A ranging method, a binocular ranging system and a laser on-line detection device

Abstract

The present invention provides a ranging method, a binocular ranging system and a laser on-line detection device. The ranging method includes: irradiating the liquid surface of molten metal with a laser to form a light spot; using two cameras to respectively acquire N frames of images of the liquid surface and extract the pixel coordinates of the light spot in the images; calculating the parallax of each frame of image according to the pixel coordinates; calculating the average parallax according to the parallax; calculating the standard deviation of the viewing distance according to the parallax and the average parallax; judging the value range of the effective parallax according to the average parallax and the standard deviation of the viewing distance, and calculating the average value of the effective parallax; calculating the distance between the light spot and the baseline according to the average value of the effective parallax, the focal length of the camera and the length of the baseline between the two cameras, so as to determine the position of the liquid surface, and thereby adjust the LIBS laser excitation position in real time, which can effectively reduce the errors caused by the short-term irregular violent fluctuation of the liquid surface and improve the laser detection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of molten metal detection, and particularly relates to a ranging method, a binocular ranging system and a laser on-line detection device. Background Art

[0002] When using Laser-induced breakdown spectroscopy (LIBS) to detect molten metal in a smelting plant, the change of the liquid level will have a great impact on the spectral intensity and the detection result. Usually, the LIBS laser excitation position is the average value of the height under the normal fluctuation of the liquid level. However, in the process of the smelting plant, it is easy to cause short-term irregular and violent fluctuations of the liquid level. Using the average position of the liquid level at this time will lead to large errors in laser detection. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, one of the purposes of the present invention is to provide a ranging method.

[0004] The present invention provides the following technical solutions:

[0005] A ranging method is applied to a binocular ranging system, and the binocular ranging system includes two cameras;

[0006] The ranging method includes:

[0007] Use a laser to irradiate the liquid surface of the molten metal to form a light spot;

[0008] Use the two cameras to respectively acquire N frames of images of the liquid surface, and extract the pixel coordinates of the light spot in the images;

[0009] Calculate the parallax of each frame of the image according to the pixel coordinates;

[0010] Calculate the average parallax according to the parallax;

[0011] Calculate the standard deviation of the distance based on the parallax and the average parallax;

[0012] Judge the value range of the effective parallax according to the average parallax and the standard deviation of the distance, and calculate the average value of the effective parallax;

[0013] Calculate the distance between the light spot and the baseline according to the average value of the effective parallax, the focal length of the camera and the length of the baseline between the two cameras.

[0014] As a further optional solution to the ranging method, the average parallax is , and the standard deviation of the distance is , and the effective parallax is ;

[0015] The step of determining the value range of the effective parallax according to the average parallax and the standard deviation of the viewing distance includes:

[0016] Determine the state of the liquid surface;

[0017] When the liquid surface is in an irregular and violent fluctuation state, the value range of the effective parallax is

[0018] ,

[0019] where 1 ≤ k1 ≤ 1.5;

[0020] When the liquid surface is in a stable state, the value range of the effective parallax is

[0021] ,

[0022] where 2 ≤ k2 ≤ 3.

[0023] As a further optional solution to the ranging method, the camera includes a first camera and a second camera, and the connection line between the first camera and the second camera is horizontal;

[0024] The step of using the two cameras to respectively acquire N frames of images of the liquid surface and extract the pixel coordinates of the light spot in the images includes:

[0025] Use the first camera to acquire N frames of images of the liquid surface and extract the pixel coordinates of the light spot in the images ;

[0026] Use the second camera to acquire N frames of images of the liquid surface and extract the pixel coordinates of the light spot in the images ;

[0027] where N is an integer greater than 1, and t is a positive integer not greater than N.

[0028] Another object of the present invention is to provide a binocular ranging system.

[0029] The present invention provides the following technical solutions:

[0030] A binocular ranging system is applied to a laser on-line detection device. The binocular ranging system is used to execute the above ranging method. The binocular ranging system includes a laser sight, a data processing unit, and two cameras, and the data processing unit is electrically connected to the two cameras respectively.

[0031] As a further optional solution for the binocular ranging system, the binocular ranging system further includes a first external filter, which is correspondingly arranged with the camera, and the first external filter is used to reduce the light intensity entering the corresponding camera.

