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Fiber Bragg Grating-Based Oil-Film Pressure Measurement in Journal Bearings
摘要： The on-line measurement of oil-film pressure inside a journal bearing based on an optical fiber Bragg grating (FBG) is proposed and described for the first time. Two methods are described, one includes inserting the packaged FBG into the bearing using rubber and the other is involved the packaged FBG being directly embedded on the bearing surface. The inserted method has a higher sensitivity than the embedded version, while the embedded method incurs less damage to the bearing being small in size. Experiments to verify the feasibility of both methods are described with parameters being measured over the full motor operating range. Experimental results of the oil film pressure measured by these two methods agree well with simulated values, demonstrating excellent prospects for using the sensing schemes described in this paper as the basis for real industrial measurement systems. Furthermore, due to its small size and high sensitivity, coupled with excellent immunity to external electromagnetic interference the FBG sensor is an ideal candidate for measurement in which a strong electromagnetic field exists, e.g., in the case of electrical motors and generators.
关键词： temperature compensation,optical fiber sensors,oil film,pressure measurement,Fiber Bragg gratings (FBGs)
更新于2025-09-19 17:15:36
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - The fabrication mechanism and spectral characteristics of Fiber Gratings fabricated by point-by-point direct-writing based on femtosecond laser pulses
摘要： In this paper, a series of fiber gratings with different spectrum characteristics are fabricated in standard telecommunication fiber without hydrogen loading by point-by-point direct writing method based on 100 femtosecond laser amplifier system at 800-nm central wavelength. They are including the fourth-order fiber Bragg grating, fiber Bragg grating Fabry-Perot cavity, sampling fiber Bragg grating and cascaded long period fiber grating. The experimental results show that the spectrum characteristics of fourth-order fiber Bragg gratings with Λ=1.93 μm period are obtained at the center wavelength λ=1394.5 nm, and the fiber Bragg grating Fabry-Perot cavity can be inscribed when the gating period is Λ=1.95 μm. Furthermore, the sampled fiber Bragg gratings with different sampled periods are fabricated by adjusting the sampling period. Finally, the spectrum of the cascaded long period fiber gratings is achieved by changing the grating pitch of long period grating with 3 mm, 5 mm and 7 mm, respectively. This study will provide a powerful experimental gist and theoretical basis for the fabrication of different types of fiber gratings by femtosecond laser point-by-point writing directly method.
关键词： fiber Bragg gratings (FBGs),sampled fiber Bragg grating (S-FBG),point-by-point (PBP) direct-writing method,cascaded long period fiber grating(C-LPFG)
更新于2025-09-16 10:30:52
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Magnetic Optical FBG Sensors Using Optical Frequency-Domain Reflectometry
摘要： The optical frequency-domain reflectometry (OFDR) sensing system and signal processing method, which is based on the short-time Fourier transform, enable us to interrogate reflected wavelengths of fiber Bragg gratings (FBGs) and their relative position along the optical fiber with high spatial resolution. An FBG is an optical fiber with an appropriately inscribed periodic refractive index modulation. When a broadband optical signal is launched into the FBG, narrow wavelength bandwidth is reflected. Due to an attached transducer, such as Terfenol-D, the reflected wavelength changes with the applied magnetic field. The proposed magnetic FBG sensor consists of a small rod of magnetostrictive alloy TbDyFe, also known as Terfenol-D, which has large magnetostriction. The FBG is attached to the Terfenol-D rod with UV glue. Consequently, the external magnetic field is applied to the sensor and as a result, the Terfenol-D rod length increases. The reflected wavelength shift is observed and measured by the OFDR sensing system. Therefore, we determine the external magnetic field along the optical fiber from the reflected Bragg wavelength shift. The measurement results show that the proposed magnetic field sensors based on Terfenol-D using OFDR can be successfully used for measurement of the external magnetic field along an optical fiber.
关键词： Terfenol-D,optical frequency-domain reflectometry (OFDR),magnetic field sensor,Fiber Bragg gratings (FBGs)
更新于2025-09-09 09:28:46