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Tang T, Zhang M, Mujumdar AS. Intelligent detection for fresh-cut fruit and vegetable processing: Imaging technology. Compr Rev Food Sci Food Saf 2022; 21:5171-5198. [PMID: 36156851 DOI: 10.1111/1541-4337.13039] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/31/2022] [Accepted: 08/23/2022] [Indexed: 01/28/2023]
Abstract
Fresh-cut fruits and vegetables are healthy and convenient ready-to-eat foods, and the final quality is related to the raw materials and each step of the cutting unit. It is necessary to integrate suitable intelligent detection technologies into the production chain so as to inspect each operation to ensure high product quality. In this paper, several imaging technologies that can be applied online to the processing of fresh-cut products are reviewed, including: multispectral/hyperspectral imaging (M/HSI), fluorescence imaging (FI), X-ray imaging (XRI), ultrasonic imaging, thermal imaging (TI), magnetic resonance imaging (MRI), terahertz imaging, and microwave imaging (MWI). The principles, advantages, and limitations of these imaging technologies are critically summarized. The potential applications of these technologies in online quality control and detection during the fresh-cut processing are comprehensively discussed, including quality of raw materials, contamination of cutting equipment, foreign bodies mixed in the processing, browning and microorganisms of the cutting surface, quality/shelf-life evaluation, and so on. Finally, the challenges and future application prospects of imaging technology in industrialization are presented.
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Affiliation(s)
- Tiantian Tang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China.,Jiangsu Province International Joint Laboratory on Fresh Food Smart Processing and Quality Monitoring, Jiangnan University, Wuxi, Jiangsu, China
| | - Min Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China.,China General Chamber of Commerce Key Laboratory on Fresh Food Processing & Preservation, Jiangnan University, Wuxi, Jiangsu, China
| | - Arun S Mujumdar
- Department of Bioresource Engineering, Macdonald Campus, McGill University, Montreal, Quebec, Canada
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2
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Cho H, Kil E, Jang J, Kang J, Song I, Yoo Y. Air-Coupled Ultrasound Sealing Integrity Inspection Using Leaky Lamb Waves in a Simplified Model of a Lithium-Ion Pouch Battery: Feasibility Study. SENSORS (BASEL, SWITZERLAND) 2022; 22:6718. [PMID: 36081176 PMCID: PMC9459724 DOI: 10.3390/s22176718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/31/2022] [Accepted: 09/03/2022] [Indexed: 06/15/2023]
Abstract
Inspecting the sealing integrity of lead tabs is an important means of ensuring the reliability and safety of pouch-type lithium-ion (Li-ion) batteries with a thin multi-layered aluminum (Al) laminated film. This paper presents a new air-coupled ultrasonic non-destructive testing (NDT) inspection method based on leaky Lamb wave transmission; and reception for evaluating the sealing integrity between the lead tab and the Al pouch film. The proposed method uses the critical incidence angle between the air and the layer with the fastest Lamb wave velocity to maximize the signal-to-noise ratio in the through-transmission mode. To determine the critical incidence angle, phantom experiments with two test pieces (i.e., an Al tab and an Al tab sealed with an Al pouch film) are conducted. In addition, 2D scans are performed at various incidence angles for an inhouse pouch-type Li-ion battery with a 1-mm-wide foreign material inserted as a defect. At the critical incidence angle (i.e., 22°), the proposed air-coupled ultrasonic NDT method in through-transmission mode successfully identifies the shape and location of the defect through c-scan image reconstruction. These preliminary results indicate that the proposed air-coupled ultrasonic NDT method with leaky Lamb waves can be used to inspect the sealing integrity of Li-ion pouch batteries in dry test conditions.
