CN109060041B

CN109060041B - Optical fiber temperature and humidity sensor

Info

Publication number: CN109060041B
Application number: CN201811066489.7A
Authority: CN
Inventors: 温晓东; 李永超; 付伯艳; 宋秋艳
Original assignee: Qufu Normal University
Current assignee: Qufu Normal University
Priority date: 2018-09-10
Filing date: 2018-09-10
Publication date: 2020-07-10
Anticipated expiration: 2038-09-10
Also published as: CN109060041A

Abstract

The invention discloses an optical fiber temperature and humidity sensor, comprising: the device comprises a light source, a coupler, a tube, a liquid column, an optical detector and cloth, wherein a first port of the coupler is connected with the light source through a first tail fiber, a second port of the coupler is connected with the optical detector through a second tail fiber, a third port of the coupler is connected into one end of the tube through a third tail fiber and is sealed, and a fourth port of the coupler is connected into the other end of the tube through a fourth tail fiber and is sealed; in the tube, a liquid column is positioned in the middle of the tube, a space between the liquid column and the tail fiber III is filled with a gas I, and a space between the liquid column and the tail fiber IV is filled with a gas II; the cloth is wrapped at one end of the pipe close to the first gas; the distance between the end face of the liquid column close to the gas one side and the end part of the tail fiber three is h1, the distance between the end face of the liquid column close to the gas two side and the end part of the tail fiber four is h2, and h1 and h2 are positive numbers. The invention has the beneficial effects that: the method reduces the measurement error, improves the sensitivity, and is easy to quantize the output data and continuously measure and record the data for a long time.

Description

Optical fiber temperature and humidity sensor

Technical Field

The invention relates to the technical field of machinery industry and instrument manufacturing, in particular to an optical fiber temperature and humidity sensor based on an interference principle.

Background

The thermometer and the hygrometer are sensing instruments for measuring the ambient temperature and the air humidity, and are mainly applied to the occasions of indoor and outdoor environment monitoring, weather forecasting and the like.

At present, the existing thermometers and hygrometers are difficult to meet the requirements of production and development, and particularly, the common liquid column type temperature and humidity sensor based on scale line reading and electronic type temperature and humidity sensor based on electric sensitivity cannot meet the precision requirement, and mainly shows that the adjusting capacity is weak and the processing sensitivity of data is not high. Therefore, the research on the novel temperature and humidity sensor with higher resolution and better performance has important practical significance. With the development of the optical field, laser levels have also emerged. The laser level meter has the advantages of accurate and rapid measurement, is widely applied to large buildings and decoration projects, but has strict requirements on light sources and structural errors, and has a complex structure and high price.

Disclosure of Invention

In order to solve the above problems, an object of the present invention is to provide an optical fiber temperature and humidity sensor with more accurate measurement and higher sensitivity.

The invention provides an optical fiber temperature and humidity sensor, comprising: a light source, a coupler, a tube, a liquid column, a light detector and cloth;

a first port of the coupler is connected with the light source through a first tail fiber, a second port of the coupler is connected with the optical detector through a second tail fiber, a third port of the coupler is connected and sealed through one end of a third tail fiber access tube, and a fourth port of the coupler is connected and sealed through the other end of a fourth tail fiber access tube; in the tube, a liquid column is positioned in the middle of the tube, a space between the liquid column and the tail fiber III is filled with a gas I, and a space between the liquid column and the tail fiber IV is filled with a gas II; the cloth is wrapped at one end of the pipe close to the first gas;

the distance between the end face of the liquid column close to the gas I side and the end part of the tail fiber III is h1, the distance between the end face of the liquid column close to the gas II side and the end part of the tail fiber IV is h2, and h1 and h2 are positive numbers.

As a further improvement of the invention, the end part coating film of the third tail fiber changes the reflectivity of the three end parts of the tail fiber, and the reflectivity value range is 1-60%; the end part of the tail fiber four is coated with a film to change the reflectivity of the four end parts of the tail fiber, and the reflectivity value range is 1-60%.

As a further improvement of the invention, the axial shape of the tube is one of a straight line shape, a U-shape, a V-shape and an arc shape.

As a further development of the invention, the cross-sectional dimension inside the tube is less than 1 mm.

As a further improvement of the invention, the third tail fiber and the fourth tail fiber are respectively inserted into the central axis of the tube.

