CN111239063A - A capillary-based fiber optic water quality monitoring probe structure - Google Patents

Abstract

The invention provides an optical fiber water quality monitoring probe structure based on a capillary tube, which is characterized in that: the probe structure is formed by embedding a light emergent end I of an incident optical fiber and a light incident end II of an emergent optical fiber at two ends of a capillary tube with a slotted structure together, and is placed in an environment to be detected, wherein the light incident end I of the incident optical fiber is connected with a light source, and the light emergent end II of the emergent optical fiber is connected with a spectrometer; the light emergent end I of the incident optical fiber is provided with a hemispherical optical fiber micro lens; the lengths of the light emergent end I of the incident optical fiber and the light incident end II of the emergent optical fiber in the capillary are both smaller than the length of the part, which is not grooved, of the two ends of the grooved structure of the capillary. The invention can utilize the transmission spectrum method to monitor the change of water quality on line in real time, and solves the problems that the traditional water quality sensor has large volume and is not easy to monitor on line.

Description

A capillary-based fiber optic water quality monitoring probe structure

technical field

The invention relates to the technical field of optical water quality detection, in particular, to a capillary-based optical fiber water quality monitoring probe structure.

Background technique

Environmental monitoring of marine water quality is the lifeline that affects the development of marine agriculture, but with the development of social economy and the continuous increase of population, a large number of pollutants are discharged into the ocean. Marine pollutants have the characteristics of diversity (many types of physical and chemical quantities) and interference complexity (multi-factor coupling), and marine water quality monitoring requires long-term and large-scale real-time online monitoring, which has great impact on the price, volume, and power consumption of the detection system. Certain requirements make marine environmental monitoring particularly difficult and directly affect the coordinated development of the marine ecological environment and economy.

The marine water quality sensor is the key core device to realize marine monitoring. However, the existing marine water quality sensing system has limited detection parameters and is mainly based on the assembly of multiple types of different sensor units. , the weakness of large error and easy interference, it is difficult to be used in real-time online marine anomaly monitoring system.

In the prior art, there are many optical fiber detection equipment for water quality, but there are some deficiencies in terms of structure, service life, process conditions, etc., such as:

Application Publication No. CN104568946A discloses an optical fiber sensor for water pH measurement. The optical fiber sensor probe mainly includes an optical fiber probe, a coupler, a sensitive film, a reflector, a metal casing, and the like. Using dual optical path detection, the light from the sending fiber bundle is reflected by the mirror and then received by the receiving fiber bundle, and the purpose of detection is achieved by comparing the signal light changes. However, due to the fact that the mirror is installed, the structure is complicated, and the sensitive film needs to be prepared, the life of the sensor is affected by the life of the film.

Authorized Announcement No. CN105352554B discloses a fiber grating pH/temperature sensor, which includes a section of optical fiber, and long-period fiber gratings with two ends are arranged at intervals on the fiber core of the optical fiber. Coating smart hydrogel (pH and temperature sensitive type) on long period fiber grating realizes fiber grating pH and temperature sensing. However, hydrogels usually have shortcomings such as low strength and poor toughness, which need to be replaced regularly, making it difficult to achieve long-term online monitoring.

Authorized Announcement No. CN204988999U proposes a wide-spectrum optical fiber water quality detector, which uses an optical lens to convert the optical fiber outgoing beam into parallel light to pass through the liquid to be measured, and realizes water quality monitoring through changes in light intensity. However, there are many components of the sensor, including water pump, optical collimating mirror, etc., which lead to the complex structure and large volume of the sensor.

Authorization Bulletin No. CN203870017U discloses a water quality detection device for optical fiber sensing. The optical fiber is stripped and part of the coating layer is wrapped around the bracket to be taut and straightened, and the de-cladding section is in contact with the water environment. wave for water quality monitoring. The sensor fiber core is exposed to the water environment in a large area, and the lifespan is affected. The optical fiber is fragile and easy to break. During the preparation process, the optical fiber must be stretched and straightened, and the process requirements are very high.

In conclusion, it is necessary to propose a water quality monitoring device with strong practicability, simple structure and miniaturized volume to solve the deficiencies in the prior art.

SUMMARY OF THE INVENTION

According to the above technical problems, such as the existing water quality sensor is large in size, low in integration, and difficult to monitor online, a low-power, low-cost, and small-volume fiber optic water quality monitoring probe structure is provided. The invention mainly adopts the capillary tube to connect with the optical fiber. By changing the structure of the capillary tube, the external environment and the internal environment of the tube are communicated by means of slotting, and the miniaturization of the water quality multi-parameter monitoring probe is realized.

