A device and method for measuring sand velocity and particle size based on a multi-core optical fiber

Abstract

The application provides a sand particle velocity and particle size measuring device and method based on a multi-core optical fiber, and belongs to the technical field of laser detection. The device comprises, in sequence along the light path propagation direction, a light source, an optical splitter, a first multi-core optical fiber fan-in fan-out module, a probe, a second multi-core optical fiber fan-in fan-out module, a bifurcated optical fiber bundle and a photoelectric detector, and optical fibers are used to connect adjacent components; the light emitted by the light source is split into n paths of incident light by the optical splitter, then enters the first multi-core optical fiber fan-in fan-out module and then enters the first multi-core optical fiber, the n beams of light emitted by the first multi-core optical fiber are received by the second multi-core optical fiber, coupled by the second multi-core optical fiber fan-in fan-out module and then enter each branch end of the bifurcated optical fiber bundle, and the common end of the bifurcated optical fiber bundle outputs an optical signal to the photoelectric detector to be converted into an electrical signal; during the process of the sand particles passing through the groove, the beams of the first multi-core optical fiber are sequentially blocked, and the electrical signal of the photoelectric detector can be used to calculate the sand particle velocity and particle size of the sand particles.

Description

Technical Field

[0001] This invention relates to the field of laser detection technology, and in particular to a device and method for measuring the velocity and size of sand particles based on multi-core optical fibers. Background Technology

[0002] Currently, traditional techniques for directly observing sand particle velocity and size mainly include: particle dynamic analysis and laser Doppler velocimetry based on the optical Doppler effect, as well as high-speed photography, particle image velocimetry, and particle tracking velocimetry based on image processing. The most significant problem is that these devices are bulky, often containing sophisticated optical and mechanical components, and have poor anti-interference capabilities. They can only be applied in spacious indoor measurement environments. In certain special working conditions, such as harsh outdoor environments or confined spaces like pipelines, these techniques and equipment cannot be deployed or function properly. Summary of the Invention

[0003] In view of this, the present invention provides a sand particle velocity and particle size measuring device based on multi-core optical fiber, which has the advantages of simple structure and small size, and can be flexibly arranged in a small space.

[0004] The technical solution adopted by the embodiments of the present invention to solve its technical problem is as follows:

[0005] A device for measuring the velocity and size of sand grains based on multi-core optical fiber includes: a light source (1), an optical splitter (2), a first multi-core optical fiber fan-in and fan-out module (3), a probe (4), a second multi-core optical fiber fan-in and fan-out module (5), a branched optical fiber bundle (6), and a photodetector (7) arranged sequentially according to the optical path propagation direction. Adjacent components are connected by optical fiber.

[0006] The probe housing of the probe (4) has a sand passage groove structure. The two side walls of the sand passage groove structure are made of light-transmitting material. Inside the probe housing, a multi-core fiber optic transmitter (4-1), a microlens array (4-2), the two side walls of the sand passage groove, and a multi-core fiber optic receiver (4-3) for fixing the second multi-core fiber optic port are arranged according to the optical path propagation direction. The multi-core fiber optic transmitter (4-1) is connected to the first multi-core fiber fan-in and fan-out module (3) by the first multi-core fiber. The cores of the first multi-core fiber are arranged in a straight line at equal intervals along the direction of movement of the sand through the sand passage groove and are aligned with the cores of the second multi-core fiber. The multi-core fiber optic receiver (4-3) is connected to the second multi-core fiber fan-in and fan-out module (5) by the second multi-core fiber.

[0007] The probe light emitted by the light source (1) is split into n incident beams by the optical splitter (2) and enters the n input ports of the first multi-core fiber fan-in / fan-out module (3). It then enters the first multi-core fiber through the output port of the first multi-core fiber fan-in / fan-out module (3) and is collimated by the microlens array (4-2). The n beams emitted from the first multi-core fiber are received by the second multi-core fiber and output to the second multi-core fiber fan-in / fan-out module (5) for coupling. The second multi-core fiber fan-in / fan-out module (5) outputs n... The single-mode outgoing light enters each branch of the branched fiber bundle (6) for optical multiplexing. The common end of the branched fiber bundle (6) outputs an optical signal to the photodetector (7). The photodetector (7) converts the detected optical signal into an electrical signal. As the sand grain passes through the sand grain passage groove, the light beam emitted by the first multi-core fiber is blocked in sequence. The electrical signal output by the photodetector (7) changes. The electrical signal output by the photodetector (7) is used to calculate the sand grain velocity and particle size.