[0032] As a further optional solution for the binocular ranging system, the binocular ranging system further includes a second external filter, which is stacked with the first external filter, and the second external filter includes at least one of a narrowband filter, a band-stop filter, and a high-pass filter.

[0033] As a further optional solution for the binocular ranging system, the binocular ranging system further includes a rotating lens, which is correspondingly arranged with the camera, and at least two of a narrowband filter, a band-stop filter, and a high-pass filter are arranged on the rotating lens;

[0034] Wherein, the narrowband filter is adapted to the laser sight, the band-stop filter is adapted to the molten metal, and the high-pass filter is adapted to the laser online detection device.

[0035] As a further optional solution for the binocular ranging system, the binocular ranging system further includes a fixing member, and at least one of the cameras is slidably arranged on the fixing member along the connection direction of the two cameras and is detachably connected to the fixing member.

[0036] As a further optional solution for the binocular ranging system, the wavelength range of the laser emitted by the laser sight is 532±10nm; and / or

[0037] The binocular ranging system further includes a ball joint, and the laser sight is arranged on the ball joint.

[0038] Another object of the present invention is to provide a laser online detection device.

[0039] The present invention provides the following technical solutions:

[0040] A laser online detection device includes the above-mentioned binocular ranging system.

[0041] The embodiments of the present invention have the following beneficial effects:

[0042] When using laser-induced breakdown spectroscopy (LIBS) technology to detect molten metal, a laser is used to irradiate the liquid surface of the molten metal to form a light spot. At the same time, two cameras are used to respectively acquire N frames of images of the liquid surface, and the pixel coordinates of the light spot in the images are extracted. According to each pixel coordinate, the parallax, average parallax, and standard deviation of the parallax of each frame of the image are calculated, and the value range of the effective parallax is further determined, so as to calculate the average value of the effective parallax. Finally, based on the average value of the effective parallax, the focal length of the camera, and the length of the baseline between the two cameras, the distance between the light spot and the baseline can be calculated, thereby determining the position of the liquid surface, and adjusting the LIBS laser excitation position in real time, which can effectively reduce the error caused by the short-term irregular violent fluctuation of the liquid surface and improve the laser detection accuracy.

[0043] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0045] Figure 1 Shows the flowchart of the steps of a ranging method provided by an embodiment of the present invention;

[0046] Figure 2 Shows the schematic structural diagram of a binocular ranging system provided by an embodiment of the present invention;

[0047] Figure 3 Shows the overall schematic structural diagram of a binocular ranging system provided by an embodiment of the present invention;

[0048] Figure 4 Shows the partial schematic structural diagram of a binocular ranging system provided by an embodiment of the present invention.

[0049] MAIN ELEMENT SYMBOL DESCRIPTION:

[0050] 100 - Camera; 110 - First Camera; 120 - Second Camera; 200 - Light Spot; 300 - Laser Aiming Device; 400 - Data Processing Unit; 500 - Ball Joint; 600 - Fixing Member; 610 - Base Plate; 620 - First Mounting Plate; 630 - Second Mounting Plate; 640 - Third Mounting Plate; 650 - Fourth Mounting Plate; 651 - Lens Bracket; 700 - First External Filter; 800 - Second External Filter; 900 - Rotating Lens. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0052] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a middle element at the same time. In contrast, when an element is referred to as being "directly on" another element, there is no middle element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0053] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. It can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0054] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is two or more unless otherwise clearly specifically defined.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this template herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0056] Taking the measurement of molten chalcopyrite in a smelter as an example, the molten chalcopyrite flows into the next process link through a chute, and the liquid level of the molten chalcopyrite in the chute shows a fluctuating state. When analyzing the grade of molten metal by laser spectroscopy, the laser excitation position is usually the average height under the normal fluctuating state of the liquid level.

[0057] To prevent the slag notch from being blocked by the cooled chalcopyrite slag, workers need to knock off the cooled slag in a timely manner. When the upstream slag falls into the chute, it will cause a huge short-term fluctuation in the liquid level. If the laser excitation position is not adjusted accordingly, it will lead to a large error in laser detection.

