Imaging discrimination method and system for KDP (potassium dihydrogen phosphate) crystal cone-column growth region

Abstract

The invention discloses an imaging discrimination method and system for a KDP crystal cone-column growth region, and relates to the technical field of KDP crystal quality detection. The method comprises the following steps: obtaining a KDP crystal to be detected, and checking the KDP crystal to be detected; the method comprises the following steps: establishing an imaging discrimination system, imaging a to-be-detected KDP crystal by using the imaging discrimination system to obtain a scattered light image of the KDP crystal, placing the to-be-detected KDP crystal in the imaging discrimination system, obliquely emitting scattered laser to the surface of the to-be-detected KDP crystal to enable the crystal to move in the horizontal direction, and capturing the scattered light image in real time by using a CCD camera matrix; and judging the crystal growth areas of all the measurement areas of the KDP crystal to be measured according to the scattered light image. According to the method, the cone-column growth region of the KDP crystal can be directly judged by quickly and effectively utilizing the scattering image, the judgment method is simpler, and the judgment result is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of KDP crystal quality detection, and particularly to an imaging discrimination method and system for the cone-column growth region of KDP crystals. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Potassium dihydrogen phosphate (KH 2 PO 4 , abbreviated as KDP) and its deuteride (KD X H (2-X) PO 4 , abbreviated as DKDP), ammonium dihydrogen phosphate (NH 4 H 2 PO 4 , abbreviated as ADP) and its deuteride (N(D X H 1-X ) 4 (D Y H 1-Y ) 2 PO 4 , abbreviated as DADP) and other crystal materials are collectively referred to as KDP crystal materials. Tetragonal KDP crystals have many advantages such as a wide light transmission band, strong anti-laser damage performance, high non-linear conversion efficiency, the ability to grow into large single crystals and easy processing, and are widely used in high-tech fields such as laser frequency conversion and electro-optic Q-switching. In recent years, the inertial confinement fusion (ICF) project has attracted widespread attention. Large-sized KDP crystals are the only non-linear optical crystal materials that can be used for electro-optic switches and frequency conversion in the ICF project so far. With the continuous improvement of the transmitted laser energy in the ICF project, the improvement of crystal quality and anti-laser damage ability has also become one of the research focuses.

[0004] There are mainly two preparation methods for KDP crystals, namely the traditional growth method and the point-seed rapid growth method. Among them, the KDP crystals grown by the traditional growth method grow along the

[001] direction through the (101) cone surface, with a growth rate of 0.5 - 1 mm / day, a long growth period, and a large seed crystal recovery area in the grown crystal. The crystals in this area belong to the polycrystalline region and cannot be actually utilized. Therefore, this growth method has a long cycle, high risk, high cost, and low crystal utilization rate. The point-seed rapid growth technology developed in recent years can enable the crystal to grow simultaneously along the

[100] and

[001] directions, with a growth rate of up to 10 - 20 mm / day, greatly shortening the crystal growth cycle, reducing the cost, and having a very small crystal recovery area, which greatly improves the crystal utilization rate. Therefore, the rapid growth method of KDP crystals has great application prospects.

[0005] The dot-seed rapid growth method uses a dot-shaped seed crystal to rapidly grow simultaneously along two directions of

[001] and

[100] in a solution with a relatively high supersaturation. The finally obtained crystal includes a columnar region grown on the columnar surface and a conical region grown on the conical surface. Therefore, there is a conical-columnar interface at the junction of the conical region and the columnar region inside the crystal, and the quality of this part of the crystal is poor and cannot meet the requirements. Due to the electrical properties of the columnar surface, the columnar region of the crystal is more likely to adsorb impurity ions in the solution, resulting in a relatively large linear absorption coefficient, and the components made therefrom are difficult to meet the engineering requirements. Therefore, there are significant quality differences between the conical surface and the columnar growth regions of KDP-type crystals grown by the rapid growth method, which is the biggest drawback in the rapid growth process and restricts the application of the crystals in engineering. Certain measures need to be taken to distinguish the conical-columnar regions and improve the utilization rate of the crystals.

[0006] The Chinese invention patent with the invention name of "Discrimination method and measurement device for conical-columnar growth regions of KDP-type crystals", publication date of March 2, 2021, and publication number of CN112432898A uses the different transmittances of different regions of the crystal as the evaluation criterion. However, this method has high requirements for the quality of the crystal, the judgment criteria cannot be unified under different conditions, the judgment at the conical-columnar junction is relatively fuzzy, which is not conducive to actual operation, and the laser band used belongs to deep ultraviolet light, and the operation needs to be carried out by professionals. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide an imaging discrimination method and system for conical-columnar growth regions of KDP-type crystals, which can quickly and effectively directly discriminate the conical-columnar growth regions of KDP-type crystals by using the scattering image, the discrimination method is simpler, and the discrimination result is more accurate.