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Affiliation(s)
- Hyunwoo Cho
- Department of Electronic Engineering, Sogang University, Seoul 04107, Korea
| | - Eunwoo Kil
- Department of Electronic Engineering, Sogang University, Seoul 04107, Korea
| | - Jihun Jang
- Medical Solutions Institute, Sogang University, Seoul 04107, Korea
| | - Jinbum Kang
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Ilseob Song
- Medical Solutions Institute, Sogang University, Seoul 04107, Korea
| | - Yangmo Yoo
- Department of Electronic Engineering, Sogang University, Seoul 04107, Korea
- Medical Solutions Institute, Sogang University, Seoul 04107, Korea
- Department of Biomedical Engineering, Sogang University, Seoul 04107, Korea
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3
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Pan J, Yang Z, Yap SHK, Zhang X, Xu Z, Li Y, Luo Y, Zamburg E, Liu EX, Tham CK, Thean AVY. Non-destructive online seal integrity inspection utilizing autoencoder-based electrical capacitance tomography for product packaging assurance. Food Packag Shelf Life 2022. [DOI: 10.1016/j.fpsl.2022.100919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Chen D, Xiao H, Xu J. An improved Richardson-Lucy iterative algorithm for C-scan image restoration and inclusion size measurement. ULTRASONICS 2019; 91:103-113. [PMID: 30081330 DOI: 10.1016/j.ultras.2018.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 07/24/2018] [Accepted: 07/31/2018] [Indexed: 06/08/2023]
Abstract
The accuracy of measuring inclusion size in direct C-scan image of immersion ultrasonic testing is restricted by the lateral resolution of the focused transducer, even if a high frequency is used, and the blurred edge due to scattering of sound waves at inclusions. In this work, an improved image restoration method that is based on the Richardson-Lucy (RL) iterative algorithm is proposed, which is used to restore the C-scan image and improve the accuracy of inclusion size measurement in immersion ultrasonic testing. For the improved RL iterative algorithm, the point spread function (PSF) is derived based on the multi-Gaussian beam model and Kirchhoff approximation, which considers the propagation properties of sound waves at water-steel interface and the spectral characteristics of the transducer with high frequency. In order to determine the final iteration number, the relationship between final iteration number and size of the inclusion in the image is established by restoring the simulated C-scan image and further calibrated with size correction factor. The size correction factor considers the effect of sound attenuation and electro-mechanical transformation encountered in practical testing equipment. Experimental results show that the inclusion sizes measured in restored C-scan images agree well with the optical micrograph results, which prove the effectiveness of the proposed method.
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Affiliation(s)
- Dan Chen
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, PR China; Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Huifang Xiao
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.
| | - Jinwu Xu
- Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China
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5
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Männicke N, Schöne M, Liukkonen J, Fachet D, Inkinen S, Malo MK, Oelze ML, Töyräs J, Jurvelin JS, Raum K. Species-Independent Modeling of High-Frequency Ultrasound Backscatter in Hyaline Cartilage. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:1375-1384. [PMID: 27038804 DOI: 10.1016/j.ultrasmedbio.2016.01.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 01/24/2016] [Accepted: 01/27/2016] [Indexed: 06/05/2023]
Abstract
Apparent integrated backscatter (AIB) is a common ultrasound parameter used to assess cartilage matrix degeneration. However, the specific contributions of chondrocytes, proteoglycan and collagen to AIB remain unknown. To reveal these relationships, this work examined biopsies and cross sections of human, ovine and bovine cartilage with 40-MHz ultrasound biomicroscopy. Site-matched estimates of collagen concentration, proteoglycan concentration, collagen orientation and cell number density were employed in quasi-least-squares linear regression analyses to model AIB. A positive correlation (R(2) = 0.51, p < 10(-4)) between AIB and a combination model of cell number density and collagen concentration was obtained for collagen orientations approximately perpendicular (>70°) to the sound beam direction. These findings indicate causal relationships between AIB and cartilage structural parameters and could aid in more sophisticated future interpretations of ultrasound backscatter.
