Passive millimetre-wave imaging and how it differs from terahertz imaging.

Area of Science:

• Applied Physics
• Electromagnetics
• Imaging Technology

Background:

• Millimeter-wave (MMW) systems excel in penetrating obscurants like dust and smoke, unlike infrared or visible light systems.
• MMW imaging enables navigation and surveillance in poor visibility conditions.
• The dielectric penetration capability of MMW allows for the detection of concealed objects under clothing.

Purpose of the Study:

• To design and construct a novel, real-time, mechanically scanned, passive millimeter-wave imager.
• To explore the application of optical system designs in MMW imaging.
• To evaluate MMW imaging performance at 35 GHz and 94 GHz.

Main Methods:

• A passive millimeter-wave imager was designed using a combination of Schmidt camera and conical scanner principles.
• Polarization techniques, adapted from centimetric band systems, were employed for optical folding.
• The system was constructed and tested in both 35 GHz and 94 GHz versions.

Main Results:

• The developed imager operates in real-time with mechanical scanning.
• The system leverages optical design principles for antenna elements and scanning mechanisms.
• Both 35 GHz and 94 GHz prototypes were successfully built, demonstrating the feasibility of the design.

Conclusions:

• Passive millimeter-wave imaging is a viable technology for surveillance and detection in challenging environments.
• The integration of optical system designs enhances the performance and capabilities of MMW imagers.
• The developed real-time imagers at 35 GHz and 94 GHz show promise for practical applications.