[0008] Preferably, it also includes a microprocessor (8), which is electrically connected to the photodetector (7) and is used to receive the electrical signal and calculate the sand particle velocity and particle size based on the electrical signal.

[0009] Preferably, the core spacing of both the first multi-core optical fiber and the second multi-core optical fiber is d.

[0010] Preferably, the light source (1), the optical splitter (2), the first multi-core fiber fan-in fan-out module (3), the second multi-core fiber fan-in fan-out module (5), the branched fiber bundle (6), the photodetector (7), and the microprocessor (8) are all integrated in the housing (9), and the housing (9) is fixedly connected to the probe housing.

[0011] Preferably, the electrical signal output by the photodetector (7) is a time-domain signal f(t), and the average velocity V of the sand grain passing through the sand grain passage groove is:

[0012]

[0013] Where f is the frequency of f(t).

[0014] Preferably, the relationship between the radius r of the sand grain and the fiber core spacing d and the signal coefficient K is expressed by the following two formulas:

[0015]

[0016]

[0017] Among them, h maxh min These represent the peak and trough values ​​of the signal with the largest amplitude in the entire segment of the f(t) signal during the process of a single particle passing through the sand grain through the trough, respectively, where J1 is a first-order Bessel function of the first kind, n is an integer, and l n =2n-1, where M is the number of fiber cores.

[0018] Preferably, it also includes a display screen electrically connected to the microprocessor (8), the display screen being used to display the V and the r.

[0019] Furthermore, the present invention provides a method for measuring sand particle velocity and particle size based on multi-core optical fiber, wherein the main implementer is the aforementioned sand particle velocity and particle size measuring device based on multi-core optical fiber, and the steps include:

[0020] In step S1, as the sand grains pass through the sand grain passage trough, the sand grains sequentially block the speed of light, and the photodetector (7) continuously sends an electrical signal to the microprocessor (8), the electrical signal being a time-domain signal f(t).

[0021] Step S2, the microprocessor calculates the sand particle velocity V and particle size r using the electrical signal:

[0022] V = df

[0023] Where f is the frequency of f(t);

[0024] The relationship between the radius r of the sand grain, the fiber core spacing d, and the signal coefficient K is expressed by the following two formulas:

[0025]

[0026]

[0027] Among them, h max h min These represent the peak and trough values ​​of the signal with the largest amplitude in the entire segment of the f(t) signal during the process of a single particle passing through the sand grain through the trough, respectively, where J1 is a first-order Bessel function of the first kind, n is an integer, and l n =2n-1, where M is the number of fiber cores.

[0028] As can be seen from the above technical solution, the present invention provides a sand particle velocity and particle size measurement device based on multi-core optical fiber. The device includes a light source, an optical splitter, a first multi-core optical fiber fan-in / fan-out module, a probe, a second multi-core optical fiber fan-in / fan-out module, a branched fiber bundle, and a photodetector arranged sequentially in the optical path propagation direction. Adjacent components are connected by optical fibers. The light emitted by the light source is split into n incident beams by the optical splitter and then enters the first multi-core optical fiber after entering the first multi-core optical fiber fan-in / fan-out module. The n beams of light emitted from the first multi-core optical fiber are received by the second multi-core optical fiber, coupled by the second multi-core optical fiber fan-in / fan-out module, and then enter the branches of the branched fiber bundle. The common end of the branched fiber bundle outputs an optical signal to the photodetector, which converts it into an electrical signal. During the process of sand particles passing through the sand particle passage groove, the beam of light from the first multi-core optical fiber is blocked sequentially. The electrical signal from the photodetector can be used to calculate the sand particle velocity and particle size. The sand particle velocity and particle size measurement device based on multi-core optical fiber of the present invention has the advantages of simple structure and small size, can be flexibly arranged in a small space, has the ability to resist electromagnetic interference, is corrosion resistant, and has a wider range of applicable particle sizes. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the sand particle velocity and particle size measurement device based on multi-core optical fiber according to the present invention.

[0030] Figure 2 This is an end-face view of the multi-core fiber transmitter and receiver.

