It’s a well-known fact that both humans and mammals depend upon visible light to see. Many nocturnal animals, including raccoons and opossums, have unusually large eyes to help them see better in the night, helping them sneak up on unsuspecting prey. Back in 2019, Andrew Karp’s feature, Turning Nighttime Into Sight Time explored our ability to see at night. He wrote, “Although humans lack the ability to see in the dark, they can compensate for it with the help of technology. Night vision goggles are a popular option for hunters and other outdoor enthusiasts, as well as the military. Most rely on some type of sensor that can detect heat, also called infrared, or thermal, energy.” It’s looking like night vision technology is about to get a much needed reboot—researchers at Raytheon Technologies Corp. and the University of California at San Diego are developing night-vision devices far smaller and lighter in weight than today's night-vision goggles, which would be about the same size and weight as a typical pair of eyeglasses.

“Night vision googles essentially work by converting low levels of photons—or in some cases infrared light emitted by animals and objects in the dark—into higher levels of electrons,” explained science writer Cheryl Murphy, OD. As Dr. Murphy shows in her illustration, the original photons captured are first turned into electrons and then multiplied to make their signals stronger.
In late September of 2021, officials of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., awarded a $3 million contract to Raytheon BBN Technologies Corp. in Cambridge Mass., and a $2.3 million contract to UC San Diego for the Enhanced Night Vision in eyeglass form factors, also known as the ENVision project.

Today's night-vision goggles typically are as bulky as 4 inches long and as heavy as 2.2 pounds. This causes a large torque on the wearer’s neck, which limits the wearer’s agility and often leads to chronic injury over prolonged use of these electro-optical devices. Today's night-vision goggles also burden the wearer with a narrow field of view and generally have limited spectral access to the near-infrared spectral band, which limits situational awareness.

These drawbacks from refractive optics for imaging, and image-intensifier tubes are two technologies in modern night-vision systems that have remained largely the same since their inception. Instead, the DARPA ENVision program seeks to overcome these limitations by developing enhanced, direct-view night-vision systems that are of a size and weight near those of typical eyeglasses.

FLIR Recon BN10 Thermal Binocular (l) are equipped with thermal imaging cameras for each eye. Avangard Optics' NVG1Pro 1x26 Night Vision Binocular (r) features a built-in infrared illuminator for casting extra infrared light on targets.

Raytheon BBN and UC San Diego researchers will develop small and lightweight night-vision eyeglasses to extend visual access beyond near infrared to include shortwave, midwave, and long-wave infrared spectral bands through a common aperture, giving users access to spectral ranges from 1.5 to 12 microns. These night-vision eyeglasses, furthermore, will widen the user's field of view to natural eyesight of about 100 degrees.

Optical specialists have attempted to widen the fields of view for today's night-vision goggles, but improvements come at the cost of increased systems size, weight, and wear-and-tear on the user. The ENVision project seeks to explore the next technical leap in night-vision technologies by achieving direct vision of the infrared through a process known as photon upconversion.

While current night vision systems use a multi-step process, the physics to upconvert infrared photons directly to visible light in one step has been known since the invention of the laser in 1960. Direct photon upconversion involves the absorption of two or more photons and re-emission of a photon of higher energy.

Currently, these processes are inefficient and are limited in the bandwidth of light that can be upconverted simultaneously. Yet recent advances in material systems, such as polaritonic structures and sensitized core-shell nanoparticles have opened up new avenues in exploring photon upconversion. The process of photon upconversion-based night vision would eliminate the need for several components and could lead to even simpler, all-optical night-vision systems in the future, such as night vision contact lenses, DARPA researchers said.


The ENVision project seeks to explore the next technical leap in night-vision technologies by achieving direct vision of the infrared through a process known as photon upconversion.
Planar optics and planar image intensifiers could enable direct vision of several infrared bands through one common aperture. Structured materials such as diffractive optics and metamaterials enable one to embed optical functionalities far beyond those of traditional refractives into one optical element.

While wide field of view, broad bandwidth, and high imaging quality all are achievable individually, combining these traits in practice remains a challenge. In addition to planar optics, image intensification is necessary to convert the often weak infrared light into visible photons detectable by the naked eye.

The ENVision program, which will last for four-years and will be structured in two, two-year phases, has two technical areas: prototypes and upconversion. Those participating in the first technical area will develop prototypes of enhanced night vision systems in eyeglass form-factors, while those in the second technical area will investigate broadband direct photon upconversion.

For more information about this new technology contact Raytheon BBN online at, the University of California at San Diego at, or DARPA at

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