[0008] In order to achieve the above purpose, the present invention is realized through the following technical solutions:

[0009] The first aspect of the present invention provides an imaging discrimination method for conical-columnar growth regions of KDP-type crystals, including the following steps:

[0010] Obtain the KDP-type crystal to be measured and inspect the KDP-type crystal to be measured;

[0011] Build an imaging discrimination system, use the imaging discrimination system to image the KDP-type crystal to be measured, and obtain the scattering light image of the KDP-type crystal. Among them, place the KDP-type crystal to be measured in the imaging discrimination system, and the scattered laser obliquely irradiates the surface of the KDP-type crystal to be measured, and move the crystal horizontally, and the CCD camera matrix captures the scattering light image in real time;

[0012] Judge the crystal growth regions at all measurement regions of the KDP-type crystal to be measured through the scattering light image.

[0013] Further, the KDP-like crystal to be measured is a type-II cut KDP crystal with rapid growth.

[0014] Further, the KDP-like crystals include potassium dihydrogen phosphate and its isotopic compound potassium dihydrogen phosphate-d; ammonium dihydrogen phosphate and its isotopic compound ammonium dihydrogen phosphate-d.

[0015] Further, the criteria for inspecting the KDP-like crystal to be measured are as follows:

[0016] The KDP-like crystal to be measured has been cut, oriented, polished, and has no obvious processing defects on the surface, and no obvious growth defects inside the crystal.

[0017] Further, the specific steps for imaging the KDP-like crystal to be measured using the imaging discrimination system are as follows:

[0018] Place the KDP-like crystal to be measured on the displacement platform, and the scattered laser obliquely irradiates the surface of the KDP-like crystal to be measured;

[0019] The CCD camera matrix lens is focused on the surface of the KDP-like crystal to be measured;

[0020] The scattered light is captured by the CCD camera matrix and imaged after being read by the software in the computer.

[0021] Furthermore, the laser source emits continuous laser, and the laser energy fluctuation ≤ 1%, where the wavelength of the continuous laser is 380 nm - 780 nm.

[0022] Furthermore, the angle between the laser and the surface of the KDP-like crystal to be measured is 30° - 60°, the laser spot is shaped into a line by the lens, and the linear laser coincides with the crystal edge.

[0023] Furthermore, the length of the focusing field of view of the CCD camera matrix lens is less than the length of the linear laser.

[0024] Further, the specific steps for judging the crystal growth region at all measurement regions of the KDP-like crystal to be measured through the scattered light image are as follows:

[0025] There are two regions with different brightness levels in the scattered light image, and there is an obvious dividing line between the two regions. Among them, the region with higher brightness is the region with more obvious scattered light, which is the cylindrical growth region of the KDP-like crystal to be measured; the region with lower brightness has less obvious scattered light, which belongs to the conical growth region of the KDP-like crystal to be measured; the dividing line in the middle of the crystal belongs to the cone-column junction of the KDP-like crystal to be measured.

[0026] In the second aspect of the present invention, there is provided an imaging discrimination system for the imaging discrimination method of the cone-column growth region of KDP-like crystals described in the first aspect, including a laser light source, a lens, a displacement platform, a CCD camera, and a computer. The displacement platform is used to place the KDP-like crystal to be measured. The laser beam generated by the laser light source becomes a line light source through the lens and obliquely irradiates the surface of the displacement platform. The CCD camera matrix lens is above the displacement platform and is used to capture the reflected light. The CCD camera matrix lens focuses on the surface of the KDP-like crystal to be measured. After the transmitted light is scattered by the KDP-like crystal to be measured, it is captured by the CCD camera matrix lens. The CCD camera is connected to the computer, and the displacement platform is controlled by the computer to move the KDP-like crystal to be measured in the horizontal direction, and images are obtained in real time.

