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Study On Force And Temperature Fabry-perot Fiber-optic Sensor

Posted on:2018-04-14Degree:MasterType:Thesis
Country:ChinaCandidate:Y Z JiaoFull Text:PDF
GTID:2428330566498734Subject:Physical Electronics
Abstract/Summary:PDF Full Text Request
Optical Fabry–Perot(F-P)fiber sensor is to realize the double beam interference by constructing the F-P cavity on optical fiber.When the physical quantity to be measured changes in the environment,the medium refractive index or the length of the F-P cavity changes,the coherent optical phase difference would change,thus resulting in the interference spectrum shift.This kind of sensor has many advantages,such as small size,simple structure,easy encapsulation,which has gained wide attention.In this paper,several new schemes are proposed for the measurement of multi-parameters such as force and heat of F-P type by searching data and reading related literatures.And through theoretical research and simulation,a series of design and experimental verification has been carried out.We have test strain,pressure and temperature sensors for further study.This paper presents a strain sensor based on a single F-P cavity.The strain-sensitive F-P cavity was constructed by hollow-core photonic crystal fiber,and the strain test was realized.In this paper,the theoretical model of the sensor is deduced and the experiment is verified.By constructing sensors with different F-P cavity lengths and testing the sensitivity of the strain,we draw the conclusion that the shorter is the F-P cavity length,the higher strain sensitivity is the sensor,and vice versa.Aiming at the low sensitivity of fiber-optic strain sensor,in this paper,a strain sensor based on cascaded F-P cavities and Vernier effect is proposed.An optical fiber strain sensor prepared by cascading an air cavity formed by an ordinary optical tube fiber and a silica cavity formed by standard single-mode fiber,and the sensor is designed based on Vernier effect.It's not only saving the manufacturing cost but also can effectively achieve the high sensitivity of the strain response,increasing the sensitivity of a dozen times.Aiming at the problem that optical fiber strain sensor is affected by temperature cross-talk,this paper presents a sensor based on cascaded F-P cavity to measure strain and temperature simultaneously.We use hollow fiber capillaries and single-mode fiber to form two F-P cavity cascade structures.The spatial frequency spectrum after the frequency-selective filtering method can get separated interference spectral information of two separate cavities,and then we construct the sensitivity coefficient matrix equation by strain and temperature sensitivities of each cavity to compensate the strain-temperature cross sensitivity.And the sensor preparation process is simple,the use of ordinary fiber,compact structure,low cost,and small size,which are conducive to the popularity of sensor applications.Aiming at the problem that the optical fiber pressure sensor is affected by the temperature cross-interference,a sensor based on cascaded double F-P cavities measurement of air pressure and temperature simultaneously is proposed in this paper.Fiber capillaries and photonic crystal fibers are used to form an open cavity cascaded double F-P cavity sensor.Through frequency-selective filtering,the interference spectra of two cavities are separated,the sensitivity of each cavity to different pressures and temperatures is tested,the matrix of sensitivity coefficients is established,and the cross-sensitivity is compensated by different sensitivities of two cavities to pressures and temperatures.The sensor is small in size,space utilization is enhanced and the preparation method is simple and easy to operate.
Keywords/Search Tags:fiber-optic sensors, Fabry-Perot, optical measurement
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