[0058] For the above problems, please refer to Figure 1 , this embodiment provides a ranging method, which is applied to a binocular ranging system and is used to determine the laser excitation position of an on-line laser detection device for molten metal. Please combine Figure 2 , where the binocular ranging system includes two cameras 100.

[0059] The ranging method includes the following steps:

[0060] S1, Use a laser to irradiate the liquid surface of the molten metal to form a light spot 200.

[0061] It should be noted that the current binocular cameras are sensitive to the lighting conditions, and the molten metal is a high-temperature melt, which will generate strong infrared radiation and visible light reflection, resulting in blurred images or insufficient contrast, affecting the accuracy of the binocular matching algorithm.

[0062] Therefore, use a laser to irradiate the liquid surface of the molten metal to form a light spot 200 on the liquid surface, and use the light spot 200 to represent the liquid surface position, which is convenient for the camera 100 to focus, thereby helping to improve the image clarity and the accuracy of parallax matching.

[0063] In some embodiments, the laser is a green laser with a wavelength range of 532±10nm. Relatively speaking, the thermal radiation emitted by the molten metal is concentrated in the infrared and red light ranges (550–1050nm), and the wavelength range of the green laser has a high distinguishability from this, which can produce an obvious contrast and is convenient for the camera 100 to capture.

[0064] S2, Use two cameras 100 to respectively obtain N frames of images of the liquid surface and extract the pixel coordinates of the light spot 200 in the images.

[0065] Specifically, after obtaining the image of the liquid surface, it is necessary to use an image processing algorithm to identify the position of the light spot 200 in the image, so as to extract the corresponding pixel coordinates.

[0066] In some embodiments, the camera 100 includes a first camera 110 and a second camera 120. The connection line of the first camera 110 and the second camera 120 is horizontal and parallel to the liquid surface.

[0067] Correspondingly, the step of using two cameras 100 to respectively obtain N frames of images of the liquid surface and extract the pixel coordinates of the light spot 200 in the images includes:

[0068] Use the first camera 110 to obtain N frames of images of the liquid surface, and extract the pixel coordinates of the light spot 200 in the images. .

[0069] Use the second camera 120 to obtain N frames of images of the liquid surface, and extract the pixel coordinates of the light spot 200 in the images. .

[0070] Where N is an integer greater than 1, and t is a positive integer not greater than N.

[0071] Understandably, is the pixel coordinate of the light spot 200 in the t-th frame of image obtained by the first camera 110, is the pixel coordinate of the light spot 200 in the t-th frame of image obtained by the second camera 120, and x is the coordinate of the light spot 200 along the connection direction of the first camera 110 and the second camera 120.

[0072] S3. Calculate the parallax of each frame of image according to the pixel coordinates.

[0073] Specifically, denote the parallax of the t-th frame of image as , then:

[0074] .

[0075] S4. Calculate the average parallax according to the parallax.

[0076] Specifically, denote the average parallax as , then:

[0077] .

[0078] S5. Calculate the standard deviation of the viewing distance according to the parallax and the average parallax.

[0079] Specifically, denote the standard deviation of the viewing distance as , then:

[0080] .

[0081] S6. Judge the value range of the effective parallax according to the average parallax and the standard deviation of the viewing distance, and calculate the average value of the effective parallax.

[0082] In some embodiments, denote the average parallax as , denote the standard deviation of the viewing distance as , denote the effective parallax as .

[0083] Correspondingly, the steps of judging the value range of the effective parallax according to the average parallax and the standard deviation of the viewing distance include:

[0084] Judge the state of the liquid surface.

[0085] When the liquid level is in an irregular and violent fluctuation state, the value range of the effective parallax is

[0086] ,

[0087] where 1 ≤ k1 ≤ 1.5.

[0088] When the liquid level is in a stable state, the value range of the effective parallax is

[0089] ,

[0090] where 2 ≤ k2 ≤ 3.

[0091] It should be noted that the irregular and violent fluctuation of the liquid level is usually caused by worker operation or process. When the liquid level is in an irregular and violent fluctuation state, choosing a smaller k1 as the coefficient of the stadia standard deviation can strictly filter the obtained parallax .

[0092] Conversely, when the liquid level fluctuation is relatively stable, choosing a larger k2 as the coefficient of the stadia standard deviation only filters 5% - 1% of the sequential parallax.

