Five wavelength interrogation technique for miniature fibre optic Fabry-Pérot sensors

Ezbiri, A.; Tatam, Ralph P.

doi:10.1016/s0030-4018(96)00445-2

Cited by 10 publications

(4 citation statements)

References 8 publications

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“…The size of the error is dependent upon the algorithm used to calculate the phase [15]. For example, it has recently been shown that a five-step algorithm [16] can have ±10% error on a π/2 phase step with a concomitant error in the calculated phase of less than 1% [17].…”

Section: Resultsmentioning

confidence: 99%

The calibration of the path-length imbalance in optical fibre ESPI systems employing source-wavelength modulation

Olszak¹,

Tatam²

1997

Meas. Sci. Technol.

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A technique is presented that allows simple and potentially automated determination of the optical path-length imbalance in ESPI systems that utilize source-wavelength modulation to obtain phase shifting. The method is based on modulating the emission wavelength of the laser synchronously with the framing rate of the CCD/image processing board and recording the average speckle intensity of the image. The injection current is increased until a 2π, or multiple of 2π, change in the phase has been achieved. Repeating this measurement for two different optical path-length imbalances of known difference allows determination of the laser diode ( ν/ i ) coefficient and the optical path-length imbalance without the use of additional spectrometers.

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Section: Resultsmentioning

confidence: 99%

The calibration of the path-length imbalance in optical fibre ESPI systems employing source-wavelength modulation

Olszak¹,

Tatam²

1997

Meas. Sci. Technol.

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“…These limitations have been overcome using passive and active phase demodulation techniques. Passive schemes rely on the use of multiple lasers that have a quadrature phase shift between each source, allowing two orthogonal signals to be constructed and the phase changes determined trigonometrically [14][15][16]. Although high sampling rates and an improved dynamic range can be achieved, the cavity length of the FP must be matched to the interrogation sources to ensure quadrature thus restricting the design of the sensor [17].…”

Section: Introductionmentioning

confidence: 99%

Optical fibre pressure sensing using a frequency modulated laser-based signal processing technique

Barrington

James

Kissinger

et al. 2023

Meas. Sci. Technol.

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Range resolved interferometry (RRI) applied to the interrogation of an extrinsic Fabry-Perot based pressure sensor in laboratory and wind tunnel environments is presented. A simple, compact sensor head design was fabricated and subsequently characterised using RRI, which was shown to have a sensitivity of 1.627×10−3 rad/Pa with a noise standard deviation of 9 Pa over a data rateof 1.5 kHz. When installed in a high-lift wing for surface pressure evaluation during wind tunnel testing, the approach outlined here was able to perform as well as a conventionally employed commercial device for relative static pressure measurements.

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“…phase algorithms (two [9], three [10], four [11] and five [12] wavelength techniques), FFT algorithm [13], [14] and its improved algorithms [1], [2], [15], DTG algorithm [9], wavelet phase extracting (WPE) algorithm [16], and Least-Squares fitting (LSF) [17] and its improved algorithms [18]. Yet, the models of the above-mentioned algorithms were all established on the static FP spectrum.…”

Section: Introductionmentioning

confidence: 99%

A Demodulation Model of Dynamic Low-Finesse Fabry-Perot Cavity Based on the Instantaneous Frequency

Zhang

Xiong²,

Shao

et al. 2020

IEEE Access

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If the measurand changes during the spectrum acquisition process, it easily leads to the failure of the classic demodulation algorithms of low-finesse optical fiber Fabry-Perot (FP) sensors. To address this problem, a novel demodulation model is proposed based on the definition of the instantaneous frequency. The proposed model establishes the relationship between the optical path length (OPL) of the FP cavity and the instantaneous frequency distribution of the FP interference spectrum. The link between the classic FFT algorithm and this model is discussed, and it is found that this model can be viewed as a generalized form of the FFT algorithm. Based on this model, the Doppler-induced demodulation error is analyzed. The analysis uncovers that the average frequency of the FP interference spectrum should be used for the evaluation of the error, and the error is proportional to the variation of OPL during the spectrum acquisition period. Further, numerical simulation and an experiment were carried out to verify the proposed model, and results show that the proposed model is effective for the dynamic low-finesse FP cavity. It is the first time that the idea of instantaneous frequency is introduced for the FP demodulation, and this model provides us a new way to cope with the FP sensing signal.

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Five wavelength interrogation technique for miniature fibre optic Fabry-Pérot sensors

Cited by 10 publications

References 8 publications

The calibration of the path-length imbalance in optical fibre ESPI systems employing source-wavelength modulation

The calibration of the path-length imbalance in optical fibre ESPI systems employing source-wavelength modulation

Optical fibre pressure sensing using a frequency modulated laser-based signal processing technique

A Demodulation Model of Dynamic Low-Finesse Fabry-Perot Cavity Based on the Instantaneous Frequency

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