[0031] Figure 3 This is a schematic diagram of a typical signal output by the device.

[0032] In the diagram: 1 is the light source, 2 is the optical splitter, 3 is the multi-core fiber fan-in / fan-out module, 4 is the probe, 4-1 is the multi-core fiber transmitter, 4-2 is the microlens array, 4-3 is the multi-core fiber receiver, 4-4 is the probe cavity, 5 is the multi-core fiber fan-in / fan-out module, 6 is the branched fiber bundle, 7 is the photodetector, 8 is the microprocessor, and 9 is the outer casing. Detailed Implementation

[0033] The technical solution and effects of the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 As shown, the present invention provides a sand particle velocity and particle size measurement device based on multi-core optical fiber. The device consists of a light source 1, an optical splitter 2, a first multi-core optical fiber fan-in and fan-out module 3, a probe 4, a second multi-core optical fiber fan-in and fan-out module 5, a branched optical fiber bundle 6, and a photodetector 7 arranged sequentially according to the optical path propagation direction. Adjacent components are connected by optical fiber.

[0035] The probe housing of probe 4 has a sand passage groove structure. The two side walls of the sand passage groove structure are made of light-transmitting material. Inside the probe housing, a multi-core fiber optic transmitter 4-1 for fixing the first multi-core fiber optic port, a microlens array 4-2, the two side walls of the sand passage groove, and a multi-core fiber optic receiver 4-3 for fixing the second multi-core fiber optic port are arranged according to the direction of light propagation. The multi-core fiber optic transmitter 4-1 is connected to the first multi-core fiber optic fan-in and fan-out module 3 by the first multi-core fiber optic. The cores of the first multi-core fiber optic are arranged in a straight line at equal intervals along the direction of movement of the sand through the sand passage groove and are aligned with the cores of the second multi-core fiber optic. The multi-core fiber optic receiver 4-3 is connected to the second multi-core fiber optic fan-in and fan-out module 5 by the second multi-core fiber optic.

[0036] The detection light emitted by light source 1 is split into n incident beams by optical splitter 2 and enters the n input ports of the first multi-core fiber fan-in / fan-out module 3. After passing through the output port of the first multi-core fiber fan-in / fan-out module 3, it enters the first multi-core fiber and is collimated by microlens array 4-2. The n beams emitted by the first multi-core fiber are received by the second multi-core fiber and output to the second multi-core fiber fan-in / fan-out module 5 for coupling. The second multi-core fiber fan-in / fan-out module 5 outputs n single-mode outgoing beams, which enter the branches of the branched fiber bundle 6 for optical multiplexing. The common end of the branched fiber bundle 6 outputs an optical signal to photodetector 7. The photodetector 7 converts the detected optical signal into an electrical signal. As the sand grains pass through the sand grain passage groove, the beams emitted by the first multi-core fiber are blocked in sequence, and the electrical signal output by the photodetector 7 changes. The electrical signal output by the photodetector 7 is used to calculate the sand grain velocity and particle size.

[0037] Figure 1 The device also includes a microprocessor 8, which is electrically connected to a photodetector 7 and is used to receive electrical signals and calculate the sand particle velocity and particle size based on the electrical signals. The light source 1, optical splitter 2, first multi-core fiber fan-in / fan-out module 3, second multi-core fiber fan-in / fan-out module 5, branched fiber bundle 6, photodetector 7, and microprocessor 8 are all integrated within a housing 9, which is fixedly connected to the probe housing.

[0038] The core spacing of both the first and second multi-core optical fibers is d. The electrical signal output by the photodetector 7 is a time-domain signal f(t). The formula for calculating the average velocity V of the sand grains passing through the sand passage channel by the microprocessor 8 is as follows:

[0039] V=df (1)

[0040] Where f is the frequency of f(t).

[0041] The relationship between the radius r of the sand grain, the fiber core spacing d, and the signal coefficient K is approximately as follows:

[0042]

[0043]

[0044] Among them, reference Figure 3 The signal waveform diagram shown, h max h min Let J1 and L2 be the peak and trough values ​​of the maximum amplitude signal in the entire f(t) signal during the process of a single particle passing through a sand grain through a trough, respectively. J1 is a first-order Bessel function of the first kind, n is an integer, and l is a constant. n =2n-1, where M is the number of fiber cores.

