Mr. Dong Chen Profile

Dong Chen

at Systems Engineering Research Institute

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Publications (4)

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Proceedings Article | 12 March 2020 Paper

Machine vision based recognition and integrity inspection of printing characters on food package

Zekun Jing, Changjie Liu, Xinlin Jia, Zixiong Li, Dong Chen

Proceedings Volume 11439, 114391F (2020) https://doi.org/10.1117/12.2550049

KEYWORDS: Image segmentation, Image processing, Neural networks, Machine vision, Optical character recognition, Image filtering, Defect detection

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Food packaging bags are fast-moving consumer products with large output and fast production speed. Instant noodle bags need to be printed on the production date and number before packaging the food. For the possible date or code printing error, character sticking, incompleteness, etc., the correctness of the characters cannot be judged in real time by the human eye. A set of automatic recognition characters and detection systems are used to binarize, filter and tilt the picture, and use image morphology and horizontal and vertical projection to segment a single character. BP neural network is used to identify the character and compare it to the template to obtain the degree of defect and compare it with the threshold to determine whether the character is qualified. The detection speed of the system can reach 3 images per second, which can realize real-time recognition and detection of characters, so as to eliminate non-conforming products in time.

Proceedings Article | 18 December 2019 Paper

Design of tracking fast-moving target depending on rotating mirror

Guoqing Wang, Jincheng Wang, Lei Ming, Dongliang Wang, Zixuan Fang, Qi Zhao, Jingmin Wang, Dong Chen

Proceedings Volume 11338, 1133838 (2019) https://doi.org/10.1117/12.2547959

KEYWORDS: Mirrors, Cameras, Target detection, Mathematical modeling, Imaging systems, Particles, Signal detection, Sensors, Actuators, Relays

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Detecting fast-moving particle receives more and more attention both in physics and biology, and the study has shown its significant value either in supersonic speed or in movement of tiny biological particles. A significant amount of preparatory work has already been done to optimize this study. Always using multiple cameras or increasing the distance between detector and target, researchers can obtain favorable results. However, As the application of this technique increases, more and more challenges are emerging. One of the most obvious limitations is that confined space to lay detector. In some sense, rotating mirror can be introduced to make the system compact. It is necessary to analyze how to bring in mirror and built the system. Here, in order to use mirror capturing fast-moving target, we take a piezoelectric actuator to drive mirror, thus adopting a high angular rate to adapt to compact environment. Besides, A series of mathematical formulas and relational model are established to guide the construction of this system. Another advantage of the system, synchronous trigger signal can be triggered by laser and other means wirelessly with high precision. Therefore, having the aid of rotating mirror and wireless trigger, a fast-moving target detection system that has the virtues of no restriction of space is completed. In order to make this system in a successful operation, it is of importance to set up light path under the guidance of theoretical analysis. The experiment of trapping particles can be an effective method to show the system workflow.

Proceedings Article | 24 October 2017 Paper

Design of remote laser-induced fluorescence system's acquisition circuit

Guoqing Wang, Yue Lou, Ran Wang, Debao Yan, Xin Li, Xin Zhao, Dong Chen, Qi Zhao

Proceedings Volume 10461, 104610R (2017) https://doi.org/10.1117/12.2283552

KEYWORDS: Laser induced fluorescence, Laser development, Laser systems engineering

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Laser-induced fluorescence system(LIfS) has been found its significant application in identifying one kind of substance from another by its properties even it’s thimbleful, and becomes useful in plenty of fields. Many superior works have reported LIfS’ theoretical analysis , designs and uses. However, the usual LIPS is always constructed in labs to detect matter quite closely, for the system using low-power laser as excitation source and charge coupled device (CCD) as detector. Promoting the detectivity of LIfS is of much concern to spread its application. Here, we take a high-energy narrow-pulse laser instead of commonly used continuous wave laser to operate sample, thus we can get strong fluorescent. Besides, photomultiplier (PMT) with high sensitivity is adopted in our system to detect extremely weak fluorescence after a long flight time from the sample to the detector. Another advantage in our system, as the fluorescence collected into spectroscopy, multiple wavelengths of light can be converted to the corresponding electrical signals with the linear array multichannel PMT. Therefore, at the cost of high-powered incentive and high-sensitive detector, a remote LIFS is get. In order to run this system, it is of importance to turn light signal to digital signal which can be processed by computer. The pulse width of fluorescence is deeply associated with excitation laser, at the nanosecond(ns) level, which has a high demand for acquisition circuit. We design an acquisition circuit including, I/V conversion circuit, amplifying circuit and peak-holding circuit. The simulation of circuit shows that peak-holding circuit can be one effective approach to reducing difficulty of acquisition circuit.

Proceedings Article | 24 October 2017 Paper

Study of improving signal-noise ratio for fluorescence channel

Guoqing Wang, Xin Li, Yue Lou, Dong Chen, Xin Zhao, Ran Wang, Debao Yan, Qi Zhao

Proceedings Volume 10461, 104610M (2017) https://doi.org/10.1117/12.2283358

KEYWORDS: Luminescence, Laser induced fluorescence, Laser systems engineering

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Laser-induced fluorescence(LIFS), which is one of most effective discrimination methods to identify the material at the molecular level by inducing fluorescence spectrum, has been popularized for its fast and accurate probe’s results. According to the research, violet laser or ultraviolet laser is always used as excitation light source. While, There is no atmospheric window for violet laser and ultraviolet laser, causing laser attenuation along its propagation path. What’s worse, as the laser reaching sample, part of the light is reflected. That is, excitation laser really react on sample to produce fluorescence is very poor, leading to weak fluorescence mingled with the background light collected by LIFS’ processing unit, when it used outdoor. In order to spread LIFS to remote probing under the complex background, study of improving signal-noise ratio for fluorescence channel is a meaningful work. Enhancing the fluorescence intensity and inhibiting background light both can improve fluorescence’ signal-noise ratio. In this article, three different approaches of inhibiting background light are discussed to improve the signal-noise ratio of LIFS. The first method is increasing fluorescence excitation area in the proportion of LIFS’ collecting field by expanding laser beam, if the collecting filed is fixed. The second one is changing field angle base to accommodate laser divergence angle. The third one is setting a very narrow gating circuit to control acquisition circuit, which is shortly open only when fluorescence arriving. At some level, these methods all can reduce the background light. But after discussion, the third one is best with adding gating acquisition circuit to acquisition circuit instead of changing light path, which is effective and economic.

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