This paper presents a measuring system of vibration acceleration for acoustic emission wave using wavelet signal
reconstruction technology. Continuous wave modulation frequency and wavelength division multiplex technology are
adopted to realize distributed sensing system demodulation. Double FBGs acceleration probe with compressive stress
and tensile stress applying simultaneity is designed. In this way, the influence of temperature noise on sensing signals is
eliminated and measurement sensitivity and resolution are enhanced. Using wavelet signal processing methods not only
completed the optical wavelength absolute code, improve imbalanced and nonlinear optical signal efficiently, but also
reconstruct micro accelerate signal. This system has some advantages such as simple structure, high scan frequency, high
resolution and good linearity.
A novel method for achieving high resolution for static strain measurement is proposed and demonstrated. This method
is based on the combination of two fiber Bragg grating (FBG) and an all-fiber Fabry-Perot sensor (FFPI) formed by the
two FBGs. The wavelength shift of the FBGs is used for determining the fringe number of the interferometic signal
while the FFPI and the pseudo-heterodyne are used to carry out high-resolution measurement. The resolution for static
strain by the actual measuring is 31nε.
Frequency shift in Brillouion back-scattering light can be changed when strain is exerted to an optical fiber. Brillouin scattering can be used to measure strain in distributed manner. A new fully distributed fiber optical strain sensing is proposed based on Brilliouin optical-fiber frequency domain reflectometry (BOFDR). A new measurement is reported by utilizing fiber Bragg grating Fabry-Perot interferometer (FBGFPI) to directly separate the Brilliouin signal. The experimental setup and result are presented. Primary result confirms this configuration feasible.
The supersmooth surface roughness measurement is becoming more and more important with the development of the processing technique. This paper studies an on-line measurement system of the supersmooth surface roughness using optical heterodyne method. The simple structure and strong practicability of this system are researched. The experimental results show that this system has the feature of the good stability and high measured accuracy.
The Fabry-Perot interferometer (FPI) has been traditionally used to examine either small spectral ranges or relatively simple spectra. Recently, however, the studies have shown that the FPI can be competitive with the Michelson interferometer over extended spectral ranges. A relatively new FPI is described based on two gratings. In order to measure angular micro-displacement, a novel grating angular displacement transducer using a multiplex Fabry-Perot interference technology has been developed in this paper.
An optical fiber dual-interferometer for measuring small displacement has been developed in this paper. A wavelength- scanning source is used to simultaneously illuminate two Fabry-Perot cavities. One is as the sensing cavity, the other is as the reference cavity. If the length of the reference cavity is pre-calibrated and maintain constant, and the scanning wavelength is taken as an inter-converter to compare the gap length of the sensing cavity with the reference cavity length, using the frequency spectrum separator, absolute measurement can be obtained.
A novel wavelength scanning optical fiber dual-interferometer for measuring small distance has been developed in this paper. A wavelength-scanning source is used to simultaneously illuminate Fabry-Perot (F-P) cavities. One is as the sensing cavity, the other is as a reference cavity. If the length of the reference cavity is pre-calibrated and maintain constant, and the scanning wavelength is taken as an inter-converter to compare the gap length of the sensing cavity with the reference cavity length, using the frequency spectrum separator, absolute measurement can be obtained.
A novel grating angular displacement transducer using a multiplex Fabry-Perot interface technology has been developed. The Fabry- Perot interferometer (FPI) has been traditionally used to examine either small spectral ranges or relatively simple spectra. Recently, however, the studies have shown that the FPI can be competitive with the Michelson interferometer over extended spectral ranges. A relatively new FPI is described based on two gratings.
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