Fiber Bragg Grating Vibration Sensor Research Articles

A non-contact FBG vibration sensor with double differential temperature compensation

This paper has presented a non-contact fiber Bragg grating (FBG) vibration sensor with double differential temperature compensation. Two FBGs and two states of the sensor have been employed to achieve double differential temperature compensation. Based on magnetic coupling and FBG sensing principle, it can be used to realize non-contact measurement of vibration of the rotating shaft. Experimental results show that the working band ranges are within 0–150 Hz; the sensitivity is −0.67 pm/µm, and the linearity is 3.87 % within a range of 2–2.6 mm. The fitting equation of temperature compensation which is caused by structural inflation can be expressed as: Δλ 1′ − Δλ 2′ = 1.51 × T − 32.97. When used to amend a temperature error, the sensor’s temperature error will be reduced to 1.19 % in the range of 25–60 °C.

Pasted type distributed two-dimensional fiber Bragg grating vibration sensor.

A pasted type distributed two-dimensional fiber Bragg grating (FBG) vibration sensor has been proposed and studied in this paper. The optical fiber is directly considered as an elastomer. The two-dimensional vibration can be separated by subtraction/addition of two FBGs' center wavelength shift. The principle of the sensor as well as numerical simulation and experimental analyses are presented. Experimental results show that the resonant frequencies of the sensor x/y main vibration direction are separately 1300/20.51 Hz, which are consistent with the numerical simulation analysis result. The flat frequency range resides in 10-750 Hz and 3-12 Hz, respectively; dynamic range is 28.63 dB; in the x main vibration direction, the sensor's sensitivity is 32.84 pm/g, with linearity 3.91% in the range of 10-60 m/s(2), while in the y main vibration direction, the sensor's sensitivity is 451.3 pm/g, with linearity 1.92% in the range of 1.5-8 m/s(2). The cross sensitivity is 3.91%. Benefitting from the two dimensional sensing properties, it can be used in distributed two-dimensional vibration measurement.

Study on the non-contact FBG vibration sensor and its application

A non-contact vibration sensor based on the fiber Bragg grating (FBG) sensor has been presented, and it is used to monitor the vibration of rotating shaft. In the paper, we describe the principle of the sensor and make some experimental analyses. The analysis results show that the sensitivity and linearity of the sensor are −1.5 pm/μm and 4.11% within a measuring range of 2 mm–2.6 mm, respectively. When it is used to monitor the vibration of the rotating shaft, the analysis signals of vibration of the rotating shaft and the critical speed of rotation obtained are the same as that obtained from the eddy current sensor. It verifies that the sensor can be used for the non-contact measurement of vibration of the rotating shaft system and for fault monitoring and diagnosis of rotating machinery.

基于平均周期图法提高光纤光栅微弱振动信号检测能力的研究

基于平均周期图法提高光纤光栅微弱振动信号检测能力的研究

A high-performance compact vibration sensor based on fiber Bragg grating

A high-performance compact vibration sensor based on fiber Bragg grating (FBG) is designed. The acceleration sensitivity of the FBG vibration sensor is measured to be larger than 30 pm/g. From 10 Hz to 250 Hz, a quite flat frequency-response curve can be obtained with additional damping, which suppresses the resonance peak effectively. A phase-generated carrier (PGC) demodulation technique realized by compact reconfigurable input and output (RIO) system is applied in our sensing system.

150-km Long Distance FBG Temperature and Vibration Sensor System Based on Stimulated Raman Amplification

A 150-km long distance fiber Bragg Grating (FBG) temperature and vibration sensor system was proposed and demonstrated by using the stimulated Raman amplification. It can achieve 150-km measurement range by using a low power 1480-nm laser as the Stokes of the pump laser at 1395 nm in the progress of stimulated Raman amplification. And the whole system only consist one Raman pump laser source with 1-W power at 1395 nm, a low-power 1480-nm laser and two segments of erbium doped fiber (EDF) at the location of 50 km and 75 km separately.

