A crystal carrier and application thereof in limiting adjacent cylindrical surface growth of KDP type crystal

Abstract

The application belongs to the technical field of crystal growth, and relates to a crystal loading frame and application of the crystal loading frame in limiting growth of adjacent cylindrical surfaces of KDP type crystals. The crystal loading frame comprises an upper plate, a support plate and a lower plate. The upper plate is arranged opposite to the lower plate. The support plate is used for supporting and connecting the upper plate and the lower plate. The lower plate is in a V-shaped structure. An opening of the V-shaped structure faces a bottom surface of the upper plate. An included angle of the V-shaped structure is denoted as alpha, and 30 DEG < alpha < 180 DEG. The V-shaped structure can inhibit growth of two adjacent cylindrical surfaces of a crystal. The remaining cylindrical surfaces and conical surfaces of the crystal can grow freely. The KDP type crystal has a large aspect ratio, the yield of a KDP type crystal doubling frequency optical element is improved, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of crystal growth technology and relates to a crystal carrier and its application in restricting the growth of adjacent cylindrical surfaces of KDP-type crystals. Background Technology

[0002] With economic development, global energy demand continues to grow, and at the same time, people's awareness of environmental protection is increasing, making the promotion and application of clean energy an inevitable trend. Laser nuclear fusion, as a future clean energy source, has attracted widespread attention, and KDP-type crystals are currently the only nonlinear optical crystals that can be used in laser nuclear fusion engineering.

[0003] The invention patent with application number 201510186495.1 discloses a crystal carrier and growth method for KDP-type crystals. The crystal carrier includes an upper horizontal bar, two side bars, a lower horizontal plate, and a seed crystal rod. The two side bars, the upper horizontal bar, and the lower horizontal plate form a "U"-shaped structure. The seed crystal rod is fixed in the middle position of the upper horizontal bar. The KDP-type crystal grown using this crystal carrier and growth method is an aggregate of a square prism and a square monopyramid. The aspect ratio of this aggregate is small, resulting in low yield and high production cost when cutting second-harmonic optical elements. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a crystal carrier and its application in restricting the growth of adjacent cylindrical surfaces of KDP-type crystals. The grown KDP-type crystal has the shape of an aggregate of a square prism and two square pyramids with a large aspect ratio. Multiple second-harmonic optical elements can be cut from a single crystal, improving the yield of second-harmonic optical elements from KDP-type crystals and reducing production costs.

[0005] The present invention provides a crystal carrier frame, including an upper plate, a support plate and a lower plate, wherein the upper plate and the lower plate are disposed opposite to each other, the support plate is used to support and connect the upper plate and the lower plate, and the lower plate has a "V" shaped structure, wherein the opening of the "V" shaped structure faces the bottom surface of the upper plate.

[0006] According to an embodiment of the present invention, the included angle of the “V” shaped structure is denoted as α, where 30° < α < 180°; for example, 60° ≤ α ≤ 120°, and α = 90° is an example.

[0007] According to an embodiment of the present invention, the support plate serves to connect and support the upper and lower plates without affecting crystal growth. For example, the support plates are symmetrically arranged on both sides of the upper and lower plates; for example, the number of support plates on each side is one, two, or more. Preferably, the total number of support plates is two or four.

[0008] According to an embodiment of the present invention, the upper end of each support plate is connected to the upper plate, and the lower end of each support plate is connected to the lower plate.

[0009] According to an embodiment of the present invention, the upper plate, the support plate, and the lower plate surround each other to form a non-enclosed space.

[0010] According to an embodiment of the present invention, the lower plate includes a first lower plate and a second lower plate, the bottoms of the first lower plate and the second lower plate are in contact and fixed to form a "V" shape, and the tops of the first lower plate and the second lower plate are connected to the bottoms of the corresponding support plates.

[0011] Preferably, the included angle of the "V" shaped structure has the definition described above.

[0012] According to an embodiment of the present invention, the crystal carrier further includes a central rod connected to the center of the upper surface of the upper plate. The central rod is used to connect to a power mechanism and drive the crystal carrier to rotate. The power mechanism is, for example, an electric motor.

[0013] During crystal growth, the power mechanism drives the crystal carrier to operate, which enhances the flow of the crystal growth solution in the growth tank and provides a sufficient supply of solute for crystal growth.

