Foreign object detection by sub-terahertz quasi-Bessel beam imaging.
Food quality monitoring, particularly foreign object detection, has recently become a critical issue for the food industry. In contrast to X-ray imaging, terahertz imaging can provide a safe and ionizing-radiation-free nondestructive inspection method for foreign object sensing. In this work, a quasi-Bessel beam (QBB) known to be nondiffracting was generated by a conical dielectric lens to detect foreign objects in food samples. Using numerical evaluation via the finite-difference time-domain (FDTD) method, the beam profiles of a QBB were evaluated and compared with the results obtained via analytical calculation and experimental characterization (knife edge method, point scanning method). The FDTD method enables a more precise estimation of the beam profile. Foreign objects in food samples, namely crickets, were then detected with the QBB, which had a deep focus and a high spatial resolution at 210 GHz. Transmitted images using a Gaussian beam obtained with a conventional lens were compared in the sub-terahertz frequency experimentally with those using a QBB generated using an axicon.
Food Safety Research Group, Korea Food Research Institute, Sungnam, Gyeonggi-do, Korea. ocknet88@naver.com
Gyeongsik
G
Ok
Sung-Wook
SW
Choi
Kyung Hyun
KH
Park
Hyang Sook
HS
Chun
D000465:Algorithms; D000818:Animals; D004867:Equipment Design; D005433:Flour; D005506:Food Contamination; D019649:Food Industry / Q000295:instrumentation* / Q000379:methods; D006135:Gryllidae; D008962:Models, Theoretical; D016011:Normal Distribution; D012542:Scattering, Radiation; D055069:Terahertz Imaging / Q000379:methods*