Effect of Imaging Range on Performance of Terahertz Coded-Aperture Imaging

Area of Science:

• Physics
• Imaging Science
• Electrical Engineering

Background:

• Terahertz coded-aperture imaging (TCAI) is a powerful technique for non-destructive evaluation and security screening.
• Understanding factors affecting TCAI performance is critical for its practical application.

Purpose of the Study:

• To investigate the non-monotonic relationship between TCAI performance and imaging range.
• To elucidate the underlying physical mechanisms causing performance degradation.
• To provide guidance for optimizing TCAI system design.

Main Methods:

• Mathematical modeling of phase-induced spatiotemporal correlations in the reference-signal matrix (RSM).
• Definition and analysis of a dimensionless criterion governing image quality.
• Evaluation of degradation mechanisms, including RSM column/row correlations and wavefront encoding effects.
• Comparative analysis of reconstruction algorithms, specifically the Two-step Iterative Shrinkage/Thresholding (TwIST) algorithm.

Main Results:

• A counterintuitive, non-monotonic dependence of TCAI performance on imaging range was revealed.
• Image quality deteriorates when a specific dimensionless criterion reaches integer values, indicating strong RSM correlations.
• Two degradation mechanisms—increased RSM column correlation and reduced phase coverage—emerge beyond a critical imaging range threshold.
• Reconstruction failure is primarily linked to correlations involving dominant scatterers.

Conclusions:

• The study identifies specific imaging ranges that lead to significant TCAI performance degradation.
• Phase-induced correlations in RSM are the primary cause of this counterintuitive phenomenon.
• The TwIST algorithm shows robustness in challenging conditions, and insights guide optimal TCAI system design and range selection.