Two-dimensional spatially encoded cross-sectional velocity distribution measurements based on coherent bias-frequency encoding and wavelength-division multiplexing

Maru, Koichi

doi:10.1016/j.optcom.2020.126740

Cited by 5 publications

(3 citation statements)

References 21 publications

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“…Since Mazumder [1] and Penney [2] developed the dual beam laser Doppler velocimeter (LDV) sysetm in 1969, dual beam LDV has been widely used in measurements of the velocity of the flow [3,4], vibration [5,6] and length [7] in scientific researches and industrial applications. A typically dual beam LDV system employs an equal optical path beam splitter to split the input beam into two parallel beams of equal intensity and equal optical length.…”

Section: Introductionmentioning

confidence: 99%

Theory analysis for interference fringes of the dual beam laser Doppler velocimeter

Huang,

Wang,

Nie

et al. 2024

2024 International Conference on Optoelectronic Information and Optical Engineering (OIOE 2024)

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The theory analysis of the interference fringe for the dual beam system is currently based on the ordinary Gaussian beam model where the velocity measured by dual beam LDV is v =λ fd/ (2sinα0 ) . αo is the half intersection angle between two intersecting laser beams. And the direction of the velocity is along the normal of the bisector of the optical axis of two output beams ( y axis) after focused by the positive lens. This study establishes two interference fringe models for the dual beam LDV based on the ordinary Gaussian beam and off-axis Gaussian beam model, respectively. In Model one and Model two, the velocity of the particles running through the measurement volume is vmodel1 = λfd/(sinα1+ sinα2 and Vmodel2 = λfd/(2tanα0) , respectively, where α1 is the angle between optical axis of one output beam and the positive lens, and α2 is the angle between optical axis of other output beam and the positive lens. Two models indicate that when the distances between the optical axis of two input parallel beams and the positive lens is not equal, there is an angle between the distributing direction of the interference fringe and y axis.

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Section: Introductionmentioning

confidence: 99%

Theory analysis for interference fringes of the dual beam laser Doppler velocimeter

Huang,

Wang,

Nie

et al. 2024

2024 International Conference on Optoelectronic Information and Optical Engineering (OIOE 2024)

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“…Laser Doppler velocimetry (LDV) is a noninvasive technique for measuring the speed of moving solid-state surfaces or particle velocity in a fluid by laser interferometry [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Researchers continuously develop and design LDV devices suitable for different applications [15][16][17][18][19]. LDV devices with a dual-beam structure Sensors 2023, 23, 8411 2 of 10 have been widely used for fluid flow measurements for many years [20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Laser Velocimetry for the In Situ Sensing of Deep-Sea Hydrothermal Flow Velocity

Sun,

Zhang,

et al. 2023

Sensors

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Laser Doppler velocimetry (LDV) based on a differential laser Doppler system has been widely used in fluid mechanics to measure particle velocity. However, the two outgoing lights must intersect strictly at the measurement position. In cross-interface applications, due to interface effects, two beams of light become easily disjointed. To address the issue, we present a laser velocimeter in a coaxial arrangement consisting of the following components: a single-frequency laser (wavelength λ = 532 nm) and a Twyman–Green interferometer. In contrast to previous LDV systems, a laser velocimeter based on the Twyman–Green interferometer has the advantage of realizing cross-interface measurement. At the same time, the sensitive direction of the instrument can be changed according to the direction of the measured speed. We have developed a 4000 m level laser hydrothermal flow velocity measurement prototype suitable for deep-sea in situ measurement. The system underwent a withstand voltage test at the Qingdao Deep Sea Base, and the signal obtained was normal under a high pressure of 40 MPa. The velocity contrast measurement was carried out at the China Institute of Water Resources and Hydropower Research. The maximum relative error of the measurement was 8.82% when compared with the acoustic Doppler velocimeter at the low-speed range of 0.1–1 m/s. The maximum relative error of the measurement was 1.98% when compared with the nozzle standard velocity system at the high-speed range of 1–7 m/s. Finally, the prototype system was successfully evaluated in the shallow sea in Lingshui, Hainan, with it demonstrating great potential for the in situ measurement of fluid velocity at marine hydrothermal vents.

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“…In the WDM technology, FBG sensors with different central wavelengths are connected in series. It reduces work quantity but decreases the broadband light source power, which fails to meet the multipoint and distributed sensing measurements [13]. All FBG sensors are connected to an optical switch used to control and select the transmission channel in the SDM technology.…”

Section: Introductionmentioning

confidence: 99%

Development of a Fault Detection Instrument for Fiber Bragg Grating Sensing System on Airplane

Kong

Chen

2022

Micromachines

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This study develops a fault detection device for the fiber Bragg grating (FBG) sensing system and a fault detection method to realize the rapid detection of the FBG sensing system on airplanes. According to the distribution of FBG sensors on airplanes, the FBG sensing system is built based on wavelength division multiplexing (WDM) and space division multiplexing (SDM) technologies. Furthermore, the hardware and software of the fault detection device and the relevant FBG demodulator are studied in detail. Additionally, in view of the similar features of the healthy FBG sensor in the same measuring point, a rapid fault diagnosis method based on a synthetical anomaly index is proposed. The features (light intensity I, signal length L, standard deviation of original sampleand energy value in time-domain P) of FBG sensors are extracted. The aggregation center value of the above feature values is obtained through the loop iteration method. Furthermore, the separation degrees of features are calculated and then form the synthetical anomaly index so as to make an effective diagnosis of the state of the FBG sensor. Finally, the designed fault detection instrument and proposed fault detection method are used to monitor the 25 FBG sensors on the airplane, the results indicated that three faulty and two abnormal FBG sensors on the airplane are identified, showing the effectiveness of the proposed fault detection method.

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Two-dimensional spatially encoded cross-sectional velocity distribution measurements based on coherent bias-frequency encoding and wavelength-division multiplexing

Cited by 5 publications

References 21 publications

Theory analysis for interference fringes of the dual beam laser Doppler velocimeter

Theory analysis for interference fringes of the dual beam laser Doppler velocimeter

Laser Velocimetry for the In Situ Sensing of Deep-Sea Hydrothermal Flow Velocity

Development of a Fault Detection Instrument for Fiber Bragg Grating Sensing System on Airplane

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