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Proceedings Paper

Near-infrared imaging system for detecting small organic foreign substances in foods
Author(s): Hiroto Tashima; Tsuneaki Genta; Yuya Ishii; Takeshi Ishiyama; Shinichi Arai; Mitsuo Fukuda
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Paper Abstract

Contamination of foodstuffs with foreign substances is a serious problem because it often has negative effects on consumer health. However, detection of small organic substances in foods can be difficult because they are undetectable with traditional inspection apparatus. In this work, we developed new equipment that can detect small organic contaminant substances in food at high speed using a near-infrared (NIR) imaging technique. The absorption spectra of various foods were measured, and the spectra showed low absorbance at wavelengths from 600 nm to 1150 nm. Based on the observable wavelength range of a CMOS camera, which has a high dynamic range, superluminescent diodes (SLDs) with a wavelength of 830 nm were selected as light sources. We arranged 40 SLDs on a flat panel and placed a diffusion panel over them. As a result, uniformly distributed light with an intensity of 0.26 mW/cm2 illuminated an area of 6.0 cm × 6.0 cm. Insects (3 mm wide) and hairs (0.1 mm in diameter) were embedded in stacked ham slices and in chocolate, with a total thickness of 5 mm in each case, and the transmission images were observed. Both insects and hairs were clearly observed as dark shadows with high contrast. We also compensated the images by using software developed in this study to eliminate low spatial frequency components in the images and improve the sharpness and contrast. As a result, the foreign substances were more clearly distinguished in the 5-mm-thick ham.

Paper Details

Date Published: 25 September 2013
PDF: 7 pages
Proc. SPIE 8841, Current Developments in Lens Design and Optical Engineering XIV, 884117 (25 September 2013); doi: 10.1117/12.2023541
Show Author Affiliations
Hiroto Tashima, Toyohashi Univ. of Technology (Japan)
Tsuneaki Genta, Toyohashi Univ. of Technology (Japan)
Yuya Ishii, Toyohashi Univ. of Technology (Japan)
Takeshi Ishiyama, Toyohashi Univ. of Technology (Japan)
Shinichi Arai, Toyohashi Univ. of Technology (Japan)
Mitsuo Fukuda, Toyohashi Univ. of Technology (Japan)

Published in SPIE Proceedings Vol. 8841:
Current Developments in Lens Design and Optical Engineering XIV
R. Barry Johnson; Virendra N. Mahajan; Simon Thibault, Editor(s)

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