Optical fiber sensors intensity modulation sensors. Related content and download information correct at time of download. Intensity modulated fiber optic sensors have the many distinct advantages associated with fiber optics that makes them suitable for several industrial and military applications. The trueapparent strain ambiguity associated with structurally embedded sensors of strain can be avoided with a novel sensor that measures deformation curvature. A reflective intensity modulated fiber optic sensor based on microelectromechanical systems mems for pressure measurements is proposed and experimentally demonstrated. We theoretically and experimentally demonstrated an optical fiber magnetic field sensor based on a singlemodemultimodesinglemode sms structure immersed into the magnetic fluid mf. Single fiber reflective sensor light leaves the fiber end in a cone pattern, and strikes a movable reflector. Commercially available fiber optic sensors are widely used in mechanical and industrial automation. By controlling the physical dimensions of the device, we can tune the frequency of its natural resonance to achieve a desired sensitivity and bandwidth combination. Throughout the late 1980s and 1990s the use of ramanbased.
Optimization of wideband fiber optic hydrophone probe for ultrasound sensing applications a thesis submitted to the faculty of. Although, the accuracy of the sensor is far less that for interferometric sensors, the accuracy is more than sufficient for most process control situations. Intensity modulation is one of the simplest to measure because it only requires a photodetector to measure the light intensity. Fiber optic sensors operate by the modulation of an optical carrier signal by some optical mechanism present in the sensing region that is itself responsive to the external parametric measurand field.
Fiber optic sensors have found applications in multiple industries, and their use has been gradually growing since the 1980s. The intensity of the light wave traveling through an optical fiber can be modified by microbending of the optical fiber, by a change in. Light intensity is the simplest parameter to manipulate in intrinsic sensors because only a. Chirpedfbg cfbg based intensity modulated sensors show potential applications in various sensing areas due to their many advantages, including inherent independence of temperature, high measurement speed, and low cost, in addition to the merits of all fiber optic sensors. Intensity modulation an overview sciencedirect topics. Intensitymodulated magnetic field sensor based on fiber. Sensors that vary the intensity of light are the simplest, since only a simple source and detector are. Modulated principles of various intensity based sensors and their industrial applications are presented in this paper. Referencing schemes for intensity modulated optical fiber.
A highly sensitive intensitymodulated optical fiber. With the development of optical fiber sensing technology, optical fiber sensors have increasingly become the research focus. Passive optical ctpt epc intensity modulated optical. A broadband light source bls is externally modulated at a single frequency f by an acoustooptic modulator aom. A fiberoptic sensor is a sensor that uses optical fiber either as the sensing element intrinsic. Sensors free fulltext a differential reflective intensity optical. An intensitymodulated optical fiber sensor with concave. The system utilizes a single broadband led source whose emission is spectrally sliced to provide two separate narrowband wavelength signals, one. A strain sensor includes an optical fiber with at least one optical fiber, a reflector body with a reflective surface, a housing affixed to the optical fiber probe and to the reflector body. We also presented a novel fiber optic sensor with a special construction like a spoke and the sensor was composed of a single mode emitting fiber as well as eight multimode receiving fibers.
Based on the characteristic of a transmissive intensity. Victor giurgiutiu, in structural health monitoring of aerospace composites, 2016. An initial rotation angle is designed between two perturbations for the. Included in the discussion are acoustic towed arrays, several types of phase modulated and intensity modulated seismometers, and a fiber optic magnetometer. Introduction to fiber optic sensors 7 intensity modulated fos phase modulated fos polarization modulated fos wavelength modulated fos phase modulated sensors usually use an interferometer and sense the output signal by comparing the phase of the received signal with a reference signal. Fibre optic sensor an overview sciencedirect topics. Wavelength modulated fibre optic sensors among these modulation techniques, the first three modulation schemes are most commonly employed in a wide range ofapplications. Multilayer cylindrical fiber optic phase modulated acoustic sensor 17 17 fig 2. Bending the fiber as the deformer closes on the fiber, radiation losses increase and the. The sensor with ir light source has more sensitivity.