[0027] The above one or more technical solutions have the following beneficial effects:

[0028] The present invention discloses an imaging discrimination method and system for the cone-column growth region of KDP-like crystals, which performs surface treatment on the KDP-like crystals; places the KDP-like crystals in the scattering optical path system; and uses a CCD camera array to collect the scattering images. This method can simply and efficiently obtain the distribution images of the cone-column growth regions of rapidly growing KDP-like crystals. Compared with the complex structures of the prior art, the discrimination system of the present invention has a simple structure, is easy to implement, and can directly image. The cone-column growth regions of KDP-like crystals can be discriminated according to the imaging results. The overall automation effect is high, manual experience judgment is not required, the technical requirements for experimental personnel are reduced, and the judgment results are more accurate.

[0029] The advantages of the additional aspects of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0031] Figure 1 It is the structure diagram of the imaging discrimination system in Embodiment 1 of the present invention;

[0032] Figure 2 It is the imaging effect diagram of the scattered light image in Embodiment 1 of the present invention;

[0033] Among them, 1. Laser light source, 2. Lens, 3. Displacement platform, 4. CCD camera, 5. Computer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, 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 the present invention pertains.

[0035] It should be noted that the terms used herein are merely for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] Example 1:

[0037] Example 1 of the present invention provides an imaging discrimination method for the cone-column growth region of KDP-type crystals. The KDP-type crystal to be measured is subjected to scattering scanning in the visible light range, and the cone-column growth region of the fast-growing KDP-type crystal can be directly discriminated according to the scanning image. The specific steps are as follows:

[0038] Step 1: Obtain the KDP-type crystal to be measured and inspect the KDP-type crystal to be measured.

[0039] In a specific embodiment, the KDP-type crystal to be measured is a fast-growing type-II cut KDP crystal with a crystal size of 30 mm × 30 mm × 10 mm. The standard for inspecting the KDP-type crystal to be measured in this embodiment is that the KDP-type crystal to be measured has undergone processing steps such as cutting, orientation, and polishing and has no obvious processing defects such as scratches on the surface, and there are no obvious growth defects inside the crystal.

[0040] KDP-type crystals include potassium dihydrogen phosphate and its isotopic compound potassium dihydrogen phosphate-d, ammonium dihydrogen phosphate and its isotopic compound ammonium dihydrogen phosphate-d.

[0041] Step 2: Build an imaging discrimination system and use the imaging discrimination system to image the KDP-type crystal to be measured to obtain a scattered light image of the KDP-type crystal. Among them, the KDP-type crystal to be measured is placed in the imaging discrimination system, and the scattered laser is obliquely incident on the surface of the KDP-type crystal to be measured, and the crystal is moved in the horizontal direction, and the scattered light image is captured in real time by the CCD camera matrix.

[0042] Step 2.1: Build an imaging discrimination system.

[0043] In a specific embodiment, as Figure 1As shown in the figure, the imaging discrimination system of the imaging discrimination method includes a laser light source 1, a lens 2, a displacement platform 3, a CCD camera 4, and a computer 5. The displacement platform 3 is used to place the KDP crystal to be measured. The laser beam generated by the laser light source 1 becomes a line light source through the lens and is obliquely incident on the surface of the displacement platform 3. The CCD camera matrix lens is above the displacement platform and is used to capture the reflected light. The CCD camera matrix lens is focused on the surface of the KDP crystal to be measured. After the transmitted light is scattered by the KDP crystal to be measured, it is captured by the CCD camera matrix lens. The CCD camera 4 is connected to the computer 5, and the displacement platform 3 is controlled by the computer 5 to move the KDP crystal to be measured in the horizontal direction, and images are obtained in real time.

[0044] Step 2.2: Place the KDP crystal to be measured on the displacement platform, and the scattered laser is obliquely incident on the surface of the KDP crystal to be measured.

[0045] In a specific embodiment, the plane angle between the laser light source 1 and the displacement platform 3 is 45°, and the CCD camera matrix lens is placed perpendicular to the displacement platform 3 to allow the 45° reflected light to enter the lens.

[0046] The laser light source 1 is a visible light laser light source, and the laser light source emits continuous laser. The laser energy fluctuation is ≤1%. The wavelength of the continuous laser is 380nm - 780nm. Preferably, in this embodiment, the wavelength of the continuous laser is 532nm. This solution has strong applicability, and any wavelength within the visible light range (380nm - 780nm) can be taken. In this embodiment, a 532nm wavelength laser with relatively mature manufacturing technology is selected. The cost of the laser is relatively low and it is safer. The 532nm visible light band continuous light emitted by the laser light source 1 is obliquely incident on the surface of the displacement platform after passing through the lens 2, and the laser energy fluctuation <1%. The angle between the laser and the surface of the KDP crystal to be measured is 30° - 60°. Preferably, in this embodiment, the angle between the laser and the surface of the KDP crystal to be measured is 45°. The laser spot is shaped into a line by the lens, and the line laser coincides with the crystal edge. The coincidence of the line laser and the crystal edge can ensure a complete image and easier positioning. In this embodiment, the lens 2 is a Powell prism with a focal length of 10cm, and the moving accuracy of the two-dimensional displacement platform in the X and Y directions is 100μm.

