Broadband long-range thermal imaging via meta-correctors

Area of Science:

• Optics and Photonics
• Infrared Imaging Technology

Background:

• Long-range thermal infrared imaging is crucial for surveillance and monitoring.
• Traditional systems use large, heavy, and expensive refractive lenses with aspheric profiles.
• Metasurface optics offer weight reduction but suffer from chromatic aberrations in the long-wave infrared (LWIR) band.

Purpose of the Study:

• To develop a high-quality, broadband thermal imaging system for long-range applications.
• To overcome the limitations of existing refractive and metasurface-only optics.
• To create a lightweight, cost-effective LWIR imaging solution.

Main Methods:

• Designed a hybrid optical system combining four refractive lenses and two all-silicon metasurface correctors (meta-correctors).
• Evaluated system performance against refractive-only systems.
• Conducted outdoor testing to assess real-world imaging capabilities.

Main Results:

• The hybrid system achieved a threefold contrast enhancement at the detector's half-Nyquist frequency compared to refractive-only systems.
• Demonstrated noticeably sharper images in outdoor testing, with clear human feature recognition at 250 meters.
• Utilized off-the-shelf refractive elements and avoided germanium, mitigating supply chain risks.

Conclusions:

• Hybrid meta-corrector systems offer a viable path to high-quality, broadband LWIR imaging.
• The developed system enables long-range, lightweight, and cost-effective thermal imaging solutions.
• This approach addresses key challenges in current long-wave infrared optical design.