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Wu G.,Henan University of Science and Technology | Zhang H.,Henan University of Science and Technology | Li Y.,Henan University of Science and Technology | Zhang B.,Xuchang Vocational and Technical College
IEEE International Conference on Automation and Logistics, ICAL | Year: 2012

An algorithm to extract contour of palmprint based on corner point features is proposed. Firstly, a lot of excircles were made along the edges of palmprint; Secondly the approximate corner point positions of palmprint can be located by calculating the intersection number of palmprint edges and the excircles; Finally, extract ROI region by the means of inscribed circle of square, then extract and match the texture feature by combining with palmprint features and relative knowledge. On the basis of corner positions, a consistent ROI can be extracted for each palmprint, and feature vectors can be calculated for each ROI to match all the palmprint images in the database. The experimental results show that the palmprint is a good biological feature for identity authentication recognition, and the corner point detection algorithm not only can position the corner point quickly and accurately, but also can improve the matching efficiency effectively. © 2012 IEEE. Source


Di C.,CAS Chengdu Institute of Optics and Electronics | Di C.,University of Chinese Academy of Sciences | Yan W.,CAS Chengdu Institute of Optics and Electronics | Hu S.,CAS Chengdu Institute of Optics and Electronics | And 4 more authors.
IEEE Photonics Journal | Year: 2014

Focusing and leveling are two imperative processes to adjust the wafer onto the ideal focal plane of projection lithography tools. Based on moiré fringes formed by particularly designed dual-grating marks, the four-channel focusing and leveling scheme is proposed and demonstrated. These relationships between the tilted amount of wafer, the vertical defocusing amount, and the phase distributions of moiré fringes are deduced. A single-channel experimental setup is constructed to verify the performances of proposed method. Results indicate that the tilted amount and the vertical defocusing amount can be precisely detected with accuracy at 10-4 rad and several nanometers level, respectively, and therefore meet the demand of the high-demanding focusing and leveling processes. © 2014 IEEE. Source


Wang N.,CAS Chengdu Institute of Optics and Electronics | Wang N.,University of Chinese Academy of Sciences | Tong J.,Xuchang Vocational and Technical College | Zhou W.,CAS Chengdu Institute of Optics and Electronics | And 5 more authors.
IEEE Photonics Journal | Year: 2015

In this paper, we report the design, analysis, and simulation of a novel quadruple-band metamaterial absorber at microwave frequencies. The absorber is composed of delicate periodic patterned structures and a metallic background plane, which are separated by a dielectric substrate. By manipulating the periodic patterned structures, nearly perfect absorption can be obtained at four specific resonance frequencies. Moreover, the significantly high absorptions of quadruple peaks are insensitive to polarization independence, and the influence of the incident angle on the absorption for both TE and TM modes was also analyzed. To explain the absorption mechanism of the suggested structures, the electric and magnetic field distributions and the resistance matching principle were given. Importantly, the design idea has the ability to be extended to other frequencies, such as terahertz, infrared, and optical frequencies. © 2009-2012 IEEE. Source


Di C.,CAS Chengdu Institute of Optics and Electronics | Di C.,University of Chinese Academy of Sciences | Hu S.,CAS Chengdu Institute of Optics and Electronics | Yan W.,CAS Chengdu Institute of Optics and Electronics | And 4 more authors.
IEEE Photonics Journal | Year: 2014

Focusing of wafer plane is an essential factor to determine the ultimate feature size of the stepper such as projection lithographic system. Based on Michelson interferometeric system, this paper demonstrates an interferometric focusing scheme for projection lithography to coaxially locate the ideal focal plane of the projective objective. The collimated incident laser beam is divided into the reference arm and object arm. The latter propagates through the objective lens and then interferes with the slightly deflected reference beam that reflected back by a fixed mirror, giving rise to an interferential pattern on the CCD. Any amounts of defocusing can be directly indicated from the demodulated phase of the interferential pattern. In this manner, the focusing sensitivity at nanometer scale is experimentally attainable, which shows great superiority over traditional methods, particularly the limited focal length of current projective objective lens. © 2009-2012 IEEE. Source


Cheng Y.,Chinese Academy of Sciences | Chen L.,Institute of Optics and Electronic | Zhao L.,Institute of Optics and Electronic | Song H.,Institute of Optics and Electronic | Tong J.,Xuchang Vocational and Technical College
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Now it's more and more higher for the image quality of lithography systems .Due to the errors in the processing and assembly, the image quality of the traditional lens becomes lower and deviates from the theoretical value of the design. To improve image quality, it's necessary to adjust some lens. The new objective lens having the adjustment mechanism and the measuring means were designed. A closed loop was designed to achieve the x, y, z, θx, θy of lens. Since the assembly errors existed, the theoretical relationship between the executive mechanism, measuring means and lens position needed to be calibrated. Ultimately we achieved about 150nm regulation accuracy of the x, y direction, 300nm regulation accuracy of z direction ,and 0.15″ regulation accuracy of the θx, θy direction. © 2014 SPIE. Source

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