CN111473896A - An optical fiber pressure sensor based on soft silicon diaphragm and its detection method - Google Patents

Abstract

The invention discloses an optical fiber pressure sensor based on a soft silicon diaphragm and a detection method thereof. The pressure sensor includes a pipe body, a soft silicon diaphragm and an optical fiber, and the optical fiber is placed in the pipe body and is close to the The silicon film is attached to the optical path formed by the input optical fiber, such as the front end, inner side or lateral surface of the nozzle. The ultra-thin silicon diaphragm is prepared by using silica gel. When the external pressure changes, the deformation of the film will be caused. Direct detection or detection based on the principle of coherent light interference can be used to investigate the vibration deformation of the silicon diaphragm, measure the deformation of the silicon diaphragm and set the corresponding The pressure value and the measurable pressure range are calculated, and the functional relationship between the pressure value in the measurable range and the deformation depth is calculated, so as to achieve the function of being able to test the pressure.

Description

An optical fiber pressure sensor based on soft silicon diaphragm and its detection method

technical field

The invention relates to the technical field of micro sensors, in particular to an optical fiber pressure sensor based on a soft silicon diaphragm and a detection method thereof.

Background technique

Optical fiber sensing technology was first widely researched in western countries such as the United States and Europe, and it has been gradually matured since its development, and it is developing in the direction of high performance and high practicability.

The following disadvantages are common in the prior art:

1. Most of the diaphragm-type pressure measuring probes used today have complex film-making methods and high costs, which are not suitable for animal in vivo testing.

2. The preparation of most pressure measuring probes is too complicated. The film collection and adhesion process needs to be operated under a microscope, which requires high operating environment and experimental materials, and is generally difficult to prepare.

3. General pressure measuring probes are not suitable for the detection of special objects to be measured, such as those that are easy to conduct and pollute, and are susceptible to electromagnetic interference.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the present invention aims to provide an optical fiber pressure sensor based on a soft silicon diaphragm and a detection method thereof, specifically, the preparation material of the thin film is silica gel. The soft silicon film in the sensor can be formed into a film by mixing, shaping and air-drying in equal proportions such as AB silica gel, and adhered to the optical path formed by the input fiber, such as the front end, inner side or lateral surface of the nozzle, but not limited to this, the film is mainly It is used to sense the effect of pressure and deformation, and constitute the sensing probe itself.

The pressure sensing principle adopts the FP interference principle, and the FP interference requires two parallel interfaces. In the present invention, the prepared soft silicon diaphragm is adhered to the mouth of the tube body through silica gel to form a simple FP cavity; then, an optical fiber is placed close to the film Used to detect film deformation. Using the principle of interference of light, because the reflectivity of light in different media is different, the light will be reflected when it passes through the air and the silicon diaphragm, and the two beams of light reflected back to the system will interfere. The reflected light interferes with the optical fiber return coupler and is analyzed by the system to obtain the optical path difference, and then the sensitivity of the sensor is determined according to the deformation value and the pressure value. Alternatively, the optical path difference can be obtained by interference analysis between the reflected light of the diaphragm and the reflected light of the reference optical path in the interference system.

In order to achieve the above object, the present invention adopts the following technical solutions:

An optical fiber pressure sensor based on a soft silicon diaphragm, with a direct measurement device or an interference system, the pressure sensor includes a tube body, a silicon diaphragm and an optical fiber, and the silicon diaphragm is pasted in the optical path formed by the input optical fiber , the optical fiber is placed in the tube and the outgoing light can be irradiated to the silicon film.

Preferably, the silicon diaphragm is pasted on the surface of the nozzle using silica gel for internal measurement.

Preferably, the outer diameter of the pressure sensor may be less than 2 mm.

The present invention also provides a method for detecting pressure by a silicon diaphragm-based optical fiber pressure sensor with input light, and the method includes the following steps:

S1 will also form a reflected light A when the light reaches the nozzle of the optical fiber;

The input light of S2 passes through the optical fiber and passes through the air to reach the surface of the soft silicon diaphragm, which will produce reflected light B;

S3 reflected light A and reflected light B interfere with the optical fiber return coupler and obtain the optical path difference through system analysis;

S4 further obtains the functional relationship between the pressure value in the measurable range and the deformation depth through calculation, so as to achieve the performance that can predict the pressure.

Further, the present invention provides a method for detecting pressure by a silicon diaphragm-based optical fiber pressure sensor with input light, and the method includes the following steps:

The input light of S1 passes through the optical fiber and passes through the air to reach the surface of the soft silicon diaphragm, which will produce reflected light B;

S2 can obtain the optical path difference by interference analysis between the reflected light B and the reflected light of the reference optical path in the interference system.

S3 obtains the functional relationship between the pressure value within the measurable range and the deformation depth through calculation, so as to achieve the performance of being able to predict the pressure.

The beneficial effects of the present invention are:

1. The ultra-thin soft silicon diaphragm is attached to the optical path formed by the input optical fiber. When the external pressure changes, the film will deform. It can be directly detected or based on the principle of coherent light interference to survey and measure the vibration and deformation of the diaphragm. The deformation value of the soft silicon film is determined and the corresponding pressure value and the measurable pressure range are set, and then the functional relationship between the pressure value within the measurable range and the deformation depth is obtained by calculation, so as to achieve the performance of predicting the pressure.