[0093] Thus, the irregular and violent fluctuation of the page caused by workers or processes can be excluded, a series of effective parallaxes can be obtained, and then the average value of the effective parallaxes can be calculated and denoted as .

[0094] S7. Calculate the distance between the light spot 200 and the baseline according to the average value of the effective parallax, the focal length of the camera 100, and the length of the baseline between the two cameras 100.

[0095] Specifically, denote the focal length of the camera 100 as f, the length of the baseline as B, and the distance between the light spot 200 and the baseline as Z. Then:

[0096] .

[0097] Since the position of the camera 100 is predetermined, that is, the height of the baseline is known, after calculating the distance between the light spot 200 and the baseline, the average height of the liquid level can be determined as the LIBS laser excitation position.

[0098] In summary, when using laser-induced breakdown spectroscopy to detect molten metal, a laser is used to irradiate the liquid surface of the molten metal to form a light spot 200. At the same time, two cameras 100 are used to respectively acquire N frames of images of the liquid surface, and the pixel coordinates of the light spot 200 in the images are extracted. According to each pixel coordinate, the parallax, average parallax, standard deviation of the distance of sight, and the value range of the effective parallax are calculated, and further the average value of the effective parallax is calculated. Finally, based on the average value of the effective parallax, the focal length of the camera 100, and the length of the baseline between the two cameras 100, the distance between the light spot 200 and the baseline can be calculated, so as to determine the position of the liquid surface, and thereby adjust the LIBS laser excitation position in real time, which can effectively reduce the error caused by the short-term irregular violent fluctuation of the liquid surface and improve the laser detection accuracy.

[0099] This embodiment also provides a binocular ranging system, which is applied to an online laser detection device. The binocular ranging system is used to execute the above ranging method to determine the laser excitation position of the molten metal online laser detection device.

[0100] Please refer to Figure 3 and Figure 4 The above binocular ranging system includes a laser sight 300, a data processing unit 400, and two cameras 100. The data processing unit 400 is electrically connected to the two cameras 100 respectively.

[0101] During use, the laser sight 300 emits a laser to irradiate the liquid surface of the molten metal, thereby forming a light spot 200. After the two cameras 100 acquire the images of the page, the data processing unit 400 processes the images, extracts the pixel coordinates of the light spot 200 in the images, and calculates the parallax, average parallax, standard deviation of the distance of sight, the average value of the effective parallax, and the distance between the light spot 200 and the baseline.

[0102] In some embodiments, the wavelength range of the laser emitted by the laser sight 300 is 532 ± 10 nm.

[0103] At this time, the laser sight 300 emits a green laser. Relatively, the thermal radiation emitted by the molten metal is concentrated in the infrared and red light ranges (550–1050 nm). The wavelength range of the green laser has a high degree of differentiation from this, can produce an obvious contrast, and is convenient for the camera 100 to capture.

[0104] In some embodiments, the above binocular ranging system further includes a ball joint 500, and the laser sight 300 is arranged on the ball joint 500.

[0105] The ball joint 500 enables the laser sight 300 to have better flexibility and can be quickly adjusted. During use, the ball joint 500 is fixed to a suitable position of the online laser detection device.

[0106] In some embodiments, the binocular distance measurement system further includes a fixing member 600. At least one camera 100 is slidably disposed on the fixing member 600 along the direction of the connection line of the two cameras 100, and is detachably connected to the fixing member 600.

[0107] When in use, the camera 100 is slid on the fixing member 600 according to the required measuring range on site, and the measuring range is adjusted by changing the length of the baselines of the two cameras 100. After the measuring range is determined, the camera 100 is fixed.

[0108] Specifically, the fixing member 600 includes a bottom plate 610 and a first mounting plate 620 which are perpendicular to each other. The bottom plate 610 is fixed on the laser online detection device, and the first mounting plate 620 is connected to the bottom plate 610. Both cameras 100 are slidably arranged on the first mounting plate 620, and are detachably connected to the first mounting plate 620 by screws and nuts.

[0109] Optionally, the fixing member 600 further includes a second mounting plate 630. The second mounting plate 630 is parallel to the first mounting plate 620 and is located on the side of the first mounting plate 620 away from the liquid surface. The data processing unit 400 uses a circuit board, which is fixedly arranged on the second mounting plate 630 and connected to the two cameras 100 through a flexible flat cable.

