CN114046856A

CN114046856A - Optical fiber liquid level detection device and measurement method thereof

Info

Publication number: CN114046856A
Application number: CN202111302833.XA
Authority: CN
Inventors: 孙小燕; 张立木; 张伟
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2022-02-15

Abstract

The invention discloses an optical fiber liquid level detection device and a measurement method thereof. The method comprises an optical fiber, an optical power meter, a signal light source, an optical fiber coupler and a motion control system. The motion control system includes: a motion platform, a fixture for fixing the optical fiber, a computer and a motion control program; the measurement method is to use the reflected power of the fiber cutting end face to have different magnitudes in different media, and the reflected power in different media cross-sections suddenly changes significantly. The power sudden change point can accurately measure the liquid level position. The measuring device has the advantages of simple structure, anti-interference and high measuring accuracy.

Description

Optical fiber liquid level detection device and measurement method thereof

Technical Field

The invention relates to the technical field of liquid level detection, in particular to an optical fiber liquid level detection device and method.

Background

The liquid level detection relates to the industrial production fields of petroleum engineering, mechanical manufacturing and the like, and has important practical application significance for timely and accurate detection of the liquid level. The commonly used liquid level detection methods comprise differential pressure type liquid level detection, magnetostrictive liquid level detection, capacitance type liquid level detection, ultrasonic liquid level detection, optical fiber liquid level detection and the like, the differential pressure measurement error is large, the magnetostrictive structure is complex, the requirement on the use environment is high, the capacitance type liquid level detection method is easy to short circuit and poor in corrosion resistance.

The optical fiber type liquid level detection sensor based on the structures of the FBG, the FPI and the like has the advantages of compact structure, strong anti-electromagnetic interference and corrosion capability, strong multiplexing capability, distributable measurement, easiness in constructing a sensing network and the like of the optical fiber type liquid level detection sensor, but the process is complex, the manufacturing cost is high, and the stability of the system is reduced by the additional components.

Disclosure of Invention

Technical problem to be solved

Based on the problems, the invention provides a liquid level detection device and method based on optical fiber end surface reflection, which can detect the liquid level position timely and accurately.

(II) technical scheme

Based on the technical problem, the invention provides an optical fiber liquid level detection device and method, which comprise an optical fiber, an optical power meter, a signal light source, an optical fiber coupler and a motion control system. The motion control system includes: the device comprises a motion platform, a clamp for fixing the optical fiber, a computer and a motion control program;

furthermore, the end face of the optical fiber is parallel to the liquid level to be measured.

Furthermore, the motion platform consists of a lifting platform and a translation platform, and the displacement direction of the lifting platform is parallel to the axis of the optical fiber.

Preferably, the optical fiber may be a single mode fiber, a multimode fiber, or the like.

Preferably, the optical fiber material may be quartz, plastic, etc.

The invention discloses an optical fiber liquid level measuring method, which comprises the following steps:

s1, connecting any end of the optical fiber with a signal light source and an optical fiber power meter through an optical fiber coupler respectively, flattening the other end by using an optical fiber cutter, and recording the reflected power when the optical fiber is not in contact with the liquid surface;

s2, fixing the optical fiber clamp on the lifting motion platform, fixing the optical fiber on the optical fiber clamp, and adjusting the cutting end face of the optical fiber clamp to be parallel to the liquid level to be measured;

s3, connecting the motion platform and the optical power meter with a computer, and recording the reflected light power at different positions in real time through a motion control program;

s4, when the end face of the optical fiber contacts the liquid level, the optical power suddenly drops, and micron-level measurement of the liquid level can be realized through the change of the power.

