Performance of the FIBER OPTIC networks with different physical topologies such as point-to-point, bus, ring and star, with respect to requirements as bit rates, topology structure, bit. error rate (BER) and OPTICal component characteristics including OPTICal amplifiers, filters, sources and detectors, are analyzed and simulated.For this purpose, maximum number of supportable nodes and throughput, crosstalk due to OPTICal amplifiers and OPTICal filters, reliability, physical limitations and FIBER induced limitations such as dispersion and nonlinear effects (self phase modulation) are considered as performance evaluation criteria of different topologies. Dispersion and nonlinearities are simulated with split-step Fourier method, sometimes referred to as beam-propagation method. The FIBER length can be estimated by this method, with respect to above effects and maximum tolerable power penalties. Parameters such as maximum number of supportable nodes and crosstalk are evaluated using amount of degradation in BER of receiver, BER is calculated using Gaussian approximation. Reliability of networks is modeled on the bypassing of the failed station as recovery mechanism in ring and bus networks and reliable assumption for central node in star network. By the way physical limitations in each topology, regarding its structure, are derived as an economical criterion. Results indicate that no topology can be preferred to others, however imposed limitations and requirements determine the optimum topology. Neglecting economical aspects, star topology is preferred from different points of view such as reliability, crosstalk and maximum number of supportable nodes. Results of above simulations can be used in calculating power penalties of different factors such as dispersion, crosstalk and nonlinearities. This penalties perform important role in estimating power budget of networks.

In this paper, the set-up of a multi-mode FIBER OPTIC sensor for measuring glucose in aqueous solutions is investigated and evaluated. The basis of this sensor is based on the Fresnel Reflection. In this setup, a helium-neon laser is used as a light source, a FIBER OPTIC probe, photocell as detector and a digital multimeter. The statistical analysis of the recorded data shows a highly linear behavior in the range of 2 to 25 mM in the glucose solution. The sensitivity and detection limit of this FIBER OPTIC sensor are 11. 4 mV/mM and 2. 5 mM, respectively.

Star tracker is one of the most important devices used on satellites for attitude determination. Since its output is discontinuous, it needs a complementary unit to cover its discontinuities. Using gyroscope unit is the most suitable choice for aiding the star tracker. However, using these two kinds of sensor simultaneously has some challenges. In other words, not only not only sensor biases decrease the accuracy of attitude determination, but also the installation error has a significant effect on the accuracy. In this paper, after presenting the important role of installation errors between star tracker and gyroscope in the accuracy of attitude determination, an effective method is proposed to determine the misalignment error between these two sensors which is only based on their measurements, and the mathematical formulation is presented in detail. Finally, to validate the performance of the proposed method, it is implemented to calculate the instantiation error of an experimental dataset gathered in the Mount Pooladkaf, And the results are reported in the form of graphs and tables.

Different glasses suitable for temperature sensing in the FIBER OPTIC sensors were studied in this article. The phase changes for eight different glass materials were calculated and results were compared. Our results showed that extra dense flint glass is the most sensitive one, while pure silica results in the lowest phase change. In another study the effect of wavelength on the phase variation was also investigated and the results were presented. Finally, the effect of glass formation in phase change was considered for different glasses, which were prepared using different techniques. The result showed that the Corning glass #7940 offers the highest sensitivity in comparison with the other three glasses for temperature sensing. Our studies for different silica glasses indicated that glass formation is important in preparing the glass materials required for the FIBER sensors.

In this paper, two structures of surface plasmon resonance FIBER OPTIC biosensors with the addition of a thin layer of titanium dioxide and barium titanate are introduced and studied comparatively. The sensitivity of these biosensors has been calculated using the transfer matrix method. Adding a thin layer of barium titanate and titanium dioxide after the gold layer, both make increase the sensitivity of the biosensor due to the transfer of free charge between the gold and the dielectric. The obtained results of the comparative study show that the titanium dioxide layer can be a suitable alternative to barium titanate for further increase of the sensitivity of the FIBER OPTIC surface plasmon resonance biosensor.

Pleural biopsy is a principal diagnostic evaluation of respiratory problems, especially in localized pleural disease, in which surgical exploration or prolonged clinical observation is inevitable. The new technology of flexible FIBER OPTIC endoscopic instruments for obtaining biopsies provides considerable resolution, facilitation and diagnostic accuracy, especially in malignancies.To evaluate the efficiency and safety of flexible FIBER OPTIC pleuroscopy, 20 patients (75% male, mean age=57.9±14.1 years) with pleural effusion, who were hospitalized in the Department of Internal Medicine at Imam Khomeini Hospital affiliated to Tehran University of Medical Sciences (2005-2006) and required pleural biopsy for definite diagnosis were enrolled.The study was approved by the university Ethics Committee and informed consents were taken from all patients.

Measurement of ionizing radiation in various fields, such as environmental safety, industrial detection processes, radiation protection and medical is very important. Radiation dosimetry plays an important role in determining the amount of energy absorbed and the effects of radiation. Recent OPTICal FIBER sensors have been shown to be radiation dosimeters. Our goal here is to investigate the effect of ionizing radiation on FIBER OPTICs. Thus, in this paper, the effect of electron beam radiation on the loss of light passing through the FIBER OPTICs after the end of radiation in the wavelength range of 1300-1550 nm is investigated. OPTICal FIBERs with doses of of 22 and 47 kGy were irradiated. All measurements were carried out at a temperature of 25 ± 2 ° C. The results show that the light dissipation of the FIBER OPTICally increases with the radiation dose and decreases with the passage of time after the end of radiation.