Polarization synthesis-based high-power line laser and hot-rolled strip steel edge wave detection system
By using a high-power line laser based on polarization synthesis in industrial detection and using optical elements to realize the polarization beam combination, the problem of difficulty in overcoming the fluctuations in the reverse (scattering) characteristics caused by the polarization orientation of the material texture in the prior art is solved, and the stability of efficient imaging and detection results is achieved.
Patent Information
- Application Number
- CN202311616472.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-30
- Publication Date
- 2025-05-30
AI Technical Summary
The prior art is difficult to generate high-power line lasers in industrial detection, and it is difficult to overcome the fluctuations in the reverse (scattering) characteristics caused by the polarization orientation of the material texture, affecting the imaging quality and detection results.
A high-power linear laser based on polarization synthesis is used to form an orthogonal polarization linear laser through two-way polarization laser synthesis, and a polarization beam combination is achieved using optical components such as 1/2 wave plate, polarization spectroscopic prism, laser beam expanding mirror and pentagonal prism to generate lasers with high power and orthogonal linear polarization characteristics.
It achieves low heat generation and can effectively overcome the ups and downs of the material texture polarization orientation, meets the industrial site's demand for 3D detection lasers, and improves the imaging quality and stability of detection results.
Smart Images
Figure CN120073482A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technology of line lasers, and more specifically, to a high-power line laser based on polarization synthesis and a hot-rolled strip edge wave detection system. Background Art
[0002] With the increasingly widespread application of surface detection and three-dimensional topography detection technologies, higher requirements are put forward for line lasers that produce high brightness and are insensitive to the polarization reflection (scattering) characteristics of the material surface. This is mainly reflected in:
[0003] 1) High power. Since the object to be detected online runs at high speed and the integration time of the imaging camera is only a dozen to a few microseconds, it is necessary to greatly improve the brightness of the illumination laser line at this time, so it is necessary to use multi-laser synthesis to achieve it;
[0004] 2) Orthogonal linearly polarized line laser illumination. Since the morphologies of the materials to be detected are diverse, the emission or scattering characteristics of the materials have polarization characteristics, that is, the reflection and scattering rate changes with the polarization direction of the incident polarized light.
[0005] However, the light emitted by the laser used as the illumination source is generally linearly polarized laser. Therefore, the intensity of the reflected or scattered light of the material may have a large brightness fluctuation effect due to different textures of the material, which has a great impact on the imaging quality and detection results and needs to be overcome in online detection. A feasible way to overcome this phenomenon is that the generated high-power line laser has simultaneous orthogonal linear polarization characteristics.
[0006] At present, the methods for generating high-power line lasers mainly include the one-dimensional beam expansion method of a single high-power laser and the collimated illumination method of a high-power LED line array. The one-dimensional beam expansion method of a single high-power laser is to use a single high-power laser to achieve high-power line laser. However, since the current single high-power semiconductor laser generally can only generate linearly polarized light in a single direction, it cannot meet the simultaneous orthogonal linear polarization characteristics and is difficult to overcome the fluctuation of the reflection (scattering) characteristics caused by the polarization orientation of the material texture. Moreover, the cost of a single high-power laser is high and it generates a lot of heat, which is not conducive to large-scale popularization and use in the industrial detection field. The collimated illumination method of a high-power LED line array uses high-power LEDs to form a line light source through cylindrical collimation. This light source is easy to generate a high-power and natural random polarized line light source and can better meet the illumination requirements for various texture material detections. However, due to the divergence of the LEDs, it is difficult to form a highly collimated line light source with a simple cylindrical lens, which does not meet the requirements for a high-brightness line light source in the detection of the edge wave of strip materials. Summary of the Invention
[0007] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a high-power line laser based on polarization synthesis and a hot-rolled strip edge wave detection system, which has low heat generation and can effectively overcome the fluctuation of the reflection (scattering) characteristics caused by the polarization orientation of the material texture, and can meet the requirements of the industrial site for 3D detection lasers.
[0008] To achieve the above object, the present invention adopts the following technical solutions:
[0009] In a first aspect of the present invention, there is provided a high-power line laser based on polarization synthesis, comprising a first linearly polarized laser, a second linearly polarized laser, a half-wave plate, a polarization beam splitter prism, a laser line expander, and a pentaprism;
[0010] The half-wave plate is disposed on the output side of the linearly polarized laser emitted by the first linearly polarized laser;
[0011] The pentaprism is disposed on the output side of the linearly polarized laser emitted by the second linearly polarized laser;
[0012] The polarization beam splitter prism is disposed on the output side of the linearly polarized laser rotated by the half-wave plate and the pentaprism;
[0013] The laser line expander is disposed on the output side of the linearly polarized laser deflected by the polarization beam splitter prism.
