A method for growing long KDP-like crystal seed crystal limiting column region

Abstract

The application discloses a KDP crystal long seed crystal limiting columnar zone growth method and belongs to the technical field of KDP crystal growth. A KDP crystal growth device is used for growth, a long seed crystal with a [001] direction height is fixed at the center of a crystal loading frame, physical limiting is formed on both sides of the seed crystal by using parallel baffles, the growth of the crystal in [100] and [010] directions is inhibited, and the crystal is guided to grow rapidly in a [001] direction on a conical surface. In the growth process, the crystal loading frame is preheated, and overheating treatment and rotation process are adopted. The method significantly improves the crystal growth speed, the obtained crystal conical zone is regular, the conical zone proportion is high, and the growth efficiency of the large-size KDP crystal and the utilization rate of the slice are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of KDP-type crystal growth technology, specifically relating to a method for growing KDP-type crystal seed crystals in a confined column region. Background Technology

[0002] Potassium dihydrogen phosphate / potassium dideuterium phosphate (KDP / DKDP) crystals are indispensable key materials for frequency doubling and electro-optics in large-aperture laser devices (such as ICF) due to their excellent nonlinear optical properties. To meet the growing demand for large-aperture, high-quality crystals, their growth methods have evolved from the "traditional growth method" to the "point-seed crystal rapid growth method". The traditional growth method grows slowly in a single direction (

[001] direction) under low supersaturation. Although it can obtain a high-quality full-conical crystal, the growth cycle is too long and the efficiency is low. The point-seed crystal rapid growth method significantly improves the growth rate by allowing the crystal to grow rapidly in both the

[001] and

[100] directions at the same time. However, this introduces a poor-quality interface between the cone and column regions. Furthermore, the column region crystal is more prone to adsorbing impurities due to its intrinsic properties, making it difficult for the fabricated components to meet the requirements of high-performance applications.

[0003] It is evident that existing growth technologies struggle to balance crystal growth rate and final quality, creating a significant contradiction: restricting the growth direction (such as traditional methods) severely limits growth efficiency, while allowing unrestricted multi-directional rapid growth (such as point-seed crystal rapid growth) introduces internal defects and impurities, leading to a decline in crystal quality. How to effectively improve the growth efficiency of KDP / DKDP crystals while ensuring optical quality, achieving a balance between "rapid growth" and "high-quality crystals," has become a critical technical problem urgently needing to be solved in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for confined column growth of KDP-type crystal seed crystals.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for growing a KDP-type crystal seed crystal in a confined column region, using a KDP-type crystal growth apparatus, the growth apparatus comprising a motor and a crystal carrier; the crystal carrier comprising: a connecting rod, an upper panel, a lower tray, supporting side rods, and baffles; one end of the connecting rod is fixedly connected to the upper surface of the upper panel, and the other end is fixedly connected to the rotating shaft of the motor; a supporting side rod is provided between the upper panel and the lower tray, and two baffles parallel to each other and perpendicular to the upper panel and the lower tray are provided between the supporting side rods; The method for growing KDP-type crystals in a confined column region with long seed crystals includes the following steps: A long seed crystal with a height direction of

[001] and a horizontal direction of

[010] is fixed at the center of the lower tray. The length of the long seed crystal is equal to the distance between the two baffles. The crystal carrier with the seed crystal is preheated to 4-6°C above the saturation point of the growth solution. After being removed, it is placed in the growth solution. The connecting rod is connected to the motor and rotated. After overheating, it is cooled and grown to obtain KDP-type crystals.

[0006] Preferably, the crystal carrier on which the seed crystal is mounted is preheated to 5°C above the saturation point temperature of the growth solution.

[0007] Preferably, the height of the baffle is the distance between the upper panel and the lower tray.

[0008] Preferably, the saturation point of the growth solution is 50-70°C.

[0009] Preferably, the rotation speed is in the range of 15-30 rpm, and the rotation pattern adopts a cycle of forward rotation for 90s - deceleration for 2s - stop for 15s - reverse acceleration for 2s - reverse rotation for 90s - deceleration for 2s - stop for 15s - forward acceleration for 2s.