2. Under this technical solution, the size of the entire fiber optic probe can be adjusted according to the experimental requirements, which effectively improves the sensitivity of the probe without affecting the function.

3. When detecting and diagnosing special objects to be tested such as special conductive and easily polluted objects, the use of fiber optic probes has a higher safety factor than other metal conductive probes, effectively avoiding various safety hazards and improving detection efficiency and accuracy.

4. The production cost and time are greatly reduced.

5. The diaphragm has moderate hardness and can withstand a large pressure range.

Description of drawings

FIG. 1 is a schematic structural diagram of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the following examples are based on the technical solution, and provide detailed implementations and specific operation processes, but the protection scope of the present invention is not limited to the present invention. Example.

The present invention is an optical fiber pressure sensor based on a soft silicon diaphragm prepared from silica gel, with a coupler generating interference meridian system, the pressure sensor includes a tube body 1, a soft silicon diaphragm 2 and an optical fiber 3, the soft The silicon film 2 is pasted in the optical path formed by the input optical fiber 3 , and the optical fiber 3 is placed in the tube body and is close to the flexible silicon film 2 .

Preferably, the flexible silicon film is pasted in the optical path formed by the input optical fiber, such as a nozzle.

The present invention also provides a method for detecting pressure by an optical fiber pressure sensor based on a silicon diaphragm, which has input light. There are two measurement methods, which can be directly measured or interferometrically measured. The first method includes the following steps:

S1 will also form a reflected light A when the light reaches the nozzle of the optical fiber;

The input light of S2 passes through the optical fiber and passes through the air to reach the surface of the soft silicon diaphragm, which will produce reflected light B;

S3 reflected light A and reflected light B interfere with the optical fiber return coupler and obtain the optical path difference through system analysis;

S4 further obtains the functional relationship between the pressure value in the measurable range and the deformation depth through calculation, so as to achieve the performance that can predict the pressure.

The second involves the following steps:

The input light of S1 passes through the optical fiber and passes through the air to reach the surface of the soft silicon diaphragm, which will produce reflected light B;

S2 can obtain the optical path difference by interference analysis between the reflected light B and the reflected light of the reference optical path in the interference system.

S3 obtains the functional relationship between the pressure value within the measurable range and the deformation depth through calculation, so as to achieve the performance of being able to predict the pressure.

Example 1

The soft silicon diaphragm 2 made of silica gel such as AB silica gel is stuck in the optical path formed by the input optical fiber, such as the nozzle, and the optical fiber 3 is close to the soft silicon diaphragm 2 to detect its deformation. Further, the principle of the present invention is to use the principle of interference of light, because the reflectivity of light in different media is different, so the light will be reflected when it passes through the air and the soft silicon diaphragm, and the two beams of light reflected back to the system will occur. put one's oar in. Specifically, when the light reaches the nozzle of the optical fiber, a reflected light A will also be formed. When the light emitted by the laser passes through the optical fiber 3 and passes through the air to reach the surface of the flexible silicon diaphragm, a reflected light B will be generated. The fiber end face and An FP cavity is formed between the films. Finally, the reflected light A and the reflected light B interfere with the optical fiber return coupler, and the optical path difference is obtained by systematic analysis, and then the sensitivity of the sensor is determined according to the deformation amount and pressure value of the FP cavity cavity length. Alternatively, the optical path difference can be obtained by interference analysis between the reflected light B and the reflected light of the reference optical path in the interference system.

For those skilled in the art, various corresponding changes and deformations can be given according to the above technical solutions and concepts, and all these changes and deformations should be included within the protection scope of the claims of the present invention.

Claims (5)

1. The utility model provides an optic fibre pressure sensor based on soft silica diaphragm has direct measuring equipment or interference system, its characterized in that, pressure sensor includes body, silica diaphragm and optic fibre, the silica diaphragm paste in the light path that input optical fibre formed, optic fibre is arranged in the body and emergent light can shine the silicon film.

2. A flexible silicon diaphragm-based optical fiber pressure sensor as in claim 1, wherein said silicon diaphragm is adhered to the optical path formed by said input optical fiber by silica gel, such as the front end, inner side or lateral surface of the tube orifice.

3. The silicon diaphragm-based fiber optic pressure sensor of claim 1, wherein the pressure sensor can have an outer diameter of less than 2 mm.

4. A method of detecting pressure using a silicon diaphragm based fiber optic pressure sensor as claimed in claim 1 having an input light, the method comprising the steps of:

s1, when the light reaches the mouth of the optical fiber, a reflected light A is formed;

s2, the input light passes through the optical fiber and then passes through the air to reach the surface of the flexible silicon membrane to generate reflected light B;

s3, returning the reflected light A and the reflected light B to the coupler through the optical fiber to generate interference, and analyzing the interference by the system to obtain an optical path difference;

s4 further obtains the function relation between the pressure value in the measurable range and the deformation depth through calculation, and therefore the performance of predicting the pressure is achieved.

5. A method of detecting pressure using a silicon diaphragm based fiber optic pressure sensor as claimed in claim 1 having an input light, the method comprising the steps of:

s1, the input light passes through the optical fiber and then passes through the air to reach the surface of the flexible silicon membrane to generate reflected light B;

s2 may use the reflected light B to interfere with the reflected light of the reference optical path in the interference system to obtain the optical path difference.

S3, the pressure value is calculated to be in a function relation with the deformation depth in the measurable range, and therefore the performance of predicting the pressure is achieved.

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