[0014] Preferably, the parameter settings of the first linearly polarized laser and the second linearly polarized laser are the same.
[0015] Preferably, the power of the first linearly polarized laser and the second linearly polarized laser is 3 to 5 watts.
[0016] Preferably, the beam diameter d of the linearly polarized laser emitted by the first linearly polarized laser and the second linearly polarized laser is 4 to 6 mm;
[0017] The divergence angle θ is 0.2 to 0.4 mrad.
[0018] Preferably, the expansion multiple r of the laser line expander is 3 to 4 times.
[0019] Preferably, the length of the line laser formed by the linearly polarized laser emitted by the laser line expander at a distance R is L = 2Rtg(α / 2), and the width is W = Γd + θL / Γ, in mm;
[0020] In the formula, α represents the divergence angle of the laser line expander, and the value range is 15 to 30°.
[0021] Preferably, the distance R at which the linearly polarized laser emitted by the laser line expander is taken is 2.8 to 3.5 meters.
[0022] In a second aspect of the present invention, there is provided a hot-rolled strip edge wave detection system based on polarization synthesis, comprising a camera, a detection server, and the high-power line laser based on polarization synthesis provided in the first aspect of the present invention;
[0023] The high-power line laser is arranged above the strip steel to be measured;
[0024] The high-power line laser emits line laser, which is parallelly irradiated on the surface of the strip steel to be measured along the width direction of the strip steel to be measured, and covers the area to be detected of the strip steel to be measured along the width direction of the strip steel to be measured;
[0025] The camera is used to take pictures of the area to be detected and send the images to the detection server.
[0026] A high-power line laser based on polarization synthesis and a hot-rolled strip edge wave detection system provided by the present invention can adopt an external trigger mode during on-site use and testing, and perform stroboscopic lighting in coordination with the camera shooting rhythm. By using the present invention, it is possible to ensure the irradiation brightness and enable the camera to clearly image under the conditions of relatively fast on-site production speed and extremely short camera exposure time. By identifying and analyzing the strip edge images, quality anomaly information such as strip waves can be detected, and timely treatment such as sealing can be carried out to prevent it from entering the downstream production line, reduce the finishing time, improve labor efficiency, and reduce quality objections. Description of the Drawings
[0027] Figure 1 is a schematic structural diagram of the high-power line laser of the present invention;
[0028] Figure 2 is a schematic diagram of the line laser formed by the linearly polarized laser emitted by the laser line expander in the high-power line laser of the present invention at a position with a distance R;
[0029] Figure 3 is a schematic installation and layout diagram of the hot-rolled strip edge wave detection system of the present invention. Detailed Embodiments
[0030] In order to better understand the above technical solutions of the present invention, the technical solutions of the present invention will be further described below with reference to the drawings and embodiments.
[0031] Combined with Figure 1 As shown, a high-power line laser based on polarization synthesis provided by the present invention includes a first linearly polarized laser 1, a second linearly polarized laser 2, a half-wave plate 3, a polarization beam splitter prism 4, a laser line expander 5, and a pentagonal prism 6.
[0032] The half-wave plate 3 is arranged on the output side of the linearly polarized laser emitted by the first linearly polarized laser 1 (such as Figure 1 the arrow direction in
[0033] The pentagonal prism 6 is arranged on the output side of the linearly polarized laser emitted by the second linearly polarized laser 2;
[0034] The polarization beam splitter prism 4 is arranged on the output side of the 1 / 2 wave plate 3 and the pentagonal prism 6 for rotating linearly polarized laser;
[0035] The laser beam expander 5 is arranged on the output side of the polarization beam splitter prism 4 for deflecting linearly polarized laser.
[0036] After the linearly polarized laser emitted by the first linearly polarized laser 1 passes through the 1 / 2 wave plate 3, the direction of the linearly polarized laser rotates by 90°, and is orthogonal to the original polarization direction of the emitted laser.
[0037] After the linearly polarized laser emitted by the second linearly polarized laser 2 passes through the pentagonal prism 6, the direction of the linearly polarized laser deflects by 90°.
