Dark field detection based optical-fiber macrobending coupling structure liquid-level probe

An optical fiber macro-bending and dark-field detection technology, which is applied in the field of liquid level probes, can solve problems such as poor stability, low precision, and poor robustness, and achieve the effects of increasing strength, ensuring stability, and low power consumption

Active Publication Date: 2014-12-10
ZHONGBEI UNIV
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Problems solved by technology

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, l

Method used

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  • Dark field detection based optical-fiber macrobending coupling structure liquid-level probe

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Example

CMFTIR effect enhancement experiment (finger touch)

A single straight optical fiber, one end connected to the led light source, one end to the optical power meter. Lightly touch the fiber with a finger, and the power measured by the power meter does not change, indicating that there is almost no CMFTIR effect observed in the intact straight fiber.

A single optical fiber forms a macrobend ring structure, one end is connected to a 1ed light source, and one end is connected to an optical power meter. When a finger touches the top of the bent part of the fiber, the normalized power measured by the power meter drops by about 5%, indicating that the CMFTIR effect has increased to a certain extent. This is because the macrobending of the optical fiber causes the change of the internal mode field of the optical fiber, and relatively more cladding modes are generated in the bent optical fiber. The light touch of the finger causes more cladding modes to radiate out, which cause...

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Abstract

The invention discloses a dark field detection based optical-fiber macrobending coupling structure liquid-level probe. The liquid level sensing principle based on 'CMFTIR (cladding mode frustrated total internal reflection) effect' is proposed for the first time and applied successfully. By means of macrobending, mode field distribution in optical fibers is changed, ratio of cladding mode energy in the optical fibers is increased, and the CMFTIR effect is enhanced; meanwhile, due to macrobending radiation effect, macrobending coupling between the two optical fibers is realized; by means of macrobending coupling, a sensing signal is transferred to a dark field, modulation depth is increased during coupling, higher cladding mode energy ratio can be obtained in the passive optical fiber, and the CMFTIR effect is further enhanced; meanwhile, stability of the coupling structure and consistency of sensors are guaranteed, signal to noise ratio of increased by detection of effectiveness of dark field signals, the liquid-level probe is low in cost and power consumption and high in performance, and discrimination is higher than 4dB.

Description

technical field 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 In the field of petroleum, chemical and chemical production, the automatic detection of the liquid level of liquid chemicals is an important guarantee for safe operation; the monitoring of the 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 ...

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Application Information

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IPC IPC(8): G01F23/292
Inventor 刘文怡侯钰龙苏珊张会新刘俊熊继军甄成方张迦卫
Owner ZHONGBEI UNIV
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