[0010] Preferably, the cooling growth after overheating treatment includes: heating the growth solution to 2°C above the saturation point temperature, and then cooling it to make the supersaturation of the growth solution between 5-10%, thereby growing crystals and obtaining KDP-type crystals.

[0011] Preferably, the connection of the crystal carrier is smooth and seamless.

[0012] Preferably, the KDP-type crystal is a KDP crystal or a DKDP crystal.

[0013] In a second aspect, the present invention provides a KDP-type crystal, which is prepared by the KDP-type crystal long seed crystal confined column region growth method described in the first aspect.

[0014] Preferably, the sample is taken from the cone region of the KDP-type crystal, and the crystal utilization rate of the KDP-type crystal is 20-25%.

[0015] The beneficial effects of this invention are as follows: This invention provides a method for confined columnar growth of KDP-type crystals using long seed crystals. By employing long seed crystals of specific orientation and size, combined with precise preheating, overheating, and cooling growth processes, it achieves efficient and controllable crystal growth in a single dominant direction. Experiments show that this method can obtain high-quality KDP / DKDP crystals with dimensions of 60 cm × 45 cm × 60 cm in approximately six months, significantly improving the growth rate compared to the 2-3 year cycle required by traditional growth methods. Simultaneously, the obtained crystals exhibit intact internal structures and excellent optical homogeneity, effectively overcoming the common problems of internal defects and impurity accumulation during rapid growth. Thus, while ensuring the optical quality of the crystal, it significantly increases the usable volume and slicing efficiency, providing a reliable crystal material basis for the fabrication of large-aperture, high-performance nonlinear optical components. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 This is a schematic diagram of the assembly of the growth tank and crystal carrier used in the KDP-type crystal long seed crystal confined column region growth method of the present invention.

[0018] Figure 2 This is a schematic diagram of the crystal carrier used in the KDP-type crystal long seed crystal confined pillar region growth method of the present invention.

[0019] Figure 3 This is a schematic diagram of cutting multiple third harmonic devices from KDP-type crystals grown using the seed crystal confined column region growth method of the present invention.

[0020] Wherein, 1: growth tank; 2: growth solution; 3: crystal carrier; 4: rotating shaft; 5: motor; 6: connecting rod; 7: upper panel; 8: first support side rod; 9: second support side rod; 10: first baffle; 11: second baffle; 12: lower tray; 13: seed crystal; 14: KDP crystal; 15: third frequency harmonic device. Detailed Implementation

[0021] Terminology Explanation: In this invention, "saturation point" refers to the saturation temperature. T satThe saturation point (SOP) refers to the temperature at which a solution reaches a saturated equilibrium state at its current concentration. When the solution temperature equals this SOP, the solution is perfectly saturated, neither crystallizing nor dissolving. When the solution temperature is above this SOP, the solution is in an unsaturated state (metastable state), and crystals placed in it will slightly dissolve the surface, acting as a leveling agent. When the solution temperature is below this SOP, the solution is in a supersaturated state, generating a driving force for crystallization, and crystals begin to grow.

[0022] In this invention, "supersaturation" refers to the actual concentration of the growth solution at the current temperature during the cooling growth process. C ) and the saturation concentration at that temperature ( C* The relative difference between () and (). Its calculation formula is usually expressed as σ = ( C - C* ) / C* ×100%. This invention maintains this value between 5-10% by controlling the cooling rate, ensuring high-quality and high-efficiency growth of KDP-type crystals within the thermodynamically stable metastable region.

[0023] In this invention, "crystal utilization rate" refers to the volume percentage of a cultured crystal blank that can be actually cut into laser elements that meet performance requirements.

[0024] The core of this invention is to disclose a method for growing KDP-type crystals in a confined column region with long seed crystals, so as to quickly obtain high-quality KDP-type crystals.