[0038] Then, the two linearly polarized lasers with orthogonal propagation directions and orthogonal polarization directions enter the polarization beam splitter prism 4 simultaneously, and through its polarization beam combination, a beam of laser with two orthogonal directions is output.
[0039] The combined orthogonally polarized laser beam irradiates the laser beam expander 5, and is expanded in one-dimensional direction through the laser beam expander 5.
[0040] The parameter settings of the first linearly polarized laser 1 and the second linearly polarized laser 2 are the same, the power is 3 - 5 watts, the beam diameter d of the emitted linearly polarized laser is 4 - 6 mm, and the divergence angle θ is 0.2 - 0.4 mrad.
[0041] The expansion multiple r of the laser beam expander 5 is 3 - 4 times.
[0042] As Figure 2 shown, the length L of the linear laser formed by the linearly polarized laser emitted by the laser beam expander 5 at a distance R position (such as 3 meters) is L = 2Rtg(α / 2), and the width is W = Γd + θL / Γ, unit mm;
[0043] In the formula, α represents the diffusion angle of the laser beam expander, and the value range is 15 - 30°.
[0044] The distance R at which the laser beam expander 5 emits linearly polarized laser ranges from 2.8 to 3.5 meters.
[0045] By selecting the laser beam expander 5 with different diffusion angles α, structured light with the required length L is generated at the specified working distance R. And the adjustment of the length direction of the linear laser is realized by rotating the laser beam expander 5.
[0046] Combined with Figure 3 shown, the present invention also provides a hot-rolled strip edge wave detection system based on polarization synthesis, including a camera 7, a detection server 8, and the high-power line laser 9 of the present invention.
[0047] The high-power line laser 9 is assembled and formed, and after being enclosed, it is installed above the strip steel 10 to be measured. And according to the detection requirements, the number of laser lines to be emitted by the high-power line laser 9 is designed.
[0048] The high-power line laser 9 emits line laser, which is parallelly irradiated on the surface of the strip steel 10 to be measured along the width direction of the strip steel 10 to be measured, and covers the area to be detected of the strip steel 10 along the width direction of the strip steel 10 to be measured.
[0049] The camera 7 is used to take pictures of the area to be detected and send the images to the detection server 8.
[0050] To sum up, the present invention adopts the principle of polarization beam combination, which perfectly unifies the formation of orthogonally polarized line laser by the combination of two linearly polarized lasers and the formation of high-power line laser by the combination of two lasers. One device realizes power combination and polarization combination at the same time; the performance parameters of two high-power linearly polarized lasers are adopted, including the same polarization direction. By inserting a half-wave plate at the laser output end of one of them, two lasers with orthogonal polarizations are formed. The requirement for the type of laser is reduced, and the laser is the main component consumed during the long-term use of such products, thus reducing the number of product spare parts and maintenance costs; by axially rotating the Powell prism (laser line expander), the length direction adjustment of the high-power line laser is realized, so that it coincides with the imaging field of view of the linear array camera of the detection system.
[0051] Embodiment
[0052] Refer again to Figure 1 As shown, the high-power line laser in this embodiment includes:
[0053] The first linearly polarized laser 1 with a high power of 3W emits linearly polarized laser, and its output beam parameters are that the beam diameter d is 1mm and the divergence angle θ is 0.3mrad. After passing through the half-wave plate 3, the polarization direction of the output light rotates by 90°, which is orthogonal to the original output laser polarization direction. The second linearly polarized laser 2 with a high power of 3W has the same performance parameters as the first linearly polarized laser 1, and the linearly polarized laser emitted by it makes its propagation direction deflect by 90° through the pentaprism 6. Then, two lasers with orthogonal propagation directions and orthogonal polarization directions enter the polarization beam splitter prism 4 at the same time, and a beam of laser with two orthogonal directions is output through its polarization beam combination. The combined orthogonally polarized laser beam irradiates the laser line expander 5, and its expansion multiple Γ is 3. The laser line expander 5 with a diffusion angle α of 30° expands the beam in one-dimensional direction. The parameters of the line laser formed by the output beam after passing through the laser line expander 5 at a distance R = 3m: the length L is 1607mm, and the width W is 3.3mm. And so on.