(III) advantageous effects

The technical scheme of the invention has the following advantages:

(1) the invention realizes the micron-level detection of the liquid level through the reflected light power change of the end surface of the optical fiber;

(2) the measuring device has the advantages of simple structure, interference resistance, high measuring precision and the like.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

FIG. 1 is a schematic view of an optical fiber liquid level measuring device in an embodiment of the present invention;

FIG. 2 is a schematic view of an optical fiber liquid level measuring device used in an embodiment of the present invention;

in the figure: 1: the motion platform 2: an optical fiber clamp; 3: a signal light source; 4: an optical power meter; 5: liquid to be measured; 6: a computer; 7: a fiber coupler; 8: an optical fiber.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The optical fiber liquid level detection device comprises an optical fiber, an optical power meter, a signal light source, an optical fiber coupler and a motion control system. As shown in fig. 1, the motion control system includes: 1, a motion platform, 2, an optical fiber clamp, 6, a computer and a motion control program; the liquid 5 to be detected can be water, alcohol and silicone oil; the central wavelength of the signal light source 3 is 1550 nm; the optical fiber coupler 7 is a 3dB coupler; the optical fiber 8 is a single-mode silica fiber.

The method for measuring the upper and lower limits of the liquid level comprises the following steps:

s1, connecting any end of the optical fiber 8 with a signal light source 3 and an optical fiber power meter 4 through a 3dB coupler respectively, cutting the other end flat by using an optical fiber cutter, and recording the reflected power when the optical fiber is not in contact with the liquid surface;

s2, fixing the optical fiber clamp 2 on the lifting motion platform 1, fixing the optical fiber 8 on the optical fiber clamp, and adjusting the cutting end face of the optical fiber clamp to be parallel to the liquid level 5 to be measured;

s3, connecting the motion platform 1 and the optical power meter 4 with the computer 6, and recording the optical power at different positions in real time through the motion control program 6;

s4, when the end face of the optical fiber 8 contacts the water, alcohol and silicon oil liquid surface, the corresponding optical power is respectively reduced by 11.5dBm, 11.8dBm and 12.9dBm, the corresponding displacement changes are respectively 50 μm, 10 μm and 10 μm, and as shown in figure 2, the micron-level measurement of the liquid level can be realized through the change of the power.

In summary, the optical fiber liquid level detection device and the measurement method thereof have the following advantages:

(1) according to the invention, the micron-level detection of the liquid level is realized through the change of the reflected power of the end face of the optical fiber;

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An optical fiber liquid level detection device, characterized in that the device comprises an optical fiber, an optical power meter, a signal light source, an optical fiber coupler, and a motion control system. The motion control system includes: a motion platform, a fixture for fixing the optical fiber, a computer and a motion control program.

2. An optical fiber liquid level detection device according to claim 1, wherein the sensing head is an optical fiber; the optical fiber can be a single-mode optical fiber, a multi-mode optical fiber, etc.; the optical fiber material can be quartz, plastic and other materials.

3 . The optical fiber liquid level detection device according to claim 1 , wherein the end face of the optical fiber is parallel to the liquid level to be measured. 4 .

4 . The optical fiber liquid level detection device according to claim 1 , wherein the motion control system consists of a motion platform, a computer and a motion control program, and the displacement direction of the motion platform is parallel to the optical fiber axis. 5 .

5. A measuring method of an optical fiber liquid level detection device according to any one of claims 1-4, characterized in that, comprising the following steps:

S1, any end of the optical fiber is respectively connected with the signal light source and the optical fiber power meter through the optical fiber coupler, and the other end is cut flat with an optical fiber cutter, and the reflected power when not contacting the liquid surface is recorded;

S2, the optical fiber fixture is fixed on the lifting motion platform, and the optical fiber is fixed on the optical fiber fixture, and the cutting end face thereof is adjusted to be parallel to the liquid surface to be measured;

S3, the motion platform is connected with the optical power meter and the computer, and the reflected optical power at different positions is recorded in real time through the motion control program;

S4. When the end face of the optical fiber touches the liquid level, the optical power will drop suddenly. Through the change of power, the liquid level micron level detection can be realized.