Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Wavelength Division Multiplexing (WDM) is a boon of Light wave Technology as it increases the transmission capacity and enhances the transmission distance by using optical amplification. The capacity of the present system is limited by the noise generated by the amplifiers and interactions due to nonlinearities like Cross Phase Modulation (XPM), Self Phase Modulation(SPM), Four Wave Mixing(FWM) and Stimulated Raman Scattering(SRS). This paper focuses on the design of WDM Network in order to analyze the effect of XPM on the optical transmission rate. Also the papers focus on the suppression methods that can be used in order to remove the degrading effects of these non linearity's. © 2012 Springer-Verlag.

Mechanical

School of Mechanical Engineering

Chennai Campus

VIT Unitversity

Department of Instrumentation

School of Electrical Engineering

Vellore Campus

Communications in Computer and Information Science Global Trends in Computing and Communication Systems

Design of WDM Optical Networks for the Analysis of Cross Phase Modulation and Self Phase Modulation

We describe a system for the automated diagnosis of diabetic retinopathy and glaucoma using fundus and optical coherence tomography (OCT) images. Automatic screening will help the doctors to quickly identify the condition of the patient in a more accurate way. The macular abnormalities caused due to diabetic retinopathy can be detected by applying morphological operations, filters and thresholds on the fundus images of the patient. Early detection of glaucoma is done by estimating the Retinal Nerve Fiber Layer (RNFL) thickness from the OCT images of the patient. The RNFL thickness estimation involves the use of active contours based deformable snake algorithm for segmentation of the anterior and posterior boundaries of the retinal nerve fiber layer. The algorithm was tested on a set of 89 fundus images of which 85 were found to have at least mild retinopathy and OCT images of 31 patients out of which 13 were found to be glaucomatous. The accuracy for optical disk detection is found to be 97.75%. The proposed system therefore is accurate, reliable and robust and can be realized. © 2012 Pachiyappan et al.; licensee BioMed Central Ltd.

World University root node

Fulltext

Lipids in Health and Disease

Automated diagnosis of diabetic retinopathy and glaucoma using fundus and OCT images

The setup is based on the concept of free space optical communication. In this process, communication between PC to PC using LASER light is established. The project uses IC MAX 232, which needs only a single power supply of 5V (for TTL to RS-232 and vice-versa level conversion). The communication over the short distance of 2-3 m is possible using IR diodes. The range could be increased up to hundred meters, using the laser diode module in place of IR LEDs . The laser module used is easily available as laser pointer (having about 3 mW power output). The laser beam of one module is pointed on to the photodiode of another module connected to other PC and vice-versa. By loading serial communication software and setting the port parameters to 9600 n 8 1 (here, 9600 represents baud rate, n stands for parity none, 8 represents bits per character and 1 indicates no. of stop bits)communication is established. The software program for the purpose is written in C language. Using this codes chatting and data transfer between two nodes is possible on condition that Line of Sight must exist between two nodes. © EuroJournals Publishing, Inc. 2012.

Department of Communication Engineering

School of Electronics Engineering

European Journal of Scientific Research

Laser based optical transceiver for data transfer of free space optical communication

Wind speed forecast is essential in wind energy conversion system and may fail to operate power plant at non optimal region if not properly forecasted. This paper focuses the short term wind speed forecasting using conventional statistical method and artificial neural networks such as back propagation network (BPN), generalized regression neural network (GRNN) and radial basis function networks (RBFN). The developed algorithms and networks are trained and tested for wind speed data which are measured at an interval of 15 minutes. In this paper we compared the performance of RBFN and other networks for effective wind speed forecasting. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.

International Review on Modelling and Simulations

Forecasting of wind speed using artificial neural networks

Wireless Multimedia Sensor Network (WMSN) is the most popular sensor network and is getting fame over the past half a decade. The main compositions of the WMSN are the sensor nodes comprising of any of sensor systems like cameras, microphones, receiving systems and so on. In such a system with the sensor nodes emitting the confidential data, an extra authentication could be incorporated to the system with steganography principles. In this paper the cover image from WMSN has been employed in transform domain with appropriate co-efficient selection by Graph Theory for data embedding. In this proposed method, embedding a normal LOGO (generally fixed) in cover image from WMSN is successfully done along with the authentication and steganography. © 2012 Pillay Engineering College.

IEEE-International Conference on Advances in Engineering, Science and Management, ICAESM-2012

Authenticated wireless image sensor secret network - Graph guided steganography

Steganography is used to hide a secret message within a cover image, thereby yielding a stego image such that even the trace of the presence of secret information is wiped out. The purpose of steganography is to maintain secret communication between two users. Steganography has several technical challenges namely high hiding capacity and imperceptibility. In this paper we propose a modern steganographic technique with Integer Wavelet transform (IWT) and double key to achieve high hiding capacity, high security and good visual quality. Here cover image is converted in to wavelet transform co-efficients and the coefficients are selected randomly by using Key-1 for embedding the data. Key-2 is used to calculate the number of bits to be embedded in the randomly selected coefficients. Finally the Optimum Pixel Adjustment Process (OPAP) is applied to the stego image to reduce the data embedding error. © 2011 IEEE.

