scholarly journals Enhancement of the Performance and Data Processing Rate of an Optical Frequency Domain Reflectometer Distributed Sensing System Using A Limited Swept Wavelength Range

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3480 ◽  
Author(s):  
Kunpeng Feng ◽  
Jiwen Cui ◽  
Yihua Jin ◽  
Xun Sun ◽  
Dong Jiang ◽  
...  
Keyword(s):  
Data Processing ◽  
Frequency Domain ◽  
Spatial Resolution ◽  
Wavelength Range ◽  
Distributed Sensing ◽  
Optical Frequency ◽  
Local Similarity ◽  
Processing Rate ◽  
Spectrum Range ◽  
Measurable Range

A novel optical frequency domain reflectometer (OFDR) processing algorithm is proposed to enhance the measurable range and data processing rate using a narrow swept spectrum range and reducing the time consuming of the process distributed sensing results. To reduce the swept wavelength range and simultaneously enhance strain measurable range, the local similarity characteristics of Rayleigh scattering fingerprint spectrum is discovered and a new similarity evaluation function based on least-square method is built to improve the data processing rate and sensing performance. By this method, the strain measurable range is raised to 3000 µε under a highest spatial resolution of 3 mm when the swept spectrum range is only 10 nm and the data processing rate is improved by at least 10 times. Experimental results indicate that a nonlinearity of less than 0.5%, a strain resolution of better than 10 µε, a repeatability at zero strain of below ±0.4 GHz and a full-scale accuracy is lower than 0.85 GHz under a highest spatial resolution of 3 mm can be achieved. Advantages of this method are fast processing rate, large strain measurable range, high SNR, and applicability with current OFDR systems.

scholarly journals An Optical Frequency Domain Angle Measurement Method Based on Second Harmonic Generation

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 670
Author(s):  
Wijayanti Dwi Astuti ◽  
Hiraku Matsukuma ◽  
Masaru Nakao ◽  
Kuangyi Li ◽  
Yuki Shimizu ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Second Harmonic Generation ◽  
Frequency Domain ◽  
Harmonic Generation ◽  
Measurement Method ◽  
Second Harmonic ◽  
Angle Measurement ◽  
Laser Source ◽  
Optical Frequency ◽  
Measurable Range

This paper proposes a new optical angle measurement method in the optical frequency domain based on second harmonic generation with a mode-locked femtosecond laser source by making use of the unique characteristic of the high peak power and wide spectral range of the femtosecond laser pulses. To get a wide measurable range of angle measurement, a theoretical calculation for several nonlinear optical crystals is performed. As a result, LiNbO3 crystal is employed in the proposed method. In the experiment, the validity of the use of a parabolic mirror is also demonstrated, where the chromatic aberration of the focusing beam caused the localization of second harmonic generation in our previous research. Moreover, an experimental demonstration is also carried out for the proposed angle measurement method. The measurable range of 10,000 arc-seconds is achieved.

scholarly journals Realization of a polarization-insensitive optical frequency-domain reflectometer using an I/Q homodyne detection

2021 ◽  
Author(s):  
Alin Jd ◽  
Marcelo A. Soto ◽  
Marius Enachescu ◽  
Dominik Ziegler
Keyword(s):  
Frequency Domain ◽  
Spatial Resolution ◽  
Optical Fibers ◽  
Local Oscillator ◽  
Acquisition Time ◽  
Optical Frequency ◽  
Homodyne Detection ◽  
Software Environment ◽  
Very High Spatial Resolution ◽  
Phase Amplitude

Abstract We report on the development and implementation of an optical frequency-domain reflectometer (OFDR) sensing platform. OFDR allows to measure changes in strain and temperature using optical fibers with a length of several tens of meters with very high spatial resolution. We discuss the operation principles and challenges to implement an OFDR system using optical homodyne detection based on a dual-polarization 90º optical hybrid. Our setup exhibits polarization and phase diversity, fully automated data acquisition and data processing using a LabVIEW-based implemented software environment. Using an optical hybrid enables to discriminate phase, amplitude and polarization by interfering the Rayleigh scatter signal and a local oscillator with four 90° phase stepped interferences between the two signals. Without averaging and a fast acquisition time of 230 ms, our preliminary results show a spatial resolution of 5 cm and a temperature resolution of about 0.1 Kelvin on a 3 m-long fiber.

A dual-ended 400 km OFDR for vibration detection

2022 ◽  
Author(s):  
Zujun Qin ◽  
Yiwei Hu ◽  
Yaoli Yue ◽  
Chao Tan
Keyword(s):  
Frequency Domain ◽  
Spatial Resolution ◽  
Cross Correlation ◽  
High Spatial Resolution ◽  
Vibration Monitoring ◽  
Optical Frequency ◽  
Detection Range ◽  
Vibration Detection

Abstract Optical frequency-domain reflectometer (OFDR) has been widely used in vibration detection because of its unique advantages of simple configuration and high spatial resolution. Based on remote fiber amplification, an unrepeatered OFDR is experimentally investigated for vibration monitoring. To locate the vibration, we present an algorithm by calculating segmental cross-correlation between the beating signals with and without disturbances on the sensing fiber. It is shown that the OFDR demonstrates the ability of detecting the vibration over 222 km testing distance (112 km + 110 km). After sensing the first spool fiber of 112 km, the remnant laser is amplified by a remote-pumped EDFA before proceeding to probe the vibration in the second spool one of 110 km. To be specific, the PZT-induced vibrations positioned at z=110.9 km and z=220.9 km are both detected. More importantly, the OFDR system can be extended to operate in bi-directional sensing mode and to double detection range from 200 km to 400 km.

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