Laser beat frequency sensing technology-based high-precision inclinator and measurement method

Abstract

The invention discloses a laser beat frequency sensing technology-based high-precision inclinator and a measurement method, and is applied to the inclination change measurement of the crust. The high-precision inclinator comprises two communicated water tanks, floaters, optical fibers, sensing fiber Bragg gratings, reference fiber Bragg gratings, fixed side plates and sensing signal generation and demodulation devices. A principle for realizing inclination measurement is dual-ring cavity single longitudinal mode fiber laser-based laser beat frequency sensing demodulation technology, and two inclination measurement implementation schemes are provided for different base lengths of a water pipe inclinator. A laser beat frequency sensing technology is applied to the measurement of a crustal inclination signal through an ingenious structural design, and a corresponding fiber water pipe inclinator device is designed; and therefore, compared with the prior art, a system has the advantages of high demodulation precision, high reliability, simple structure, lower cost, high stability, automatic temperature compensation mechanism and the like.

Description

technical field [0001] The invention relates to the technical field of geoscience observation, in particular to an optical fiber water pipe inclinometer suitable for measuring crustal tilt changes. Background technique [0002] At present, the high-precision inclinometer is one of the main instruments for solid tidal deformation observation, and it is also an important part of the crustal deformation observation instrument. It can be widely used in the observation of solid tides, large-scale land-based scientific instruments (such as laser interference gravitational wave antenna) Measurement of ground tilt movement and monitoring and early warning of geological disasters. As an important implementation of high-precision inclinometers, the water pipe inclinometer is a long-baseline inclinometer that uses the free water surface as a reference to measure the relative elevation change between two observation points separated by a certain distance. Its basic structure is to use ...

AI Technical Summary

Problems solved by technology

[0003] The liquid level sensors of traditional water pipe inclinometers use magnetic, pressure, and capacitive measurement methods, such as Nie Lei et al. in the article "Design and Development of FSQ Type Float Water Pipe Inclinometer", Crustal Deformation and Earthquake, vol.4, The water pipe inclinometer introduced in No.1, p.91-102 uses a magnetic liquid level sensor, which has the characteristics of small zero drift and low cost. However, due to the inherent weak anti-interference ability of the magnetic sensor itself, the accuracy is low and the networking Poor capacity, poor dynamic performance and other shortcomings make it have certain limitations in application; in recent years, the DSQ type water pipe inclinometer improved based on FSQ has stronger intelligence and automation, and its dynamic performance and measurement accuracy have improved. However, the core liquid level sensor still uses an electrical sensor based on a differential transformer, which makes it very demanding on environmental conditions during use, and is easily affected by electromagnetic interference and temperature, which is not conducive to working in the harsh environment of deep geology

[0004] Due to some inherent advantages of optical sensing, some optical-based inclinometer structures and measurement schemes have appeared in recent years, such as the US invention patent "Inclination angle metering apparatus (patent number US5392112)" applied by Masahiro Nakamura. The inclinometer uses the fixed surface of the instrument and the liquid surface to respectively reflect two beams of light divided by one beam and focus them on a detector, and calculate the inclination angle of the instrument from the relative position of the space points of the two sub-beams; another example is Kool The patent "Optical Inclinometer (Patent No. CN1659420A)" applied by Te Erne et al. The inclinometer designed in this patent emits radiation from the radiation source, and focuses on the camera after passing through the containing element. position, the inclination of the inclinometer can be deduced: these schemes are innovative in principle and meet high requirements in accuracy, but the structure is relatively complex, and the stability and reliability of the system are limited by the radiation source and light source , there are certain limitations in practical applications

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