[0045] Sand grains can pass through the trough Figure 1 The example of a half-groove with side openings can also be a closed-loop passageway with openings at both ends.

[0046] The output of the photodetector 7 can also be connected to a host computer for more precise and complex data processing.

[0047] The microprocessor 8 has a host computer connection port, which can be directly connected to a host computer and transmit data to the host computer; the microprocessor 8 can be further connected to a wireless transmission module, which can send signals and transmit computing data to an external receiving terminal.

[0048] Furthermore, based on Figure 1 An example of a multi-core optical fiber-based sand particle velocity and particle size measurement device; the present invention provides a multi-core optical fiber-based sand particle velocity and particle size measurement method, the steps of which include:

[0049] In step S1, as the sand grains pass through the trough, they successively block the speed of light. The photodetector 7 continuously sends electrical signals to the microprocessor 8. The electrical signals are time-domain signals f(t).

[0050] Step S2: The microprocessor calculates the sand particle velocity V and particle size r using electrical signals.

[0051] V = df

[0052] Where f is the frequency of f(t).

[0053] The relationship between the radius r of the sand grain, the fiber core spacing d, and the signal coefficient K is approximately as follows:

[0054]

[0055]

[0056] Among them, h max h minLet J1 and L2 be the peak and trough values ​​of the maximum amplitude signal in the entire f(t) signal during the process of a single particle passing through a sand grain through a trough, respectively. J1 is a first-order Bessel function of the first kind, n is an integer, and l is a constant. n =2n-1, where M is the number of fiber cores.

[0057] Please see Figure 1 The illustrated embodiment divides the optical path into 5 paths: the light source 1 emits an optical signal which is split into 5 paths by the optical splitter 2. The 5 optical signals are then sent to the multi-core fiber optic transmitter 4-1 after passing through the multi-core fiber fan-in / fan-out module 3. The optical signals output from the multi-core fiber optic transmitter 4-1 are collimated by the microlens array 4-2 and then projected into the multi-core fiber optic receiver 4-3 in a parallel light manner. That is, the optical signal output from each fiber core in the multi-core fiber optic transmitter 4-1 is collimated by the microlens array 4-2 and enters the corresponding fiber core in the multi-core fiber optic receiver 4-3 in a one-to-one manner, thereby completing the efficient coupling of the optical signals.

[0058] The sand grain 9 moves through the probe cavity 4-4 in the direction indicated by the arrow. At this time, the light signal projected from 4-1 to 4-3 changes. This changed light signal is captured by 4-3 and input into the multi-core fiber fan-in fan-out module 5. After being multiplexed by the branched fiber bundle 6, it is sent to the photodetector 7 and finally converted into an electrical signal.

[0059] Please see Figure 2 The correspondence between the multi-core optical fiber transmitter and receiver is as follows:

[0060] 4-1-1 corresponds to 4-3-1, 4-1-2 corresponds to 4-3-2, 4-1-3 corresponds to 4-3-3, 4-1-4 corresponds to 4-3-4, and 4-1-5 corresponds to 4-3-5, meaning that each transmitting fiber core corresponds to only one receiving fiber core; the distance between adjacent fiber cores is d.

[0061] Based on formulas (2) and (3), and combined with the signals measured by the device, the radius r of the sand grain can be calculated.

