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This study presents a wireless electromagnetic sensing system based on the resonant properties of the star-fractal antenna. Thus, it has been used for measuring the complex electrical permittivity of sodium sulfite solutions, according to both transmission and reflection efficiencies of the incident electromagnetic wave. The proposed antenna has been designed and simulated using the HFSS-Software (Ansoft High-Frequency Structure Simulator). The optimum resonant dimensions of the designed star-fractal antenna are (24.5 × 23 × 1.64) mm with a dielectric substrate (ε = 2.2). The proposed antenna operates on a single band applications, at frequency 2.4 GHz. Based on this antenna, several parameters have been calculated, such as the return loss, input impedance, and radiation patterns. Therefore, in this study, the designed antenna was used to fabricate a sensor to measure the electrical properties of liquids that depend on its concentrations. Thus, the various high concentrations of Na2SO3 solution (1–5) mol/L, were sensitized. Which were compared with the theoretical results using a special mathematical model to calculate the electrical properties of each concentration. Consequently, the good qualitative agreement results were measured for the real and imaginary parts of the complex permittivity at 99% and 92%, respectively. [ABSTRACT FROM AUTHOR]

Photopolymer materials have received a great deal of attention because they are inexpensive, self-processing materials that are extremely versatile, offering many advantages over more traditional materials. To achieve their full potential, there is significant value in understanding the photophysical and photochemical processes taking place within such materials. This paper includes a brief review of recent attempts to more fully understand what is needed to optimize the performance of photopolymer materials for Holographic Data Storage (HDS) and Self-Written Waveguides (SWWs) applications. Specifically, we aim to discuss the evolution of our understanding of what takes place inside these materials and what happens during photopolymerization process, with the objective of further improving the performance of such materials. Starting with a review of the photosensitizer absorptivity, a dye model combining the associated electromagnetics and photochemical kinetics is presented. Thereafter, the optimization of photopolymer materials for HDS and SWWs applications is reviewed. It is clear that many promising materials are being developed for the next generation optical applications media. [ABSTRACT FROM AUTHOR]

In this study, a microwave active antenna sensor (MAAS) was designed and manufactured from PCB boards operating at a frequency of approximately 3 GHz to sense the characteristics of mineral oils (high voltage transformer oils) and chemical liquids such as methanol, chloroform, and ethanol. The proposed sensor has been designed using the automation software system named ADS (advanced design system). The antenna was linked with a radio amplifier; therefore, the antenna is called active antenna. As a result, the reflection coefficient changed from − 39.98 dB to − 66.26 dB, and also the quality factor changed from 350 to 27,000. The measuring and simulation results were quite identical in both active and passive antenna cases. An M-shaped channel with a capacity of 150 μL was built on a microscope glass slide, where the glass slide was placed in contact with the above face of the designed antenna (near field). That a slit channel was placed on the areas in which the electric field is concentrated. Then, the sensor was tested by injecting the channel with new and damaged transformer oil. Despite the small sample size, the amount of resonant frequency change was 2.23 MHz and 1.48 MHz for the active and passive antennas, respectively. A mathematical model was built to calculate the breakdown voltage of high voltage transformer oil, and the error value in the breakdown voltage value did not exceed ± 0.1606%. The other application of the antenna is to sense chemical liquids and to calculate the electrical permittivity of those samples by finding a mathematical model based on the resonant properties of the antenna. The measured permittivity of the liquids have been compared with the theoretical values, which gives a good qualitative agreement for our results. [Display omitted] • The antenna was linked with a radio amplifier. • quality factor changed from 350 to 27,000. • The sensor was tested by injecting the channel with new and damaged transformer oil. • mathematical model was built to calculate the breakdown voltage of high voltage transformer oil. • finding a mathematical model based on the resonant properties of the antenna where the measured permittivity's of the liquids. [ABSTRACT FROM AUTHOR]

In this study a new structure of a star-shaped fractal antenna was designed, simulated and fabricated, to operating at dual band applications. The geometrical of this antenna begins from two conducting squares shape to create an eight-shaped star. Added to that, the fractal geometry slot has been designed using four squares rotating in four angles to forming sixteen triangular slots. Whereas semi-circle slot shaped has been loaded in the center of the proposed antenna. The suggested antenna was designed and simulated using an Ansoft High Frequency Structure Simulator (HFSS). A few parameters such as return loss, input impedance, and radiation patterns were studying. It is found that the fabricated antenna has a dual band at two resonance frequencies 1.3308 GHz and 2.6992 GHz. The first band is used in the aviation service. While, the second band is used in the space research services, radio astronomy, and earth exploration-satellite. These dual band meets the applications in L- and S-band respectively. The simulated and measured results for return loss of the designed antenna are in a good agreement. Also, the measured and simulated values of the impedance bandwidth of the proposed antenna are (2.31% and 3.62%) and (2.57% and 3.32%), respectively. Interestingly, the semi-circle slot dimensions have significant effect on the simulation results of return loss and antenna efficiency. [ABSTRACT FROM AUTHOR]