[0025] To enable those skilled in the art to better understand the present invention, embodiments of the present invention will be described below with reference to the accompanying drawings. Furthermore, the embodiments shown below do not limit the scope of the invention as described in the claims. Additionally, the complete content of the configurations represented in the following embodiments is not limited to those necessary for the solution of the invention as described in the claims.

[0026] In the existing technology, the growth of KDP-type crystals faces an irreconcilable core contradiction between "efficiency" and "quality," which stems from the inherent limitations of crystallographic properties and growth kinetics. From a crystallographic perspective, the growth characteristics of different crystal faces of KDP-type crystals vary greatly. Among them, the cone face (such as the

[101] face) is positively charged, has a stable growth interface, and has a weak adsorption capacity for impurity cations, making it a high-quality growth region with excellent optical quality. On the other hand, the cylindrical face (such as the

[100] face) is negatively charged, and its growth face is extremely sensitive to impurity cations in the solution, making it more prone to forming inclusions, scattering centers, and other defects, thus constituting a low-quality growth region, whose linear absorption coefficient is significantly higher than that of the cone crystal.

[0027] Traditional growth methods employ a low supersaturation approach, allowing crystals to grow slowly only along the

[001] direction. Essentially, this ensures the crystal is entirely grown from high-quality cone surfaces, resulting in high-quality, fully cone-shaped crystals without internal abrupt interfaces. However, this method, while suppressing cylindrical development, also sacrifices growth rate, leading to excessively long growth cycles that fail to meet the time-sensitive requirements of large-diameter crystals.

[0028] To improve efficiency, the point-seed rapid growth method employs high supersaturation and allows the crystal to grow freely and competitively in both the

[001] and

[100] directions. While this significantly shortens the growth cycle, it inevitably stimulates the rapid development of both high-quality cones and low-quality cylinders. This leads to two insurmountable quality problems: first, the crystal inevitably forms interfaces between cone and cylinder regions with drastically degraded optical properties; second, the rapidly growing cylinder regions become areas of impurity enrichment, resulting in a decline in the overall macroscopic optical quality of the crystal. Therefore, this method sacrifices crystal quality for increased growth efficiency.

[0029] This invention addresses the core contradiction in existing KDP-type crystal growth methods, which struggle to balance growth rate and crystal quality. It proposes a directional constraint growth concept. By precisely controlling the geometry and orientation of the seed crystal, this invention physically pre-limits the crystal's growth dimensions, guiding the crystal to grow rapidly and stably primarily along a single, high-quality crystal orientation. Based on this concept, the technical solution employs a specific elongated seed crystal with its height direction aligned with the

[001] direction, precisely fixed within the growth apparatus, aligning the seed crystal's growth direction with the specific crystal orientation. This design establishes a physical constraint framework from the initial growth stage, ensuring rapid crystal growth under high supersaturation while essentially suppressing the development of lower-quality cylindrical surfaces, forcing the crystal growth material to preferentially and concentratedly accumulate towards the high-quality conical surface direction.

[0030] This invention ingeniously unifies the seemingly contradictory goals of rapid growth and high-quality growth. Using a seed crystal with a specific geometric shape as a growth template and spatial constraint, it guides the preferred orientation of crystal growth at the microscopic level and simplifies the crystal morphology and eliminates internal quality abrupt interfaces at the macroscopic level, achieving a stable and controllable cone-prism interface. The growth rate is several times faster than traditional methods, while avoiding the cone-prism interface and columnar region impurity problems caused by rapid growth methods. By achieving stable and controllable cone-prism interface growth, the cone-prism interface is perfectly avoided during cutting, enabling single-cone region sampling. This fundamentally overcomes the limitations of existing technologies, achieving efficient and controllable preparation of high-quality, large-diameter KDP-type crystals. Furthermore, when cutting third harmonic generation devices from the obtained KDP-type crystals, more blanks can be obtained in the cone region, avoiding the influence of the cone-prism interface.

