Dr. Yu Chen Profile

Dr. Yu Chen

at Changchun Univ of Science and Technology

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Publications (14)

Proceedings Article | 16 August 2017 Open Access

Teaching autonomy: turning the teaching evaluation of the Applied Optics course from impart knowledge to the new intelligent thinking

Huifu Zhao, Yu Chen, Dongmei Liu

Proceedings Volume 10452, 104523Y (2017) https://doi.org/10.1117/12.2265361

KEYWORDS: Solids

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There is a saying that “The teacher, proselytizes instructs dispels doubt.” Traditional teaching methods, constantly let the students learn the knowledge in order to pursue the knowledge of a solid grasp, then assess the teaching result by evaluating of the degree of knowledge and memory. This approach cannot mobilize the enthusiasm of students to learn, and hinders the development of innovative thinking of students. And this assessment results have no practical significance, decoupling from practical application. As we all know, the course of Applied Optics is based on abstract theory. If the same teaching methods using for this course by such a "duck", it is unable to mobilize students' learning initiative, and then students’ study results will be affected by passive acceptance of knowledge. How to take the initiative to acquire knowledge in the class to the students, and fully mobilize the initiative of students and to explore the potential of students, finally evaluation contents more research on the practical significance? Scholars continue to innovate teaching methods, as well as teaching evaluation indicators, the best teaching effect to promote the development of students. Therefore, this paper puts forward a set of teaching evaluation model of teaching autonomy.

This so-called "autonomous teaching" is that teachers put forward the request or arrange the task and students complete the learning content in the form of a group to discuss learning before the lesson, and to complete the task of the layout, then teachers accept of students' learning achievements and answer questions. Every task is designed to evaluate the effectiveness of teaching. Every lesson should be combined with the progress of science and technology frontier of Applied Optics, let students understand the relationship between research and application in the future, mobilize the students interest in learning, training ability, learn to take the initiative to explore, team cooperation ability. As well, it has practical significance to every evaluation, making the teaching to active learning in teaching, cultivating students' creative potential, deep, solid foundation for the day after learning work.

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Proceedings Article | 8 March 2017 Paper

Design of a novel nonimaging Fresnel concentrator with high uniformity

Hui-fu Zhao, Yu Chen

Proceedings Volume 10255, 102550U (2017) https://doi.org/10.1117/12.2268169

KEYWORDS: Solar concentrators, Nonimaging optics, Photovoltaics, Optical systems, Solar cells, Solar energy, Receivers, Geometrical optics, Ray tracing, Sun

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Proceedings Article | 7 November 2016 Paper

Design of a solar-blind ultraviolet detection system

Wenwen Fan, Sirui Kang, Yu Chen

Proceedings Volume 10141, 101411N (2016) https://doi.org/10.1117/12.2256349

KEYWORDS: Ultraviolet radiation, Aspheric lenses, Image quality standards, Binary data, Missiles, Optical components, Ultraviolet detectors, Optical design, Imaging systems, Image quality

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Proceedings Article | 7 November 2016 Paper

Design of a solar-blind ultraviolet zoom lens in corona detection

Sirui Kang, Wenwen Fan, Yu Chen

Proceedings Volume 10141, 101411Q (2016) https://doi.org/10.1117/12.2256448

KEYWORDS: Ultraviolet radiation, Zoom lenses, Aspheric lenses, Distortion, Modulation transfer functions, Image quality, Optical design, Coronagraphy, Imaging systems, Sensors

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Proceedings Article | 4 March 2015 Paper

Solar-blind ultraviolet optical system design for missile warning

Yu Chen, Furong Huo, Liqin Zheng

Proceedings Volume 9521, 95210X (2015) https://doi.org/10.1117/12.2175626

KEYWORDS: Ultraviolet radiation, Aspheric lenses, Missiles, Diffractive optical elements, Optical design, Ultraviolet detectors, Image quality, Spherical lenses, Optical components, Imaging systems

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Proceedings Article | 24 November 2014 Paper

Application of automatic threshold in dynamic target recognition with low contrast

Hua Miao, Xiaoming Guo, Yu Chen

Proceedings Volume 9301, 930128 (2014) https://doi.org/10.1117/12.2072569

KEYWORDS: Image processing, Target recognition, Joint transforms, Fourier transforms, Optical correlators, Target detection, Automatic target recognition, Image segmentation, CCD cameras, Optoelectronics

