The User-Friendly Foveated LED Smart Contact Lens for Realistic Metaverse

With the advancement of semiconducting technologies including optoelectronic devices and displays in internet of things (IoT) era, there is growing attention to realize a hyper-connected society where various subjects such as people, objects, and systems. A “metaverse” is of interest to seamlessly blend virtual and real world spaces, which enables users to experience not only a sense of reality but also a virtual information without constraints of space and time. In this regard, the demonstration of a hyper-realistic virtual space that blurs the boundary between real and virtual space has become crucial factor in the display technologies. The augmented reality (AR), the one of the major visualization technologies of metaverse, is a technology that synthesizes information of virtual objects or spaces onto the scene of the real world through the device. However, the most devices such as head-mounted display (HMD) for the AR have limitations of the need for additional displays and cameras to integrate virtual objects or information into the real world due to the blockage between the user and outer physical space during wearing the HMD. In addition, the HMD causes cybersickness, generating the discomfort to users due to visual occlusion and discrepancies between sensory inputs and visual stimuli. Thus, there is an emerging demand for alternative technologies that can effectively alleviate user’s fatigue and seamlessly integrate metaverse visualization into daily life. Many studies in sunglasses-type displays to improve the large and heavy volume of HMD have been demonstrated, but fundamental issues (e.g., cybersickness) are remaining challenges. In this study, we present the foveated LED smart contact lenses system by incorporating transparent LED displays into the center of contact lenses. These smart contact lens-based technologies aim to achieve ultra-realistic virtual space that naturally blend the boundaries between the real world and the metaverse in user-friendly way.<br/>The foveated imaging function in smart contact lens shows the maximum image quality in the main visual fields relating to the user's gaze, while having the background area in relatively low image quality to increase the user's immersion and reduce data processing speed. The foveated LED smart contact lens was designed by inserting the LED pixels to the human eye model through the commercial ray tracing software. The lens design was optimized with a basis of optical properties of the conventional contact lens polymer; refractive index (1.4-1.5), thickness (100-150 um), and radius of curvature (8.5-8.9 mm). In particular, LED displays should be designed small enough not to cast their shadows on the retina, and the LEDs are assumed that emitted light goes in the vertical direction of the LED device along the waveguide structure, unlike general LEDs emit light in radial direction under the substrate. When the fovea area was set as a detector region, the curvature of the lens and the LED greatly affected the image formation of the fovea. At a curvature of 8.6-8.9 mm, which is mainly used as the RoC for commercial contact lenses, small images are focused on areas outside of the fovea. However, if the contact lens is flattened than this curvature, it occurs user’s discomfort to actually wear it. Therefore, the LEDs is placed to flat only the center of the lens by dividing the layer, because the area occupied by the LED is sufficiently small, which is effective rather than controlling the curvature of the entire lens. As a result, we designed an optical system of the foveated LED smart contact lenses that is user-friendly and enables a realistic metaverse implementation. The proposed system is expected to open the way for the development and commercialization of user-friendly AR devices for metaverse.