High-angular-resolution adaptive terahertz scanning imaging via dynamic zoom optics and beam steering metasurfaces

Area of Science:

• Terahertz (THz) imaging
• Optical engineering
• Metasurface applications

Background:

• Current THz imaging systems struggle with balancing wide field-of-view for multi-target detection and high angular resolution for single-target discrimination.
• Limitations include output power of THz sources, detector sensitivity, and focal-plane array (FPA) resolution.

Purpose of the Study:

• To develop an adaptive THz scanning imaging system that overcomes the limitations of current systems.
• To enable simultaneous wide field-of-view and high angular resolution for THz imaging.

Main Methods:

• Integration of a dual-lens zoom objective (NA 0.66-0.65) for continuous field-of-view adjustment (±8.1° to ±4.1°).
• Utilized a 64×64 FPA with 0.4mm pixel size.
• Employed a frequency-dispersive metasurface for 2D beam steering (frequency tuning for θ-direction, mechanical rotation for φ-direction).
• Operated within the 0.332-0.358 THz band.

Main Results:

• Achieved an angular resolution of 0.2°.
• Demonstrated high-quality imaging through obscurants like smoke and camouflage.
• The system supports both wide-area multi-target detection and high-resolution single-target discrimination.

Conclusions:

• The adaptive THz scanning imaging system successfully integrates zoom optics, THz FPA, and metasurface beam steering.
• This novel system provides a versatile solution for challenging THz imaging applications requiring adaptable field-of-view and high resolution.