[0031] A first typical embodiment of the present invention provides a method for growing KDP-type crystals in a confined column region using a seed crystal growth apparatus. The structure of the growth apparatus is as follows: Figure 1 and Figure 2 As shown, the device includes a motor 5 and a die carrier 3. The die carrier 3 includes a connecting rod 6, an upper panel 7, a lower tray 12, supporting side rods, and baffles. One end of the connecting rod 6 is fixedly connected to the upper surface of the upper panel 7, and the other end is fixedly connected to the rotating shaft 4 of the motor 5. Supporting side rods (first supporting side rod 8 and second supporting side rod 9) are provided between the upper panel 7 and the lower tray 12. Two baffles (first baffle 10 and second baffle 11) are provided between the supporting side rods and are parallel to each other and perpendicular to the upper panel 7 and the lower tray 12. The method for growing KDP-type crystals in a confined column region with long seed crystals includes the following steps: A long seed crystal 13 with a height direction of

[001] and a horizontal direction of

[010] is fixed at the center of the lower tray 12. The length of the long seed crystal 13 is equal to the distance between the two baffles. The crystal carrier 3, on which the seed crystal 13 is mounted, is preheated to 4-6°C above the saturation point of the growth solution. After being removed, it is placed in the growth solution. The connecting rod 6 is connected to the motor 5 and rotated. After overheating, it is cooled and grown to obtain KDP-type crystals.

[0032] refer to Figure 1 The growth apparatus of this invention also includes a growth tank 1, which has an open top structure for holding the growth solution 2 and the crystal carrier 3. The first support rod 8, the second support rod 9, the upper panel 7, and the lower tray 12 provide rigid support for the seed crystal 13, ensuring the stability of the seed crystal's position during growth (especially during long-cycle, 60 cm-scale large-size growth), preventing displacement or deformation, and providing a mechanical basis for the confined growth of the seed crystal. Baffles, acting as flow field guiding components, are vertically arranged at both ends of the seed crystal 13, guiding the solution flow towards the seed crystal surface and preventing solution circumvention. This, combined with the variable-speed rotation process (15-30 rpm, forward and reverse rotation cycle), confines the convection generated by rotation to the vicinity of the seed crystal, enhancing the efficiency of solution scouring the seed crystal surface and solute transport. The connecting rod 6 connects the upper panel 7 to the motor 5, transmitting rotational power and ensuring that the periodic motion of the variable-speed rotation (forward-stop-reverse rotation) accurately acts on the crystal carrier and the seed crystal, synchronizing fluid disturbance with the seed crystal growth surface.

[0033] In another embodiment of the invention, the crystal carrier on which the seed crystal is mounted is preheated to 5°C above the saturation point temperature of the growth solution.

[0034] This invention does not impose requirements on the size of the long seed crystal; those skilled in the art can set it according to actual conditions. For example, the horizontal length of the long seed crystal can be 430-450 mm, and the horizontal width and height can both be 8-12 mm. More specifically, the horizontal length of the long seed crystal can be 440 mm, and the horizontal width and height can both be 10 mm.

[0035] The horizontal length of the long seed crystal is the same as the distance between the baffles, restricting the disordered expansion in the

[100] direction; the small and regular cross-section constrains the growth freedom in the

[010] direction. This geometric design forces the growth material to preferentially and rapidly accumulate along the

[001] direction (the dominant direction of the cone), suppressing the formation of inferior columnar regions at the physical level. Under the rapid growth conditions of high supersaturation, high-quality crystals with excellent cone regions as the main body, complete structure, and few internal defects can still be obtained, thus achieving an engineering unity between growth rate and crystal quality.

[0036] In another embodiment of the present invention, the height of the baffle is the distance between the upper panel and the lower tray. The baffle height is the distance between the upper panel and the lower tray, which can construct a full-height physical isolation barrier. The

[100] and

[010] directions are lateral, and the

[001] direction grows upward. Traditional point seed crystal method leads to disordered expansion of the column region due to lack of lateral constraint. However, the present invention forms a seamless vertical blocking surface on both sides of the seed crystal through the close cooperation between the baffle and the crystal carrier structure, preventing solute from depositing on the column surface, and avoiding defects caused by the lateral growth of the crystal beyond the range of the baffle. Combined with the size limitation of the long seed crystal (length equal to the baffle spacing, small cross-section), this structure ensures that the growth driving force under high supersaturation is concentrated on the axial conical surface development. While maintaining rapid growth (obtaining 60 cm-level crystals within half a year), it maximizes the proportion of high-quality conical regions, minimizes the conical-column interface and impurity adsorption area, and ultimately achieves a simultaneous improvement in crystal utilization and optical quality.

