Theoptical Fiber Research Articles

Design of Amplifier Circuit of Optical Fiber Sensor and Its Application in Cloud Computing of Mechanical Vibration Fault

Photoelectric detection technology has been widely used in industry, agriculture, medicine, and other fields. The signal collected by photoelectric signal detection equipment is weak and vulnerable to noise interference. Therefore, a preamplifier circuit with good performance is needed to amplify the original signal effectively. Firstly, considering that a single-mode fiber coupler is more sensitive to the length of the coupling region, a coupled optical fiber vibration sensor is designed. Secondly, the appropriate operational amplifier (Op-amp) is chosen based on the photodetector. By listing and selecting the OPA656 Op-amp produced by TI Company, the basic current and voltage conversion circuit of photoelectric detection equipment is analyzed. In addition, a basic trans-impedance circuit with a phase compensation function is proposed and the calculation method of optimal phase compensation capacitance is derived. Finally, in the process of monitoring the vibration data of equipment, cloud computing technology (fuzzy C-means clustering algorithm+MapReduce model) is used for distributed processing of mechanical vibration data. In the test, the coupled optical fiber vibration sensor designed with an amplifier circuit and moving coil vibration sensor are placed on the ship equipment at the same time, and the rubber hammer is employed to hit the surface of the ship machinery. The test results of the two sensors are the same, which proves that the optical fiber sensor designed in this study meets the requirements of vibration measurement.

PENGUKURAN KUALITAS LAYANAN JARINGAN KABEL SERAT OPTIK LINK BENCULUK-JIMBARAN

Optical fiber is a telecommunication transmission medium that has a high bandwidthand bit rate so that it can meet the needs of today's information services with high reliability andefficiency. Optical fiber applications are increasingly widespread for underwater networks,terrestrial networks, metropolitan and regional network coverage, also small-scale networksincluded. Optical fiber communication system has internal and external factors that affect thequality of network performance. Those factors possibly able to reduce the performance of theoptical fiber networks. Then, can cause attenuation and other transmission losses. In an effortto prevent sudden and significant deterioration in the quality of a network, it is necessary tocarry out periodic maintenance activities such as measuring the quality of scheduled fiber opticcable network services. These maintenance activities can help determine the decision toincrease network capacity at a later date. The service quality parameters that often measuredare the attenuation of the transmission and the received signal power (power receive). Thisstudy examines the measurement of attenuation of the Benculuk-Jimbaran fiber optic cableusing OTDR EXFO FTB-150. The measurement results of 8 idle cores were analyzed usingOptisystem 7.0 and the calculation of total attenuation and receive sensitivity. Themeasurement results of core 1 to core 12 have total attenuation ranging from 29, 942 dB -30.654 dB at a distance of 169, 646 km - 170, 323 km. The value of power received on cores 1to 12 has a value ranging from -17,339 dBm - 18,204 dBm, where all idle cores fulfill the receivesensitivity requirements set by ITU-T, which is greater than -28 dBm. Based on the performance analysis according to total attenuation and power receive parameters, the Benculuk-Jimbaranfiber optic link network has good performance quality.

Barely visible impact damage detection for composite sandwich structures byoptical-fiber-based distributed strain measurement

The authors developed an impact damage-detection system for large-scale compositesandwich structures using an optical fiber network running throughout the structure. ABrillouin-based sensing system with high spatial resolution (pre-pump pulse Brillouinoptical time-domain analysis (PPP-BOTDA)) was utilized for distributed strainmeasurement. The PPP-BOTDA sensing system can measure axial strain along theoptical fiber by employing stimulated Brillouin scattering. The system realizes aspatial resolution of 10 cm, a sampling interval of 5 cm, and a sensing range ofmore than 1 km. Our previous study revealed that a non-uniform axial strainwithin centimeter spatial resolution broadens the width of the Brillouin gainspectrum, which is the output of the PPP-BOTDA. The specific response of thePPP-BOTDA was employed to detect non-uniform strain distribution along a residualfacesheet dent in a damaged area. First, the response of the optical fiber sensornetwork, formed in the adhesive layer, was simulated to clarify the effectivenessand limitations of the proposed damage-detection technique. The system wasthen validated by an experiment. As the damage became larger, the width of theBrillouin gain spectra became broader. Consequently, the location and size ofbarely visible damage could be estimated. The system developed is quite usefulfor a first inspection of large-scale sandwich structures in aerospace and marineapplications.

