Microsystem optical fiber gas sensor, sensing system and sensing method

Abstract

A micro system optical fiber gas transducer is formed by two short - cycle optical fiber gratings and two long - cycle optical fiber gratings on one section of optical fiber. The sensing system formed by said gas transducers consists of wideband light source, wideband coupler, microsysem optical fiber gas transducer, optical fiber spectrum demodulator and computer. The sensing method calibrates temperature coefficient and sensitive coefficient of transducer first and then measures out concentration of gas to be tested.

Description

technical field [0001] The invention belongs to the technical fields of optical fiber sensing, gas chemistry and safety, and in particular relates to a micro-system optical fiber gas sensor, a sensing system and a sensing method. Background technique [0002] In terms of mining safety, for a long time, major and extraordinarily large coal mine accidents have occurred frequently around the world, with hundreds of casualties. Every major accident brings huge property losses, especially irreparable losses to the lives of industrial workers, and poses a threat to families and society. One of the main causes of coal mine accidents is the explosion caused by high-concentration gas, and coal mine gas explosions often occur all over the world. 40% of my country's coal mines are high gas and outburst mines, which have serious safety problems. At present, the effective monitoring and control of gas is still a worldwide problem. People have invested a lot of manpower and financial re...

AI Technical Summary

Problems solved by technology

However, there are still many problems in the contact combustion gas sensor: poor resistance to high-concentration impact and poor stability; the sensor needs to be adjusted frequently, once every 2 weeks; The service life is short, usually only 1 year; the sensor detects gas by catalytic combustion on the sensing surface, and gas is a flammable and explosive gas, which itself is a serious accident induction source; the sensor has a long reaction time to gas, about 30 seconds, difficult to detect and control in time

Its disadvantages are: (1) the sensor has a large volume, complex structure, and distributed detection is difficult; (2) it has high requirements for the sensing environment, and coal dust is easy to adhere to the two concave mirrors, resulting in failure of the optical reflection surface; (3) ) The concave mirror surface is on the inner wall of the gas chamber, and it is difficult to clean the coal dust on the mirror surface; (4) The relative positions of multiple parts in the sensor must be precisely aligned, and its vibration resistance is poor, and assembly is difficult

However, there are still some shortcomings in this optical fiber evanescent wave gas sensor: (1) The fabrication of the sensor is cumbersome and difficult, and the optical fiber cladding needs to be removed by chemical corrosion or abrasion, and the removal position of the optical fiber cladding is difficult to precisely control

At the same time, the surface of the fiber core after chemical corrosion or abrasion of the fiber cladding is a rough non-optical interface, which affects the optical performance at the interface, and the noise of the signal light is very large, which affects the measurement accuracy

(2) The sensing system uses a single optical path intensity measurement method. The fluctuation and interference of the light source, optical path and circuit system have a great impact on the reliability and accuracy of the sensing system, and it is difficult to achieve higher precision biomolecular measurement and measurement. analyze

(3) The system structure is relatively complex, and its detectors generally use photomultiplier tubes, which require high-voltage partial pressure systems and cooling systems

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