[0037] In another embodiment of the invention, the saturation point of the growth solution is 50-70°C. This saturation temperature range falls within the linear range of the solubility curve, where solubility is relatively high and changes relatively gently. This ensures that the solution has sufficient solute reserves to maintain the high-speed stacking growth of large-sized crystals (e.g., 60cm-sized crystals), and also utilizes the good matching of the thermal expansion coefficients of the solution and crystal at this temperature range to effectively reduce thermal stress during crystal growth and subsequent cooling, thereby avoiding cracking and reducing impurity encapsulation. If the saturation point is too low (below 50°C), the solubility of the solution decreases significantly, and insufficient solute reserves will severely restrict the growth rate, making it difficult to achieve the goal of efficient and rapid growth. If the saturation point is too high (above 70°C), although the solubility is further improved, the difference in thermal expansion between the solution and the crystal intensifies, leading to excessive thermal stress during cooling, which can easily cause crystal cracking. At the same time, high temperatures may increase the activity of impurity ions or cause excessive solvent evaporation, thus degrading the optical quality of the crystal.

[0038] In another embodiment of the invention, the rotation speed ranges from 15 to 30 rpm, and the rotation pattern adopts a cycle of 90 s forward rotation - 2 s deceleration - 15 s stop - 2 s reverse acceleration - 90 s reverse rotation - 2 s deceleration - 15 s stop - 2 s forward acceleration. This invention, by forcing periodic fluid disturbance and boundary layer renewal, maintains high supersaturation (rapid growth) while suppressing component supercooling and impurity adsorption from a fluid dynamics perspective, thereby resolving the contradiction between growth rate and crystal quality. The 15-30 rpm rotation speed range and the alternating forward and reverse rotation cycle synergistically achieve periodic boundary layer disruption and renewal, ensuring efficient solute transport under high supersaturation (maintaining rapid growth) while suppressing component supercooling and impurity adsorption (improving crystal quality), allowing the crystal to maintain low defect density and high optical uniformity even during high-speed growth.

[0039] In another embodiment of the present invention, the cooling growth after overheating treatment includes: heating the growth solution to 2°C above the saturation point temperature, and then cooling it to achieve a supersaturation of 5-10% in the growth solution, thereby growing crystals and obtaining KDP-type crystals. The present invention achieves synergy between speed and quality through precise thermodynamic control. The overheating treatment to 2°C above the saturation point eliminates metastable nuclei and impurity aggregation in the solution, providing a clean foundation for growth and preventing impurities from accumulating in dead zones of the crystal carrier 3. The 5-10% supersaturation drives the solute to migrate rapidly to the seed crystal surface, while the rigid support of the crystal carrier 3 ensures that the long seed crystal 13 maintains its posture during high-speed growth, matching the requirement of "large-size growth of long seed crystals" while remaining below the critical value for compositional supercooling, thus avoiding defects.

[0040] In another embodiment of the present invention, the connection of the crystal carrier 3 is smooth and seamless. The surface of the crystal carrier 3 may be coated with a polytetrafluoroethylene film to ensure a smooth and seamless surface.

[0041] In another embodiment of the present invention, the KDP-type crystal is a KDP crystal or a DKDP crystal.