Measurement of Acoustic Emission Wave by Using Optical Fiber Sensor during Microsecond Discharge

In this study, we investigate the effect of discharge current on the occurrence of burst AE wave caused by microsecond discharge. Electrical discharge duration was changed from about 1µs to 8µs by using condenser circuit. Effect of current behavior was estimated by comparing with experimental signal and simulation one. AE wave was detected by optical fiber vibration sensor. The optical fiber vibration sensor is located on an aluminum work-piece (cathode) plate. Simulation was carried out with MSC. Marc. As the results, it was found that AE wave was occurred by a force depending on electrical current behavior. The force direction was machining direction. The force has been occurred during microsecond discharge.

Development of Heat Resistant AE Monitoring System Using Optical Fiber Sensor

We developed an advanced optical fiber Acoustic Emission (AE) monitoring system with a phase compensation feed back circuit. Two lasers transmitted through the reference and sensing arms are combined by a 2x2 coupler and detected by two photodiodes as the intensity change of the interfered laser. Outputs of the photodiodes are then combined in a differential amplifier which extracts error signal and improves the S/N ratio. The developed system was demonstrated to detect weak guided wave AE signals such as zero-th order longitudinal cylindrical wave (Lo-mode) with the S/N ratio higher than that of PZT sensor. This system was utilized to monitor the oxidation resistance of various alloys during thermal cycles from 300 K to 1273 K. We detected weak AE signals from micro fractures of growing oxide films of boiler tube and austenitic stainless steel, but no AE from Inconel 600 tubes. Here the optical fiber sensor was wound over the tube at 600 K. Both the AE counts and amplitudes during thermal cycles showed clear tendency depending on the oxidation resistances of the alloys.

In-flight health monitoring of a subscale wing using a fiber Bragg grating sensorsystem

In this paper, fiber Bragg gratings (FBGs) were applied to measure dynamic strainsinside a subscale wing under real-time wind tunnel testing. Two re-coated FBGswere embedded in the wing skin. The FBG sensor system includes a wavelengthswept fiber laser with a wavelength indicator and fast signal processing modules.The agreement among the three kinds of sensor inside the subscale wing (FBG,electric strain gauge and PZT sensor) was confirmed in the bench test. Theoptical fiber strain sensors had an excellent resolution (< 5με) inthe time domain and could detect a frequency response up to 100 Hz. Throughthe wind tunnel test of the subscale smart wing, the flutter was experimentallydetected using FBG sensors and their usefulness as an in-flight health monitoringsystem was demonstrated.

Damage monitoring and impact detectionusing optical fiber vibration sensors

Intensity-based optical fiber vibrations sensors (OFVSs)are used in damage monitoring of fiber-reinforced plastics, invibration sensing, and location of impacts. OFVSs were constructed byplacing two cleaved fiber ends in a capillary tube. This sensor isable to monitor structural vibrations. For vibration sensing, theoptical fiber sensor was mounted on the carbon fiber reinforcedcomposite beam, and its response was investigated for free and forcedvibration. For locating impact points, four OFVSs were placed atchosen positions and the different arrival times of impact-generatedvibration signals were recorded. The impact location can bedetermined from these time delays. Indentation and tensile tests wereperformed with the measurement of the optical signal and acousticemission (AE). The OFVSs accurately detected both free and forcedvibration signals. Accurate locations of impact were determined on anacrylate plate. It was found that damage information, comparable inquality to AE data, could be obtained from the OFVS signals.