Experimental spatial sampling study of the real-time ultrasonic pulse-echo BAI-mode imaging technique

Area of Science:

• Non-destructive testing
• Ultrasonic imaging
• Materials science

Background:

• Hermetically sealed flexible food packages require reliable integrity inspection.
• Current methods may lack sensitivity for detecting micro-defects.
• Ultrasonic pulse-echo backscattered amplitude integral (BAI)-mode imaging offers potential for high-resolution inspection.

Purpose of the Study:

• To investigate the impact of spatial sampling on BAI-mode imaging performance.
• To optimize the scanning protocol for real-time inspection of flexible package seals.
• To determine the relationship between image quality metrics and spatial sampling parameters.

Main Methods:

• Utilized a zigzag scanning protocol with 17.3 MHz and 20.3 MHz transducers.
• Acquired radio frequency (RF) echo data from plastic film samples with known defect arrays.
• Assessed image quality using average BAI-value difference (deltaBAI) and contrast-to-noise ratio (CNR).

Main Results:

• Image quality (deltaBAI and CNR) degraded with increased spatial scanning step size.
• A trade-off exists between BAI-mode image quality and spatial sampling resolution.
• Optimal spatial sampling step size was identified as 1-2 times the transducer's -6-dB focal beam diameter.

Conclusions:

• The zigzag scanning protocol effectively simulates real-time inspection for BAI-mode imaging.
• Spatial sampling parameters significantly influence the detection of micro-defects in flexible packaging.
• Optimized spatial sampling ensures reliable seal integrity inspection, crucial for food safety.