[0110] In some embodiments, the binocular distance measurement system further includes a first outer filter 700. The first outer filter 700 is disposed corresponding to the camera 100, and the first outer filter 700 is used to reduce the intensity of light entering the corresponding camera 100.

[0111] When in use, the first outer filter 700 can avoid detail loss caused by overexposure by reducing the intensity of light entering the camera 100 , thereby helping the camera 100 to capture the details of the light spot 200 more accurately.

[0112] Exemplarily, the first outer filter 700 is a Neutral Density Filter (ND filter), which can reduce the intensity of light of all wavelengths without changing the spectral distribution, and thus can reduce the intensity of light entering the lens of the camera 100 .

[0113] Specifically, the fixing member 600 further includes a third mounting plate 640. The third mounting plate 640 is parallel to the first mounting plate 620 and is located on a side of the first mounting plate 620 away from the second mounting plate 630. The first outer filter 700 is disposed on the third mounting plate 640.

[0114] Further, the above binocular ranging system further includes a second external filter 800. The second external filter 800 is stacked with the first external filter 700 and is fixed to the third mounting plate 640 together. In addition, the second external filter 800 includes at least one of a narrowband filter, a band-stop filter, and a high-pass filter.

[0115] Among them, the narrowband filter is adapted to the laser sight 300, its central wavelength is 532 nm, and it allows light in the 532 ± 10 nm band to pass through. When in use, the narrowband filter can enhance the effect of the green light spot 200, which is beneficial for the camera 100 to capture the details of the light spot 200 more precisely.

[0116] The band-stop filter is adapted to molten metal and can block the light in the range of 600 - 1050 nm from passing through. When in use, the band-stop filter can suppress the high-intensity infrared radiation and visible light reflection generated by the molten metal, which is also beneficial for the camera 100 to capture the details of the light spot 200 more precisely.

[0117] The high-pass filter is adapted to the laser on-line detection device and allows light with a wavelength above 1050 nm to pass through. Correspondingly, the laser excited by the laser on-line detection device is usually 1064 nm, so the high-pass filter can enhance the effect of the laser detection light spot 200 captured by the camera 100.

[0118] Thus, each second external filter 800 can be used in combination with the first external filter 700 according to the on-site needs to cope with the complex on-site environment.

[0119] In some embodiments, the above binocular ranging system further includes a rotating lens 900. The rotating lens 900 is correspondingly arranged with the camera 100, and at least two of a narrowband filter, a band-stop filter, and a high-pass filter are arranged on the rotating lens 900.

[0120] Among them, the narrowband filter is adapted to the laser sight 300, the band-stop filter is adapted to molten metal, and the high-pass filter is adapted to the laser on-line detection device, and their functions will not be elaborated here.

[0121] Specifically, the fixing member 600 further includes a fourth mounting plate 650. The fourth mounting plate 650 is parallel to the first mounting plate 620 and is located on the side of the second mounting plate 630 away from the first mounting plate 620. A lens bracket 651 is arranged on the fourth mounting plate 650, and the lens bracket 651 is correspondingly arranged with the rotating lens 900. The rotating lens 900 is rotatably arranged on the corresponding lens bracket 651 and is connected to the lens bracket 651 by screws.

[0122] When in use, adjust the rotating lens 900 according to the on-site needs. After determining the applied filter, press-fit and connect it to the lens bracket 651 through screws for fixation.

[0123] Specifically, the first external filter 700, the camera 100, and the lens bracket 651 are connected by long screws. Similar to the camera 100, the first external filter 700 is slidably arranged on the third mounting plate 640 and is detachably connected to the third mounting plate 640 by screws and nuts; the lens bracket 651 is slidably arranged on the fourth mounting plate 650 and is detachably connected to the fourth mounting plate 650 by screws and nuts.

[0124] In summary, when the above binocular ranging system executes the above ranging method, through multi-frame image analysis, the drastic fluctuations of the liquid level caused by worker operations or process influences are excluded, enabling the laser on-line detection device to find the accurate excitation position.

