Dynamic Clearance Measurement Using Fiber-Optic Frequency-Swept and Frequency-Fixed Interferometry

Shao, Bin; Zhang, Wei; Zhang, Peng; Chen, Weimin

doi:10.1109/lpt.2020.3023006

Cited by 22 publications

(9 citation statements)

References 22 publications

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“…Therefore, for the spectra collected by wavelength scanning, the conventional WLI algorithm is not applicable. Shao et al 72 combined frequency swept interferometry (FSI) and frequency fixed interferometry (FFI), and used the fusion processing of interferometer signals. This method can not only eliminate the Doppler error, but also give a cavity length at each sampling point.…”

Section: Fast Interrogation Techniquesmentioning

confidence: 99%

Fast interrogation of dynamic low‐finesse Fabry‐Perot interferometers: A review

Liu

Peng

2021

Micro & Optical Tech Letters

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Low‐finesse fiber‐optic Fabry–Perot (F‐P) interferometric sensor has the advantages of high sensitivity, anti‐electromagnetic interference, and compact size, and is one of the most widely used optical fiber sensors. With the development of sensor design and demodulation algorithms, F‐P sensing technique plays an increasingly important role in high‐speed dynamic measurement, such as dynamic temperature or pressure, acoustic vibration, dynamic displacement, and distance. Signal demodulation methods largely determine the performance of the entire sensing system. Compared with quasi‐static measurement, high‐precision measurement of dynamic F‐P cavity is more challenging. The advancement of fast tunable laser technology in telecommunication field provides novel perspectives for demodulation methods and dynamic applications based on F‐P sensors. This article reviews the latest developments in fast interrogation techniques for dynamic low‐finesse F‐P sensors, including intensity demodulation, quadrature phase demodulation and absolute cavity length demodulation. In addition, array multiplexing and multi‐parameter measurement techniques are also involved.

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Section: Fast Interrogation Techniquesmentioning

confidence: 99%

Fast interrogation of dynamic low‐finesse Fabry‐Perot interferometers: A review

Liu

Peng

2021

Micro & Optical Tech Letters

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“…where L(t) and v(t) are the real-time distance and velocity (v(t) is negative when the target approaches the fiber probe). Thus, using the dψ(t)/dt, the measured dynamic distance Lm(t) can be obtained as [32] ( ) ( ) ( ) (…”

Section: The Basics Of Fsimentioning

confidence: 99%

“…However, if the target moves during the frequency sweep, due to the Doppler effect, the phase ψ ( t ) in Equation (1) becomes [ 24 ] (note that, Jia et al [ 24 ] gives the instantaneous frequency of the FSI signal, which equals dψ ( t )/(2 πdt ))

where L ( t ) and v ( t ) are the real-time distance and velocity ( v ( t ) is negative when the target approaches the fiber probe). Thus, using the dψ ( t )/ dt , the measured dynamic distance L m ( t ) can be obtained as [ 32 ]

where f avg is the average of f r ( t ). In Equation (3), the term f avg v ( t ) T / B is the Doppler error, which is sensitive to the target velocity v ( t ).…”

Section: Theorymentioning

confidence: 99%

“…As a famous absolute distance measurement technique, frequency-swept interferometry (FSI) is widely used in various ranging applications. Since the dynamic accuracy of FSI is severely restricted by the well-known Doppler effect [ 23 , 24 , 25 ], the previously reported works mainly focused on the elimination of the Doppler error of FSI [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Because the goal of these methods was to measure the absolute dynamic distance, they were not applied for the measurement of the rotor parameters.…”

Section: Introductionmentioning

confidence: 99%

“…Because the goal of these methods was to measure the absolute dynamic distance, they were not applied for the measurement of the rotor parameters. In our previous work [ 32 ], we proposed an FSI-based method which is suitable for dynamic clearance measurement, but the core idea is still to remove the Doppler error in FSI. For absolute distance measurement, the Doppler effect is an undesirable property that needs to be eliminated, but we found, it is exactly this property that makes the multi-parameter measurement of the rotor possible.…”

Section: Introductionmentioning

confidence: 99%

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Multi-Parameter Measurement of Rotors Using the Doppler Effect of Frequency-Swept Interferometry

Shao

Wei

Zhang

et al. 2020

Sensors

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The Doppler effect of frequency-swept interferometry (FSI) is often seen as an obstacle to the dynamic ranging accuracy. However, the potential of this obstacle is rarely noticed and used. In this paper, by combining the periodical characteristics of the rotational Doppler effect, an FSI-based multi-parameter measurement method for the rotor is proposed. Through the establishment of the rotational Doppler formula of FSI, it is found that the frequency, direct component, and amplitude of the dynamic distance given by FSI can be utilized to estimate the angular velocity, axial clearance, and tilt angle of the rotor, respectively. A rotor platform and a fiber-optic FSI system were constructed, and a series of experiments were carried out to verify the proposed method. The experimental results showed that the relative errors of the measured axial clearance, angular velocity, and tilt angle were less than 3.5%. This work provides a new perspective on the multi-parameter measurement of the rotor and makes it possible to directly perform multi-parameter measurement inside the space-confined rotating machinery as only a single small-size fiber-optic probe is needed.

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