P. Azimi

Bio: P. Azimi is an academic researcher from Islamic Azad University. The author has contributed to research in topics: Materials science & Capacitive sensing. The author has an hindex of 5, co-authored 6 publications receiving 128 citations.

Design and performance of a plastic optical fiber leakage sensor

Abstract: In this article design and operation of a plastic optical fiber (POF) sensor based on the unconventional light leakage from one fiber to another one causing intensity modulation are presented. The dominant loss mechanism was found to be the evanescent loss and based on this phenomenon the optical fiber sensor was designed. The penetration depth of evanescent wave as a function of different refractive index of cladding was calculated. Operation of this sensor was tested as a liquid level sensor for different liquids and the experimental results are compared. The dry (air interface layer) and wet output (liquid interface layer) signals for this probe were measured for a series of measurements and important factors concerning sensor operation are described. The precision of measured values, reproducibility of the results (1.35% error), and the stability of sensing operation as a function of time at different launching powers are also reported (0.85% error). The reported results for this design are promising and verify the successful operation of such a device as a liquid level probe and also as an on/off level switch.

Simultaneous measurements of the resistance and capacitance using a cylindrical sensor system

Abstract: In this article, the design and operation of a cylindrical capacitive sensor based on the dielectric reactance capacitance and conductance changes of the gap medium is reported. The proposed system was used to determine characteristics of different water liquids as a result of the capacitance and resistance variations. The air gap capacitance (dry signal) is measured and then by filling the gap with a liquid, the capacitance (wet signal) is monitored for different liquids. A reported sensor is used for the distilled, tap, boiled, and salt water measurements and the capacitance and resistance results are compared. A big difference of about 38.5 μF in the measured capacitance values for the salt and distilled water shows a high sensitivity, which can be used to recognize different water liquids. The experimental results are promising for water liquids and verify the successful operation of such a device as a liquid sensor, a useful method for checking the electrical quality of the water that is required for...

Optical methods for distance and displacement measurements

Abstract: This tutorial reviews various noncontact optical sensing techniques that can be used to measure distances to objects, and related parameters such as displacements, surface profiles, velocities and vibrations. The techniques that are discussed and compared include intensity-based sensing, triangulation, time-of-flight sensing, confocal sensing, Doppler sensing, and various kinds of interferometric sensing with both high- and low-coherence sources.

The effect of using different materials on erbium-doped fiber amplifiers for indoor applications

Abstract: This paper investigated the different materials of optical fibers, two of them are plastic optical fibers that are namely polysulfone (PSU)/vinyl-phenyl acetate (VPAC) with refractive indices of 1.63/1.567, and the second plastic material namely sapphire (S)/polysulfone (PSU) with refractive indices of 1.77/1.63. One of the other materials consists of fluorite (FT)/polytetrafluorophenylmethacrylate (PTFPMA) with refractive indices of 1.433/1.422, where the second material consists of fluoride (FD)/poly methylmethacrylate (PMMA) with refractive indices of 1.56/1.49. Finally, the third material consists of silica (Si)/tetrafluoropropylmethacrylate (TFPMA) with refractive indices of 1.46/1.373. The simulation results are done by using optiwave simulation version 13. FT/PTFPMA fiber channel has outlined 19.23 Tb/s bit-rate with maximum Q-factor of 11.01, a minimum bit error rate of 1.05 × 10−28, gain value of 36.57 dB, and noise figure of 5.67 dB in the presence of vertical-cavity surface-emitting laser (VCSEL). It is observed that VCSEL has superior to continuous wave (CW) laser by the improvement of the performance parameters understudy at the same operating conditions.

Mathematical Modeling of Intensity-Modulated Bent-Tip Optical Fiber Displacement Sensors

Abstract: Intensity-modulated optical fiber displacement sensors have a potential to be used in a number of applications, including those in industry, military, aerospace, and medicine. Compared with other types of optical fiber sensors, intensity-modulated sensors offer distinctive advantages in that they are usually less complex, inexpensive, and less sensitive to thermal-induced strain. They are able to perform accurate contactless sensing while being of a small size and having a wide dynamic range. A common form of the intensity-modulated optical fiber sensor performs its measurement by making use of a pair of straight parallel optical fibers integrated with a moving reflector modulating the reflected optical signal intensity. Although such an optical modulation configuration exhibits good sensing ability, improvement on its performance could still be made to widen the extent of its application areas. This leads to the development of more effective intensity modulation mechanisms utilizing bent-tip optical fibers and a reflector that can either laterally slide or longitudinally move with reference to the central axis of the fibers. This paper describes such alternative sensing structures and demonstrates the derivations of mathematical models proposed for analyzing their sensing characteristics. Based on experimental studies, the models are verified and validated for the analysis of sensitivity and linearity.