The technical means adopted in the present invention are as follows:

A capillary-based optical fiber water quality monitoring probe structure, characterized in that:

The probe structure is composed of the light exit end I of the incident fiber and the light entrance end II of the exit fiber, which are jointly nested at both ends of the capillary tube with the slotted structure, placed in the environment to be measured, and the light entrance end of the incident fiber is placed in the environment to be measured. I is connected to the light source, and the light exit end II of the exit fiber is connected to the spectrometer;

Wherein, the light outgoing end I of the incident fiber is provided with a hemispherical fiber microlens; the lengths of the light outgoing end I of the incident fiber and the light incident end II of the outgoing fiber in the capillary are both smaller than the opening of the capillary. The length of the unslotted portion at both ends of the slot structure.

Further, the slotted structure means that two slots for liquid circulation are provided on the tube wall of the capillary.

Further, the two slots are symmetrical and transparent from top to bottom, which facilitates material exchange with the external environment.

Further, the notch is a rectangular groove with a width of 300-500 μm and a length of 1000-5000 μm.

Further, the inner diameter of the capillary tube is equal to or slightly smaller than the outer diameter of the incident optical fiber and the outgoing optical fiber, so that the part of the optical fiber entering the capillary tube is closely attached to the inner wall of the capillary tube.

Further, the light source is an ultraviolet-visible light broadband light source.

Further, both ends of the capillary are also provided with sealing glue for encapsulation.

Compared with the prior art, the present invention has the following advantages:

1. The water quality monitoring probe structure designed by the present invention is prepared by taking advantage of the small volume of the capillary, and replaces the traditional water quality sensor detection pool by slotting the capillary wall. The slotted opening is used to circulate the water environment to be measured, which can greatly reduce The volume of the small sensing probe can be used in a narrow and difficult to measure environment, which greatly reduces the volume of the sensing probe;

2. The present invention utilizes optical fiber microlenses arranged on the light exit end face of the incident optical fiber to replace the use of complex optical devices in traditional water quality sensors, simplifies the structure of the sensor, greatly reduces the size of the water quality monitoring probe, and greatly reduces the cost;

3. The sensor in the present invention utilizes the light transmission performance of the optical fiber, and does not require processes such as cladding stripping, wire drawing, etc., which is easy to prepare and guarantees the life of the sensor.

The invention can use the transmission spectroscopy method to monitor the changes of water quality online in real time, generate different absorption spectra for different substances to be tested, identify and analyze the substances to be tested efficiently and accurately, and solve the problem of high cost and low integration of traditional water quality sensors. , The problem of simple assembly, large volume, and difficulty in online monitoring.

Based on the above reasons, the present invention has broad application prospect and value in the field of liquid detection such as water quality monitoring and oil quality detection.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic diagram of the structural application of the capillary-based optical fiber water quality monitoring probe provided by the present invention.

FIG. 2 is a schematic structural diagram of the capillary probe part in the capillary-based optical fiber water quality monitoring probe structure provided by the present invention.

FIG. 3 is a schematic diagram of the capillary-based optical fiber water quality monitoring probe structure in the monitoring of the sensing device provided by the present invention.

In the figure: 1, light source; 2, incident fiber; 3, capillary; 3-1, slotted structure; 4, exit fiber; 5, spectrometer.

Detailed ways

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is only a part of the embodiments of the present invention, but not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise. Meanwhile, it should be understood that, for convenience of description, the dimensions of various parts shown in the accompanying drawings are not drawn in an actual proportional relationship. Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the authorized specification. In all examples shown and discussed herein, any specific values should be construed as illustrative only and not limiting. Accordingly, other examples of exemplary embodiments may have different values. It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

In the description of the present invention, it should be understood that the orientations indicated by orientation words such as "front, rear, top, bottom, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" etc. Or the positional relationship is usually based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and these orientation words do not indicate or imply the indicated device or element unless otherwise stated. It must have a specific orientation or be constructed and operated in a specific orientation, so it should not be construed as a limitation on the scope of protection of the present invention: the orientation words "inside and outside" refer to the inside and outside relative to the contour of each component itself.

For ease of description, spatially relative terms, such as "on", "over", "on the surface", "above", etc., may be used herein to describe what is shown in the figures. The spatial positional relationship of one device or feature shown to other devices or features. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or features would then be oriented "below" or "over" the other devices or features under its device or structure". Thus, the exemplary term "above" can encompass both an orientation of "above" and "below." The device may also be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing corresponding components. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood to limit the scope of protection of the present invention.

As shown in FIG. 1 , the present invention provides a capillary-based fiber optic water quality monitoring probe structure, which can use transmission spectroscopy to monitor changes in water quality online in real time, and solve the problems that traditional water quality sensors are bulky and difficult to monitor online. Specifically, the probe structure is formed by the light exit end I of the incident optical fiber 2 and the light incident end II of the exit optical fiber 4 nested together at both ends of the capillary 3 having the slotted structure 3-1, that is, the incident optical fiber 2 It is connected with the outgoing fiber 4 through the capillary 3 and fixed and placed in the environment to be measured.