This study is novel for several reasons: We used a thin drop cast layer of dry photosensitive materials to study the behaviors of wet photopolymer media using microscopic distances during the Self-Written Waveguide (SWW) process; then, we examined the self-trajectories formed inside the solid material. The results provide a framework for theoretical and experimental examinations by handling the effects of manipulating the alignment of fibers. The other main advantage of these techniques is their lightweight, easy to process, highly flexible, and ultimately low-cost nature. First, the SWW process in wet photopolymer media (liquid solutions) was examined under three cases: single-, counter-, and co-fiber exposure. Then, the SWWs formed inside the solid material were examined along with the effects of manipulating the alignment of the fibers. In all cases, high precision measurements were used to position the fiber optic cables (FOCs) before exposure using a microscope. The self-writing process was indirectly monitored by observing (imaging) the light emerging from the side of the material sample during SWW formation. In this way, we examined the optical waveguide trajectories formed in Acrylamide/Polyvinyl Alcohol (AA/PVA), a photopolymer material (sensitized at 532 nm). First, the transmission of light by this material is characterized. Then, the bending and merging of the waveguides that occur are investigated. The predictions of our model are shown to qualitatively agree with the observed trajectories. The largest index changes taking place at any time during exposure, i.e., during SWW formation, are shown to take place at the positions where the largest exposure light intensity is present. Typically, such maxima exist close to the input face. The first maximum is referred to as the location of the Primary Eye. Other local maxima also appear further along the SWW and are referred to as Secondary Eyes, i.e., eyes deeper within the material. [ABSTRACT FROM AUTHOR]

The linear canonical transform (LCT) is used in modeling a coherent light-field propagation through first-order optical systems. Recently, a generic optical system, known as the quadratic phase encoding system (QPES), for encrypting a two-dimensional image has been reported. In such systems, two random phase keys and the individual LCT parameters (α; β; γ) serve as secret keys of the cryptosystem. It is important that such encryption systems also satisfy some dynamic security properties. We, therefore, examine such systems using two cryptographic evaluation methods, the avalanche effect and bit independence criterion, which indicate the degree of security of the cryptographic algorithms using QPES. We compared our simulation results with the conventional Fourier and the Fresnel transform-based double random phase encryption (DRPE) systems. The results show that the LCT-based DRPE has an excellent avalanche and bit independence characteristics compared to the conventional Fourier and Fresnel-based encryption systems. [ABSTRACT FROM AUTHOR]

The asymptotic property of the maximum likelihood estimator (MLE) has been utilized to reconstruct three-dimensional (3D) sectional images in the photon counting imaging (PCI) regime. At first, multiple 2D intensity images, known as Elemental images (EI), are captured. Then the geometric ray-tracing method is employed to reconstruct the 3D sectional images at various depth cues. We note that a 3D sectional image consists of both focused and defocused regions, depending on the reconstructed depth position. The defocused portion is redundant and should be removed in order to facilitate image analysis e.g., 3D object tracking, recognition, classification and navigation. In this paper, we present a subpixel level three-step based technique (i.e. involving adaptive thresholding, boundary detection and entropy based segmentation) to discard the defocused sparse-samples from the reconstructed photon-limited 3D sectional images. Simulation results are presented demonstrating the feasibility and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

As clinical evidence on the colorectal application of indocyanine green (ICG) perfusion angiography accrues, there is also interest in computerizing decision support. However, user interpretation and software development may be impacted by system factors affecting the displayed near-infrared (NIR) signal. We aim to assess the impact of camera positioning on the displayed NIR signal across different open and laparoscopic camera systems. The effects of distance, movement, and target location (center versus periphery) on the displayed fluorescence signal of different systems were measured under electromagnetic stereotactic guidance from an ICG-albumin model and in vivo during surgery. Systems displayed distinct fluorescence performances with variance apparent with scope optical lens configuration (0 deg versus 30 deg), movement, target positioning, and distance. Laparoscopic system readings fitted inverse square function distance-intensity curves with one device and demonstrated a direction dependent sigmoid curve. Laparoscopic cameras presented central targets as brighter than peripheral ones, and laparoscopes with angled optical lens configurations had a diminished field of view. One handheld open system also showed a distance-intensity relationship, whereas the other maintained a consistent signal despite distance, but both presented peripheral targets brighter than central ones. Optimal clinical use and signal computational development requires detailed appreciation of system behaviors. [ABSTRACT FROM AUTHOR]