[0042] The growth apparatus and growth method of this invention establish a robust system architecture of hardware support, fluid control, and thermodynamic drive. Through the spatial constraints of the physical structure and the precise matching of fluid dynamics and thermodynamics, the dual goals of rapid growth and high-quality crystals are achieved. The three main functions of the crystal carrier 3—rigid support, flow field guidance, and power transmission—form a closed loop with the process parameters of superheat / supersaturation and variable-speed rotation. The structure of the growth apparatus provides a stable growth carrier and a controllable flow field space for the process, ensuring that the process parameters can effectively act on the seed crystal surface. The process parameters, in turn, activate the fluid control potential of the production apparatus (baffle guidance + variable-speed rotation to enhance convection), achieving high-speed solute transport, low-impurity encapsulation, and high-quality crystal deposition under the premise of long seed crystal confinement growth.

[0043] A second typical embodiment of the present invention provides a KDP-type crystal, which is prepared by the KDP-type crystal long seed crystal restricted column region growth method described above.

[0044] In another embodiment of the present invention, a sample is taken from the cone region of the KDP-type crystal, and the crystal utilization rate of the KDP-type crystal is 20-25%.

[0045] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0046] Example 1 This embodiment provides a method for confined columnar growth of KDP crystal seed crystals, including the following steps: S1. A growth tank 1 for crystal growth is fabricated. A motor 5 is installed on the upper part of the growth tank 1. The lower end of the rotating shaft 4 of the motor 5 is connected to the connecting rod 6 of the crystal carrier 3.

[0047] S2. The crystal carrier 3 used for crystal growth: The crystal carrier 3 includes an upper panel 7, a lower tray 12, a connecting rod 6, a first supporting side rod 8, a second supporting side rod 9, a first baffle 10, and a second baffle 11. The upper panel 7 is a round plate with smooth edges. The connecting rod 6 is a hollow round rod fixed in the center of the upper panel 7. The lower tray 12 is a round plate. The lower ends of the first supporting side rod 8 and the second supporting side rod 9 are welded to the two ends of the lower tray 12 with the same diameter. The upper ends of the first supporting side rod 8 and the second supporting side rod 9 are welded to the two ends of the upper panel 7. The first baffle 10 and the second baffle 11 are perpendicular to the first supporting side rod 8 and the second supporting side rod 9. The center of the upper surface of the lower tray 12 is the fixed position for the seed crystal 13. All connections are smoothly connected to ensure smoothness.

[0048] S3. Fabricate a KDP long seed crystal 13 with a height direction of

[001] : The length of the KDP long seed crystal 13 is equal to the distance between the first baffle 10 and the second baffle 11 (100 mm), and the horizontal width and height of the KDP long seed crystal 13 are both 10 mm.

[0049] S4. Apply glue to the lower end face of the KDP long seed crystal 13 and install it at the center of the upper surface of the lower tray 12 of the crystal carrier 3, with both ends of the long seed crystal 13 tightly attached to the baffle.

[0050] S5. Prepare KDP crystal growth solution 2 with a saturation point of 55℃.

[0051] S6. Place the crystal carrier 3 with the KDP seed crystal 13 installed in the oven and preheat for 24 hours at a temperature of 57°C.

[0052] S7. After preheating, place the crystal carrier 3 with the KDP seed crystal 13 installed into the prepared KDP growth solution 2, connect the connecting rod 6 of the crystal carrier 3 to the rotating shaft 4 of the motor 5, start the motor 5, set the speed to 30 rpm, and the rotation mode adopts a cycle of forward rotation 90 s - deceleration 2 s - stop 15 s - reverse acceleration 2 s - reverse rotation 90 s - deceleration 2 s - stop 15 s - forward acceleration 2 s, where s is seconds.

[0053] S8. The KDP growth solution 2 is heated to 57°C for heat treatment, so that all three exposed surfaces of the KDP seed crystal 13 are dissolved but not broken. Then the temperature is lowered so that the supersaturation of the KDP growth solution 2 is always 10%. The KDP crystal then begins to grow on the KDP seed crystal 13 in a single cone. After 14 days of growth, a KDP crystal with a size of 100 mm × 116 mm × 103 mm is obtained, and the crystal utilization rate is 20%.