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Affiliation(s)
- Nils Männicke
- Berlin-Brandenburg Center for Regenerative Therapies and Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Martin Schöne
- Berlin-Brandenburg Center for Regenerative Therapies and Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jukka Liukkonen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Dominik Fachet
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Satu Inkinen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Markus K Malo
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Michael L Oelze
- Bioacoustics Research Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Juha Töyräs
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Jukka S Jurvelin
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Kay Raum
- Berlin-Brandenburg Center for Regenerative Therapies and Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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6
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Forbes MDE. What We Talk About When We Talk About Light. ACS CENTRAL SCIENCE 2015; 1:354-63. [PMID: 27162995 PMCID: PMC4827676 DOI: 10.1021/acscentsci.5b00261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Indexed: 06/05/2023]
Abstract
UNESCO (the United Nations Educational, Scientific, and Cultural Organization) has declared 2015 the "International Year of Light and Light-Based Technologies". In celebration of this proclamation, this Outlook provides a general history of light and its applications, from the earliest moments of the Big Bang through its present impact on all forms of life on the planet. Special emphasis is placed on fundamental advances in the generation and use of artificial light, as well as the harvesting and use of light from the Sun and other natural sources. During the past century, the role of light in the fields of physics, chemistry, and biology has expanded to include emerging fields such as environmental engineering, agriculture, materials science, and biomedicine. In this regard, future research challenges and new potential applications in these areas, in the context of "the central science", are presented and discussed.
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Affiliation(s)
- Malcolm D. E. Forbes
- Center for Photochemical
Sciences, Department of Chemistry, Bowling
Green State University, Bowling
Green, Ohio 43403, United States
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7
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Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays. J FOOD ENG 2012. [DOI: 10.1016/j.jfoodeng.2012.02.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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8
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Detection of occluded small objects in glass bottles filled with beverages via ultrasound center frequency tracing. Lebensm Wiss Technol 2009. [DOI: 10.1016/j.lwt.2008.05.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Bjørndal E, Frøysa KE, Engeseth SA. A novel approach to acoustic liquid density measurements using a buffer rod based measuring cell. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2008; 55:1794-1808. [PMID: 18986922 DOI: 10.1109/tuffc.2008.863] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A new method for measuring the pressure reflection coefficient in a buffer rod configuration is presented, together with experimental results for acoustic measurements of the liquid density, based on the measurement of the liquid's acoustic impedance. The method consists of using 2 buffers enclosing the liquid in a symmetrical arrangement with a transducer fixed to each buffer. One of the transducers is used in a pulse-echo mode while the other transducer operates as a receiver. The echo amplitudes leading to the pressure reflection coefficient as found by this method possess advantages such as reduced attenuation due to a shorter liquid transmission path and reduced interference, as compared with the ABC method. Measurements with distilled water and with special density calibration oil qualities have been performed using both the new method and the ABC method and are shown for the new method to give a density span within +/- 0.15% of the reference values. A comparison of the measured densities based on both a time-domain and a l(2)-norm frequency domain integration signal processing approach is given, along with a recommendation as to how the signal processing should be performed.
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ZHAO BOSEN, BASIR OTMANA, MITTAL GAURIS. MAXIMUM COMPONENTS INTEGRATION FOR IMAGE PROCESSING: AN APPLICATION OF ULTRASOUND FOR DETECTION OF SMALL OBJECTS IN CONTAINERS. J FOOD PROCESS ENG 2007. [DOI: 10.1111/j.1745-4530.2007.00107.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Hybrid of multi-signal processing methods for detection of small objects in containers filled with beverages using ultrasound. Lebensm Wiss Technol 2007. [DOI: 10.1016/j.lwt.2006.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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OZGULER AYHAN, MORRIS SCOTTA, O'BRIEN WILLIAMD. Ultrasonic Imaging of Micro-Leaks and Seal Contamination in Flexible Food Packages by the Pulse-Echo Technique. J Food Sci 2006. [DOI: 10.1111/j.1365-2621.1998.tb15810.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Morita Y, Dobroiu A, Otani C, Kawase K. A real-time inspection system using a terahertz technique to detect microleak defects in the seal of flexible plastic packages. J Food Prot 2005; 68:833-7. [PMID: 15830679 DOI: 10.4315/0362-028x-68.4.833] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A method to detect production faults in flexible plastic packages with the use of terahertz radiation is presented. Relying on the large difference between the absorption coefficients of plastic and water (for water-filled channel defects) and on the refraction index difference between plastic and air (for air-filled channel defects), our technique consists of focusing and scanning a terahertz beam on the sealed area of the package, followed by detection of the transmitted signal. Compared with previous methods, such as visual and ultrasound inspection, our technique can be applied to optically opaque packages and does not require immersion in a matching liquid. We tested our system on defects that we fabricated as water-filled and air-filled channels imbedded in polyethylene films, with diameters in the range of 10 to 100 microm. The detection limit (the minimum size of a detectable defect) depends on the conveying speed; this relationship was determined and analyzed. The results show that our system has the potential for application in an actual production line for real-time inspection.
