Mar 13 2020
Scientists have developed a unique camera using a single lens that has a thickness of about one-thousandth of an inch. This camera does not need focusing and provides significant advantages over conventional cameras, like the ones used in a majority of the smartphones, in which numerous lenses are required to form in-focus, high-quality images.
Using a single lens that is about one-thousandth of an inch thick, researchers have created a camera that does not require focusing. The new lens could drastically reduce the weight, complexity, and cost of cameras and other imaging systems, while increasing their functionality. Image Credit: Rajesh Menon, University of Utah.
Our flat lenses can drastically reduce the weight, complexity and cost of cameras and other imaging systems, while increasing their functionality. Such optics could enable thinner smartphone cameras, improved and smaller cameras for biomedical imaging such as endoscopy, and more compact cameras for automobiles.
Rajesh Menon, Study Team Leader, University of Utah
Menon and collaborators have detailed their unique flat lens in Optica, The Optical Society’s (OSA) journal dedicated to high-impact research. The researchers demonstrated that this flat lens could maintain focus for objects that are spaced approximately 6 m from one another.
Instead of using bulky plastic or glass, flat lenses utilize nanostructures that are patterned on a flat surface to realize the significant optical characteristics that regulate the way light travels.
“This new lens could have many interesting applications outside photography such as creating highly efficient illumination for LIDAR that is critical for many autonomous systems, including self-driving cars,” added Menon.
According to scientists, the latest design strategy used by them can potentially be extended to produce optical components with any number of characteristics like lower cost, easier manufacturability, or extreme bandwidth.
Questioning the Textbook
Traditional cameras, whether they are used for microscopy or in smartphones, need focusing to make sure that an object’s details are sharp. If numerous objects are located at varying distances from the camera, then each object had to be focused individually.
The new lens eliminates the need for focusing and allows any camera to keep all the objects in focus simultaneously. Conventional cameras also use multiple lenses to keep different colors of light in focus simultaneously. Since our design is very general, we can also use it to create a single flat lens that focuses all colors of light, drastically simplifying cameras even further.
Rajesh Menon, Study Team Leader, University of Utah
To focus light, conventional lenses generally convert parallel light waves into spherical waves that converge into a focal spot. In a groundbreaking discovery, the scientists realized that a similar effect could be produced by waves that have other types of shapes, thereby considerably boosting the number of potential designs of the lens.
In stark contrast to what is taught in optics textbooks, our research has shown that there is more than one way that light transmission is affected by an ideal lens—a concept known as pupil function. This opened essentially infinite possibilities for the lens pupil function, and we searched through these possibilities for one that achieved an extreme depth of focus.
Rajesh Menon, Study Team Leader, University of Utah
Experimental Confirmation
The scientists first selected the most optimal lens design for a depth of focus and then utilized nanofabrication methods to produce a prototype lens. The novel lens performed as predicted and acquired an extreme depth of focus, as confirmed by experiments. This depth of focus was several orders of magnitude greater than that of an analogous traditional lens.
The team successfully showed the novel flat lens utilizing infrared light and comparatively low numerical aperture—a number that defines the range of angles over which the lens can discharge or accept light. The researchers are now planning to expand the flat lens to bigger numerical apertures and to utilize it with the full visible light spectrum.
However, to produce these lenses on a large scale, more research is required before they can be commercialized.
“This research is a good example of how abandoning traditional notions can enable devices previously considered impossible. It serves as a good reminder to question dictates from the past,” concluded Menon.