[0014] According to an embodiment of the present invention, a connecting flange is provided at the top of the central rod, and the central rod is connected to the output shaft of the power mechanism through the connecting flange. For example, the connecting flange is a hollow structure, and after the central rod passes through the bottom of the connecting flange, its end is flush with the top of the connecting flange.

[0015] According to an embodiment of the present invention, the connecting flange is connected to the output shaft via a connector. The connecting flange is provided with a plurality of holes for connecting the connector, the number of which is 2-12, preferably 4-10, for example, 6 or 8. For example, the connector is threaded, and the holes are threaded holes; for example, the upper surface of the connecting flange is provided with 6 threaded holes.

[0016] According to an embodiment of the present invention, the horizontal cross-section of the central rod is circular.

[0017] According to an embodiment of the present invention, the horizontal cross-section of the upper plate is square.

[0018] According to an embodiment of the present invention, the horizontal cross-section of the support plate is square, and preferably the horizontal cross-section of the support plate is rectangular.

[0019] According to an embodiment of the present invention, the connection between the above-mentioned components and parts is a fixed connection, such as welding, and preferably the connection is a smooth transition through an arc, resulting in a seamless connection.

[0020] According to an embodiment of the present invention, the crystal carrier is made of metal, for example, the metal is selected from stainless steel, aluminum alloy, magnesium alloy or titanium alloy; for example, stainless steel or aluminum alloy.

[0021] According to an embodiment of the present invention, all surfaces of the crystal carrier are provided with an anti-corrosion film, the material of which is selected from PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene propylene copolymer), PFA (soluble polytetrafluoroethylene) or ETFE (ethylene-tetrafluoroethylene copolymer), for example, the anti-corrosion film is formed by uniformly spraying PTFE.

[0022] The present invention also provides the use of the above-mentioned crystal carrier in crystal growth, preferably for restricting the growth of adjacent cylindrical surfaces of KDP type crystals.

[0023] Preferably, the crystal is a KDP-type crystal. For example, the KDP-type crystal is a KDP crystal, a DKDP crystal, an ADP crystal, or a DADP crystal.

[0024] The present invention also provides a method for growing KDP-type crystals, including growing KDP-type crystals using the above-described crystal carrier.

[0025] According to an embodiment of the present invention, the growth method includes the following steps:

[0026] S1. Fix the seed crystal on the crystal carrier, place the crystal carrier into the growth tank, and connect the central rod to the power mechanism;

[0027] S2. Inject the growth solution into the growth tank, turn on the power mechanism to drive the crystal carrier to rotate, and grow under cooling conditions to obtain the KDP type crystal.

[0028] According to an embodiment of the present invention, step S1 includes: preparing a seed crystal, marking crystal face A and crystal face B, and attaching crystal face A and crystal face B to the center position of the inner wall of the "V" shaped structure of the lower plate. The attachment can be performed using methods known in the art, such as fixing with adhesives, for example, using epoxy resin to fix the seed crystal to the center position of the inner wall of the lower plate.

[0029] According to an embodiment of the present invention, the seed crystal is a KDP-type blocky seed crystal.

[0030] According to an embodiment of the present invention, the seed crystal is a right square prism, which includes four sides connected in sequence: (100) crystal face, (010) crystal face, A crystal face and B crystal face, as well as a top face (001 crystal face) and a bottom face (00-1 crystal face), wherein the included angle between the A crystal face and the B crystal face is equal to the included angle α of the "V" shaped structure as described above, the length of the (100) crystal face is a, the length of the (010) crystal face is b, the length of the A crystal face is c, the length of the B crystal face is d, and the height of the right square prism is e;

[0031] Where lengths a, b, c, and d are horizontal lengths, and height e is vertical height.

[0032] Preferably, the size of the seed crystal is 5mm×5mm×(5×√2 / (2×sin(α / 2)))mm×(5×√2 / (2×sin(α / 2)))mm×3mm~30mm×30mm×(30×√2 / (2×sin(α / 2)))mm×(30×√2 / (2×sin(α / 2)))mm×20mm. For example, the seed crystal is selected as a KDP type block seed crystal with a size of 20mm×20mm×20mm×20mm×15mm or a KDP type block seed crystal with a size of 10mm×10mm×8.16mm×8.16mm×8mm.