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Affiliation(s)
- Yasuyuki Morita
- The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
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14
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Ozguler A, Morris SA, O'brien WD. Ultrasonic monitoring of the seal quality in flexible food packages. POLYM ENG SCI 2004. [DOI: 10.1002/pen.10780] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Yin X, Morris SA, O'Brien WD. Experimental spatial sampling study of the real-time ultrasonic pulse-echo BAI-mode imaging technique. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2003; 50:428-440. [PMID: 12744399 DOI: 10.1109/tuffc.2003.1197966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The ultrasonic pulse-echo backscattered amplitude integral (BAI)-mode imaging technique has been developed to inspect the seal integrity of hermetically sealed, flexible food packages. With a focused 17.3-MHz transducer acquiring radio frequency (RF) echo data in a static rectilinear stop-and-go pattern, this technique was able to reliably detect channel defects as small as 38 microm in diameter and occasionally detect 6-microm-diameter channels. This contribution presents our experimental spatial sampling study of the BAI-mode imaging technique with a continuous zigzag scanning protocol that simulates a real-time production line inspection method in continuous motion. Two transducers (f/2 17.3 MHz and f/3 20.3 MHz) were used to acquire RF echo data in a zigzag raster pattern from plastic film samples bearing rectilinear point reflector arrays of varying grid spacings. The average BAI-value difference (deltaBAI) between defective and intact regions and the contrast-to-noise ratio (CNR) were used to assess image quality as a function of three spatial sampling variables: transducer spatial scanning step size, array sample grid spacing, and transducer -6-dB pulse-echo focal beam spot size. For a given grid size, the deltaBAI and CNR degraded as scanning step size in each spatial dimension increased. There is an engineering trade-off between the BAI-mode image quality and the transducer spatial sampling. The optimal spatial sampling step size has been identified to be between one and two times the -6-dB pulse-echo focal beam lateral diameter.
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Affiliation(s)
- Xiangtao Yin
- Bioacoustics Research Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Shah NN, Rooney PK, Ozguler A, Morris SA, O'Brien WD. A real-time approach to detect seal defects in food packages using ultrasonic imaging. J Food Prot 2001; 64:1392-8. [PMID: 11563517 DOI: 10.4315/0362-028x-64.9.1392] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The microbial integrity of many types of flexible food packages depends on a zero defect level in the fused seam seal. Human inspection for defects in these seals is marginal at best, and secondary incubation protocols are often used to spot packages with compromised integrity before releasing product for sale. A new type of inspection method has been developed and is being evaluated for robustness. The purpose of the study was to evaluate a new raster scanning geometry to simulate continuous motion, online ultrasonic inspection of the seal region in flexible food package seals. A principal engineering tradeoff of scanning inspection systems is between increased line speed that results from decreased spatial sampling (less acquired data to process) and decreased image quality. The previously developed pulse-echo Backscattered Amplitude Integral (BAI) mode imaging technique is used to form ultrasound images using the new scanning geometry. At an ultrasonic frequency of 22.9 MHz, 38- and 50-microm-diameter air-filled channel defects in all-plastic transparent trilaminate are evaluated. The contrast-to-noise ratio (CNR) of the processed BAI-mode image is used to quantify image quality as a function of spatial sampling. Results show seal defects (38- and 50-microm diameter) are still detectable for undersampled conditions, although image quality degrades as spatial sampling decreases. Further, it is concluded that the raster scanning geometry is feasible for online inspection.