[0054] Example 2 This embodiment provides a method for growing DKDP crystals with 70% deuteration in a confined column region, including the following steps: S1. A growth tank 1 for crystal growth is made. A motor 5 is installed on the upper part of the growth tank 1. The lower end of the shaft 4 of the motor 5 is connected to the connecting rod 6 of the crystal carrier 3.

[0055] S2. The crystal carrier 3 used for crystal growth: The crystal carrier 3 includes an upper panel 7, a lower tray 12, a connecting rod 6, a first supporting side rod 8, a second supporting side rod 9, a first baffle 10, and a second baffle 11. The upper panel 7 is a round plate with smooth edges. The connecting rod 6 is a hollow round rod fixed in the center of the upper surface of the upper panel 7. The lower tray 12 is a round plate. The lower ends of the first supporting side rod 8 and the second supporting side rod 9 are welded to the two ends of the same diameter of the lower tray 12. The upper ends of the first supporting side rod 8 and the second supporting side rod 9 are welded to the two ends of the upper panel 7. The first baffle 10 and the second baffle 11 are perpendicular to the first supporting side rod 8 and the second supporting side rod 9. The center of the upper surface of the lower tray 12 is the fixed position for the seed crystal 13. All connections are smoothly connected to ensure smoothness.

[0056] S3. Fabricate a DKDP long seed crystal 13 with the height direction in the

[001] direction: The length of the DKDP long seed crystal 13 is equal to the distance between the first baffle 10 and the second baffle 11 (100 mm), and the horizontal width and height of the DKDP long seed crystal 13 are both 10 mm.

[0057] S4. Apply glue to the lower end face of the DKDP long seed crystal 13 and install it at the center of the upper surface of the lower tray 12 of the crystal carrier 3, with both ends of the DKDP long seed crystal 13 tightly attached to the baffle.

[0058] S5. Prepare DKDP crystal growth solution 2 with a saturation point of 60℃.

[0059] S6. Place the crystal carrier 3 with the DKDP long seed crystal 13 installed in the oven and preheat for 12 hours at a temperature of 62°C.

[0060] S7. After preheating, place the crystal carrier 3 with the DKDP seed crystal 13 installed into the prepared DKDP growth solution 2. Connect the connecting rod 6 of the crystal carrier 3 to the rotating shaft 4 of the motor 5. Start the motor 5 and set the speed to 20 rpm. The rotation mode adopts a cycle of forward rotation 90 s - deceleration 2 s - stop 15 s - reverse acceleration 2 s - reverse rotation 90 s - deceleration 2 s - stop 15 s - forward acceleration 2 s, where s is seconds.

[0061] S8. The DKDP growth solution 2 was heated to 62°C for heat treatment, causing all three sides of the DKDP seed crystal 13 to dissolve completely without breaking it. Then, the solution was cooled to maintain a supersaturation of 10% in the DKDP growth solution 2, allowing the DKDP crystal to begin single-cone growth on the DKDP seed crystal 13. After 14 days of growth, a DKDP crystal with dimensions of 100 mm × 120 mm × 128 mm was obtained, with a crystal utilization rate of 23%.

[0062] When cutting the triplet element 15, the matching angle of the DKDP crystal is 59°54′ and the azimuth angle is 0° or 90°. Therefore, the grown DKDP crystal can cut an approximately square triplet element 15 in the cone region along the

[100] direction and at an angle of 30°6′ to the

[001] direction, resulting in high cutting efficiency.

[0063] Comparative Example 1 This comparative example provides a KDP crystal growth method, which differs from Example 1 in that the first baffle 10 and the second baffle 11 are not set, while the remaining steps are completely the same as in Example 1.

[0064] During the growth process, due to the lack of baffles, the crystal grows along the

[010] direction, which causes the crystal to fail to grow to the ideal size in the

[001] direction before it contacts the side support rod, resulting in crystal growth failure.

[0065] Comparative Example 2 This comparative example provides a KDP crystal growth method. The difference from Example 1 is that the rotation mode is changed to unidirectional continuous rotation, the rotation speed is set to 30 rpm, and the periodic transformation of "forward rotation-stop-reverse rotation" is canceled. The remaining steps are completely consistent with Example 1.