[0033] According to an embodiment of the present invention, preparing a seed crystal and marking the A crystal plane and the B crystal plane includes the following steps: making a KDP-type bulk seed crystal, cleaning all surfaces with anhydrous ethanol, and marking the (100) crystal plane, (010) crystal plane, (001) crystal plane, (00-1) crystal plane, A crystal plane and B crystal plane.

[0034] According to an embodiment of the present invention, in step S2, the temperature of the growth tank is set to be above the saturation point. Optionally, the temperature of the growth tank is set to be 5 to 15°C above the saturation point.

[0035] Preferably, the temperature of the growth tank is set to be 10°C above the saturation point.

[0036] According to an embodiment of the present invention, the crystal growth solution in step S2 is prepared by the following method: preparing a crude crystal growth solution with a saturation point of 40-80°C, preferably with a saturation point of 50-70°C, for example 58°C or 66°C.

[0037] According to an embodiment of the present invention, the method for preparing the crystal growth solution in step S2 includes: overheating the crude crystal growth solution to 5-15°C above the saturation point and maintaining it for 6-72 hours to obtain the crystal growth solution.

[0038] According to an embodiment of the present invention, the coarse crystal growth solution is overheated at a high temperature to 5-15°C above the saturation point, for example, overheated by 10°C.

[0039] According to an embodiment of the present invention, the overheating duration is 20-50 hours, and further, the overheating duration is 30-40 hours, for example, 30 hours or 36 hours.

[0040] As an example, a coarse crystal growth solution with a saturation point of 66°C is prepared, and the coarse growth solution is overheated to 10°C above the saturation point for 36 hours.

[0041] According to an embodiment of the present invention, after the coarse crystal growth solution is overheated in step S2, the following step is further included: filtering the overheated solution. Further, the filtration includes at least one stage of ultrafiltration, preferably more than two stages, for example, using filter cartridges with pore sizes of 0.22μm, 0.1μm, and 0.05μm to filter sequentially to obtain the filtered crystal growth solution.

[0042] According to an embodiment of the present invention, after injecting the filtered crystal growth solution into the growth tank in step S2, before turning on the motor to drive the crystal carrier to rotate, it needs to stand for 30-150 minutes, or even 50-100 minutes, for example, 45 minutes or 60 minutes.

[0043] According to an embodiment of the present invention, after the required settling time, the crystal carrier rotation control program is started.

[0044] Optionally, the rotation speed can be set to 10–70 rpm and the rotation cycle to 20–120 s.

[0045] According to an embodiment of the present invention, within each rotation cycle, the rotation sequence is, for example, forward rotation-stop-reverse rotation-stop.

[0046] Preferably, the rotation speed is set to 35 rpm and the rotation cycle is 66 s, including 30 s of forward rotation followed by 3 s of stop, 30 s of reverse rotation followed by 3 s of stop.

[0047] In this rotation mode, the solution is thoroughly stirred and the solute is evenly distributed, which is conducive to the growth of high-quality KDP-type crystals.

[0048] According to an embodiment of the present invention, the growth under cooling conditions in step S2 includes cooling to the growth point of the corresponding KDP-type crystal for growth.

[0049] According to an embodiment of the present invention, the growth point is 1 to 10°C below the saturation point, for example, the growth point is 6°C below the saturation point.

[0050] According to an embodiment of the present invention, after step S2, the method further includes: after maintaining a constant temperature at the growth point for 24 hours, continuing to cool down and grow until a crystal of the desired size is obtained, depending on the crystal growth rate. For example, the cooling rate is 0–3 °C / d, preferably 0–2 °C / d, and further, the cooling rate is 0–1 °C / d, for example 0–1.6 °C / d or 0–0.5 °C / d.

[0051] As an example, step S2 includes: setting the temperature of the growth tank to 76℃, preparing a crude KDP-type crystal growth solution with a saturation point of 66℃, superheating the crude KDP-type crystal growth solution to 78℃ for 36 hours, filtering the KDP crystal growth solution sequentially with filter elements with pore sizes of 0.22μm, 0.1μm, and 0.05μm, injecting the filtered KDP-type crystal growth solution into the growth tank, letting it stand for 60 minutes, starting the motor to drive the central rod to rotate, setting the rotation speed to 35rpm, and the rotation cycle to 66s, including 30s of forward rotation followed by 3s of stop, 30s of reverse rotation followed by 3s of stop, cooling down to the growth point of 60℃, maintaining the temperature at the growth point for 24 hours, switching to the automatic cooling program, with a cooling range of 0~1.6℃ / d, until the crystal grows to the required size, thus obtaining the KDP-type crystal.

