Three-channel low-frequency fiber-optic voltage sensor

1994 ◽  
Vol 19 (3) ◽  
pp. 228 ◽  
Author(s):  
L. Fabiny ◽  
S. T. Vohra ◽  
F. Bucholtz ◽  
A. Dandridge
Keyword(s):  
Fiber Optic ◽  
Low Frequency ◽  
Voltage Sensor

FDM three-channel fiber-optic low-frequency voltage sensor

1994 ◽  
Author(s):  
L. Fabiny ◽  
S. T. Vohra ◽  
F. Bucholtz ◽  
A. Dandridge
Keyword(s):  
Fiber Optic ◽  
Low Frequency ◽  
Voltage Sensor

Ultra-low-drift, sub-microvolt low-frequency fiber optic voltage sensor

1994 ◽  
Author(s):  
Larry Fabiny ◽  
Sandeep T. Vohra ◽  
Frank Bucholtz
Keyword(s):  
Fiber Optic ◽  
Low Frequency ◽  
Voltage Sensor ◽  
Low Drift

scholarly journals Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

2016 ◽  
Vol 23 (2) ◽  
pp. 309-316
Author(s):  
Marcin Lipiński ◽  
Przemysław Krehlik ◽  
Łukasz Śliwczyński ◽  
Łukasz Buczek ◽  
Jacek Kołodziej
Keyword(s):  
Fiber Optic ◽  
Data Transfer ◽  
Acoustic Noise ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Propagation Delay ◽  
Optical Signal ◽  
Testing Time ◽  
Optical Noise ◽  
Signal Phase

Abstract The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F) fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

scholarly journals Pendulum-Type Hetero-Core Fiber Optic Accelerometer for Low-Frequency Vibration Monitoring

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2528 ◽  
Author(s):  
Hiroshi Yamazaki ◽  
Ichiro Kurose ◽  
Michiko Nishiyama ◽  
Kazuhiro Watanabe
Keyword(s):  
Fiber Optics ◽  
Electromagnetic Interference ◽  
Large Scale ◽  
Fiber Optic ◽  
Low Frequency ◽  
Fiber Optic Sensor ◽  
Vibration Monitoring ◽  
Vibration Measurement ◽  
Displacement Sensor ◽  
Core Fiber

In this paper, a novel pendulum-type accelerometer based on hetero-core fiber optics has been proposed for structural health monitoring targeting large-scale civil infrastructures. Vibration measurement is a non-destructive method for diagnosing the failure of structures by assessing natural frequencies and other vibration patterns. The hetero-core fiber optic sensor utilized in the proposed accelerometer can serve as a displacement sensor with robustness to temperature changes, in addition to immunity to electromagnetic interference and chemical corrosions. Thus, the hetero-core sensor inside the accelerometer measures applied acceleration by detecting the rotation of an internal pendulum. A series of experiments showed that the hetero-core fiber sensor linearly responded to the rotation angle of the pendulum ranging within (−6°, 4°), and furthermore the proposed accelerometer could reproduce the waveform of input vibration in a frequency band of several Hz order.

Modeling of fiber-optic strain responses to hydraulic fracturing

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. A45-A50
Author(s):  
Zhishuai Zhang ◽  
Zijun Fang ◽  
Joe Stefani ◽  
James DiSiena ◽  
Dimitri Bevc ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Strain Rate ◽  
Fiber Optic ◽  
Low Frequency ◽  
Displacement Discontinuity ◽  
Hydraulic Fractures ◽  
Quantitative Interpretation ◽  
Current Application ◽  
Monitoring Well ◽  
And Inversion

We modeled cross-well strain/strain rate responses of fiber optic sensing, including distributed strain sensing (DSS) and low-frequency distributed acoustic sensing (DAS), to hydraulic stimulation. DSS and low-frequency DAS have been used to measure strain or the strain rate to characterize hydraulic fractures. However, the current application of DSS/DAS is limited to acquisition, processing, and qualitative interpretations. The lack of geomechanical models hinders the development of the technology toward quantitative interpretation and inversion. We have developed a strategy to use the displacement discontinuity method to model the strain field around kinematically propagating fractures. For a horizontal monitoring well, modeling results were able to explain the heart-shaped extending pattern before a fracture hit, the polarity flip due to fracture interaction during stimulation, and the V-shaped pattern when a fracture does not intersect with the monitoring well. For a vertical monitoring well, modeling shows the different characters of strain rate responses when a fracture is near and far away from a vertical monitoring well. We also investigated the effects of fractures with various geometries such as elliptic and layered fractures. We compared and verified the modeling with field data from the Hydraulic Fracturing Test Site 2, a research experiment performed in the Permian Basin. Our modeling work can be used to identify patterns in field observations. The results also help to improve acquisition design and lay the groundwork for quantitative interpretation and inversion.

scholarly journals Feedforward Control Based on Error and Disturbance Observation for the CCD and Fiber-Optic Gyroscope-Based Mobile Optoelectronic Tracking System

Electronics ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 223 ◽  
Author(s):  
Yong Luo ◽  
Wei Ren ◽  
Yongmei Huang ◽  
Qiunong He ◽  
Qiongyan Wu ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Control Method ◽  
Feedforward Control ◽  
Tracking System ◽  
Sampling Rate ◽  
Low Frequency ◽  
Integration Time ◽  
Fiber Optic Gyroscope ◽  
Loop Control ◽  
Boresight Error

In the mobile optoelectronic tracking system (MOTS) based on charge-coupled device (CCD) and fiber-optic gyroscope (FOG), the tracking performance (TP) and anti-disturbance ability (ADA) characterized by boresight error are of equal importance. Generally, the position tracking loop, limited by the image integration time of CCD, would be subject to a non-negligible delay and low-sampling rate, which could not minimize the boresight error. Although the FOG-based velocity loop could enhance the ADA of the system, it is still insufficient in the case of some uncertain disturbances. In this paper, a feedforward control method based on the results of error and disturbance observation was proposed. The error observer (EOB) based on the CCD data and model output essentially combined the low-frequency tracking feedforward and closed-loop disturbance observer (DOB), which could simultaneously enhance the low-frequency TP and ADA. In addition, in view of the poor low-frequency performance of the FOG due to drift and noise that may result in the inaccuracy of the observed low-frequency disturbance, the FOG-based DOB was used to improve the relatively high-frequency ADA. The proposed method could make EOB and DOB complementary and help to obtain a high-precision MOTS, for in practical engineering, we give more attention to the low-frequency TP and full-band ADA. Simulations and experiments demonstrated that the proposed method was valid and had a much better performance than the traditional velocity and position double-loop control (VPDC).

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