Microbending optical fiber sensors and their applications. Fiber optic sensors are fiberbased devices that use optical fibers to detect certain quantities such as mechanical strain or temperature, concentrations of chemical species, acceleration, rotations, pressure, vibrations and displacements. Finally, the generic microbend sensor has been tested demonstrating good performance. This novel approach to sensing has not been utilized before and has the advantage that the sensor involves simple fabrication compared to existing fiberoptic voltage sensors. The measured sensor characteristics show that a sensor with alcohol as the working fluid has a maximum sensitivity of 1.
Figure 3 illustrates the concept of microbending for a fiber optic sensor. Figure 14 shows the concept underpinning a typical microbending sensor. A microbent fiber optic ph sensor request pdf researchgate. Handbook of optical sensors optical waveguide sensors. When pressure acts on the fixture, a little displacement may occur, and luminous. In response to the pressure wave, the opposed pistons push a pair of deformer plates against an optical fiber to deform the fiber thereby intensity modulating an optical signal passing. A fiberoptic microbending temperature sensor request pdf. Another meritorious capability is its high flexibility and as a point sensor they can be used to sense normally inaccessible regions without perturbing the transmitted signals.
Apnea detection with microbend fiberoptic sensor 209 the optical. This novel approach to sensing has not been utilized before and has the advantage that the sensor involves simple fabrication compared to. Request pdf microbending optical fiber sensors and their applications microbending optical fiber sensors based on bendinduced loss in optical fiber have. Request pdf a microbent fiber optic ph sensor optical fiber sensors developed for measuring ph values usually employ an unclad and. It mainly includes strain sensor, liquid lever and pressure sensor, differential force and displacement sensor, and temperature sensor specially. High density fiber optic sensing hdfos in composites. It consists of the pressure gasket, the microbending regulator and the metal clamp with fine adjustment structure. Unlike macrobending, the imperfection may not always be visible contrast with macrobend. High density fiber optic sensing hd fos in composites contents. Prediction of force measurements of a microbend sensor. Analysis of fiber optic microbend sensors for use in vehicle classification and weighinmotion systems. Introduction to fiber optic sensors and their types. A fiberoptic sensor is a sensor that uses optical fiber either as the sensing element intrinsic sensors, or as a means of relaying signals from a remote sensor to the electronics that process the signals extrinsic sensors.
It then explains the application of fiber optic sensors in the biomechanics of rigid bodies, then moves on to deformable bodies, and finishes with fluids, in particular intramuscular and intraarticular pressures. Fiberoptic current and voltage sensors for highvoltage. Request pdf embedded fibre optic microbend sensor for measurement of high pressure and crack detection this paper reports fibre optic pressure sensor based on periodic microbending loss. The period of the fiber microbending is resulting of the threading constant, the perforations are located only in the support high stress zones. Stability and reproducibility problems in single and multimode fibreoptic microbend strain sensors are found to be due to interference between the core mode and cladding modes in the bend region. The use of cylindrical sensing elements for fiber optic hydrophones was first suggested by lagakos et al. A point hydrophone according to a first preferred embodiment of the present invention includes two opposed pistons which are subjected to an acoustic pressure wave. Online access to spie ebooks is limited to subscribing institutions. Distributed sensing systems allow any point along a fiber to function as a sensor, with virtually thousands of sensing points along a single fiber that may exceed 30 km in length. Light can leak out of a fiber when the fiber is bent.
Fiber optic micro bend sensor is typically formed by passing the fiber between two sets of corrugations as shown in figure 14. Fiber optic sensors are available at mouser electronics. The easy to install optical sensor for strain, tilt, temperature and acceleration. Microbending optical fiber pressure sensor is designed with the sensing unit based on multimode fiber in this paper. An alternative fiber optic sensor useful for the measurement of length variations is based on the principle of microbending. Microbend losses have always been a curse to the fiber optic cable designer, but it is this very. An overview of macrobending and microbending of optical. This support has a periodic array of holes inside which the optical fiber is threaded to consti tute the optical fiber stress sensor. The passive region of the sensor is used to connect the sensor to the reading unit and can be up to a. Microbend loss fiber optic direction and amplitude sensors. Microbend losses have always been a curse to the fiber optic cable designer, but it is this very same microbend loss effect in optical fibers which was exploited by the microbend sensor designer who adapted the microbend effect to the measurement of many physical parameters and physical variables such as temperature. Optimizing fiber optic microbend sensor, proceedings of. Fiber optic sensors fundamentals and applications, fourth edition, 2014 available at.