[0052] As another example, step S2 includes: setting the temperature of the growth tank to 68℃, preparing a crude KDP-type crystal growth solution with a saturation point of 58℃, superheating the crude KDP-type crystal growth solution to 70℃, superheating for 30 hours, filtering the KDP-type crystal growth solution sequentially with filter elements with pore sizes of 0.22μm, 0.1μm and 0.05μm, injecting the filtered KDP-type crystal growth solution into the growth tank, letting it stand for 45 minutes, starting the motor to drive the central rod to rotate, setting the speed to 30rpm, the rotation cycle to 56s, including 25s forward rotation, 3s stop, 25s reverse rotation, 3s stop, cooling down to the growth point of 52℃, maintaining the temperature at the growth point for 24 hours, switching to the automatic cooling program, with a cooling range of 0~0.5℃ / d, until the crystal grows to the required size, obtaining the KDP-type crystal.

[0053] The present invention also provides a KDP-type crystal, which is prepared by the above method.

[0054] According to an embodiment of the present invention, the KDP-type crystal is an aggregate of a tetragonal prism and two tetragonal pyramids, wherein the tetragonal prism and / or tetragonal pyramids are regular or irregular shapes.

[0055] As an example, when α = 90° in the "V"-shaped structure, the KDP-type crystal has an external shape that is an aggregate of a regular-shaped tetragonal prism and two regular-shaped tetragonal pyramids. For example, the KDP-type crystal has a basic shape as shown in the figure. Figure 6 The structure shown.

[0056] As another example, when α = 120° in the "V"-shaped structure, the KDP-type crystal has an external shape that is an aggregate of an irregularly shaped tetragonal prism and two irregularly shaped tetragonal pyramids. For example, the KDP-type crystal has a basic shape as follows: Figure 7 The structure shown.

[0057] According to an embodiment of the present invention, the aspect ratio of the KDP-type crystal is greater than 1, preferably greater than 1.5, further preferably greater than 1.7, and preferably 1.8-3.5, for example 1.75 or 1.97.

[0058] Beneficial effects

[0059] The crystal carrier provided by this invention has a "V" shaped structure on the inner side of its lower plate. The "V" shaped structure can suppress the growth of two adjacent cylindrical surfaces of the crystal, while the remaining cylindrical and conical surfaces of the crystal can grow freely. This results in a large aspect ratio of the grown KDP-type crystal, allowing multiple second-harmonic optical elements to be cut from a single crystal. This improves the yield of KDP-type crystal second-harmonic optical elements and reduces production costs. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the crystal carrier structure in Example 1;

[0061] Figure 2 This is a schematic diagram of the crystal carrier and the KDP crystal in combination;

[0062] Figure 3 This is a schematic diagram of the structure of a KDP crystal grown on a crystal carrier with α = 90° in Example 2, which is used to cut a frequency-doubled optical element;

[0063] Figure 4 A schematic diagram of the included angle α of the "V" shaped structure;

[0064] Figure 5 This is a schematic diagram of the seed crystal structure;

[0065] Figure 6 This is a schematic diagram of the structure of the KDP crystal grown on the crystal carrier with α = 90° in Example 2;

[0066] Figure 7 This is a schematic diagram of the structure of the KDP crystal grown on the crystal carrier with α = 120° in Example 3.

[0067] In the diagram: 1-Connecting flange, 2-Center rod, 3-Upper plate, 4-Support plate, 5-Lower plate, 6-KDP block seed crystal, 7-KDP-type crystal, 8-Frequency doubling optical element, 51-First lower plate, 52-Second lower plate. Detailed Implementation

[0068] The structure, preparation method, and application of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0069] Example 1: A die carrier

[0070] See Figure 1 As shown, the crystal carrier includes a connecting flange 1, a central rod 2, an upper plate 3, a support plate 4, and a lower plate 5. The connecting flange 1 is fixed to the upper end of the central rod 2, and the upper surface of the connecting flange 1 is flush with the upper surface of the central rod 2. The central rod 2 is connected to the output shaft of the motor through the connecting flange 1. The six threaded holes on the upper surface of the connecting flange 1 are used to connect the motor output shaft. The central rod 2 is fixed at the center of the upper surface of the upper plate 3.

