Two-dimensional vector accelerometer based on Bragg gratings inscribed in a multi-core fiber

Abstract

We propose and demonstrate a novel orientation-sensitive two-dimensional accelerometer based on fiber Bragg gratings inscribed in a multi-core fiber. Through monitoring of the wavelength shifts of three of the seven cores, including the central core and two outer cores which are not aligned in a straight line, information on vibration orientation as well as acceleration can be obtained simultaneously. Performance of the proposed accelerometer in terms of frequency, acceleration and vibration orientation are experimentally investigated. The designed two-dimensional accelerometer is capable of obtaining all these three parameters simultaneously. A sensitivity which is strongly dependent on the orientation is achieved, with a best orientation accuracy of 0.127° over a range of 0-180°. Moreover, the resonance frequency and the sensitivity can be optimized through adjusting the length and weight of the free-fiber. The ease of fabrication as well as the versatility of the proposed sensor makes it potentially useful in dynamic monitoring for industrial applications.

Vector displacement sensor based on femtosecond laser direct writing gratings and waveguides in a seven-core fiber

“…The displacement direction reconstruction was also calculated. The displacement direction θd could be reconstructed from the following formula (1) [4], where △λ2, △λ3, λ2 and λ3 were the reflected wavelength changes and their initial wavelengths (i.e., 0-displacement wavelengths) of the core-2's FBG and core-3's FBG, θ2 and θ3 were the angles of core-2 and core-3 relative to the 0° plane, respectively. The experimental results were shown in Fig.…”

“…In recent years, various compact fiber-bending based devices have been proposed to realize displacement measurements, which exhibited excellent performances. Among them, vector displacement sensor based on multi-core fiber has many applications [4][5]. However, under normal circumstances, vector displacement sensors based on multi-core fiber usually need to inevitably use the fan-in & fan-out devices, which increases the application cost and decreases the compactness of such sensors.…”

Vector fiber Bragg gratings accelerometer based on silicone compliant cylinder for low frequency vibration monitoring

“…These sensors are small in size and high in accuracy, unfortunately, they exhibit susceptibility to the refractive index of the surrounding medium and possess demanding packaging requirements. For this problem, vector vibration sensing can be achieved using just one multicore fiber (MCF) (especially a seven-core fiber), [18] and the intermediate core can also provide temperature compensation, [19] allowing multiplexed multipoint measurements to be accomplished in confined spaces. [20] However, each core of the MCF is very close together, resulting in low sensitivity and angular resolution, and the cost of fanin/out (FIFO) device required for sensing with seven-core fiber is expensive.…”

New Fiber Bragg Grating Three-Dimensional Accelerometer Based on Composite Flexure Hinges

“…The sensor has a resonant frequency and sensitivity of approximately 368 Hz and 107.3 pm/g, respectively, and a lateral anti-interference degree of 4.8%; the errors between the theoretical and actual values of resonant frequency and sensitivity are 4.2 and 7.0%, respectively. Cui et al [ 14 ] proposed a direction-sensitive two-dimensional accelerometer based on multi-core fiber gratings. By monitoring the wavelength shift of three of the seven nuclei, including the central nucleus and two outer nuclei, which are not aligned, the vibration direction and acceleration information can be obtained simultaneously.…”

“…The smallest size of a two-dimensional FBG acceleration sensor has encapsulated 24 × 24 × 24 mm [ 26 ], and the sensitivity is 9.4 pm/g in the 30–300 Hz frequency range. The other size that is a not fully encapsulated sensor is 45.5 mm × 125 um [ 14 ], and the sensitivity is 115.5 pm/g and 50.8 pm/g at 40 Hz frequency, respectively, while the smallest size of a 3D FBG acceleration sensor is a 130 × 28 mm cylindrical integrated structure [ 18 ].…”