&lt;title&gt;Micromachined SiC fiber optic pressure sensors for high-temperature aerospace applications&lt;/title&gt;

Pulliam, Wade J.; Russler, Patrick M.; Mlcak, Richard; Murphy, Kent A.; Kozikowski, Carrie L.

doi:10.1117/12.411723

Cited by 41 publications

(29 citation statements)

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“…Fiber-optic interferometers, especially fiber FabryPerot interferometers ͑FFPI͒, have found increased applications in the past decade for the detection and measurement of a large variety of physical parameters, such as temperature, [1][2][3][4] vibration, 1,5 pressure, 3,4,6,7 acoustic waves, 1,5,8 -11 and strain. 12,13 Many interferometric sensors operate over the linear region of an interference fringe.…”

Section: Introductionmentioning

confidence: 99%

“…However, confining the operation to the linear region places difficult manufacturing constraints on the sensor head by requiring that the initial cavity length be positioned at the Q point or sometimes at one end of a linear region of the transfer function. 6 The sensors also suffer from signal fading caused by environmental perturbations, such as temperature changes, which may drive the sensors out of the linear region. The drifts are even more critical for Fabry-Perot ͑F-P͒ sensors; medium-or high-finesse F-P cavities are often necessary for higher measurement sensitivity 1,11 because of their steeper fringe slopes.…”

Section: Introductionmentioning

confidence: 99%

“…Several techniques have been developed by various researchers to stabilize the Q point, for example, intentionally applying an acoustic bias, 1 tuning the static OPD in stages, 14 and using a tunable light source, 8,9 quadrature phase-shifted demodulation or dual-wavelength interrogation, 5,6,12,15 or direct spectrum detection. 6,13,16,17 In the acoustic bias method, the low-frequency component output of a FFPI acoustic-wave sensor was compared with a constant voltage corresponding to the setting operating point, and the difference was used to adjust the acoustic bias through a voice coil.…”

Section: Introductionmentioning

confidence: 99%

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Grating-assisted demodulation of interferometric optical sensors

Wang

2003

Appl. Opt.

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Accurate and dynamic control of the operating point of an interferometric optical sensor to produce the highest sensitivity is crucial in the demodulation of interferometric optical sensors to compensate for manufacturing errors and environmental perturbations. A grating-assisted operating-point tuning system has been designed that uses a diffraction grating and feedback control, functions as a tunablebandpass optical filter, and can be used as an effective demodulation subsystem in sensor systems based on optical interferometers that use broadband light sources. This demodulation method has no signaldetection bandwidth limit, a high tuning speed, a large tunable range, increased interference fringe contrast, and the potential for absolute optical-path-difference measurement. The achieved 40-nm tuning range, which is limited by the available source spectrum width, 400-nm͞s tuning speed, and a step resolution of 0.4 nm, is sufficient for most practical measurements. A significant improvement in signal-to-noise ratio in a fiber Fabry-Perot acoustic-wave sensor system proved that the expected fringe contrast and sensitivity increase.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Grating-assisted demodulation of interferometric optical sensors

Wang

2003

Appl. Opt.

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“…However, the PD detection system does suffer from source power fluctuation caused by backreflection, initial quadrature-point ͑Q-point͒ offset because of fabrication tolerance, operating-point drift caused by static pressure in the transformer oil, and temperature drift. Although demodulation by multiwavelength interrogation 14,22 or spectral interrogation 22 is successful in solving the nonlinear transfer function, directional ambiguity, and signal fading, neither approach is suitable for PD detection because it is possible that all channels of the multiwavelength approach are not at the Q point and that neither method may have enough frequency response for PD detection.…”

Section: Introductionmentioning

confidence: 99%

Fiber Fabry-Perot sensors for detection of partial discharges in power transformers

et al. 2003

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A diaphragm-based interferometric fiber optic sensor that uses a low-coherence light source was designed and tested for on-line detection of the acoustic waves generated by partial discharges inside high-voltage power transformers. The sensor uses a fused-silica diaphragm and a single-mode optical fiber encapsulated in a fused-silica glass tube to form an extrinsic Fabry-Perot interferometer, which is interrogated by low-coherence light. Test results indicate that these fiber optic acoustic sensors are capable of faithfully detecting acoustic signals propagating inside transformer oil with high sensitivity and wide bandwidth.

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“…However, small fluctuations of background pressure could change the operating point of the sensor in an unpredictable way. Several approaches, such as multiwavelength interrogation 4,5 or spectral interrogation 5 and Q-point control using a bandpass filter, 3 have been employed to compensate the operating point drift, while the price is a significant increase in system complexity and cost. In this letter, we present a new structure for diaphragm-based EFPI optical fiber sensors to eliminate operating point dependence on background pressure fluctuations.…”

Section: Introductionmentioning

confidence: 99%