Northeastern University Background
Optics that allow the user to see in the dark or obscured conditions are critical for military as well as emergency response services. Typical night-vision devices rely on photomultipliers and phosphor screens, which make them relatively large, heavy, and uncomfortable to wear. Another option is imaging via thermal detection. This involves the detection of the infrared radiation that is emanated by all objects. Since the range of emission wavelength in the infrared region spans several micrometers, the means of detection can require several different detectors and may require cooling for a useful signal. This results in a large and heavy apparatus for detection.
For both night-vision and thermal imaging, a large form factor can be problematic for users carrying a large amount of gear in the field. The ultimate goal is to provide enhanced detection with a form factor that approaches normal eyewear. Nanoengineering provides a path for realizing such a goal. Exotic structures that can manipulate light in ways not found in naturally occurring materials, metamaterials or metasurfaces, can be used to realize the potential of flat optics and decrease size and weight.
Northeastern researchers are combining nanoscale structures to allow light of arbitrary wavelength to be absorbed efficiently and transduced into an electrical signal for imaging applications. These nanoscale structures combine metalenses with plasmonic absorbers to reduce the size and weight of the hardware required for night-vision technology.
The structures are fabricated by the directed assembly of metallic and semiconducting nanoparticles, which reduces the necessity for traditional fabrication methods.
The metalens and plasmonic absorbers are fabricated using the same methods. The method of fabrication can be top-down such as lithography and etching, or bottom-up such as printing, plating, or assembly. The metalens is designed to focus light in the near-field, so the focal point is very close to the metalens surface. It captures light received at a low angle of incidence, increasing the field of view while maintaining a flat profile.
Light weight night-vision system
Scalable fabrication methods
Exploration and recreation