Optical-fiber-interference water level sensing device and method based on sweep-frequency-laser-device demodulation

Abstract

The invention relates to an optical-fiber-interference water level sensing device and method based on sweep-frequency-laser-device demodulation. The device comprises a sweep-frequency laser device, laser generated by the laser device is divided into two ways through a coupler and transmitted through an optical fiber, one way laser generates first multiple-beam interference through a fabry-perot etalon, and the other way laser generates second multi-beam interference through a water pressure probe; the first multiple-beam interference and the second multi-beam interference are demodulated, a water pressure value in the water pressure probe is obtained, and according to the relationship of the pressure intensity and the water level, a water-level measuring value can be obtained. The water pressure probe comprises a shell, a water pressure strain gauge, a fabry-perot cavity and a fabry-perot-cavity adjusting mechanism, wherein the water pressure strain gauge is in directly contact with water and connected with the fabry-perot-cavity adjusting mechanism; when the water level is changed, the water pressure strain gauge suffers from changes of the water level to drive the abry-perot-cavity adjusting mechanism to move, the cavity length of the fabry-perot cavity is changed along with moving accordingly, and laser generates the second multi-beam interference in the water pressure probe.

Description

technical field [0001] The invention relates to an optical fiber interference water level sensing device and method based on frequency-sweeping laser demodulation. Background technique [0002] High-precision water level sensors can be used to monitor changes in various water levels, such as monitoring the water level of urban rivers, monitoring the water level of reservoirs, and monitoring changes in ocean water levels. If the water level monitoring is not carried out in advance, when the water level reaches the warning line, it will cause major disasters such as urban floods, embankment bursts, and tsunamis, which will seriously affect the safety of people's lives and economic property. Therefore, it is necessary to accurately monitor various complex water levels. , the development of high-precision water level sensor is of great significance. [0003] Water level sensors generally have different classifications such as float-type water-level sensors, pressure-type water-...

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Problems solved by technology

[0003] Water level sensors generally have different classifications such as float-type water-level sensors, pressure-type water-level sensors, and optical-fiber water-level sensors. In the Chinese patent with the published patent number CN202974389U, a float-type water level gauge using a reference water level is proposed. The water level gauge The use of mechanical structure sensors requires logging equipment and is difficult to operate. It is only suitable for low-sediment river sections with stable bank slopes and small riverbed erosion and siltation, which has great limitations.

In the published Chinese patent No. CN204286550U, a pressure-type water level gauge capable of air pressure compensation is proposed. The water level gauge adopts a circuit structure, including signal acquisition, signal processing, power supply unit, etc. The overall circuit structure is complex and transmission The distance is limited, and it cannot be used in harsh environments such as severe electromagnetic interference and strong corrosion; in the published Chinese patent No. CN204461547U, a fiber optic interference water level sensor is proposed, using fiber optic sensing technology to construct a Michelson interference structure , to achieve water level measurement through phase demodulation, but it can only measure dynamic water level changes and cannot achieve static water level measurement, which has certain limitations in practical applications

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