[0066] Because the crystal rotates continuously in one direction, the crystal surface cannot receive solute exchange due to impact, crystal growth is limited, impurities appear in the growth tank, and crystal growth fails.

[0067] Comparative Example 3 This comparative example provides a KDP crystal growth method. The difference from Example 1 is that in step S8, the KDP growth solution 2 is heated to 55°C without heat treatment. The remaining steps are completely consistent with Example 1.

[0068] Because the solution was not heat-treated, spontaneous crystallization occurred inside the solution, resulting in the aggregation of impurity crystals in the growth tank and the failure of crystal growth.

[0069] Comparative Example 4 This comparative example provides a KDP crystal growth method. The difference from Example 1 is that in step S8, the KDP growth solution 2 is heated to 60°C for heat treatment. The remaining steps are completely consistent with Example 1.

[0070] Due to the high temperature of the overheated solution, the seed crystal dissolves significantly, either breaking off or completely dissolving, resulting in crystal growth failure.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for growing KDP-type crystals in a confined column region with long seed crystals, characterized in that, A KDP-type crystal growth apparatus is used for growth, the growth apparatus including a motor and a crystal carrier; the crystal carrier includes: a connecting rod, an upper panel, a lower tray, supporting side rods and baffles, one end of the connecting rod is fixedly connected to the upper surface of the upper panel, and the other end is fixedly connected to the rotating shaft of the motor; a supporting side rod is provided between the upper panel and the lower tray, and two baffles are provided between the supporting side rods that are parallel to each other and perpendicular to the upper panel and the lower tray; The method for growing KDP-type crystals in a confined column region with long seed crystals includes the following steps: A long seed crystal with a height direction of [001] and a horizontal direction of [010] is fixed at the center of the lower tray. The length of the long seed crystal is equal to the distance between the two baffles. The crystal carrier with the seed crystal is preheated to 4-6°C above the saturation point of the growth solution. After being removed, it is placed in the growth solution. The connecting rod is connected to the motor and rotated. After overheating, it is cooled and grown to obtain KDP-type crystals.

2. The method for growing KDP-type crystals in a confined column region as described in claim 1, characterized in that, Preheat the crystal carrier with the seed crystal to 5°C above the saturation point of the growth solution.

3. The method for growing KDP-type crystals in a confined column region as described in claim 1, characterized in that, The height of the baffle is the distance between the upper panel and the lower tray.

4. The method for growing KDP-type crystals in a confined column region as described in claim 1, characterized in that, The saturation point of the growth solution is 50-70℃.

5. The method for growing KDP-type crystals in a confined column region as described in claim 1, characterized in that, The rotation speed ranges from 15 to 30 rpm, and the rotation pattern adopts a cycle of forward rotation for 90 seconds - deceleration for 2 seconds - stop for 15 seconds - reverse acceleration for 2 seconds - reverse rotation for 90 seconds - deceleration for 2 seconds - stop for 15 seconds - forward acceleration for 2 seconds.

6. The method for confined column region growth of KDP-type crystal long seed crystals as described in claim 1, characterized in that, The superheated treatment followed by cooling growth includes: heating the growth solution to 2°C above the saturation point temperature, then cooling it down to achieve a supersaturation of 5-10% in the growth solution, thereby growing crystals and obtaining KDP-type crystals.

7. The method for confined column region growth of KDP-type crystal long seed crystals as described in claim 1, characterized in that, The connection points of the crystal carrier are smooth and seamless.

8. The method for growing KDP-type crystals in a confined column region as described in claim 1, characterized in that, The KDP-type crystal is either a KDP crystal or a DKDP crystal.

9. A KDP-type crystal, characterized in that, It is prepared by the KDP-type crystal long seed crystal confined column region growth method described in any one of claims 1-8.

10. The KDP-type crystal as described in claim 9, characterized in that, Sampling was performed on the cone region of the KDP-type crystal, and the crystal utilization rate of the KDP-type crystal was 20-25%.

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