Fast THz-TDS Reflection Imaging with ECOPS-Point-by-Point versus Line-by-Line Scanning

Area of Science:

• Spectroscopy
• Materials Science
• Imaging Technology

Background:

• Terahertz time-domain spectroscopy (TDS) is a valuable non-destructive technique.
• Traditional TDS scanning can be time-consuming, limiting its application in high-throughput scenarios.
• The need for faster, high-resolution imaging in materials analysis is growing.

Purpose of the Study:

• To develop and evaluate a high-speed terahertz reflection TDS system.
• To assess the performance trade-offs between slow point-by-point and fast line-by-line scanning schemes.
• To demonstrate the system's capability for rapid, high-quality defect imaging.

Main Methods:

• Construction of a high-speed TDS setup utilizing electronically controlled optical sampling (ECOPS).
• Implementation of a gantry system with fast-speed motorized linear stages for sample movement.
• Development of a flat-bar-based metal marker for synchronizing continuous line-by-line scans.
• Comparative analysis of point-by-point versus line-by-line imaging on metallic and composite samples.

Main Results:

• The ECOPS TDS system achieved scanning speeds up to 1600 terahertz pulses per second, a 100-fold increase in the line-by-line scheme.
• Image quality, including defect size, shape, and location accuracy, remained comparable between the slow and fast scanning methods.
• The developed synchronization method ensured uniform scanning performance.

Conclusions:

• The proposed ECOPS TDS system enables extremely fast terahertz imaging without compromising image quality.
• This advancement significantly enhances the efficiency of non-destructive testing and materials characterization.
• The system is suitable for rapid, uniform scanning applications requiring high-resolution defect detection.