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Hybrid photoelectric joint transform correlator can realize automatic real-time recognition with high precision through the combination of optical devices and electronic devices. When recognizing targets with low contrast using photoelectric joint transform correlator, because of the difference of attitude, brightness and grayscale between target and template, only four to five frames of dynamic targets can be recognized without any processing. CCD camera is used to capture the dynamic target images and the capturing speed of CCD is 25 frames per second. Automatic threshold has many advantages like fast processing speed, effectively shielding noise interference, enhancing diffraction energy of useful information and better reserving outline of target and template, so this method plays a very important role in target recognition with optical correlation method. However, the automatic obtained threshold by program can not achieve the best recognition results for dynamic targets. The reason is that outline information is broken to some extent. Optimal threshold is obtained by manual intervention in most cases. Aiming at the characteristics of dynamic targets, the processing program of improved automatic threshold is finished by multiplying OTSU threshold of target and template by scale coefficient of the processed image, and combining with mathematical morphology. The optimal threshold can be achieved automatically by improved automatic threshold processing for dynamic low contrast target images. The recognition rate of dynamic targets is improved through decreased background noise effect and increased correlation information. A series of dynamic tank images with the speed about 70 km/h are adapted as target images. The 1st frame of this series of tanks can correlate only with the 3rd frame without any processing. Through OTSU threshold, the 80th frame can be recognized. By automatic threshold processing of the joint images, this number can be increased to 89 frames. Experimental results show that the improved automatic threshold processing has special application value for the recognition of dynamic target with low contrast.

Proceedings Article | 24 November 2014 Paper

Spatial distorted target recognition based on improved MACH filter

Yu Chen, Furong Huo, Liqin Zheng

Proceedings Volume 9301, 930127 (2014) https://doi.org/10.1117/12.2072504

KEYWORDS: Target recognition, Target detection, Distortion, Image filtering, Image processing, Detection and tracking algorithms, Tolerancing, Fourier transforms, Optical filters, Joint transforms

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Joint transform correlator (JTC) can make targets recognized and located accurately, but the bottleneck technique of JTC is how to recognize spatial distorted targets in cluttered scene. This has restricted the development of the pattern recognition with JTC to a great extent. In order to solve the problem, improved maximum average correlation height (MACH) filter algorithm is presented in this paper. The MACH algorithm has powerful capability of recognition for spatial distorted targets (rotation and scale changed etc.). The controlling parameters of the synthesized filter are optimized in this paper, which makes the filter have higher distortion tolerance and can suppress cluttered noise effectively. When improved MACH filter algorithm in frequency domain is projected to space domain, the MACH reference template image can be obtained which includes various forms of distorted target image. Based on amounts of computer simulation and optical experiments, MACH reference template is proved to have the capability of sharpening the correlation peaks and expanding recognizing scope for distorted targets in cluttered scene. MATLAB software is applied to produce MACH reference image for the detected target images and conduct simulation experiments for its powerful calculation capability of matrix. In order to prove the feasibility of MACH reference in JTC and determine the recognition scope, experiments for an aircraft target in the sky are carried out. After the original image is processed by edge extraction, a MACH filter reference template is obtained in space domain from improved MACH filter in frequency domain. From simulation experiments, the improved MACH filter is proved to have the feasibility of sharpening correlation peaks for distorted targets. Optical experiments are given to verify the effectiveness further. The experiments show the angular distortion tolerance can reach up to ±15 degrees and scale distortion tolerance can reach up to ±23%. Within this scope, the spatial distorted aircraft can be recognized effectively. The actual effect of the improved MACH filter algorithm has been confirmed very well.

Proceedings Article | 18 November 2014 Paper

Optical system design of solar-blind UV target receiver with large FOV

Yu Chen, Furong Huo, Liqin Zheng

Proceedings Volume 9298, 92981I (2014) https://doi.org/10.1117/12.2072415

KEYWORDS: Ultraviolet radiation, Ultraviolet detectors, Optical design, Image quality, Receivers, Objectives, Signal detection, Optical filters, Point spread functions, Diffraction

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Ultraviolet (UV) radiation of 200nm-300nm waveband from the sun is absorbed by atmosphere, which is often referred to the solar-blind region of the solar spectrum. Solar-blind characteristics of this waveband have important application value in forest-fire prevention, UV security communication, UV corona detection and other aspects. Especially in military fields such as missile warning, the application of solar-blind waveband has developed very rapidly, which is receiving more and more attention recently. In this paper, ZEMAX software is used to design an optical system of solar-blind UV target receiver with waveband 240nm-280nm, with which UV target signal can be detected. The optional materials are very few for UV optical systems to choose from, in which only CaF2 and JGS1 are commonly used. Various aberrations are not easy to be corrected. So it is very difficult to design a good UV system. Besides, doublet or triplet cannot be used in UV optical system considering possible cracking for different thermal expansion coefficients of different materials. So the doublet in initial structure is separated for this reason. During the optimization process, an aspheric surface is used to correct the aberrations. But this surface is removed before the design is finished to save production cost and enhance the precision of fabrication and test, which still keeps the image quality meeting the usage requirements. What we care for is the converging condition for different field of view from the far object on image plane. So this is an energy system. Spot diagram is taken as the evaluation criterion of image quality. The system is composed of 6 lenses with field of view (FOV) 31 degrees. In the final design results, the root mean square (RMS) radius for marginal FOV is less than 6.3 microns, while the value is only 4 microns for zero FOV. Point Spread Function and diffraction encircled energy diagram within the maximum FOV confirms the good performance of system further.