This document pdf may be used for research, teaching and private study purposes. A wide range of configurations can be used, such as fiber microbending, fibertofiber coupling, moving masksgratings, and modified cladding 6, 1017. Structural health monitoring using a fiber optic polarimetric sensor and a fiber optic curvature sensorstatic and dynamic test. A basic fiber optic sensor system consists of an optical fiber and a light modulating arrangement. This paper reports fibre optic pressure sensor based on periodic microbending loss phenomenon in embedded optical fibres. It uses two fiber bragg gratings fbg in a pushpull configuration for effective temperature compensation. To prove the feasibility of such a fiberoptic sensor, a sensor for a voltage range from 0. Embedded fibre optic microbend sensor for measurement of high.
Depending on the application, fiber may be used because of its small size. Lightscattering phenomena have emerged in the last 10 years to be a key family of technologies to enable fully distributed fiber optic sensing systems. A high sensitivity fiber optic microbend strain sensor for detecting bending of large mechanical structures has been constructed and tested. The light beam travels through the core by repeatedly bouncing off the. Overview of fiber optic sensor technologies for straintemperature sensing applications in composite materials.
A fiberoptic amplitude sensor based on the effect of microbendingcaused upsetting of total internal reflection and intended for temperature monitoring is described. The key structures and principles of microbending optical fiber sensors for special applications are introduced in this paper. A measuringsystem prototype was developed for investigating the sensor characteristics. Hence, other geome tries need to be considered for underwater applications. Microbending can cause extrinsic attenuation, a reduction of optical power in the glass. Pdf apnea detection with microbend fiberoptic sensor. Intensity modulation induced by microbending in multimode fibers is considered as a transduction mechanism for detecting environmental changes such as pressure, temperature, acceleration, and magnetic and electric fields. Unlike macrobending, the imperfection may not always be visible. Macrobending of an optical fiber is the attenuation associated with bending or wrapping the fiber. Heterocore fiber optic sensors, which have different applications in chemical measurement, displacement measurement and vibration measurement, have been developed in 2000s.
Home ebooks field guide to fiber optic sensors microbend pressure sensor. This thesis was a continuation of the weighinmotion and vehicle classification projects that have taken place at florida institute of technology. A generic microbend sensor has been defined and studied, and its components, such as sensing fiber, light source, optical fiber leads, and detector, have been examined. The pressure sensors employ cylindrical microbending structures, and are subject to the liquid pressure through expanding bellows mounted at the bottom of the fuel tank, a 2. Design of micro bending deformer for optical fiber weight sensor. When a microbend sensor is used to measure loads or. This sensor is adapted to direct concrete grout embedding or surface mounting on existing structures. In this study, we designed a weight sensor for a static load based on a power loss due to a micro bending on the optical fiber flanked on a board. Weaving the sensor into the laminate itself may also result in significant microbending of the fiber sensor. The passive region of the sensor is used to connect the sensor to the reading unit and can be up to a few kilometers long. An overview of macrobending and microbending of optical fibers. The newly developed optical sensor line newlight by hbm enables large strain measurement ranges at increased longterm stability.
Fiber parameters and attributes affecting microbending the next equation shows several design options to improve optical fiber resistance to microbending. The shown figure gives an idea about how the light intensity work as a sensing parameter as well as how this arrangement makes the fiber to work as a vibration sensor. A research of multimode microbending optical fiber. Additionally, singlemode leads reduce lead noise and allow. These characteristics made anns useful in optical fiber technology for the prediction of measurements of fiber optic sensors 9, development of. The structure is composed of singlemode leads and multimode sensing fiber. Sensors based on microbend loss in optical fibers were first proposed and demonstrated in 1980 l, 2, although careful experiments done earlier had. The fiber optic sensor has an optical fiber connected to a light source to allow for detection in tight spaces or where a small profile is beneficial. The optical fiber follows a circuitous path and is adapted to establish a detection zone. Application of fiber optic sensors to structural monitoring. We proposed and experimentally investigated a novel microbend sensor structure. Fiber optical sensors in biomechanics sciencedirect. Optimizing fiber optic microbend sensor optimizing fiber optic microbend sensor lagakos, n. Design of heterocore smart fiber optic macrobend sensors.
