Consumer technology has come a long way over the past decades. However, the optical lens, one of the premium components of advanced technology, has remained pretty much unchanged since its inception. While most other electronic devices have become more efficient and remarkably smaller in size, the underlying physics and the design of an optical lens have not evolved much. This has created a significant barrier in the development of optical systems, especially wearable gears for virtual reality. Such devices need light-weight, compact, and cost-effective elements.
Development
To remedy the situation, a team of researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) is developing next-generation of optical lenses. The team is led by Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering. The development promises to overcome the barrier by replacing the conventional bulky curved lenses with a flat surface lens. The new technology is said to use nanostructures to focus light.
Prior to this innovation, Capasso and his team had developed aberration-free, achromatic metalenses that could work across the whole perceptible spectrum of light. However, those lenses measured only tens of microns in diameter, making them too small to be used in augmented and virtual reality systems. Moving ahead, the team has built an achromatic metalens that is two millimeters in diameter and can focus RGB colors (red, green, blue) without any aberration. This would help create a miniature display for all augmented and virtual reality systems.
A new generation of optical technology
Published in Science Advances, the research promises a new generation of optical technology. Capasso, who is also a senior author of the research paper stated that the lens will open a path to a novel type of VR platform and is capable to overcome the barriers that have slowed the progress of next-generation optical devices. Zhaoyi Li, the first author of the paper and a post-doctoral fellow at the SEAS, told the press that this lens is the largest RGB-achromatic metalens till now. He further added that this is proof of the idea that optical lenses can be mass-produced, measured up to centimeter size, and incorporated in commercial usage.
Patterns and shapes
Similar to previous metalenses, this optical lens uses arrays of titanium dioxide nanofins that can equally focus different wavelengths of visible light and eliminate all chromatic aberrations. The focal length of RGB can be controlled by engineering the patterns and shapes of these nanoarrays. To integrate the lens into a virtual reality system, the researchers have developed a near-eye display component using the method of fiber scanning. This display reportedly uses an advanced optical fiber through piezoelectric tubes. When a certain voltage is applied to these tubes, the fiber tip scans around the view and forms a miniaturized display. These patterns will be focused on users’ retina, where the VR images will form.
The Harvard Office of Technology Development reserves the intellectual property of this project and is planning to explore commercialization opportunities. Further, the team of researchers aspires to scale up the metalens, making them compatible with the current mass-production techniques of optical lenses at an affordable cost.