2011 International Conference on Computer, Communication and Electrical Technology (ICCCET)

Wave (let) decide choosy pixel embedding for stego

Electrical Capacitance Tomography is employed to obtain the information about the spatial distribution of a mixture of dielectric materials inside a vessel, by measuring the electrical capacitances between the sets of electrodes placed around its periphery and converting them into an image showing the distribution of permittivity. In this paper introduction to capacitance tomographical technique is given and the existing transduction mechanisms are described. © Research India Publications.

Department of Control and Automation

International Journal of Applied Engineering Research

Introduction to Electrical Capacitance Tomography and its measurement circuitry

A watermarking scheme based on SVM is implemented and analyzed for two different forms of copyright information, a 34 × 45 binary image and a sound signal for utterance of a word. In this work, the generalization ability of SVM using a basic linear kernel for two different forms of copyright information is analyzed. During extraction, SVM is trained using an extra reference watermark. The perceptual legibility of image and the sound are taken as the objective parameter for analysis. The copyright information is embedded in the positions where the values of the pixels are well within the limit decided by the mean of the surrounding pixels. The perceptual legibility is found to be increased by the above step. The experimental results show the perceptual legibility of sound is better even when the watermarked image is heavily distorted.

Electronics

TENCON 2008 - 2008 IEEE Region 10 Conference

SVM based effective watermarking scheme for embedding binary logo and audio signals in images

The paper describes a beam steering control system for a propagating laser beam, which is essential in free-space optical link. The tilt of the laser beam is measured with an indigenously developed Shack-Hartmann Wavefront Sensor (SHWFS) and dynamically compensated using a piezo-driven tip-tilt mirror. The system uses a commercial frame grabber and a CCD camera, which are less expensive. Spatial sampling of the beam with a 10 × 10 microlens array, Zernike Polynomial decomposition up to 4th order and real-time display of tilt-map are carried out. Tilt measurement to an accuracy of 2 pradians has been achieved. Experimental results of wavefront measurements using our SHWFS as well as tilt compensation are presented. © 2006 Taylor & Francis Group, LLC.

IETE Journal of Research

Laser beam steering control system for free-space line of sight optical communication

A wavelet-based method of moment calculation with a set of basis functions is presented for centroid estimation in a Shack-Hartmann Wavefront Sensor. The method has been compared with other algorithms such as statistical averaging, FFT and least-squares method. A comparative analysis shows that wavelet method has a high accuracy and processing speed, and better suited for wavefront reconstruction applications. Further, the wavelet method presented here has a variable accuracy and resolution, and can be optimized for a particular application under consideration. © 2005 Elsevier GmbH. All rights reserved.

Optik

Measurement of moments for centroid estimation in Shack-Hartmann wavefront sensor - A wavelet-based approach and comparison with other methods

Accurate surface metrology and transmission characteristics measurements have become vital to certify the manufacturing excellence in the field of glass visors, windshields, menu boards and transportation industries. We report a simple, cost-effective and novel technique for the measurement of geometric aberrations in transparent materials such as glass sheets, Perspex, etc. The technique makes use of an array of spot pattern, we call the spot pattern test chart technique, in the diffraction limited imaging position having large field of view. Performance features include variable angular dynamic range and angular sensitivity. Transparent sheets as the intervening medium introduced in the line of sight, causing aberrations, are estimated in real time using the Zernike reconstruction method. Quantitative comparative analysis between a Shack-Hartmann wavefront sensor and the proposed new method is presented and the results are discussed. © 2005 IOP Publishing Ltd.

Measurement Science and Technology

A spot pattern test chart technique for measurement of geometric aberrations caused by an intervening medium - A novel method

Atmospheric distortion limits the quality of images obtained with ground-based telescopes. Similarly, laser beam propagation through turbulent atmosphere results in discontinuity in satellite optical links. Adaptive Optic techniques provide compensation for the aberrations introduced due to the random refractive index fluctuations of the atmosphere. In this paper, we present the practical details of the successful design and development of a low-cost Shack-Hartmann wavefront analyzer, as well as a closed loop Adaptive Optics system which compensates the global tilt and the local phase fluctuations of a wavefront. The Shack-hartmann sensor measures the wavefront profile in real time and generates correction signals. Global tilt measurements to accuracy of 19 μ radians and phase profiles up to λ/50 have been acheived. Dynamic corrections have been made with tip-tilt mirror and a deformable mirror. The Opto-mechanical system, software design, and implementation are described. Experimental results of wavefront measurements and correction of aberrations are presented.

Journal of Optics (India)

Design and development of a closed loop adaptive optics system for wavefront sensing and control

Aim: Higher order aberrations of the eye were studied to better understand their behaviour. Patients and Methods: A Shack-Hartmann wavefront sensor with 15 × 15 spatial samplings of the wavefront was used and the analysis was done with a Zernike polynomial in a healthy young Indian population. The total root mean square wavefront error was measured, ignoring the lower order aberrations. Higher order coefficients were calculated and plotted in comparison with the normal values. Contributions of spherical and comatic aberrations towards the degradation of the optical quality of the eye were analysed. Results: A slight increase in modulation transfer function in this age group and the existence of mirror symmetry could be seen. There was no significant change in aberration level, although measurement of the aberrations at the extremes of age in this study did show a slight increase in the aberration level. Conclusions: This study will help clinicians in surgical evaluation and also provides an analytic tool for visual aberration measurement and correction methodology.