The light source 1 is an ultraviolet-visible light broadband light source, and the broadband light includes light of a wavelength sensitive to the substance to be tested, and various substances in the environment to be tested can be detected by the absorption spectrum of light of different wavelengths.

As shown in Figure 2, the light exit end I of the incident fiber 2 is provided with a hemispherical fiber microlens, the radius of which is the same as the core radius of the incident fiber 2, which is used to converge the light emitted by the incident fiber 2 and convert the light into The parallel light is formed into thin parallel light and emitted to the area of the detected material, and then the detected light is received by the receiving fiber through the detected area.

The lengths of the light outgoing end I of the incident optical fiber 2 and the light incident end II of the outgoing optical fiber 4 in the capillary 3 are both smaller than the lengths of the unslotted parts at both ends of the slotted structure 3-1 of the capillary 3, ensuring that The length of the detection cell is as long as possible, the optical fiber will not be directly exposed in the environment to be measured, and the two ends of the capillary 3 are provided with sealing glue to encapsulate the sensing probe. (It should be noted that the glue is not drawn in the picture)

The slotted structure 3-1 means that two notches for liquid circulation are provided on the tube wall of the capillary 3, and the two notches are symmetrical and transparent from top to bottom to facilitate material exchange with the external environment.

The notch is a rectangular groove with a width of 300-500 μm and a length of 1000-5000 μm.

The inner diameter of the capillary 3 is equal to or slightly smaller than the outer diameter of the incident optical fiber 2 and the outgoing optical fiber 4 , so that the part of the optical fiber entering the capillary 3 is closely attached to the inner wall of the capillary 3 .

When the probe of the present invention works in the sensor device, the light source 1 generates signal light, which is transmitted into the capillary 3 through the incident optical fiber 2, and the light collected by the optical fiber microlens passes through the detection cell formed by the capillary slotted structure 3-1 and the external environment. It is received by the light receiving end of the outgoing fiber 4 and transmitted to the spectrometer 5. The spectrometer 5 completes the photoelectric conversion and demodulation of the detection light, and obtains the change of the intensity before and after the light passes through the substance to be tested, thereby inferring the composition and concentration of the substance to be tested.

The detection principle is shown in Figure 3. When the incident light passes through the substance to be tested, the substance to be tested will absorb light of a specific wavelength, and the intensity of the outgoing light will change. Therefore, the type and concentration of the substance to be tested can be quantified by detecting the attenuation intensity of the light intensity. analyze.

The detection of the device The principle formula of Lambert-Beer law:

I _out =I _in exp(-αcL)

in:

I _out is the received light intensity of the outgoing fiber;

I _in is the outgoing light intensity of the incident fiber;

α is the molar absorption coefficient, which is related to the properties of the absorbing material and the wavelength λ of the incident light;

c is the concentration of the light-absorbing substance, in mol/L;

L is the thickness of the absorption layer, in cm.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (7)

1. a capillary-based fiber optic water quality monitoring probe structure is characterized in that: The probe structure is formed by the light outgoing end I of the incident optical fiber (2) and the light incident end II of the outgoing optical fiber (4) being nested together at both ends of the capillary tube (3) having the slotted structure (3-1), In the environment to be measured, the light incident end I of the incident optical fiber (2) is connected to the light source (1), and the light exit end II of the outgoing optical fiber (4) is connected to the spectrometer (5); Wherein, the light outgoing end I of the incident optical fiber (2) is provided with a hemispherical fiber microlens; the light outgoing end I of the incident optical fiber (2) and the light incident end II of the outgoing optical fiber (4) are in the capillary (2). The lengths in 3) are all smaller than the lengths of the unslotted parts at both ends of the slotted structure (3-1) of the capillary (3). 2. The capillary-based optical fiber water quality monitoring probe structure according to claim 1, wherein the slotted structure (3-1) means that two places are opened on the pipe wall of the capillary (3) for Notches for liquid flow. 3 . The capillary-based fiber optic water quality monitoring probe structure according to claim 2 , wherein the two notches are symmetrical and transparent up and down. 4 . 4. The capillary-based fiber optic water quality monitoring probe structure according to claim 2 or 3, wherein the notch is a rectangular groove with a width of 300-500 μm and a length of 1000-5000 μm. 5. The capillary-based optical fiber water quality monitoring probe structure according to claim 1, wherein the inner diameter of the capillary (3) is equal to or slightly smaller than the diameter of the incident optical fiber (2) and the outgoing optical fiber (4). the outer diameter, so that the part of the optical fiber entering the capillary (3) closely fits on the inner wall of the capillary (3). 6. The capillary-based fiber optic water quality monitoring probe structure according to claim 1, wherein the light source (1) is an ultraviolet-visible light broadband light source. 7. The capillary-based optical fiber water quality monitoring probe structure according to claim 1 or 5, characterized in that, both ends of the capillary (3) are further provided with sealing glue for encapsulation.

Images