As a further improvement of the invention, the liquid column is mercury, and the axial length of the liquid column is greater than the radial diameter.

As a further improvement of the invention, the first gas and the second gas are gases which are insoluble in the liquid column, and the first gas and the second gas are the same gas or different gases.

The invention has the beneficial effects that:

the response time is short, the cost is low, the measurement precision is high, the output data is easy to quantify, and the data is continuously measured and recorded for a long time.

Drawings

FIG. 1 is a schematic view of an optical fiber temperature and humidity sensor according to a first embodiment of the present invention;

FIG. 2 is a second embodiment of an optical fiber temperature and humidity sensor according to the present invention;

FIG. 3 is a third embodiment of an optical fiber temperature and humidity sensor according to the present invention;

fig. 4 is a fourth embodiment of the optical fiber temperature and humidity sensor according to the present invention.

In the figure, the position of the upper end of the main shaft,

1. a light source; 2. a coupler; 3. a tube; 4. a liquid column; 5. a light detector; 6. distributing; 71. a first gas; 72. a second gas; 21. first tail fiber; 22. a second tail fiber; 23. a third tail fiber; 24. and fourthly, tail fiber.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments and with reference to the attached drawings.

Embodiment 1, as shown in fig. 1, an optical fiber temperature and humidity sensor according to a first embodiment of the present invention includes: light source 1, coupler 2, tube 3, liquid column 4, light detector 5 and cloth 6.

A first port of the coupler 2 is connected with the light source 1 through a first pigtail 21, a second port of the coupler 2 is connected with the optical detector 5 through a second pigtail 22, a third port of the coupler 2 is connected into one end of the tube 3 through a third pigtail 23 and is sealed, and a fourth port of the coupler 2 is connected into the other end of the tube 3 through a fourth pigtail 24 and is sealed; in the tube 3, the liquid column 4 is positioned in the middle of the tube 3, the space between the liquid column 4 and the tail fiber III 23 is filled with gas I71, and the space between the liquid column 4 and the tail fiber IV 24 is filled with gas II 72; cloth 6 is wrapped around the end of tube 3 near gas one 71.

The distance between the end face of the liquid column 4 close to the first gas 71 and the end part of the third tail fiber 23 is h1, the distance between the end face of the liquid column 4 close to the second gas 72 and the end part of the fourth tail fiber 24 is h2, and h1 and h2 are positive numbers.

The end part of the tail fiber III 23 is coated with a film to change the reflectivity of the end part of the tail fiber III 23, and the reflectivity value range is 1-60%; the end part of the tail fiber four 24 is coated with a film to change the reflectivity of the end part of the tail fiber four 24, and the reflectivity value range is 1-60%.

The axial line shape of the tube 3 is straight line shape, the cross section size inside the tube 3 is smaller than 1mm, and the tail fiber three 23 and the tail fiber four 24 are respectively inserted into the central axis of the tube 3.

In the present embodiment, the liquid column 4 is made of mercury, but is not limited thereto, and any liquid that can reflect part of light and has expansion/contraction characteristics may be used, and the axial length of the liquid column 4 is greater than the radial diameter.

The first gas 71 and the second gas 72 are gases insoluble in the liquid column 4, and the first gas 71 and the second gas 72 are the same gases.

An optical signal generated by the light source 1 is transmitted to the coupler 2 through the first tail fiber 21 and is divided into two beams, one beam is transmitted into the tube 3 through the third tail fiber 23, light reflection occurs at the end part of the third tail fiber 23 and the end surface of the liquid column 4 close to the cloth 6, and the reflected light returns to the coupler 2 through the third tail fiber 23 again; the other bundle is transmitted into the tube 3 through the four pigtails 24, light is reflected at the end of the four pigtails 24 and the end face of the liquid column 4 far from the cloth 6, and the reflected light returns to the coupler 2 through the four pigtails 24 again. The optical signal is finally transmitted to the optical detector 5 through the second pigtail 22. The length change conditions of h1 and h2 are obtained through calculation of the received optical signals, the axial length of the liquid column 4 is calculated, and an environmental temperature value is determined.

When the sensor is in a working state, a certain amount of water is dipped in the cloth 6, the temperature near the cloth is reduced due to the heat absorption of the water by evaporation in flowing air, and the temperature reduction amplitude is related to the air humidity; the liquid column 4 can axially expand and contract due to the expansion and contraction characteristics of the liquid, and the length of the liquid column 4 reflects the environmental temperature value.

