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HOME > No.7, Nov 2016 > Research Highlights : DNear-infrared (NIR) optical imaging system for detecting small organic objects in thick foods

Near-infrared (NIR) optical imaging system for detecting small organic objects in thick foods

By Mitsuo Fukuda
Mitsuo Fukuda

Mitsuo Fukuda and his colleagues, in cooperation with Aichi Science & Technology Foundation, have developed basic real-time imaging techniques for detecting small organic objects in foods, based on a simple technique of monitoring the distribution of the infrared light transmitted through the materials. The newly developed system has proven itself in being able to detect objects such as a human hair, a piece of plastic and a piece of rubber encased in 5-mm-thick chocolate, none of which can be picked up using an X-ray detection sensor and a metal detector.

Figure 1.
Fig.1 Images of insects and human hairs embedded in 5-mm-thick chocolate.

To be able to detect foreign objects in foods on factory production lines is important for our health and safety and is normally performed using an X-ray computed tomography apparatus or a metal detector. Dense materials such as a piece of stone or metal can be easily detected, and foods containing them are removed from the production lines.

However, foreign organic objects in foods cannot be detected with this equipment, and so the need for new techniques to detect them has been around for some time.

Now, Mitsuo Fukuda and his colleagues in TUT and Aichi Science & Technology Foundation, have developed novel real-time NIR optical imaging systems comprising a two-dimensional (2D) optical source composed of 850-nm-wavelength-band LEDs, a CMOS sensor, and optimized optical systems. The optical system accurately detected organic objects such as a human hair, part of an insect, plastic, and a piece of rubber in a piece of 5-mm-thick chocolate in real time. Additionally, the bone structures in chicken wings of about 20-mm in thickness were also able to be detected.

"We have developed some basic techniques required for constructing a real-time optical imaging system with high spatial resolution. The developed system has a simple optical structure and is tolerant of mechanical vibration. This optical imaging system is, therefore, applicable to mass-production lines of foods in factories, where real-time monitoring is required with high spatial resolution.”

Figure 2.
fig.2 Developed real-time NIR optical imaging system

The author Prof. Mitsuo Fukuda said "We only developed some basic techniques and systems for a real-time optical imaging system for detecting foreign organic objects and will need to customize them for application to each type of food in the future”.

The developed real-time NIR imaging system will be applicable for the observation of internal images of moving samples such as foods in mass-production lines in factories with high spatial resolution. Consequently, this system will promote food safety and security in our daily lives.


  • 特願2014-102334 「透過検査装置」
  • 特願2012-185373 「食品検査装置」


Souphaphone Phetchalern, Hiroto Tashima, Yuya Ishii, Takeshi Ishiyama, Shinichi Arai, Mitsuo Fukuda (2014). Near-infrared imaging equipment thatdetects small organic substances in thick foods, Proceeding of SPIE 9192, 91921A-1-91921A-6, 2014. 10.1117/12.2061455

Hiroto Tashima, Tsuneaki Genta, Yuya Ishii, Takeshi Ishiyama, Shinichi Arai, Mitsuo Fukuda (2013). Near-infrared imaging system for detecting small organic foreign substances in foods, Proceeding of SPIE 8841, 884117-1-884117-7. 10.1117/12.2023541

Tsuneaki Genta, Hiroto Tashima, R. Shimokita, Shinichi Arai, and Mitsuo Fukuda (2012). Development of a real-time optical imaging system for monitoring food quality and assessing human body parts using diffused light, Proceeding of SPIE 8550, 85500F-1 - 85500F-8. 10.1117/12.980257









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Researcher Profile

Mitsuo Fukuda
Name Mitsuo Fukuda
Affiliation Department of Electrical and Electronic Information Engineering
Title Professor
Fields of Research Photonics / Optoelectronics