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Research On Polymer Fiber Optics Displacement Sensor Based On Twisted Macro-bend Coupling & Side-coupling

Posted on:2021-03-06Degree:DoctorType:Dissertation
Country:ChinaCandidate:Abdul GhaffarFull Text:PDF
GTID:1368330602968817Subject:Instrument Science & Technology
Abstract/Summary:PDF Full Text Request
In many industrial and scientific systems,displacement or distance measurement is an essential aspect for positioning measurement.The change in position of an object corresponding to the reference point referred to as displacement.The development of the displacement sensor is helpful for the position measuring system and in other applications such angle measurement,strain,pressure and many other applications.The currently,fiber-optic displacement sensor is a leading research topic.Fiber-optics based sensors employed on various kinds of techniques and adopted the different kinds of fiber among them;we adopt polymer optical fiber.Based on the polymer optical fiber,the different displacement sensor techniques for large range and low-cost is reported in the thesis.The principle of the coupling and bending effect in polymer optical fiber is used for designing of the sensor.The bend-loss has significant advantages in the sensing application.We proposed a novel displacement sensor based on twisted macro-bend coupling phenomena.Macro-bend loss occurs during the bending of fiber,which experimentally highlighted in this proposed work.For the demonstration of the coupling of macro-bend loss in POF,two fibers were twisted and bent for the linear-displacement measurement.The macro-bending loss created in illuminating fiber due to bending effect and being coupled in receiving fiber while the coupled macro-bend loss was utilized for displacement measurement.In the proposed method,the movement of fiber corresponds to the displacement change and movement of fiber effects on the bend radius.The forward and backhaul movement of the sensor is observed.In forward movement,the bend radius become shorter and macro-bend loss arise.Whereas in the backhaul movement,the bend radius of fiber becomes increasing.The achieved range of the developed sensor is about 150 mm,and the sensor can be used for static,dynamic,and plane-in-out measurements.The sensor has excellent linearity between 0 mm to 80 mm,having a sensitivity of 1.26 nW/mm,resolution of 0.79 mm,and repeatability error of 1.26%.The temperature test also conducted,and the sensor can operate up to 70°C.The angle measurement sensor also can be used for the position measurement system such as angular displacement and is used in various industrial applications.The proposed twisted macro-bend coupling method is used for angle measurement sensors.For different angular positions,a translation stage with a stepper motor designed to convert the angular motion into linear motion.In the proposed angle sensor,the twisted fibers were attached to the translation stage.The twisted fibers pulled though the stepper motor.The designed sensor can be used for the clockwise and anti-clockwise directions.In the experiment,excellent stability and repeatability observed,and the resolution and sensitivity of the sensor are 0.45° and 2.2 nW/°,respectively.In further work,the cascading technique introduced in the TMBC method to develop the multidimensional displacement sensor.The two and three-dimensional displacement measurement sensor based on the TMBC is proposed in this thesis.In the 2-D displacement measurement system,the illuminated fiber was twice-time bent,and each bent was twisted with separate fiber.The measurement was taken from the out-put of twisted fibers.The second fiber is twisted with first bend corresponding to x-axis measurement,whereas the third fiber twisted with the second bend for the measurement of the y-axis.Whereas in the case of a 3-D displacement sensor,three bends constructed on the illuminating fiber.In the experimental setup,the four pieces of POF used in which light was launched in first fiber,and the remaining three fiber separately twisted with first fiber.Three separate fibers are twisted on each bend for measurement of the x-axis,y-axis,and z-axis.The displacement is achieved from each ax is from 0 mm to 140 mm and has a sensitivity of 6.907 nW/mm.The interference is one of the fundamental characteristics of light rays.A novel enlarge displacement measurement sensor is proposed based on the side-coupling of light rays.The intensity-variation occurs when multiple light rays launch in the fiber.Instead of the face of the fiber,the light is launched from the side of the fiber.The LED-Belt(LB)is used as a light source which has a series of light-emitting diodes.The movement of LED-Belt on the fiber is associated with displacement changes.When LB moves,the number of diodes increases,and more light rays launch in the fiber.The corresponding power variation is detected through the power meter.The linear-displacement has been achieved up to 1 meter having sensitivity about 1.532 nW/mm,and the resolution is 0.653 mm,whereas the range can easily enlarge depend on requiring the application.In the contests of other methods,the proposed novel sensor method is holistic,optimal cost-effective,easy to manufacture,and has potential advantages on industrial applications.
Keywords/Search Tags:Side-coupling
PDF Full Text Request
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