The temperature of the second gas 72 reflects the temperature of the environment, and the temperature of the first gas 71 is lower than that of the second gas 72. When the pipe 3 is horizontally placed, the air pressure of the first gas 71 and the air pressure of the second gas 72 are the same, the temperature difference between the first gas 71 and the second gas 72 is determined according to the lengths of h1 and h2, and the humidity value of the air is obtained through calculation; when the pipe 3 is not horizontally arranged, the air pressures of the first gas 71 and the second gas 72 are different, the air pressure difference value is determined by the vertical height difference of the two liquid levels of the liquid column 4, the temperature difference of the first gas 71 and the second gas 72 is determined by combining the lengths of h1 and h2, and the humidity value of the air is obtained through calculation.

Embodiment 2, as shown in fig. 2, the optical fiber temperature and humidity sensor according to the second embodiment of the present invention is different from embodiment 1 in that the axial shape of the tube 3 in this embodiment is U-shaped.

The first gas 71 and the second gas 72 are different gases, the temperature of the second gas 72 reflects the temperature value of the environment, and the temperature of the first gas 71 is lower than that of the second gas 72. The air pressure difference value of the first gas 71 and the second gas 72 is determined by the vertical height difference of two liquid levels of the liquid column 4, the temperature difference of the first gas 71 and the second gas 72 is determined by combining the lengths of h1 and h2, and the humidity value of the air is obtained by calculation.

Embodiment 3, as shown in fig. 3, the optical fiber temperature and humidity sensor according to the third embodiment of the present invention is different from embodiment 2 in that the axial shape of the tube 3 in this embodiment is V-shaped.

Embodiment 4, as shown in fig. 4, the optical fiber temperature and humidity sensor according to the fourth embodiment of the present invention is different from embodiment 2 in that the axial line of the tube 3 in this embodiment has an arc shape.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical fiber temperature and humidity sensor, comprising: the device comprises a light source (1), a coupler (2), a tube (3), a liquid column (4), a light detector (5) and cloth (6);

a first port of the coupler (2) is connected with the light source (1) through a first pigtail (21), a second port of the coupler (2) is connected with the optical detector (5) through a second pigtail (22), a third port of the coupler (2) is connected into one end of the tube (3) through a third pigtail (23) and sealed, and a fourth port of the coupler (2) is connected into the other end of the tube (3) through a fourth pigtail (24) and sealed; in the pipe (3), the liquid column (4) is positioned in the middle of the pipe (3), a first gas (71) is filled between the liquid column (4) and the tail fiber III (23), and a second gas (72) is filled between the liquid column (4) and the tail fiber IV (24); the cloth (6) is wrapped at one end of the pipe (3) close to the gas I (71);

the distance between the end face of one side, close to the first gas (71), of the liquid column (4) and the end part of the third tail fiber (23) is h1, the distance between the end face of one side, close to the second gas (72), of the liquid column (4) and the end part of the fourth tail fiber (24) is h2, and h1 and h2 are positive numbers.

2. The optical fiber temperature and humidity sensor according to claim 1, wherein the end part of the third pigtail (23) is coated with a film to change the reflectivity of the end part of the third pigtail (23), and the reflectivity ranges from 1% to 60%; the end part of the tail fiber four (24) is coated with a film to change the reflectivity of the end part of the tail fiber four (24), and the reflectivity value range is 1-60%.

3. The optical fiber temperature and humidity sensor according to claim 1, wherein the axial shape of the tube (3) is one of a straight line shape, a U-shape, a V-shape, and an arc shape.

4. Optical fiber temperature and humidity sensor according to claim 3, characterized in that the cross-sectional dimension inside the tube (3) is less than 1 mm.

5. The optical fiber temperature and humidity sensor according to claim 1, wherein the pigtail three (23) and pigtail four (24) are inserted into the central axis of the tube (3), respectively.

6. The optical fiber temperature and humidity sensor according to claim 1, wherein the liquid column (4) is mercury, and the axial length of the liquid column (4) is greater than the radial diameter.

7. The optical fiber temperature and humidity sensor according to claim 1, wherein the first gas (71) and the second gas (72) are gases that are insoluble in the liquid column (4), and the first gas (71) and the second gas (72) are the same kind of gas or different kinds of gases.