[0125] In addition, the above binocular ranging system selects the filter according to the wavelength released by the molten metal, the wavelength of the laser sight 300, or the wavelength of the laser excited by the laser on-line detection device, screens out the passable and blocked bands, suppresses the influence of the molten metal, enhances the wavelength signal of the laser, and then captures the light spot 200 on the surface of the high-temperature molten metal, reduces the influence of background light on the image, improves the quality of the image, and further enables the stereo matching algorithm to more easily identify the corresponding relationship of the light spot 200, thereby improving the accuracy of the disparity map and the precision of the depth map. According to different on-site situations, different filters can be selected to enhance the contrast of the light spot 200 in the picture.

[0126] This embodiment also provides a laser on-line detection device, including the above binocular ranging system.

[0127] In all the examples shown and described here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0128] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0129] The above-described embodiments merely represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A ranging method, characterized in that, Applied to a binocular ranging system, the binocular ranging system comprising two cameras; The ranging method comprises: Irradiating the liquid surface of molten metal with a laser to form a light spot; Using the two cameras to respectively acquire N frames of images of the liquid surface, and extracting the pixel coordinates of the light spot in the images; Calculating the parallax of each frame of the image according to the pixel coordinates; Calculating the average parallax according to the parallax; Calculating the standard deviation of the ranging distance according to the parallax and the average parallax; Judging the value range of the effective parallax according to the average parallax and the standard deviation of the ranging distance, and calculating the average value of the effective parallax; Calculating the distance between the light spot and the baseline according to the average value of the effective parallax, the focal length of the camera, and the length of the baseline between the two cameras; The average parallax is , the standard deviation of the viewing distance is , and the effective parallax is ; The step of judging the value range of the effective parallax according to the average parallax and the standard deviation of the ranging distance comprises: Judging the state of the liquid surface; When the liquid surface is in an irregular violent fluctuation state, the value range of the effective parallax is ， where 1 ≤ k1 ≤ 1.5; When the liquid surface is in a stable state, the value range of the effective parallax is ， where 2 ≤ k2 ≤ 3.

2. The ranging method according to claim 1, wherein The cameras comprise a first camera and a second camera, and the connection line between the first camera and the second camera is horizontal; The step of using the two cameras to respectively acquire N frames of images of the liquid surface, and extracting the pixel coordinates of the light spot in the images comprises: Obtain N frames of images of the liquid surface using the first camera, and extract the pixel coordinates of the light spot in the images ; Obtain N frames of images of the liquid surface using the second camera, and extract the pixel coordinates of the light spot in the images ; where N is an integer greater than 1, and t is a positive integer not greater than N.

3. A binocular ranging system, characterized in that, Applied to a laser on-line detection device, the binocular ranging system is used to execute the ranging method according to claim 1 or 2, the binocular ranging system comprising a laser sight, a data processing unit, and two cameras, and the data processing unit is electrically connected to the two cameras respectively.

4. The binocular ranging system according to claim 3, wherein The binocular ranging system further comprises a first external filter, the first external filter being correspondingly arranged with the camera, and the first external filter being used for reducing the light intensity entering the corresponding camera.

5. The binocular ranging system according to claim 4, wherein The binocular ranging system further comprises a second external filter, the second external filter being stacked with the first external filter, and the second external filter comprising at least one of a narrow-band filter, a band-stop filter, and a high-pass filter.

6. The binocular ranging system according to claim 3, characterized in that, The binocular ranging system further comprises a rotating lens, the rotating lens being correspondingly arranged with the camera, and at least two of a narrow-band filter, a band-stop filter, and a high-pass filter being arranged on the rotating lens; wherein, the narrow-band filter is adapted to the laser sight, the band-stop filter is adapted to the molten metal, and the high-pass filter is adapted to the laser on-line detection device.

7. The binocular ranging system according to any one of claims 3-6, characterized in that, The binocular ranging system further comprises a fixing member, and at least one of the cameras is slidably arranged on the fixing member along the connection line direction of the two cameras and is detachably connected to the fixing member.

8. The binocular ranging system according to any one of claims 3-6, wherein The wavelength range of the laser emitted by the laser sight is 532 ± 10 nm; and / or The binocular ranging system further comprises a ball joint, and the laser sight is arranged on the ball joint.

9. A laser on-line detection device, characterized in that, Comprising the binocular ranging system according to any one of claims 4-8.

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