New Lens Could Provide Thermal Imaging Capabilities in More Compact Camera

University of Utah researchers have developed a new kind of flat optical lens that is much thinner and lighter than conventional camera lenses. While conventional lenses for smartphone cameras are a couple of millimeters thick, the ultrathin lens is only a few micrometers thick. The new lens can also be used for thermal imaging.

The ultrathin lens has many microstructures, each bending the light at the sensor. The Utah researchers designed thin multilevel diffractive lenses (MDLs) to correct for image aberrations, including chromatic aberrations in the long-wave infrared (LWIR) band, thereby reducing the weight of the lenses. With simulations corroborated by experiments, they demonstrated that broadband LWIR imaging is possible with the new flat lens, which has a thickness of 10 μm and a weight that is about 100× less than conventional refractive optics.

A flat lens developed by researchers at the University of Utah that is much thinner and lighter than a conventional lens could enable lighter cameras for drones and night vision cameras for soldiers. Courtesy of Dan Hixson/University of Utah College of Engineering.

Since the MDLs are very thin, the researchers found that they could use polymers, which are easier to manufacture, for the lens material. The team has developed a fabrication process with a new type of polymer, along with algorithms that can calculate the geometry of the microstructures.

“You can think of these microstructures as very small pixels of a lens,” professor Rajesh Menon said. “They’re not a lens by themselves but all working together to act as a lens.”

Ultimately, the new lens could replace the thick, bumpy lenses in smartphones, providing a sleeker device while also enabling smartphones to be used for heat signatures. A more immediate use for the technology would be to allow light military drones to fly longer and soldiers in the field to carry lighter night vision cameras for longer periods of time. Menon said the new lens could also be cheaper to manufacture since the design allows it to be created out of plastic instead of glass.

The researchers’ work demonstrates the potential for lightweight, ultrathin, broadband lenses for high-quality imaging in the LWIR band. “Our lens is a hundred times lighter and a thousand times thinner, but the performance can be as good as conventional lenses,” Menon said.

The research was published in Proceedings of the National Academy of Sciences (https://doi.org/10.1073/pnas.1908447116).

Professor Menon presented a webinar to the Photonics Media audience in June 2019. Link here to watch his presentation: “From Lensless Cameras to Deep-Brain Microscopy: Exploring the Potential of Computational Imaging.”