-color μRPD platform
Color display is the core pursuit of realistic interactive experience in AR terminals. The team further integrated red, green, and blue primary color Micro-LEDs and X-Cube prisms to build the first full-color μRPD system, combining imaging fibers and coupling lenses to achieve RGB images.The precise coupling and hybrid projection of the image keep the image clear at different depths of field from 40 to 160cm, laying a key display foundation for the immersive AR experience.
In addition to architectural breakthroughs and the realization of full-color display, this research also systematically verified the application capabilities of the μRPD architecture in special environments for the first time, reflecting its huge practical potential and expansion space.
The research team took advantage of the unique advantages of optical and electrical separation of the μRPD architecture to design an underwater AR display experimental platform that does not require any waterproofing. Thanks to the flexible structure and anti-interference properties of the imaging fiber, the optical part can be placed directly in the water, while the electronic part is packaged in a safe environment. This design avoids the complexity and high cost of traditional AR equipment that requires overall sealing underwater, and achieves underwater use.clear projection. At the same time, a conceptual model of smart glasses based on the μRPD architecture is further proposed: the image source and power supply chips are centrally placed on the back end of the glasses or on the external module, and the front-end projection components are connected through imaging optical fibers to achieve lightweight and modular design. In the future, the pluggable design of optical fiber components can even be realized to achieve seamless switching between AR/ordinary glasses.
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Summary and Outlook
The full-color μRPD architecture constructed in this research not only breaks through the bottlenecks of traditional retinal projection technology in terms of structural rigidity, color display, and environmental adaptability, but also provides a new paradigm of high flexibility and high integration for wearable AR devices. With the subsequent integration of supersurface optics, micro-nano structure, AI image processing and other technologies, μRPD is expected to become the core support platform of a new generation of near-eye display systems, promoting AR from consumer electronics to industrial, medical, scientific research and other multi-scenario applications.
This work was supported by the National Key R&D Program, the National Natural Science Foundation, the Fujian Provincial Major Science and Technology Project, the Fujian Provincial Outstanding Youth Science Fund, and the Fujian Innovation Laboratory Industry-Academic-Research Integrated Development Project. Jin Huajian, a master's student from the National and Local Joint Engineering Laboratory for Flat Panel Display Technology, School of Physics and Information Engineering, Fuzhou University, and Jin Huajian, School of Advanced Manufacturing, Fuzhou University, are the first authors of this article, and Professor Chen Enguo is the only corresponding author.
ANNA