Selçuk Tarım ve Gıda Bilimleri Dergisi
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Open Access journal
ISSN (Print) 1309-0550
Published by Selcuk University [2 journals]
- The splitting mechanism of zero order diffraction pattern by roof prisms
Abstract: In order to reduce the adverse effects of the roof prism on the imaging quality of the system, the intensity distribution function in the diffraction pattern which is used to analyze the relationship between the characteristic of the zero order diffraction splitting spot and the structural parameters in one roof prism is obtained by methods of polarization ray tracing and far field diffraction integral. The methods are determined by given the general structure parameters of the roof prism, the prism refractive index and the entering azimuth angle if illuminated with linearly polarized light. Based on that, structure parameters and reflection shift on roof surfaces of the roof prisms are analyzed. The result shows that: (1) within the allowable structure angle, the splitting effect decreases with the increase of the structural angle; (2) at a certain wavelength, the optimum condition to eliminate the splitting phenomenon is that the reflection phase shift of the roof surfaces equal to π.
- Influence of Mn doping on optical properties of ZnO nanoparticles
synthesized by microwave irradiation
Abstract: In this study, manganese [Mn]-doped zinc oxide [ZnO] nanoparticles are prepared by microwave irradiation method using zinc acetate and manganese acetate as precursors. The optical properties of the samples were investigated by UV-Vis–NIR, photoluminescence (PL) and Fourier transform infrared spectroscopy. Optical absorption analysis of the samples exhibits a red shift in the absorption band edge with increasing dopant concentration, and corresponding defects in ZnO are responsible for broad bands in the visible part of the photoluminescence (PL) spectrum. The room-temperature photoluminescence shows that the intensity of near band energy (NBE) emission depends strongly on the content of Mn in ZnO. We have also discussed in the paper the types of transitions and possible assignments of the PL bands. The chemical groups of the samples were confirmed by FTIR spectra.
- An intensity-modulated optical fiber sensor with concave mirror for
measurement of displacement
Abstract: Two fiber intensity-modulated sensors are investigated and used in number of applications, including those in military, industry, biomedical, and aerospace. A common form of two fiber intensity-modulated optical fiber sensor performs its measurement by making use of a pair of straight optical fibers with a plane reflector. The reflected optical intensity is a function of distance between fiber tips and plane reflector as well as refractive index of the medium. This paper describes an alternative sensing structure with a concave reflector instead of a plane reflector and demonstrates the derivation of the geometric mathematical model for analyzing its sensing characteristics. The mathematical model shows that the blind region is minimized, when the plane reflector is replaced by a concave reflector. Such type of optical sensor can be used where space required for the measurement is the major limitation. Experimental results obtained confirm the model.
- Finite difference time domain methods to solve problems in light
scattering and propagation: new developments and extensions
Abstract: The finite difference time domain (FDTD) method was developed nearly 50 years ago, but is still a subject of active research. Here we introduce a high-accuracy version of FDTD derived from a nonstandard finite difference model to solve the scattering problem. To handle metals in the visible light region, where the real part of the electrical permittivity is negative, FDTD must be modified to include dispersion. We introduce an extension and adaptation of the recursion convolution (RC) algorithm that reduces computational cost and improves accuracy.
- Measurement of order parameter, birefringence and polarizibility of liquid
Abstract: The refractive index (RI) is a basic optical property of materials and its accurate value is often needed in many branches of physic and chemistry. There are several methods used to find refractive index of the material. We have used Hollow prism method to measure refractive indices of Cholesteric liquid crystal (CLC) solution. Measurements were made mixing CLC in a neutral solvent to make homogeneous solution at room temperature. Measurements were made at different temperatures for one molar concentration of the solution. Refractive indices both ordinary and extra ordinary were measured for three different wavelengths. The values obtained are analyzed using Vuks equation and Haller and Horn method. Birefringence, order parameter and polarizibility values obtained at various temperatures for three different wavelengths are discussed here.
- Designing an original instrument for measuring the speed of light
Abstract: This paper mainly proceeds to clarify a simple method in order to measure the speed of some natural phenomena having constant velocity such as light and sound as closely as desired. The fundamental idea supporting this design and the instrument which could be designed based on this thesis originates with some mathematical interesting properties associating with ellipses. Finally a small section is allocated to verify the possibility of another way in order to evaluate the speed of light.
- Three-input majority function with nonlinear material in all-optical
Abstract: In this paper, we have developed a nonlinear directional coupler theory to describe a novel all-optical majority function. Our scheme is composed of linear and nonlinear optical waveguides in which switching operation between them depending on the power of input light. Adjusting the refractive indices, and selecting the proper length of waveguides are simulated by use of RSoft CAD-Layout (BeamPROP) simulator.
