A kind of electric circuit is improved to optimize the linearity of edge filter demodulators in FBG .By using a logarithm amplifier and an extraction operation, the linear range of optimized edge filter demodulators h...A kind of electric circuit is improved to optimize the linearity of edge filter demodulators in FBG .By using a logarithm amplifier and an extraction operation, the linear range of optimized edge filter demodulators has been broadened effectively, and the requirement of optical filter＇s linear range has been reduced. Theoretical analyses and the simulation results indi-cated that the linear range of optimized edge fdter demodulator＇s covers the whole transition region of the edge filter, while a strict linearity of the optical filter is not necessary.展开更多
A discrimination measurement method and demodulation technique for fiber Bragg grating (FBG) sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with saw...A discrimination measurement method and demodulation technique for fiber Bragg grating (FBG) sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with sawtooth wave voltage generated by digital clock to interrogate FBG sensors. Using the analogue digital converter (ADC), the reflected FBG signals were sampled with synchronous digital clock. With the aid of digital matched filtering technique, the sampled FBG signals were processed to obtain the maximum signal-to-noise ratio (SNR) and the Bragg wavelength shift from the FBG signals was recovered. The results demonstrate that this system has a scanning range of 1 520 nm-1 575 nm,and the wavelength detection accuracy is less than 2 pm with 1.5 Hz scanning frequency.展开更多
High-precision fiber Bragg grating se nsor demodulation instrument with wide-range dynamic scanning can effectivel y improve the measuring range of the optical fiber grating sensor.Ethernet com munication module is an...High-precision fiber Bragg grating se nsor demodulation instrument with wide-range dynamic scanning can effectivel y improve the measuring range of the optical fiber grating sensor.Ethernet com munication module is an extremely important part of the high-precision grating sensor demodulation device.Network interface based on Ethernet control chip D M9000A is used to send and receive the Bragg grating sensing pulse.The network transformer YL18-2050S is used to convert and filter the pulse from network.The transmitting and receiving program of grating demodulation,hardware circuit of Ethernet transmission interface are designed.The experimental results show that the network interface can achieve accurate and real-time transmissi on of the grating sensing information at high speed.展开更多
We present an all-digital demodulation system of interferometric fiber optic sensor based on an improved arctangent-differential-self-multiplying(arctan-DSM)algorithm.The total harmonic distortion(THD)and the light in...We present an all-digital demodulation system of interferometric fiber optic sensor based on an improved arctangent-differential-self-multiplying(arctan-DSM)algorithm.The total harmonic distortion(THD)and the light intensity disturbance(LID)are also suppressed,the same as those in the traditional arctan-DSM algorithm.Moreover,the lowest sampling frequency is also reduced by introducing anti-aliasing filter,so the occupation of the system memory is reduced.The simulations show that the improved algorithm can correctly demodulate cosine signal and chirp signal with lower sampling frequency.展开更多
An asymmetric fiber （Fabry-Perot, F-P） interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the ma...An asymmetric fiber （Fabry-Perot, F-P） interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity was fabricated by depositing the multi-layer thin films on the optical fiber＇s end face. The asymmetric F-P cavity has the extensive potential application. In this paper, the demodulation method for the wavelength shift of the fiber Bragg grating （FBG） sensor based on the F-P cavity is demonstrated, and a theoretical formula is obtained. And the experimental results coincide well with the computational results obtained from the theoretical model.展开更多
文摘A kind of electric circuit is improved to optimize the linearity of edge filter demodulators in FBG .By using a logarithm amplifier and an extraction operation, the linear range of optimized edge filter demodulators has been broadened effectively, and the requirement of optical filter＇s linear range has been reduced. Theoretical analyses and the simulation results indi-cated that the linear range of optimized edge fdter demodulator＇s covers the whole transition region of the edge filter, while a strict linearity of the optical filter is not necessary.
基金Doctoral Foundation of Ministry of Education of China (No. 20040056008)
文摘A discrimination measurement method and demodulation technique for fiber Bragg grating (FBG) sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with sawtooth wave voltage generated by digital clock to interrogate FBG sensors. Using the analogue digital converter (ADC), the reflected FBG signals were sampled with synchronous digital clock. With the aid of digital matched filtering technique, the sampled FBG signals were processed to obtain the maximum signal-to-noise ratio (SNR) and the Bragg wavelength shift from the FBG signals was recovered. The results demonstrate that this system has a scanning range of 1 520 nm-1 575 nm,and the wavelength detection accuracy is less than 2 pm with 1.5 Hz scanning frequency.
文摘High-precision fiber Bragg grating se nsor demodulation instrument with wide-range dynamic scanning can effectivel y improve the measuring range of the optical fiber grating sensor.Ethernet com munication module is an extremely important part of the high-precision grating sensor demodulation device.Network interface based on Ethernet control chip D M9000A is used to send and receive the Bragg grating sensing pulse.The network transformer YL18-2050S is used to convert and filter the pulse from network.The transmitting and receiving program of grating demodulation,hardware circuit of Ethernet transmission interface are designed.The experimental results show that the network interface can achieve accurate and real-time transmissi on of the grating sensing information at high speed.
文摘We present an all-digital demodulation system of interferometric fiber optic sensor based on an improved arctangent-differential-self-multiplying(arctan-DSM)algorithm.The total harmonic distortion(THD)and the light intensity disturbance(LID)are also suppressed,the same as those in the traditional arctan-DSM algorithm.Moreover,the lowest sampling frequency is also reduced by introducing anti-aliasing filter,so the occupation of the system memory is reduced.The simulations show that the improved algorithm can correctly demodulate cosine signal and chirp signal with lower sampling frequency.
文摘An asymmetric fiber （Fabry-Perot, F-P） interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity was fabricated by depositing the multi-layer thin films on the optical fiber＇s end face. The asymmetric F-P cavity has the extensive potential application. In this paper, the demodulation method for the wavelength shift of the fiber Bragg grating （FBG） sensor based on the F-P cavity is demonstrated, and a theoretical formula is obtained. And the experimental results coincide well with the computational results obtained from the theoretical model.