A Robust and Compact Fiber Bragg Grating Vibration Sensor for Seismic Measurement

A compact fiber Bragg grating (FBG) vibration sensor consisting a flat diaphragm and two L-shaped rigid cantilever beams for seismic measurement has been proposed and experimentally demonstrated. The specially designed sensing configuration contributes many desirable features such as a wide frequency response range (10-120 Hz), an extremely high sensitivity coefficient (~100pm/g) together with a robust metal package for improving the mechanical strength and a decreased transverse sensitivity (<; 5%), making it a good candidate for in-field seismic wave measurement in oil and gas exploration.

基于级联长周期光纤光栅的光纤布拉格光栅振动传感器的动态解调

基于级联长周期光纤光栅的光纤布拉格光栅振动传感器的动态解调

Fiber-Optic Mechanical Vibration Sensor Using Long-Period Fiber Grating

Long-period fiber gratings (LPGs) are fabricated by illuminating UV laser light to a photosensitized single-mode optical fiber. By applying the intensity modulation scheme, which is known to be effective as an interrogation method for fiber Bragg grating (FBG) vibration or sound sensors, we construct a fiber-optic mechanical vibration sensor that uses an LPG as a sensing element. It is confirmed that the LPG vibration sensor yields a clear and stable signal waveform and shows good linearity when the amplitude of the vibration strain is varied. In addition, the dynamic range of the sensor is more than 90 dB. Since an LPG shows higher sensitivity to static strain when an appropriate higher cladding mode is adopted, it is expected that with proper choice of the cladding mode an LPG vibration sensor will show much higher sensitivity.

Wavelength Division Multiplexed Fiber Bragg Grating Vibration Sensor Array with Temperature Compensation

We have developed a novel method of wavelength division multiplexed operation of thermally stabilized fiber Bragg grating (FBG) vibration sensors in that simultaneous multipoint vibration detection with a temperature-insensitive operation can be achieved. One of the sensing elements of the arrayed sensors consists of a pair of FBGs, one is used for providing a narrow-spectrum light from a broad-spectrum incoherent optical source and the other is used for vibration sensing. The paired FBG configuration enables us to compensate the temperature effects that are commonly applied to the FBGs used. In the experiment, two sensing elements are arranged in tandem and the detection of simultaneous two-point multiple vibrations and the measurement of an elastic wave propagating in a metal bar are demonstrated.

Multiplexed Fiber Bragg Grating Vibration Sensor with Temperature Compensation Using Wavelength-Switchable Fiber Laser

A wavelength-switchable and tunable fiber ring laser has been proposed to implement an optical source of a fiber Bragg grating (FBG) vibration sensor array based on intensity modulation technique. The laser consists of an erbium-doped fiber amplifier (EDFA) and an optical switch with tuning FBGs, in which the lasing output is coupled out from a selected tuning FBG and serves as an optical source of one of the multiplexed FBG vibration sensor elements. By changing the channel of the optical switch, the lasing wavelength can be chosen for the sensing FBG of the respective sensor element. In addition, the temperature effects on the sensor outputs due to environmental temperature can be eliminated when the temperature changes are applied commonly to both the tuning and sensing FBGs. In the experiment, multipoint vibration detection with a temperature-insensitive operation is successfully demonstrated by constructing two sensor elements arranged in parallel.

Thermally Stabilized Fiber-Bragg-Grating Vibration Sensor Using Erbium-Doped Fiber Laser

We have proposed a novel combination of an erbium-doped fiber (EDF) laser with a fiber Bragg grating (FBG) vibration sensor to stabilize the output against the temperature disturbances. A wavelength-tunable EDF ring laser is fabricated as an optical source of the FBG sensor by using an erbium-doped fiber amplifier (EDFA), an optical circulator with a tuning FBG, and an optical fiber coupler, in which the lasing wavelength is determined by the Bragg wavelength of the tuning FBG. This combination scheme enables us to measure the vibration directly but eliminate the effect due to ambient temperature changes commonly affecting both the tuning and sensing FBGs. In the experiment it is demonstrated that the temperature-induced output variation of the sensor is less than 1.6 dB over the temperature change ranging from -10 to 50°C.