- Introduction to Aberrations in Optical Imaging Systems by José
- Degradation analysis of commercial low power LEDs
Abstract: LEDs are used in a wide variety of applications. The modern high power LEDs demonstrates long lifetimes and robustness to atmospheric conditions and shocks. As high power LEDs are very useful in reduction of energy consumption a great deal of research has been carried out to understand their degradation rate. However there is very little published work on low power commercial LEDs. In this paper we report the analysis of electrical and optical degradation of low power aged LEDs. Electrical and optical characterization includes I-V measurement, optical output verses aging time, optical output verses operating current and spectral characteristics. It is observed that the forward bias voltage increases with increasing aging time and this effect is observed earlier in the LEDs which are overstressed. The spectral response shows shifting of peak wavelength slightly with age and decrease of light output also observed as function of aging.
- A new scheme of developing all-optical 4×4 cross-connect switch for
Abstract: All optical cross-connect switch is very important in optical communication network. In this paper the author proposes a method of developing ‘4×4’ four wavelength cross-connect switch exploiting the nonlinear polarization rotation (NPR) property of the probe beam in semiconductor optical amplifier (SOA). Here all the operations of the cross-connect switches are controlled using control beams of proper frequencies. This scheme may be very simply extended as the multi-channel cross-connect switches. The switch has very high operating speed with good on-off contrast ratio and it will be very effective for wavelength division multiplexing (WDM) based telecommunication network.
- New simulative studies on performance of semiconductor optical amplifier
based optical switches like frequency converter and add-drop multiplexer
for optical data processors
Abstract: Optics has proved its successful role in parallel logic, arithmetic or algebraic operations. So many different methods on optical data processing were proposed and implemented in last few decades. For implementing the all optical logic and arithmetic devices it needs different types of encoding principle like, polarization encoding principle, frequency encoding principle, intensity encoding principle and phase encoding principle. As the frequency is the basic characteristics of light, so frequency encoding principle is the most reliable one among all other encoding principles. Currently frequency encoding technique is established as a promising one for all optical processing, as frequency of light does not change normally after reflection, refraction, absorption etc. Again Semiconductor optical amplifier (SOA) can be used for different successful frequency conversions. Here in this technique ‘1’ logic state is represented by a frequency ν2 then ‘0’ state is represented by another frequency ν1 instead of intensity variation. In this paper the authors describe the simulation study of the performances of SOA in various optical switches like frequency conversion and add-drop multiplexer.
- Tight focusing of phase modulated double ring shaped radially polarized
beam with high NA lens
Abstract: Based on the vector diffraction theory, the effect of phase modulation on the intensity distribution of double ring shaped radially polarized beam(R-TEM11*) in the focal region of high NA lens is investigated theoretically. It is observed that a properly designed complex phase filter can generate a sub wavelength focal spot having FWHM of 0.3λ with an extended focal depth of 10λ. Apart from generating focal spot segment with large focal depth, it is also observed that a properly designed complex phase filter also generate optical cage, multiple focal spot segment useful for the manipulation of optical trapping.
- Design and simulation a large stroke MEMS-based linear motor for fourier
transform spectrometer applications
Abstract: In this paper a MEMS-based linear motor for Fourier transform spectrometer (FTS) has been designed and simulated. The FTS consists of a Michelson interferometer and Linear micro motor (LMM); Linear micro motor consist of two main parts; slider, and gripper. Maximum step size is equal to 3 μm; large stroke will be achieved by repeating the step sizes sequentially. Maximum amount of the large stroke is equal to 400 μm.
- Wannier stark ladder in one-dimensional photonic crystal coupled
microcavity containing indefinite metamaterials
Abstract: One-dimensional (1D) photonic crystal coupled microcavity structure containing indefinite metamaterials was investigated. The Wannier-Stark ladder (WSL) can be obtained in both the Bragg ordinary and the well-known omnidirectional band gaps by modulating widths of the cavities. The time-resolved transmission of a short pulse showed the existence of two types of optical Bloch oscillation in such structures. The transmission and the period of the oscillation are found to decrease with the increasing gradient δ.
- Construction and bit error analysis of zero cross-correlation codes for
SAC-Optical CDMA systems
Abstract: A new code family called Single Weight Zero Cross Correlation (SWZCC) code is proposed for SAC-OCDMA systems. These codes are improved version of the ZCC codes published earlier in literature. The design and construction of this code family are simple while the code construction is comparatively different in the published papers. Since the cross correlation value is always equal to zero, the system completely eliminates the PIIN and MUI. Another feature is that the code weight of the proposed code is always equal to one, independent of the number of simultaneous users and hence the design of encoder would be simplified. It is observed that for a bit error rate of 10−9, the system with the proposed code of length 200 and weight 1 supports upto 200 simultaneous users and this number is much greater than the commonly used MQC and PMP code.