Proceedings Article | 18 November 2014 Paper

Optical system design of solar-blind UV target simulator with long focal length

Yu Chen, Furong Huo, Liqin Zheng

Proceedings Volume 9298, 92981L (2014) https://doi.org/10.1117/12.2072503

KEYWORDS: Ultraviolet radiation, Optical design, Modulation transfer functions, Light sources, Image quality, Objectives, Collimators, Lamps, Optical filters, Ultraviolet detectors

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Proceedings Article | 18 November 2014 Paper

Infrared telephoto lenses design for joint transform correlator

Yu Chen, Furong Huo, Liqin Zheng

Proceedings Volume 9298, 92981K (2014) https://doi.org/10.1117/12.2072497

KEYWORDS: Infrared radiation, Infrared imaging, Target recognition, Thermography, Target detection, Infrared lenses, Joint transforms, Infrared detectors, Lens design, Image quality

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Joint transform correlator (JTC) is quite useful for pattern recognition in many fields, which can realize automatic real-time recognition of target in cluttered background with high precision. For military application, JTC can also be applied for thermo target recognition especially at night. To make JTC recognize thermo targets, an infrared telephoto lens is designed in this paper. Long focal length and short tube length are required for this usage. So the structure of a positive lens group and a negative lens group are adopted. Besides, the effective focal length and relative aperture should be large enough to ensure the distant targets can be detected with adequate illumination. In this paper, the working waveband of adopted infrared CCD detector is 8-12μm. According to Nyquist law, the characteristic frequency of the system is 14lp/mm. The optional materials are very few for infrared optical systems, in which only several kinds of materials such as Germanium, ZnSe, ZnS are commonly used. Various aberrations are not easy to be corrected. So it is very difficult to design a good infrared optical system. Besides, doublet or triplet should be avoided to be used in infrared optical system considering possible cracking for different thermal expansion coefficients of different infrared materials. The original configuration is composed of three lenses. After optimization, the image quality can get limit diffraction. The root mean square (RMS) radii of three fields are 6.754μm, 7.301μm and 12.158μm respectively. They are all less than the Airy spot diameter 48.8μm. Wavefront aberration at 0.707 field of view (FOV) is only 0.1wavelength. After adjusting the radius to surface templates, setting tolerances and giving element drawings, this system has been fabricated successfully. Optical experimental results of infrared target recognition using JTC are given in this paper. The correlation peaks can be detected and located easily, which confirms the good image quality of the designed infrared telephoto lens.

Proceedings Article | 6 November 2014 Paper

Design of solar-blind UV optical system for missile approach warning

Yu Chen, Furong Huo, Liqin Zheng

Proceedings Volume 9272, 92721U (2014) https://doi.org/10.1117/12.2073885

KEYWORDS: Ultraviolet radiation, Missiles, Aspheric lenses, Optical design, Imaging systems, Diffractive optical elements, Optical components, Objectives, Image quality, Spherical lenses

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Proceedings Article | 27 November 2012 Paper

Optical correlation recognition research of low-light level target based on lifting wavelet transform

Qibo Zhang, Yu Chen, Su Zhang, Yu Zhang, Hua Miao, Wensheng Wang

Proceedings Volume 8559, 85590M (2012) https://doi.org/10.1117/12.999676

KEYWORDS: Image processing, Target recognition, Wavelet transforms, Joint transforms, Wavelets, Target detection, Optical correlators, Signal to noise ratio, Image filtering, Digital filtering

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Proceedings Article | 4 January 2008 Paper

Application of JTC in recognition and real-time tracking of moving targets

Yu Chen, Hua Miao, Wensheng Wang, Qunxian Zhu

Proceedings Volume 6837, 683708 (2008) https://doi.org/10.1117/12.757206

KEYWORDS: Target recognition, Joint transforms, Target detection, Optical correlators, Fourier transforms, Image processing, Image filtering, Optical filters, Charge-coupled devices, Spatial light modulators

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Proceedings Article | 11 January 2005 Paper

Hybrid optoelectronic joint transform correlator for the recognition of targets in cluttered scenes

Wensheng Wang, Yu Chen, Cuiping Liang, Hua Miao

Proceedings Volume 5642, (2005) https://doi.org/10.1117/12.567880

KEYWORDS: Joint transforms, Fourier transforms, Target detection, Optical correlators, Wavelets, Target recognition, Optical filters, CCD cameras, Optoelectronics, Nonlinear filtering

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Showing 5 of 14 publications

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