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Affiliation(s)
- N N Shah
- Department of Electrical and Computer Engineering, University of Illinois, Urbana 61801, USA
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17
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Tian Q, Sun BS, Ozguler A, Morris SA, O'Brien WR. Parametric modeling in food package defect imaging. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2000; 47:635-643. [PMID: 18238591 DOI: 10.1109/58.842051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A novel approach in food package defect detection is proposed based on system identification theory, in which the channel defect detection problem can be regarded as the conventional system identification problem, i.e., estimation of the system impulse response based on the input-output sequence using parametric and nonparametric models. The well-known parametric model ARX has been investigated in this paper. The data are collected with a focused ultrasound transducer (17.3 MHz, 6.35-mm diameter, f/2, 173 microm -6 dB pulse-echo lateral beam width at the focus) scanned over a rectangular grid, keeping the packages in the focus. Performance is measured in terms of detection rate, image contrast, and contrast-to-noise ratio. The results using the ARX model are compared with previous image formation techniques and also compared with the non-parametric method, i.e., spectral analysis. The results show that the ARX model has the comparable detection rate as RFCS and higher detection rate than BAI and RFS (except 6-microm air-filled channel in plastic trilaminate film) for channel in plastic trilaminate film. The ARX model has achieved the moderate contrast enhancement and ranks second in contrast-to-noise ratio enhancement among the compared techniques. The ARX model has a low detection rate for channel defects in aluminum trilaminate film, which shows that its performance is material-dependent. Finally, the parametric method, ARX model demonstrates better performance than the non-parametric method, spectral analysis for food package defect detection.
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Affiliation(s)
- Q Tian
- Dept. of Electr. and Comput. Eng., Illinois Univ., Urbana, IL, USA
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18
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Frazier CH, Tian Q, Ozguler A, Morris SA, O'Brien WR. High contrast ultrasound images of defects in food package seals. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2000; 47:530-539. [PMID: 18238579 DOI: 10.1109/58.842039] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Previous work to detect defects in food packaging seals using pulse-echo ultrasound inspired the backscattered amplitude integral (BAI) imaging technique, which could reliably identify channels with diameters 38 microm or larger at a center frequency of 17.3 MHz (lambda=86 microm). The current study presents two new processing techniques that more reliably reveal smaller channels ( approximately 6 microm in diameter). The RF sampling technique (RFS) displays a single, time-gated, pressure value from the received (not envelope-detected) RF waveform at each transducer position. The RF correlation technique (RFC) calculates the correlation coefficients of the RF signals with a reference signal that does not pass through a channel. The correlation coefficient can be calculated for the entire RF signal (RFCE) or over a short segment of the RF signal (RFCS). The performance of these imaging methods for detecting channel defects is investigated for plastic and aluminum foil trilaminate films with 6, 10, 15, 38, and 50 microm channels filled with water or air. Data are collected with a focused ultrasound transducer (17.3 MHz, 6.35 mm in diameter, f/2, 173 microm -6 dB pulse-echo lateral beamwidth at the focus) scanned over a rectangular grid, keeping the package in the focus. Performance is measured using detection rates, image contrast, and contrast-to-noise ratio (CNR). Both RFS and RFCS have improved detection rates relative to BAI for channels 15 microm or smaller. The RFCS technique is the most effective at smoothing the background, leading to the greatest CNR improvements.
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Affiliation(s)
- C H Frazier
- Dept. of Electr. and Comput. Eng., Illinois Univ., Urbana, IL, USA
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