- An analytical reliability model for WDM optical networks based on
heuristically generated protection trees
Abstract: An analytical model based on heuristically generated protection trees has been proposed to find the reliability performance analysis of WDM optical networks. In this model, the protection trees of the networks are generated heuristically and an analytical formula has been developed based on these protection trees. The variations of reliability with failure rate of primary and backup paths and number of wavelengths per link are estimated for WDM optical networks based on existing protection trees. This model determines the number of wavelengths to be reserved for backup paths to obtain best possible reliability. It is also seen that variation of reliability with number of wavelengths in backup paths per link (estimated with our analytical approach) closely resembles that obtained from the simulation results by existing wavelength assignment based on Alternate Path Routing.
- Twin image elimination in digital holography by combination of Fourier
Abstract: We present a new technique for removing twin image in in-line digital Fourier holography using a combination of Fourier transformations. Instead of recording only a Fourier transform hologram of the object, we propose to record a combined Fourier transform hologram by simultaneously recording the hologram of the Fourier transform and the inverse Fourier transform of the object with suitable weighting coefficients. Twin image is eliminated by appropriate inverse combined Fourier transformation and proper choice of the weighting coefficients. An optical configuration is presented for recording combined Fourier transform holograms. Simulations demonstrate the feasibility of twin image elimination. The hologram reconstruction is sensitive to phase aberrations of the object, thereby opening a way for holographic phase sensing.
- Hybrid DDCT-PCA based multi sensor image fusion
Abstract: Multi sensor image fusion algorithm based on directional Discrete Cosine Transform (DDCT) - Principal Component Analysis (PCA) hybrid technique has been developed and evaluated. The input images were divided into non-overlapping square blocks and the fusion process was carried out on the corresponding blocks. The algorithm works in two stages. In first stage, modes 0 to 8 were performed on images to be fused. For each mode, the coefficients from the images to be fused are used in the fusion process. The same procedure is repeated for other modes. Three different fusion rules are used in fusion process viz., 1. Averaging the corresponding coefficients (DDCTav), 2. Choosing the corresponding frequency band with maximum energy (DDCTek) and 3. Choosing the corresponding coefficient with maximum absolute value (DDCTmx) between the images. After this stage, there are eight fused images, one from each mode. In second stage, these eight fused images are fused using PCA. Performance of these algorithms were compared using fusion quality evaluation metrics such as root mean square error (RMSE), quality index (QI), spatial frequency and fusion quality index (FQI). It was concluded from the results that DDCTav performs poor and DDCTek performs slightly better than DDCTmx. Moreover, DDCTek is computationally simple and easily implementable on target hardware. Matlab code has been provided for better understanding.
- Effect of camera gamma and gain on the line shape and axial resolution in
a confocal microscope setup
Abstract: Confocal microscopy is an important state-of-art in the field of optical microscopy with wide ranging applications in surface microstructuring of metal and non-metal surfaces, finger print observations in forensic sciences, 3D volume rendering of biological specimen etc. The advancement in digital image processing, availability of high speed computer with high memory size and simplicity of image grabbing technique enables the use of high sensitive CCD camera in confocal microscope setup. In addition to the inherent parameters of the confocal microscope such as the size of the confocal aperture, numerical aperture of the microscope objective etc., the camera parameters mainly camera gamma and gain affects the performance of the microscope. In the present paper the effect of camera gamma and gain on the contrast and shape of the detected target lines is studied experimentally through focal plane scanning of a 1951 USAF test target in a confocal microscope setup. The effect of camera gamma on the axial resolution of the confocal microscope setup is also studied experimentally through axial scanning with a mirror.
- Impedance effect on imaging of far-field hyperlens with geometrically
increasing layer thicknesses
Abstract: The hyperlens with flat dispersion curve and geometrically growing layer thicknesses are designed to project an object to the far field beyond the diffraction limit. Three hyperlens structures (two are our hyperlens structures and the other is a structure with varying local permittivity for layer pairs in radial direction) are considered in infrared and it is found that our hyperlens structures have better performance in reducing losses within the structure and finally improve the quality of the imaging. Fabry-Perot resonance effect periodically influences the sharpness of the point source focusing as the total thickness begins to increase from a certain value, especially for the impedance matched structures. As the thickness of the outermost layer is much less than the effective wavelength of the hyperlens, the most important issue influencing the resolution ability of the system is the magnification factor. We systematically study the performance of our hyperlens as the innermost radius r 1 and ε 1 change. We find that for our hyperlens structures the impedance is not the most important issue for magnification imaging. Different parameters should be purposefully chosen for our hyperlens according to the practical requests (e.g., resolution or intensity) and our research results can provide a good guidance in the structure designing.