[0047] Step 2.3: The CCD camera matrix lens is focused on the surface of the KDP crystal to be measured.

[0048] In a specific embodiment, the CCD camera matrix lens is placed perpendicular to the displacement platform 3, and the CCD camera matrix lens is focused on the surface of the KDP crystal to be measured; the scattered light is captured by the CCD camera matrix, and the length of the focusing field of view of the CCD camera matrix lens is less than the length of the line laser.

[0049] Step 2.4: The scattered light is captured by the CCD camera matrix and the imaging is read through the software in the computer 5.

[0050] Step 2.5: Move the KDP crystal to be measured at a uniform speed in the horizontal direction, with an amplitude slightly smaller than the length of the CCD camera's field of view. In this embodiment, the moving distance each time is 0.8 times the length of the field of view, and the edge coincidence is 10%. At this time, the boundary line can be ensured to be more accurate. And the scattered light image is captured in real time by the CCD camera matrix, and then the growth area of the KDP crystal can be judged through the image.

[0051] In a specific implementation manner, in the established imaging discrimination system, keep the device at a fixed angle unchanged, and move the KDP crystal to be measured within the plane. Specifically, move the crystal to be measured in the X direction or Y direction perpendicular to the incident light plane respectively, so that the measurement light and the CCD camera matrix continuously scan the surface of the KDP crystal to be measured, and repeat the above to measure the scattered images at the corresponding positions of the crystal, and splice the scattered images of the KDP crystal by using the computer according to the corresponding measurement point coordinates in the X and Y directions.

[0052] In this embodiment, starting from the edge of the crystal, move along the X direction in turn, with a moving distance of 0.8 times the length of the CCD field of view each time. After moving in the same row is completed, return to the origin position, move 0.8 times the length of the CCD field of view in the Y direction, and continue to move along the X direction. Repeat this step to obtain all the images, and use computer software to splice the obtained images. With an edge coincidence of 10%, a complete image can be obtained, as Figure 2 shown. Then the crystal growth area at all the measurement areas of the KDP crystal to be measured can be judged through the image.

[0053] Step 3: Judge the crystal growth area at all the measurement areas of the KDP crystal to be measured through the scattered light image.

[0054] In a specific implementation manner, as Figure 2 shown, there are two areas with different brightness levels in the scattered light image, and there is an obvious boundary line between the two areas. Among them, the area with higher brightness is the area where the scattered light is more obvious, which is the columnar growth area of the KDP crystal to be measured; the area with darker brightness has less obvious scattered light, which belongs to the conical growth area of the KDP crystal to be measured; the boundary line in the middle of the crystal belongs to the cone-column junction of the KDP crystal to be measured.

[0055] Embodiment 2:

[0056] Embodiment 2 of the present invention provides an imaging discrimination system for the imaging discrimination method of the cone-column growth region of KDP crystals described in Embodiment 1, including a laser light source, a lens, a displacement platform, a CCD camera, and a computer. The displacement platform is used to place the KDP crystal to be measured. The laser beam generated by the laser light source becomes a line light source after passing through the lens and is obliquely incident on the surface of the displacement platform. The angle between the laser light source and the plane of the displacement platform is 45°. The CCD camera matrix lens is above the displacement platform and is used to capture the reflected light. Specifically, the CCD camera matrix lens is placed perpendicular to the displacement platform to allow the 45° reflected light to enter the lens. The CCD camera matrix lens is focused on the surface of the KDP crystal to be measured. After the transmitted light is scattered by the KDP crystal to be measured, it is captured by the CCD camera matrix lens. The CCD camera is connected to the computer, and the displacement platform is controlled by the computer to move the KDP crystal to be measured in the horizontal direction to obtain images in real time.

[0057] In this embodiment, the selected laser light source emits continuous laser, and the laser energy fluctuation ≤ 1%. The wavelength of the continuous laser is 380 nm - 780 nm. Preferably, the wavelength of the continuous laser is 532 nm. The lens is a Powell prism with a focal length of 10 cm. The moving precision of the two-dimensional displacement platform in the X and Y directions is 100 μm. The crystal is a type-II cut KDP crystal with rapid growth, and the crystal size is 30 mm × 30 mm × 10 mm. After being processed by cutting, orientation, polishing, etc., the surface has no obvious processing defects such as scratches, and there are no obvious growth defects inside the crystal.