Appendix 1 gives examples of the types of modulating signals used for measurement purposes and most of these have been applied to modulate light in fibre. Study of characterization of intensity modulated fiber. The reflective surface is spaced apart at a distance d from the ends of the probes fibers and receives light from the end of the fiber and to reflect at least a portion of the light into the end of the fiber. Fiber optic magnetic field sensing is an important method of magnetic field monitoring, which is essential for the safety of civil infrastructures, especially for power plant. Fiber optic sensors are playing important role in the field of sensors. Led, laser diode etc, optical fiber, sensing or modulator element. The sensor is constructed using single mode fiber smf and multimode fiber mmf in smf. However radiant signals embrace a wider field than that of optics so there are a few examples of certain forms of radiant energy being capable of modulating optical systems eg the cherenkov effect.
Introduction to fiber optic sensors and their types. A novel ag coated intensity modulated optical fiber sensors based on refractive index changes using ir and uvvis light sources are proposed. Referenced intensitymodulated optical fiber sensor system. Intensity modulated fiber optic sensors have the many distinct advantages associated with fiber optics that makes. Intensitymodulated refractive index sensor with anti. We proposed and demonstrated a reflective intensity modulated fiber optic pressure sensor that can be applied under various pressure s from 0 to 1 mpa, at room tempera tures up to 150 c. Structure of differential reflective intensitymodulated optical fiber angular displacement sensors. Phase modulation sensors and interferometric sensors. Fiber optic sensors fundamentals and applications, fourth edition, 2014 available at. This is due to spontaneous response and ease in handling. Pdf intensitymodulated fiber optic sensor for health.
We design, test, and analyze fiber optic voltage sensors based on optical reflection from a piezoelectric transducer. The general concepts associated with intensity modulation include transmission, reflection, and microbending. In this letter, we demonstrated an intensitymodulated directional torsion sensor based on an inline machzehnder interferometer in singlemode fiber. In the present work, an intensity modulated fiber optic sensor is used. Pdf fiber optic sensors and their applications researchgate. Pdf intensitymodulated fiber optic sensor for health monitoring. The relationship between fiber reflector distance and intensity of returned light example 2. The development of a dual wavelength referenced intensity modulated optical fiber sensor system is described. The last revolution appeared as designers to combine the productive results of optoelectronic devices with fiber optic telecommunication devices to create fiber optic sensors.
In the present paper, we have made use of a plastic optical fiber. When using reflectionmode sensing the modulated optical signal is retroreflected into the same optical fiber for transmission to the photodetector 8. Schematic of transmission type intensity modulated fiber optic acoustic. Since the late 1990s, the use of fiber optic sensors in the oil and gas industry has greatly expanded, especially for inwell monitoring applications 1,2. Among the above mentioned fibre optic sensing schemes, intensity modulation is the. The reflected optical intensity is a function of distance between fiber. Fibre optic intensity modulated sensors springerlink. A small portion of cladding 1cm, 2cm and 3cm is removed in the middle of the fiber. In this work, we fully characterize sensors designed with a 2 khz characteristic resonance, experimentally. A common form of two fiber intensitymodulated optical fiber sensor performs its measurement by making use of a pair of straight optical fibers with a plane reflector.
Two fiber intensity modulated sensors are investigated and used in number of applications, including those in military, industry, biomedical, and aerospace. The sensor consists of two multimode optical fibers with a spherical end, a quartz tube with dual holes, a silicon sensitive diaphragm, and a high borosilicate glass substrate hbgs. A simple intensity modulated displacement sensor is proposed and demonstrated for sensing the concentration of glucose in. Significantly, the telecommunication technology has changed the recent advances in fiber optic technology. A micromachined contactfree angle sensor was already mentioned in section 5. Fiber optic sensors engineering physics syllabus 1.
A section of the ncf is sandwiched between two parts of single mode fibers smfs to form a bandpass filter. Earlier intensity modulated configurations the initial papers reporting fiber optic sensors. Intensity modulated fiber optic sensor for health monitoring applications. Light from an optical source, such as an led, is coupled into an optical fiber for transmission to the optical sensor where it can be modulated in accordance with the state of a measurand.
Optimization of wideband fiber optic hydrophone probe for. Us7646946b2 intensity modulated fiber optic strain. Pdf intensity modulated silver coated glass optical. Intensitymodulated sensors were defined in chapter 2 as sensors that detect the variation of the intensity of light associated with the perturbing environment.
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