Light waveguide absorption type gas sensor and measuring system
A gas sensor and gas measurement technology, which is applied in the field of sensors and systems composed of them, can solve the problems of miniaturization of devices, the difficulty of guided wave high-order modes, the inability of gas analysis instruments, and the non-selectivity of samples, etc., and achieve simple structure and measurement High sensitivity and practical effect
Inactive Publication Date: 2008-07-09
SHANGHAI JIAOTONG UNIV
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Problems solved by technology
Disadvantages are: ① use distributed feedback (DFB) laser, expensive body, high system cost
②When using optical fiber to transmit signals, the frequency of the optical signal must be within the low-loss window of the optical fiber, so the characteristic frequency of the gas must also be within this range, which limits the types of gases that this sensor can detect
However, due to the use of a prism structure, it is difficult to miniaturize the device and utilize guided wave high-order modes.
In addition, because the detection amount is the change of the refractive index of the waveguide layer medium, which makes the measurement not selective for the sample, it cannot be used as a gas analysis instrument
Method used
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[0015] Such as Figure 1-Figure 4 As shown, the optical waveguide absorption gas sensor 1 of the present invention comprises: an upper layer metal film 4, an upper layer optical glass sheet 5, an air chamber 6, a lower layer metal film 7, a lower layer optical glass sheet 8, an air inlet 9, an air outlet 10, a pad Block 11, platform 12, screw micrometer 13. The upper metal film 4 is deposited on the upper optical glass sheet 5 and faces outward; the lower metal film 7 is deposited on the lower glass sheet 8 and faces inward. A hollow gasket with two small holes is placed between the two glass sheets. The two small holes are respectively used as an air inlet 9 and an air outlet 10 , and the hollow part forms an air chamber 6 . Each part is placed on the platform 12 sequentially according to the order of the upper layer metal film 4, the upper layer optical glass sheet 5, the air chamber 6, the lower layer metal film 7, the lower layer optical glass sheet 8, and the spacer 11, ...
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An air transducer of light waveguide absorption type consists of metal film and optical glass plate at top layer and bottom layer, seat pad, platform and spiral micrometer. The measuring system consists of said transducer, laser source, light signal detecting and processing unit. In the system, the metal film is deposited on glass plate which is placed on platform one by one, the laser source is used to form guidewave and photoelectric diode array is used to detect out light strength variation of outgoing light so as to know variation of air composition in air chamber.
Description
technical field [0001] The invention relates to a sensor in the technical field of measuring instruments and a system composed of it, in particular to a prism-free optical waveguide absorption gas sensor structure and a measurement system based on free space coupling. Background technique [0002] Gas sensors are widely used in environmental monitoring, production process monitoring, gas composition analysis and gas leakage alarm. At present, the commonly used gas sensors are mainly divided into several categories such as electrical, optical, and electrochemical. Among them, the fiber optic gas sensor is a new type of optical sensor that appeared after the 1980s. It uses the characteristic spectral lines of the gas in the infrared band to identify the gas and analyze its concentration. The measurement principle is: different gases have different characteristic infrared absorption spectra, and within a certain concentration range, the infrared absorbance value of each gas ha...
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IPC IPC(8): G01N21/64G01N21/01
Inventor 顾江华曹庄琪陈洸沈启舜邓晓旭
Owner SHANGHAI JIAOTONG UNIV