[0071] The upper plate 3 and the lower plate 5 are arranged opposite to each other and connected by a support plate 4. The support plate 4 is symmetrically distributed on both sides of the upper plate 3 and the lower plate 5. The upper end of the support plate 4 is flush with and fixed to the lower surface of the upper plate 3, and the lower end of the support plate 4 is fixed to the upper surface of the lower plate 5. Figure 4 As shown, the lower plate 5 is V-shaped and is formed by the relative connection of the first lower plate 51 and the second lower plate 52. The included angle α between the first lower plate 51 and the second lower plate 52 is 30° < α < 180°. Figure 4 α can be adjusted according to requirements. The top of the first lower plate 51 is connected to the support plate 4, and the bottom is connected to the second lower plate 52. The top of the second lower plate 51 is connected to another support plate 4, and the bottom is connected to the first lower plate 51.

[0072] All the above connections are fixed connections, and the fixed connection method is welding. The welded joints have a seamless, smooth arc transition. After fixing, a PTFE anti-corrosion film is uniformly sprayed onto all surfaces of the crystal carrier.

[0073] This crystal carrier is used to restrict the growth of adjacent cylindrical surfaces of KDP-type crystals.

[0074] Example 2: A method for restricting the growth of adjacent cylindrical faces of KDP-type crystals

[0075] In this embodiment, the crystal carrier used has the structure shown in Embodiment 1, wherein the included angle between the first lower plate 51 and the second lower plate 52 is 90°.

[0076] Combination Figure 1 and Figure 2 The following is a detailed description of the method for restricting the growth of adjacent cylindrical surfaces of a KDP crystal in this embodiment:

[0077] 1) Fabricate a 20mm×20mm×20mm×20mm×15mm KDP block seed crystal 6 (e.g. Figure 5 (As shown), clean all surfaces with anhydrous ethanol and mark the (100) crystal plane, (010) crystal plane, (001) crystal plane, (00-1) crystal plane, A crystal plane and B crystal plane.

[0078] 2) Use epoxy resin to fix the KDP block seed crystal 6 at the bottom center of the lower plate 5 of the crystal carrier, wherein the A crystal surface and B crystal surface of the KDP block seed crystal 6 are respectively attached to the two inner surfaces of the lower plate 5 of the crystal carrier.

[0079] 3) Connect the connecting flange 1 on the crystal carrier to the motor output shaft, and then place the crystal carrier into the growth tank and seal it.

[0080] 4) Set the temperature of the growth tank to 76℃.

[0081] 5) Prepare a crude KDP crystal growth solution with a saturation point of 66℃.

[0082] 6) The crude KDP crystal growth solution was overheated to 78°C for 36 hours.

[0083] 7) The crude KDP crystal growth solution was subjected to three-stage ultrafiltration with pore sizes of 0.22 μm, 0.1 μm and 0.05 μm, respectively.

[0084] 8) Inject the filtered KDP crystal growth solution into the growth tank.

[0085] 9) After the KDP crystal growth solution is injected into the growth tank, it is left to stand for 60 minutes. The purpose is to dissolve the microcrystals on the surface of the KDP block seed crystal 6 and prevent impurities from appearing in the subsequent growth process, which would interfere with crystal growth.

[0086] 10) After the required settling time, start the crystal carrier rotation control program, set the rotation speed to 35 rpm, and the rotation cycle to 66 s, including 30 s forward rotation, 3 s stop, 30 s reverse rotation, and 3 s stop.

[0087] 11) Start the rapid cooling program and reduce the temperature to the growth point of 60°C.

[0088] 12) After maintaining a constant temperature at the growth point for 24 hours, switch to an automatic cooling program with a cooling range of 0–1.6℃ / day. After 36 days of growth, a KDP crystal with dimensions of 200mm × 200mm × 350mm can be obtained. The crystal has an morphology of a regular tetragonal prism and two regular tetragonal pyramids (e.g., Figure 6 As shown in the figure, the aspect ratio is 1.75.

[0089] When cutting the frequency-doubled optical element 8 using the KDP crystal prepared in this embodiment, the matching angle of the KDP crystal is 41° and the azimuth angle is 45°. Cutting the KDP crystal in this embodiment yields 11 pieces of 140mm×140mm×10mm frequency-doubled optical elements 8 (e.g. Figure 3 (As shown).