[0058] Each step involved in the above Embodiment 2 corresponds to that in Method Embodiment 1. For specific implementation manners, reference can be made to the relevant description part of Embodiment 1.

[0059] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A method for imaging and distinguishing the growth area of ​​a cone column of a KDP-type crystal, characterized in that: The following steps are involved: Obtain a KDP crystal to be tested, and inspect the KDP crystal to be tested; An imaging discrimination system is built, and the imaging discrimination system is used to image the KDP crystal to be tested, so as to obtain a scattered light image of the KDP crystal, wherein the KDP crystal to be tested is placed in the imaging discrimination system, and the scattered laser is incident obliquely on the surface of the KDP crystal to be tested, so that the crystal moves in the horizontal direction, and the scattered light image is captured in real time by the CCD camera matrix; The crystal growth area at all measurement areas of the KDP crystal to be tested is determined by the scattered light image.

2. The imaging identification method of the KDP crystal cone growth region according to claim 1, characterized in that: The KDP type crystal to be tested is a fast-growing type II cut KDP crystal.

3. The imaging identification method of the KDP crystal cone growth region according to claim 1, characterized in that: KDP crystals include potassium dihydrogen phosphate and its isotope compound deuterated potassium dihydrogen phosphate crystals, ammonium dihydrogen phosphate and its isotope compound deuterated ammonium dihydrogen phosphate crystals.

4. The imaging identification method of the KDP type crystal cone column growth area according to claim 1, characterized in that: The inspection standards for the KDP crystals to be tested are: The KDP crystal to be tested has been cut, oriented, and polished and has no obvious processing defects on the surface, and no obvious growth defects inside the crystal.

5. The imaging identification method of the KDP crystal cone growth region according to claim 1, characterized in that: The specific steps of using the imaging discrimination system to image the KDP crystal to be tested are: The KDP crystal to be tested is placed on a displacement platform, and the scattered laser is incident obliquely on the surface of the KDP crystal to be tested; The CCD camera matrix lens is focused on the surface of the KDP crystal to be tested; The scattered light is captured by the CCD camera matrix and the image is read by the software in the computer.

6. The imaging identification method of the KDP crystal cone growth region according to claim 5, characterized in that: The laser light source emits continuous laser, and the laser energy fluctuation is ≤1%, wherein the continuous laser wavelength is 380nm-780nm.

7. The imaging identification method of the KDP crystal cone growth region according to claim 6, characterized in that: The angle between the laser and the surface of the KDP crystal to be tested is 30°-60°, the laser spot is shaped into a linear shape by a lens, and the linear laser coincides with the edge of the crystal.

8. The imaging identification method of the KDP crystal cone growth region according to claim 7, characterized in that: The focusing field length of the CCD camera matrix lens is shorter than the linear laser length.

9. The imaging identification method of the KDP crystal cone growth region according to claim 1, characterized in that: The specific steps of determining the crystal growth area at all measurement areas of the KDP crystal to be measured by using the scattered light image are as follows: There are two areas of different brightness in the scattered light image, and there is an obvious dividing line between the two areas. The area with higher brightness is the area with more obvious scattered light, which is the cylindrical growth area of ​​the KDP crystal to be tested; the area with darker brightness has less obvious scattered light, which belongs to the conical growth area of ​​the KDP crystal to be tested; the dividing line located in the middle of the crystal belongs to the cone-column junction of the KDP crystal to be tested.

10. An imaging discrimination system for the imaging discrimination method of the growth region of the cone column of the KDP crystal according to any one of claims 1 to 9, comprising a laser light source, a lens, a displacement platform, a CCD camera and a computer, wherein the displacement platform is used to place the KDP crystal to be tested, the laser beam generated by the laser light source becomes a line light source through the lens and is obliquely incident on the surface of the displacement platform, and the CCD camera matrix lens is above the displacement platform and is used to capture reflected light; The matrix lens of the CCD camera is focused on the surface of the KDP crystal to be tested. The transmitted light is scattered by the KDP crystal to be tested and then captured by the matrix lens of the CCD camera. The CCD camera is connected to a computer, and the displacement platform is controlled by the computer to move the KDP crystal to be tested in the horizontal direction to obtain images in real time.

Images