Point liquid level sensor device and measurement method based on optical frequency domain reflectometry

Abstract

The invention discloses a point-mode liquid-level sensor device based on an optical frequency domain reflection technology and a measuring method of the device. The sensor device comprises a linear frequency sweeping laser, an optical fiber beam splitter, an optical fiber circulator, a sensing module, an optical fiber coupler, a photoelectric detector, a data acquisition card, a computer and an alarm circuit; a frequency sweeping laser is divided into a signal light and a reference light by the optical fiber beam splitter; Fresnel reflection signals generated on the end surface at the tail end of each sensing optical fiber by the signal light returns along the way and enters a single-mode optical fiber in a coupling mode through the optical fiber beam splitter, and backward reflection signal light in the single-mode optical fiber and the reference light generate frequency beating interference signals in the optical fiber coupler; the data acquisition card collects the frequency beating interference signals in electric signals; the computer controls the linear frequency sweeping laser and the data acquisition card. According to the device, Fresnel reflection characteristics of the tail end of the optical fiber coupler are used for measuring the liquid-level height, and the single-point or multi-point liquid-level is monitored and warned.

Description

Technical field [0001] The present invention relates to the technical field of optical fiber sensing, and more specifically, to an OFDR-based point liquid level sensor and a measurement method. Background technique [0002] Liquid level monitoring involves a wide range of fields. The optical fiber level sensor has the characteristics of flame-proof and explosion-proof, high precision, high sensitivity, and strong anti-interference ability. It is especially suitable for liquid level monitoring in industrial production such as petrochemical industry. At present, the optical fiber level sensor has many shortcomings. For example, the liquid level sensor based on the all-fiber interferometer requires the use of a special optical fiber structure or special processing of the optical fiber. The repeatability is not high and the measurement range is limited; The addition of corresponding external components reduces the measurement reliability; the OTDR-based liquid level sensor has a spat...

AI Technical Summary

Problems solved by technology

At present, there are many deficiencies in optical fiber liquid level sensors. For example, liquid level sensors based on all-fiber interferometers need to use special optical fiber structures or special processing of optical fibers. The repeatability is not high and the measurement range is limited; liquid level sensors based on FBG require The addition of corresponding external components reduces the measurement reliability; the spatial resolution of the OTDR-based liquid level sensor is at the centimeter or even meter level, making it a large blind area for liquid level measurement, and the sensor head needs to be made of special optical fibers, and the fixing method is also quite complicated

[0003] At present, the measurement range and measurement accuracy of existing optical fiber liquid level sensors are not compatible. There is an urgent need for an optical fiber liquid level sensor with a large measurement range and high precision. At the same time, the accuracy and stability of the measurement must be guaranteed.

Images