[0090] Example 3: A method for restricting the growth of adjacent cylindrical faces in KDP-type crystals

[0091] In this embodiment, the die carrier used has the structure shown in Embodiment 1, wherein the included angle between the first lower plate 51 and the second lower plate 52 is 120°. Figure 1 and Figure 2 The following is a detailed description of the method for restricting the growth of adjacent cylindrical surfaces of a KDP crystal in this embodiment:

[0092] 1) Make a KDP block seed crystal 6 with a diameter of 10mm×10mm×8.16mm×8.16mm×8mm, clean all surfaces with anhydrous ethanol, and mark the (100) crystal plane, (010) crystal plane, (001) crystal plane, (00-1) crystal plane, A crystal plane and B crystal plane.

[0093] 2) Use epoxy resin to fix the KDP block seed crystal 6 at the bottom center of the lower plate 5 of the crystal carrier, wherein the A crystal surface and B crystal surface of the KDP block seed crystal 6 are respectively attached to the two inner surfaces of the lower plate 5 of the crystal carrier.

[0094] 3) Connect the connecting flange 1 on the crystal carrier to the motor output shaft, and then place the crystal carrier into the growth tank and seal it.

[0095] 4) Set the temperature of the growth tank to 68℃.

[0096] 5) Prepare a crude KDP crystal growth solution with a saturation point of 58℃.

[0097] 6) The crude KDP crystal growth solution was overheated to 70°C for 30 hours.

[0098] 7) The crude KDP crystal growth solution was subjected to three-stage ultrafiltration with pore sizes of 0.22 μm, 0.1 μm and 0.05 μm, respectively.

[0099] 8) Inject the filtered KDP crystal growth solution into the growth tank.

[0100] 9) After the KDP crystal growth solution is injected into the growth tank, it is left to stand for 45 minutes. The purpose is to dissolve the microcrystals on the surface of the KDP block seed crystal 6 and prevent impurities from appearing in the subsequent growth process, which would interfere with crystal growth.

[0101] 10) After settling, start the crystal carrier rotation control program, set the rotation speed to 30 rpm and the rotation cycle to 56 s. Each rotation cycle is set to rotate forward for 25 s, stop for 3 s, rotate backward for 25 s, and stop for 3 s.

[0102] 11) Start the rapid cooling program and reduce the temperature to the growth point of 52°C.

[0103] 12) After maintaining a constant temperature at the growth point for 24 hours, switch to an automatic cooling program with a cooling range of 0–0.5℃ / day. After 16 days of growth, a KDP crystal with dimensions of 100mm × 100mm × 197mm can be obtained. Its shape is an aggregate of one irregularly shaped tetragonal prism and two irregularly shaped tetragonal pyramids (e.g., Figure 7 As shown in the figure, the aspect ratio is 1.97.

[0104] When cutting the second-frequency optical element 8 using the KDP crystal prepared in this embodiment, the matching angle of the KDP crystal is 41° and the azimuth angle is 45°. Cutting the KDP crystal in this embodiment yields 6 pieces of 70mm×70mm×10mm second-frequency optical elements 8.

[0105] Comparative Example 1

[0106] In this comparative example, the crystal carrier structure and dimensions are the same as in Example 1, except that the lower plate 5 has an α = 180°, in which case the lower plate 5 is a horizontal straight plate.

[0107] The crystal growth method in this comparative example is the same as that in Example 2, except for step 2).

[0108] Step 2) Fix the KDP block seed crystal 6 at the bottom center of the lower plate 5 of the crystal carrier, wherein the (001) crystal surface of the KDP block seed crystal 6 is in contact with the upper surface of the lower plate of the crystal carrier.

[0109] The preparation method is the same as in Example 2, yielding a KDP crystal with dimensions of 200mm × 200mm × 180mm and an aspect ratio of 0.9. When cutting the second-harmonic optical element 8 using the KDP crystal prepared in this comparative example, the matching angle of the KDP crystal is 41° and the azimuth angle is 45°. Cutting the KDP crystal in this comparative example yields three 140mm × 140mm × 10mm second-harmonic optical elements 8.

[0110] Comparative Example 2

[0111] In this comparative example, the crystal carrier structure and dimensions are the same as in Example 3, except that the lower plate 5 has an α = 180°, in which case the lower plate 5 is a horizontal straight plate.

