On February 26th, the Metaverse and Digital Human Innovation Conference, hosted by MES 2024 International Metaverse and Esports Expo and guided by the China Electronic Imaging Industry Association, was held at the Shenzhen Futian Convention and Exhibition Center. Several well-known enterprises and institutions in the industry participated in the conference to discuss new trends and showcase new achievements. Zhang Xian, the Product Director of RaySound Technology, attended the conference and delivered a speech on the topic of "Key Breakthroughs in Pancake Technology: Curved Film Lamination and Plastic Lens Bonding."
The talk delves into the technical bottlenecks and solutions of the VR Pancake optical solution. By explaining the working principle of the Pancake optical solution, analyzing the key technological challenges affecting its performance, and showcasing Ruisheng Technology's breakthrough in the core production process of VR Pancake optics - the technology of double-curved surface bonding and surface coating of VR Pancake lenses. This technology not only expands the field of view (FOV) but also improves the display effect and slimness of the lenses, driving the ultimate pursuit of visual experience in the new generation of VR devices and providing new impetus for immersive interactive worlds.
Meeting the Three Core Demands of MR Glasses Faces Great Challenges
Apple's latest work, Apple Vision Pro, has sparked widespread interest among the industry and consumers, paving the way for the MR (Mixed Reality) glasses. MR glasses, as the "portal" between virtual and real worlds, use Visual Fusion Technology (VST) to seamlessly integrate the real world with digital information and display it clearly on high-definition screens, bringing unprecedented interactive experiences. Among them, the core technology lies in the optical display module, which is also one of the main technical bottlenecks of current MR glasses.
Specifically, on the one hand, there is still considerable room for improvement in the imaging quality and weight of the optical display module. Parameters such as field of view (FOV), modulation transfer function (MTF), lens size, ghosting, and distortion need to be improved. On the other hand, the optical display module accounts for a high proportion of hardware costs, making manufacturing costs prohibitively high. According to industry analysis, the cost of the optical display module accounts for more than 30-40% of the hardware cost of MR devices. Overall, faced with the industry's high manufacturing costs, many core demands of MR glasses, such as imaging quality, wearing comfort, and price rationality, still face enormous challenges.
It's clear that as consumers increasingly demand immersive experiences, optical display modules are crucial for enhancing perceptual experiences. Leveraging 30 years of leading global expertise in consumer electronics microdevice R&D and production, ReSound Technology has established an all-in-one MR optical production and assembly line. This ensures that every step, from product design to final assembly, meets the highest standards, enabling MR smart glasses manufacturers to reduce the mass production cost of optical display modules and thus provide consumers with high-value MR glasses.
ReSound Technology's Pancake innovative technology overcomes three major technical bottlenecks. The Pancake optical solution may become a mainstream trend.
Currently, the next generation of VR products on the market, such as the Apple Vision Pro, Meta Quest 3, and PICO 4, all adopt the Pancake optical solution. The Pancake optical solution, based on a folded optical path principle, further reduces the thickness of the optical module, significantly decreasing the weight and volume of the headsets. Moreover, it offers advantages such as high-quality imaging, low image distortion, and adjustable diopters.
At the manufacturing end, the intricate Pancake optical process poses challenges due to its complexity, requiring constant iteration in optical film, bonding techniques, polarizing films, and production processes. As technology matures, it's foreseeable that Pancake optical solutions will become the mainstream choice in the next five years, gradually overcoming many challenges in the manufacturing process.
In his presentation, Zhang Xian introduced Rui Sheng Technology's brand-new Pancake optical production process for the first time. Rui Sheng's new Pancake optical production process is precisely tailored to address the aforementioned challenges, making significant progress in three key areas: large FOV optical design, excellent imaging quality, and ultra-thin form factor.
Advantage 1: Breakthrough Optical Design for Optimized Large Curvature Lens Production
To meet the demand for expanding the field of view (FOV), Rui Sheng Technology employs breakthrough freeform (aspherical) optical designs. This approach significantly increases the FOV and delivers superior imagery.
Pancake optical lenses with large FOV provide an immersive experience, necessitating lenses with greater curvature, thereby making film bonding more challenging, particularly on curved surfaces. Rui Sheng's adopted curved surface film bonding technology offers clear advantages. Not only does it reduce costs, but it also allows for the replacement of film materials after lens production, effectively addressing the challenges of producing lenses with large FOV and high curvature.
Advantage 2: Innovative Materials and Processes for Enhanced Optical Imaging Quality
To enhance imaging quality, Rui Sheng Technology focuses on research and selection of low-stress materials, precise injection molding processes, and advanced curved surface film bonding technology to ensure image clarity and precision.
The revolution in production processes primarily focuses on new materials and techniques. Rui Sheng Technology improves materials by balancing "high refractive index" and "low-stress injection molding materials" according to optical designs, achieving an average lens stress value of 3nm. Furthermore, through precise "automated bonding" and "vacuum bonding" processes, Rui Sheng Technology enhances the uniformity of film adhesion, reducing orange peel wrinkles from 0.13 to 0.07 arcmin, resulting in nearly a 20% increase in MTF and significantly clearer optical imaging.
Advantage 3: Novel Bonding Technology for Achieving Ultra-Thin Glasses Design
Building upon the dual aspherical design, this solution introduces a plastic lens bonding technology that effectively reduces the total length of optical components, achieving even more extreme thinness for MR glasses. Rui Sheng Technology utilizes optical AA manufacturing equipment with precision up to 5 microns while ensuring the optical glue's light transmittance exceeds 99% and controlling the refractive index difference within 0.1, achieving uniform, bubble-free bonding.
Ultimately, combining precision and automated bonding technology, the fully bonded dual aspherical 3-piece design reduces the overall module thickness to 17.4mm. This figure stands out in the industry as reducing 1mm thickness represents significant technical challenges for most manufacturers. Currently, industry-standard 3P Pancake module thicknesses are around 30mm, making this solution achieve nearly a 40% thickness reduction.
In summary, Rui Sheng Technology has addressed the three core requirements of MR glasses, tackling challenges through innovative optical design, material, and process innovations, thereby creating a brand-new Pancake optical production process.
It's worth noting that at the conference, Rui Sheng Technology's aforementioned technical solutions stood out among many competing technologies, winning the coveted "Core Device Innovation Award" due to its research and development strength and performance.
According to Pancake's different design requirements, Raytac Technology can also provide one-stop optical solutions, including optical design, lens processing, coating film, alignment assembly, and imaging testing. In addition, Raytac Technology's 3P VR Pancake eyepiece module solution offers advantages of lighter and thinner host, wider field of view, and more effective suppression of ghosting, bringing superior image quality and a more comfortable user experience to VR devices.
Ruiyi Technology has been dedicated to driving innovation in the realm of perceptual experiences. Beyond optics, Ruiyi Tech has been steadily accumulating expertise in acoustics, haptics, sensors, semiconductors, precision manufacturing, and other domains. This enables us to provide robust technical support for cutting-edge consumer electronics such as VR and AR glasses, fostering high-quality immersive experiences.
