Fabry-Perotw fiber-optic pressure sensor and manufacture method therefor

Abstract

This invention relates to a kind of Fabry-Perot type fiber pressure sensor. the invention is formed by silicon slice(1), glass tube(2), optical fiber flange disk(3), and optical fiber plug(4). the character is: one end of glass tube bond with silicon slice; glass tube be fastened to optical fiber flange disk cavity; optical fiber plug ceramics contact pin through white porcelain tube(5) to fix onglass tube inside; optical fiber plug ceramics contact pin and silicon slice's undersurface form Fabry-Perot cavity. This invention also opens the method of producing this sensor.

Description

technical field [0001] The invention relates to a Fabry-Perot type optical fiber pressure sensor, in particular to a Fabry-Perot type optical fiber pressure sensor which uses a tunable laser for signal access and uses the wavelength change of the reflection spectrum to complete signal demodulation and its production method. Background technique [0002] In the past, the Fabry-Perot fiber optic sensor was mainly used to measure strain, and now it has begun to use its mature and high precision in measuring small strains to measure pressure, temperature, etc., such as figure 1 structure, a typical structure of it. A thin sheet of silicon covers the glass etched with a shallow cylindrical cavity, and the air cavity between the silicon and the glass is the Fabry-Perot cavity (FP cavity). The optical fiber is then bonded to the glass to form the sensor. The pressure deforms the silicon wafer to change the length of the FP cavity, which also changes the signal of the reflected l...

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Problems solved by technology

However, this design also has the following disadvantages: first, the system uses the light intensity demodulation method, and the fluctuation of the light source has a great influence on the solution of the cavity length; second, glass and silicon wafers can also be formed as independent FP cavities Interference signals, and these signals carry useless information, interfere with the useful interference signal formed by the air cavity, and bring difficulties to signal demodulation; third, the size of the air cavity is very small, generally only a few microns, and the deflection of the silicon wafer It is also very small, but in the application, the deflection of the silicon wafer caused by vibration is comparable to the deflection caused by pressure, which also makes demodulation very difficult, and the repeatability of the sensor is also impossible to talk about; finally, the optical fiber is required to be aligned with the cavity, And there is no special alignment structure in the design, and there is no way to ensure that the fiber and the glass are kept perpendicular

The author uses an alloy sensing film, the optical fiber is fixed through the micro-holes formed on the glass, and its end face and the alloy face form an FP cavity. This design effectively reduces the interference signal caused by multiple reflection surfaces, but it also has many disadvantages. The perfect place: first, the use of alloy sensitive film affects its scope of use, and the fatigue of the metal also seriously affects its normal service life; second, the process is difficult, and many processes are immature. It is very difficult to generate a small hole with a high aspect ratio on the glass sheet, and its cavity length is not easy to control; third, after the package is completed, the sealed air in it will make the sensor more affected by temperature; finally, and figure 1 Similarly, the optical fiber is required to be aligned with the cavity, and there is no special alignment structure in the design, and there is no guarantee that the optical fiber is perpendicular to the sensing film

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