Channel defect detection in food packages using integratedbackscatter ultrasound imaging

摘要

Hermetically-sealed flexible food packages require very effectivenseal integrity testing to extend the shelf stability of thermallynprocessed food. The initial goal of this study was to estimate thendetection limits of laboratory-generated channels which simulate defectsnin food packages using pulse-echo ultrasonic imaging techniques.nPackages with well characterized (via transmission optical microscopy)nlaboratory-generated channels that simulate defects with diametersnbetween 9 and 325 Μm in the seal plane traversing the major axis ofnthe heat seal were generated in heat-sealed microwavable retort-pouchnplastic film (trilaminate). Pulse-echo techniques in the 13-17 MHzncenter frequency range were investigated. The samples were examined withna conventional B-mode imaging technique, which was found to beninadequate for subwavelength imaging of the types of typical channelndefects found in shelf-stable food packages. Based on conventionalnB-mode image features, a new goal of this study was established tondevelop and evaluate an imaging technique which would exhibitnsubwavelength imaging capabilities. The new imaging technique callednbackscattered amplitude integral (BAI) is introduced here. It wasnobserved that BAI-mode imaging has the ability for subwavelengthndetection of channel defects, e.g., detection of a 10-Μm diameternchannel defect at a center frequency of 13.1 MHz (Λ=182 Μm)