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A fiber optic interference ultra-low frequency vibration measurement device and method with phase feedback control

A technology of optical fiber interference and phase feedback, which is used in measuring devices, measuring ultrasonic/sonic/infrasonic waves, instruments, etc., can solve the problems of difficulty in measuring natural seismic signals and high cut-off frequency, and achieves improvement of measurement sensitivity, flatness, and improvement. Effects of Vibration Measurement Accuracy

Active Publication Date: 2021-12-03
珠海任驰光电科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The inventors of the present disclosure found that although the existing optical fiber interference vibration measurement device and method have many application advantages compared with the traditional electrodynamic very broadband seismograph, the minimum measurable level of acceleration is limited by the phase noise level of the laser. In the low frequency range (lower than 0.1Hz), it is higher than the low background noise model of the earth (NLNM), which makes the cut-off frequency of the lower limit of the system's working frequency band higher, and it is difficult to measure natural seismic signals of ultra-low frequency

Method used

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  • A fiber optic interference ultra-low frequency vibration measurement device and method with phase feedback control
  • A fiber optic interference ultra-low frequency vibration measurement device and method with phase feedback control
  • A fiber optic interference ultra-low frequency vibration measurement device and method with phase feedback control

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Embodiment 1

[0070] Such as figure 1 As shown, Embodiment 1 of the present disclosure provides a general phase feedback control optical fiber interference ultra-low frequency vibration measurement device, which specifically includes: a signal generator, a laser, an isolator, a fiber coupler, a vibration probe, a phase controller, a Faraday rotation mirror, photodetector, phase demodulation module, feedback control module, phase delay compensation module, driver, filter and processor.

[0071] The signal generator outputs 3 signals, including FM signal, 1-fold frequency signal and 2-fold frequency signal. The angular frequency of the FM signal is ω c , output to the laser; 1 frequency multiplied signal and 2 frequency multiplied signal are in phase synchronization, and the angular frequencies are ω c and 2ω c , and there is a fixed phase delay with the FM signal Output to the phase demodulation module.

[0072] The laser should have a narrow linewidth characteristic. Under the excitat...

Embodiment 2

[0088] Embodiment 2 of the present disclosure provides a phase feedback control optical fiber interference ultra-low frequency vibration measurement method, including the following steps:

[0089] Step 1: The laser outputs frequency-modulated continuous light with a wavelength of 1550nm or 1330nm suitable for optical fiber transmission. The electric field expression of the continuous light is:

[0090]

[0091]

[0092] Among them, E L (t) represents the electric field intensity of the laser output continuous light, E C Indicates the amplitude value of the electric field strength, v L (t) optical frequency with frequency modulation, represents the laser phase noise that varies randomly over time, v C Indicates the DC component of the optical frequency, K v Indicates the optical frequency modulation coefficient, Indicates the initial phase of optical frequency modulation, and t indicates time.

[0093] Step 2: The continuous light passes through the fiber optic in...

Embodiment 3

[0110] Such as image 3 As shown, Embodiment 3 of the present disclosure provides an optical fiber interference ultra-low frequency vibration measurement device with phase feedback control. The phase controller in Embodiment 1 is replaced by a piezoelectric ceramic fiber stretcher, and the sensitive part of the optical fiber is placed on a piezoelectric ceramic fiber stretcher. Inside the ceramic optical fiber stretcher, the detection of the change in the axial length of the reference arm optical fiber is realized; the driver is replaced by a piezoelectric ceramic driver, and other structural settings are the same as those in Embodiment 1, and will not be repeated here.

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Abstract

The present disclosure provides a phase feedback control optical fiber interference ultra-low frequency vibration measurement device and method, including a signal generator, a laser, an isolator, a fiber coupler, a mandrel vibration probe, a feedback control module, a phase delay compensation module and a driver , phase controller, Faraday mirror, photodetector, phase demodulation module, filter and processor; this disclosure utilizes a feedback loop composed of a feedback control module, a phase delay compensation module, a driver, and a phase controller to control an optical fiber interferometer The change of the fiber length of the reference arm changes the response characteristics of the ultra-low frequency vibration measurement system and improves the measurement sensitivity of the system to ultra-low frequency special environmental vibration; on the basis of the closed-loop control system, the phase information with feedback is filtered through the filter, Improved vibration measurement accuracy and improved flatness within the operating frequency band.

Description

technical field [0001] The present disclosure relates to the technical field of vibration measurement, in particular to a phase feedback controlled optical fiber interference ultra-low frequency vibration measurement device and method. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. [0003] Modern seismographs detect seismic waves and obtain seismic records to study the source of the earthquake, the internal structure of the earth and the seismic waves themselves, and realize the prediction of impending earthquakes. However, traditional seismic wave detection systems generally have problems such as low sensitivity, small dynamic range, electric leakage, and difficult power supply, which limit the development of earthquake prediction technology. In view of the advantages of optical fiber sensing technology, such as corrosion resistance, anti-ele...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01H9/00
CPCG01H9/004
Inventor 常天英王忠民崔洪亮于淼杨悦
Owner 珠海任驰光电科技有限公司