[0054] At the hot-rolled strip production site, a high-power line laser 9 is installed 3000 mm above the strip 10 to be measured. The high-power line laser 9 emits a parallel line of structured light with a width of 3.3 mm, which is parallelly irradiated along the width direction of the strip 10 to be measured, and the irradiation range is 1607 mm, covering the entire width of the strip 10 to be measured. It realizes the detection of the operation side and the equipment side waves of the strip 10 to be measured, as Figure 3 shown.
[0055] The working process of the whole device is as follows: During the production process, before the strip 10 to be measured reaches the position to be measured, the high-power line laser 9 is triggered to emit a green parallel laser line. At the same time, the camera 7 also starts taking pictures. The strip image is sent to the detection server 8. After image processing and recognition, the relevant image and data information are saved in the database, and the on-site operator alarms and seals the strip with problems detected.
[0056] The present invention mainly designs a structured light generation method based on polarization synthesis of high-power line laser for three-dimensional imaging of strip edge waves. By adopting the principle of polarization beam combination, it perfectly unifies the formation of orthogonally polarized line laser by synthesizing two linearly polarized lasers and the formation of high-power line laser by synthesizing two lasers, and a single device realizes both power synthesis and polarization synthesis.
[0057] The performance parameters of two high-power linearly polarized lasers are adopted, including the same polarization direction. By inserting a half-wave plate at the output end of one of the lasers, two orthogonally polarized lasers are formed. It reduces the requirements for the types of lasers, and lasers are the main components consumed during the long-term use of such products, thus reducing the number of product spare parts and maintenance costs;
[0058] This method can realize the application of high-power lasers in strip shape detection, ensure that under high-speed and high-temperature environments, it meets the exposure intensity requirements of the camera for imaging, realize clear imaging of the strip surface, and greatly reduce the generation of quality objections in on-site use, with great economic and social benefits.
[0059] Those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention, rather than to limit the present invention. As long as within the scope of the essential spirit of the present invention, changes and modifications to the above-described embodiments will fall within the scope of the claims of the present invention.
Claims
1. A high-power linear laser based on polarization synthesis, characterized in that: it includes a first linear polarization laser, a second linear polarization laser, a half-wave plate, a polarization beam splitter prism, a laser line expander, and a pentaprism; the half-wave plate is arranged on the output side of the linear polarization laser emitted by the first linear polarization laser; the pentaprism is arranged on the output side of the linear polarization laser emitted by the second linear polarization laser; the polarization beam splitter prism is arranged on the output side of the half-wave plate and the pentaprism for rotating the linear polarization laser; the laser line expander is arranged on the output side of the polarization beam splitter prism for deflecting the linear polarization laser.
2. The high-power linear laser based on polarization synthesis according to claim 1, characterized in that: the parameter settings of the first linear polarization laser and the second linear polarization laser are the same.
3. The high-power linear laser based on polarization synthesis according to claim 2, characterized in that: the power of the first linear polarization laser and the second linear polarization laser is 3 to 5 watts.
4. The high-power linear laser based on polarization synthesis according to claim 3, characterized in that: the beam diameter d of the linear polarization laser emitted by the first linear polarization laser and the second linear polarization laser is 4 to 6 mm; the divergence angle θ is 0.2 to 0.4 mrad.
5. The high-power linear laser based on polarization synthesis according to claim 4, characterized in that: the expansion ratio r of the laser line expander is 3 to 4 times.
6. The high-power linear laser based on polarization synthesis according to claim 5, characterized in that: the length of the linear laser formed by the linear polarization laser emitted by the laser line expander at a distance R is L = 2Rtg(α / 2), and the width is W = Γd + θL / Γ, in units of mm; wherein, α represents the divergence angle of the laser line expander, and the value range is 15 to 30°.
7. The high-power linear laser based on polarization synthesis according to claim 6, characterized in that: the distance R at which the laser line expander emits the linear polarization laser ranges from 2.8 to 3.5 meters.
8. A hot-rolled strip edge wave detection system based on polarization synthesis, characterized in that: it includes a camera, a detection server, and a high-power linear laser based on polarization synthesis according to any one of claims 1-7; the high-power linear laser is arranged above the strip to be measured; the high-power linear laser emits a linear laser along the width direction of the strip to be measured, parallelly irradiates on the surface of the strip to be measured, and covers the area to be detected of the strip to be measured along the width direction of the strip to be measured; the camera is used to take pictures of the area to be detected and send the images to the detection server.