Retinal image is one of the robust and accurate biometrics methods to recognize a person. In this article we present a new biometric identification system based on Fourier transform and angular partitioning of the spectrum. In this method, at first, the optical disc is localized using template matching technique and used for rotating the retinal image into the reference position. It compensates the rotation effects which might occur during the scanning process. Fourier transform coefficient and angular partitioning of these coefficients are used for the purpose of feature definition in our method. The extract features are rotation invariant and robust against noise. Finally we employ Euclidean distance for feature matching. The proposed algorithm was tested using 40 images from DRIVE database and experimental results showed the efficiency of the proposed algorithm for the identification of retinal images with noise and rotation

Retinal image is one of the robust and accurate biometrics. A new biometric identification system base on combination of Fourier transform and that special partitioning and wavelet transform presented in this article. In this method, at first, optical disc is localized using template matching technique and use it for rotate the retinal image to reference position. Angular partitioning with the special structure on magnitude spectrum of retinal image and Wavelet Transform is used for feature definition. Finally we employ Euclidean distance for feature matching. The proposed method applied on a database consist 400 retinal images from 40 persons. In this article noisy and rotate retinal image are used in identification process. 99.1% identification rate can achieve in this proposed method

Due to limited availability and the rising price of telluride, the biggest challenge in solar Photovoltaic (PV) is to successfully design and fabricate optimized CdTe solar cells with reducing the cell thickness that show simultaneously high efficiency and current density. A novel structure of ultrathin CdTe solar cells is proposed in this paper that focuses on conversion efficiency. This structure achieved by rotating 90 o in the base line structure that suggests high efficiency due to the high current density. The result showed a considerable improvement over the 15% efficiency of the reference solar cell. The proposed structure is quite noteworthy in reducing the amount of material used and associated losses. Under global air mass (AM) 1.5 conditions, an open-circuit voltage (V oc) of 866 mV, a short-circuit current density (J sc) of 74.84 mA/cm 2 , and a fill factor (FF) of 48.2% were obtained corresponding to a conversion efficiency of 31.2%.

In the present work, we investigate threshold characteristics of a single mode 1.55 µm InGaAsP vertical cavity surface emitting laser (VCSEL) with two different optical confinement structures. The device employs InGaAsP active region, which is sandwiched between GaAs/AlGaAs and GaAs/AlAs distributed Bragg reflectors (DBRs). The optical confinement introduced by the oxide aperture or a single defect photonic crystal design with holes etched throughout the whole structure, is compared with previous work. Photonic crystal VCSEL shows 30.86% and 57.02% lower threshold current than that of the similar oxide confined VCSEL and previous results, respectively. This paper provides key results of the threshold characteristics, including the threshold current and the threshold power. Results suggest that, the 1.55 μm InGaAsP photonic crystal VCSEL seems to be the most optimal one for light sources in high performance optical communication systems.

No abstract