Optical fiber macro-bending coupling structure liquid level probe based on dark field detection

Abstract

The invention discloses an optical fiber macro-bending coupling structure liquid level probe based on dark field detection. The invention provides a liquid level sensing principle based on a cladding mode frustrated total internal reflection (CMFTIR) effect for the first time and successfully applies the principle. The distribution of a mould field in optical fibers is changed based on a macro-bending manner, the occupied ratio of cladding mode energy in the optical fibers is increased, and the CMFTIR effect is enhanced; meanwhile, a macro-bending radiation effect realizes the macro-bending coupling of the two optical fibers; a sensing signal is transmitted to a dark field through the macro-bending coupling manner, and the modulation depth of the coupling process is enhanced; meanwhile, the higher occupied ratio of the cladding mode energy is obtained in the passive optical fibers, and the CMFTIR effect is further enhanced; meanwhile, the stability of the coupling structure and the consistency of a sensor are guaranteed; the signal to noise ratio is effectively improved through detecting the signal of the dark field; the liquid level probe with low cost, low power consumption and high performance is realized, and the distinguishing degree is higher than 4dB.

Description

technical field [0001] The invention relates to a liquid level probe, in particular to an optical fiber macrobend coupling structure liquid level probe based on dark field detection. Background technique [0002] In the field of petroleum, chemical and chemical production, automatic detection of liquid level of liquid chemicals is an important guarantee for safe operation; monitoring of fuel level during the operation of aircraft and ships also has a wide range of demands. At present, the traditional liquid level detection methods mainly include: mechanical float type, capacitive type, ultrasonic type, etc. Among them, mechanical float electronics have defects in automation and precision; capacitive sensors have certain safety hazards in flammable and explosive environments due to the introduction of electrical signals, and a large number of signal connection lines are very susceptible to electromagnetic interference; ultrasonic liquid Position sensors often have problems s...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the above problems, the present invention provides a liquid level probe with optical fiber macrobend coupling structure based on dark field detection, which solves the problems of poor stability, low precision and poor robustness in traditional liquid level measurement methods, and realizes low energy consumption and low cost. Special probes for safe and environmentally friendly liquid level detection systems

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