[0062] Compared with the prior art, the present invention has the following advantages: 1. It uses multi-core optical fiber as the core component of the probe, which is smaller in size, has higher transmission capacity, more compact structure, is more flexible and can be flexibly arranged in a narrow space, and has advantages such as anti-electromagnetic interference and corrosion resistance; 2. The projection-type optical detection method has a higher signal-to-noise ratio than the reflection-type, so it has a natural advantage in detecting sand particles and can measure a wider range of particle sizes.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for measuring sand particle velocity and size based on multi-core optical fiber, characterized in that, include: The light source (1), optical splitter (2), first multi-core fiber fan-in fan-out module (3), probe (4), second multi-core fiber fan-in fan-out module (5), branched fiber bundle (6), and photodetector (7) are arranged in sequence according to the direction of optical propagation. Adjacent components are connected by optical fiber. The probe housing of the probe (4) has a sand passage groove structure. The two side walls of the sand passage groove structure are made of light-transmitting material. Inside the probe housing, a multi-core fiber optic transmitter (4-1), a microlens array (4-2), the two side walls of the sand passage groove, and a multi-core fiber optic receiver (4-3) for fixing the second multi-core fiber optic port are arranged according to the optical path propagation direction. The multi-core fiber optic transmitter (4-1) is connected to the first multi-core fiber fan-in and fan-out module (3) by the first multi-core fiber. The cores of the first multi-core fiber are arranged in a straight line at equal intervals along the direction of movement of the sand through the sand passage groove and are aligned with the cores of the second multi-core fiber. The multi-core fiber optic receiver (4-3) is connected to the second multi-core fiber fan-in and fan-out module (5) by the second multi-core fiber. The probe light emitted by the light source (1) is split into n incident beams by the optical splitter (2) and enters the n input ports of the first multi-core fiber fan-in / fan-out module (3). It then enters the first multi-core fiber through the output port of the first multi-core fiber fan-in / fan-out module (3) and is collimated by the microlens array (4-2). The n beams emitted from the first multi-core fiber are received by the second multi-core fiber and output to the second multi-core fiber fan-in / fan-out module (5) for coupling. The second multi-core fiber fan-in / fan-out module (5) outputs n... The single-mode output light enters each branch of the branched fiber bundle (6) for optical multiplexing. The common end of the branched fiber bundle (6) outputs an optical signal to the photodetector (7). The photodetector (7) converts the detected optical signal into an electrical signal. As the sand grain passes through the sand grain passage groove, the light beam emitted by the first multi-core fiber is blocked in sequence, and the electrical signal output by the photodetector (7) changes. The electrical signal output by the photodetector (7) is used to calculate the sand grain velocity and particle size. The core spacing of both the first multi-core optical fiber and the second multi-core optical fiber is d; The relationship between the radius r of the sand grain, the fiber core spacing d, and the signal coefficient K is expressed by the following two formulas: ， ， The electrical signal output by the photodetector (7) is a time-domain signal f(t), h max h min Let J1 and J2 be the peak and trough values ​​of the maximum amplitude signal in the entire f(t) signal during the process of a single sand grain passing through the trough, respectively. J1 is a first-order Bessel function of the first kind, and n is an integer. n =2n-1, where M is the number of fiber cores.

2. The sand particle velocity and particle size measuring device based on multi-core optical fiber as described in claim 1, characterized in that, It also includes a microprocessor (8), which is electrically connected to the photodetector (7) and is used to receive the electrical signal and calculate the sand velocity and particle size of the sand grain based on the electrical signal.

3. The sand particle velocity and particle size measuring device based on multi-core optical fiber as described in claim 2, characterized in that, The light source (1), the optical splitter (2), the first multi-core fiber fan-in fan-out module (3), the second multi-core fiber fan-in fan-out module (5), the branched fiber bundle (6), the photodetector (7), and the microprocessor (8) are all integrated in the housing (9), and the housing (9) is fixedly connected to the probe housing.

4. The sand particle velocity and particle size measuring device based on multi-core optical fiber as described in claim 3, characterized in that, The average velocity V of the sand grains passing through the trough is: ， Where f is the frequency of f(t).

5. The sand particle velocity and particle size measuring device based on multi-core optical fiber as described in claim 4, characterized in that, It also includes a display screen electrically connected to the microprocessor (8), the display screen being used to display the V and the r.

6. A method for measuring sand particle velocity and particle size based on multi-core optical fiber, characterized in that, The implementing entity is the sand grain velocity and particle size measuring device based on multi-core optical fiber as described in any one of claims 1-5, and the steps include: In step S1, as the sand grains pass through the sand grain passage trough, the sand grains sequentially block the speed of light, and the photodetector (7) continuously sends an electrical signal to the microprocessor (8), the electrical signal being a time-domain signal f(t). Step S2, the microprocessor calculates the sand particle velocity V and particle size r using the electrical signal: ， Where f is the frequency of f(t); The relationship between the radius r of the sand grains, the fiber core spacing d, and the signal coefficient K is expressed by the following two formulas: ， ， Among them, h max h min Let J1 and J2 be the peak and trough values ​​of the signal with the largest amplitude in the entire segment of the f(t) signal during the process of a single sand grain passing through the trough, respectively. J1 is a first-order Bessel function of the first kind, and n is an integer. n =2n-1, where M is the number of fiber cores.

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