[0112] The crystal growth method in this comparative example is the same as that in Example 3, except for steps 1) and 2).

[0113] Step 1) Make a 10mm×10mm×10mm×10mm×8mm KDP block seed crystal, clean all surfaces with anhydrous ethanol, and mark the (100) crystal plane, (010) crystal plane, (001) crystal plane, (00-1) crystal plane, A crystal plane and B crystal plane.

[0114] Step 2) Fix the bulk seed crystal at the bottom center of the lower plate 5 of the crystal carrier, wherein the (001) crystal surface of the bulk seed crystal 6 is in contact with the upper surface of the lower plate of the crystal carrier.

[0115] The preparation method is the same as in Example 3, yielding a KDP crystal with dimensions of 100mm × 100mm × 90mm and an aspect ratio of 0.9. When cutting the second-harmonic optical element 8 using the KDP crystal prepared in this comparative example, the matching angle of the KDP crystal is 41° and the azimuth angle is 45°. Cutting the KDP crystal in this comparative example yields one 70mm × 70mm × 10mm second-harmonic optical element 8.

[0116] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for growing KDP-type crystals, characterized in that, The growth method includes growing KDP-type crystals using a crystal frame, wherein the aspect ratio of the KDP-type crystals is greater than 1. The crystal carrier includes an upper plate, a support plate, and a lower plate. The upper plate and the lower plate are arranged opposite to each other. The support plate is used to support and connect the upper plate and the lower plate. The upper end of each support plate is connected to the upper plate, and the lower end of each support plate is connected to the lower plate. The lower plate has a "V" shaped structure, and the opening of the "V" shaped structure faces the bottom surface of the upper plate. The included angle of the "V" shaped structure is denoted as α, where 30° < α < 180°; The horizontal cross-section of the upper plate is square, and the upper plate, support plate and lower plate surround each other to form a non-closed space; The growth method includes the following steps: S1. Prepare seed crystals and mark crystal plane A and crystal plane B. Attach crystal plane A and crystal plane B to the center of the inner wall of the "V" shaped structure of the lower plate. Place the crystal carrier into the growth tank and connect the central rod to the power mechanism. S2. Inject the growth solution into the growth tank, turn on the power mechanism to drive the crystal carrier to rotate, and grow under cooling conditions to obtain the KDP type crystal.

2. The growth method according to claim 1, characterized in that, The lower plate includes a first lower plate and a second lower plate, and the bottoms of the first lower plate and the second lower plate are in contact and fixed to form a "V" shape.

3. The growth method according to claim 1, characterized in that, The lower plate includes a first lower plate and a second lower plate. The bottoms of the first lower plate and the second lower plate are in contact and fixed to form a "V" shape. The tops of the first lower plate and the second lower plate are connected to the bottoms of the corresponding support plates.

4. The growth method according to claim 1, characterized in that, The central rod is connected to the center of the upper surface of the upper plate. The central rod is used to connect to the power mechanism and drive the crystal carrier to rotate. A connecting flange is provided at the top of the central rod, and the central rod is connected to the output shaft of the power mechanism through the connecting flange.

5. The growth method according to claim 4, characterized in that, The connecting flange has a hollow structure, and the center rod passes through the bottom of the connecting flange, with its end flush with the top of the connecting flange.

6. The growth method according to claim 4, characterized in that, The connecting flange is connected to the output shaft via a connector. The connecting flange has a number of holes for connecting the connector, and the number of holes is 2-12.

7. The growth method according to any one of claims 1 to 6, characterized in that, The crystal carrier is made of metal; And / or, 60°≤α≤120°.

8. The growth method according to any one of claims 1 to 6, characterized in that, All surfaces of the crystal carrier are covered with an anti-corrosion film; The anti-corrosion membrane is made of PTFE, FEP, PFA or ETFE.

9. The growth method according to claim 1, characterized in that, The horizontal cross-section of the central rod is circular, and the horizontal cross-section of the support plate is square.

10. The growth method according to claim 1, characterized in that, The aspect ratio of the KDP-type crystal is 1.8-3.

5.

11. The growth method according to claim 1, characterized in that, The KDP-type crystal is an aggregate of a tetragonal prism and two tetragonal pyramids, wherein the tetragonal prism and / or tetragonal pyramids are either regular or irregular in shape.

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