When this fiber optic twisted pair is elongated, the fibers will induce. When a fiber is subjected to microbending along its axis, the light propagating through the core becomes unguided i. The chapter ends with final remarks about the application of fiber optic sensor technology in biomechanics. The advantages of fiberoptic sensing are well known and have been widely presented 3, 4, 2123. Microbending optical fiber sensors and their applications request. Fiber optic sensor technology is not new, but is continuing to evolve after over 60 years of development and commercialization. The fiber sensor can be either an intrinsic oneif the modulation takes place directly in the fiberor extrinsic, if the. Physical on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. The proposed structure exhibited a level of sensitivity as much as six times higher than that of the classical microbend sensor configuration when the same sensing fiber was used. Intensity based fiber optic sensors require more light and these sensors use a multimodelarge core fibers. In fiber optic transmissions, microbend is an imperfection in the optical fiber which was created during manufacturing. Fiber optic sensors based on bending effects are macrobending and microbending fiber optic sensors. The fiber sensor can be either an intrinsic oneif the modulation takes place directly in the fiber or extrinsic, if the modulation is performed by some external transducer as depicted in fig. An optical fiber has a plurality of bends arranged proximate the support structure.
Fiber bragg grating fbg based accelerometer for vibration measurements under low frequencies. Microbending loss and application in sensing aim to study a simple intensity modulated fiber optic pressure sensor based son microbending. Fiber chuck 20x mo deformer element applied pressure zzzz detector fig. Intensitybased sensor techniques have been studied and implemented in the last 25 years see figure 2. Depending on the application, fiber may be used because of its small size, or because no electrical power is needed at the. Microbend strain sensors are stabilised by preventing the interference effect. A fiber optic amplitude sensor based on the effect of microbending caused upsetting of total internal reflection and intended for temperature monitoring is described.
Us7532781b2 us11826,914 us82691407a us7532781b2 us 7532781 b2 us7532781 b2 us 7532781b2 us 82691407 a us82691407 a us 82691407a us 7532781 b2 us7532781 b2 us 7532781b2 authority us united states prior art keywords optical optical sensor light fiber support structure prior art date 20060719 legal status the legal status is an assumption and is not a legal. The microbend sensor was one of the earliest fiber optic sensors. Several fiber bragg gratings fbgs on the same fiber suited for multi point measurements of. The optical fiber consists of the core and the cladding, which have different refractive indexes. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiberoptic communications, where they permit transmission over longer distances and at higher bandwidths data rates than electrical. Comparing with the conventional electrical and electronic sensors, fiberoptic sensors fos have inherent superiorities that others. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber optic communications, where they permit transmission over longer distances and at higher bandwidths data rates than electrical. Regardless of environment or mounting style, keyence fiber optics can be used anywhere. An optical fiber is a flexible, transparent fiber made by drawing glass or plastic to a diameter slightly thicker than that of a human hair. Home ebooks field guide to fiber optic sensors microbend pressure sensor translator disclaimer you have requested a machine translation of selected content from our databases. It is the ideal choice for structural health monitoring due to its fast and easy installation and its resistance to environmental conditions such as humidity, rust, and salt. Fiber optic sensors offer a compact and versatile solution for presenceabsence detection. Otdr technique has been utilized for detecting strains at several structural points simultaneously by placing many sensors in tandem along a single fiber. Us4530078a microbending fiber optic acoustic sensor.
A research of multimode microbending optical fiber pressure. State of the art in fiber optic sensing technology and eu. Latest generation amplifier, descriptive oled display, smart fiber technology, high power, and much more. This excerpt gives a succinct explanation of microbend pressure sensor. A fiber optic sensor is a sensor that uses optical fiber either as the sensing element intrinsic sensors, or as a means of relaying signals from a remote sensor to the electronics that process the signals extrinsic sensors. The chapter ends with final remarks about the application of fiber optic sensor technology in. The sensing designs are not based on a single concept but on a variety of optical phenomena that can be used to measure a broad range of physical and chemical parameters. A generic microbend sensor has been defined and studied, and its components, such as sensing fiber, light source, optical fiber leads, and detector, have been examined and. Fiber optics, optical fiber sensing, fiber bragg gratings fbgs, interferometry, microbending, smart structures. Optimizing fiber optic microbend sensor, proceedings of spie.
The measuring range of the sensor could be adjusted by choosing different gasket. The pagination is known to be incorrect in the pdf document. Read multiple microbending opticalfibre sensors for measurement of fuel quantity in aircraft fuel tanks, sensors and actuators a. A fiberoptic voltage sensor based on macrobending structure. Microbend loss fiber optic direction and amplitude sensors for underwater applications ashish m. Fiberoptic current and voltage sensors for highvoltage substations k. Overview of fiber optic sensor technologies for strain. In that setup, an optical fiber is twisted with one ore more other fibers or with metallic wires 8 along its proc. One ofthe attractions offibre optic sensors is their multiplexing capability to large number of individual sensors in a fibre network. Periodic microbends of spatial periodicity 5 mm has been introduced in the. Opticalfibre pressure and temperature sensors have been developed that are suitable for installation in aircraft fuel tanks to monitor onground fuel quantity.