Laser frequency doubling crystal angle adjustable device and method

Abstract

The invention discloses a device and method for adjusting the angle of a laser frequency doubling crystal. The device comprises a fixed base, a fixed adjustment connecting plate is vertically arranged on the fixed base, a movable adjustment connecting plate is arranged on one side of the fixed adjustment connecting plate, wherein: ball grooves are opened at positions corresponding to the inner side surfaces of the fixed adjustment connecting plate and the movable adjustment connecting plate, and steel balls are installed between the ball grooves, and the steel balls make a gap between the fixed adjustment connecting plate and the movable adjustment connecting plate, and a plurality of telescopic springs are distributed; a first adjustment screw and a second adjustment screw are arranged on the movable adjustment connecting plate, which are respectively used to adjust the spacing of the movable adjustment connecting plate at a certain position relative to the fixed adjustment connecting plate; an L-shaped mounting plate is fixed on the outer side surface of the movable adjustment connecting plate, a crystal fixing seat is arranged on the mounting plate, the frequency doubling crystal is installed in the crystal slot on the crystal fixing seat, and the frequency doubling crystal is fixed by a crystal fixing cover.

Description

Technical Field

[0001] The invention relates to the field of laser frequency doubling, and in particular to a laser frequency doubling crystal angle adjustable device and method. Background Art

[0002] Laser frequency doubling, also known as second harmonic generation (SHG), utilizes the secondary nonlinear effect of nonlinear crystals under the action of strong lasers to convert laser light with a frequency of ω into frequency-doubled light with a frequency of 2ω after passing through the crystal. Similarly, after the fundamental frequency light excited by a high-power solid-state laser penetrates the frequency-doubled crystal, frequency-doubled light is obtained. The power of the frequency-doubled light is lower than that of the fundamental frequency light. The quality and output power of the fundamental frequency light after frequency doubling depend on the properties of the frequency-doubled crystal itself and the incident angle of the fundamental frequency light. The properties of the frequency-doubled crystal itself are determined by the processing quality, ion type, content, etc. during crystal processing, and it is difficult to change them later. In mainstream experiments, most of the second type of frequency doubling is used, which makes the incident angle of the fundamental frequency light incident on the working surface of the frequency-doubled crystal extremely important.

[0003] However, in the actual operation of the laser, it is difficult to adjust the angle of the fundamental frequency light incident on the working surface of the frequency doubling crystal. The main means is to manually adjust the fixing fixture of the frequency doubling crystal. This adjustment method is not only inefficient, but also poses a great safety hazard. Chinese patent CN 203967501U discloses a temperature control and adjustment device for a frequency doubling crystal, including a heat dissipation device, an adjustment platform, an adjustment base, a laser bottom plate, a temperature control unit, a crystal heat sink base, etc. The laser frequency doubling crystal is fixed between the heat sink base and the crystal upper pressure cover, and the crystal heat sink base and the crystal upper pressure cover are connected by screws, and a spring is provided on the screws. One side of the temperature control unit is connected to the crystal heat sink base by a high-temperature thermal conductive adhesive. The problems with this solution are:

[0004] After the crystal is fixed, the fundamental frequency light cannot be adjusted to enter the frequency doubling crystal working surface. The entire laser needs to be turned off and the frequency doubling angle needs to be adjusted manually, which is extremely inefficient. There is a triangular pyramid between the crystal heat sink base and the upper pressure cover, which has poor stability and cannot fix the crystal well inside. Summary of the invention

[0005] The purpose of the present invention is to provide a laser frequency doubling crystal angle adjustable device and method to improve the low adjustment efficiency of the existing device and solve the existing safety hazards, thereby safely adjusting the angle of the working surface of the frequency doubling crystal to efficiently double the fundamental frequency light energy.

[0006] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0007] A laser frequency doubling crystal angle adjustable device comprises a fixed base, a fixed plate is vertically arranged on the fixed base, a fixed adjustment connecting plate is arranged on the side of the fixed plate, and a movable adjustment connecting plate is arranged on one side of the fixed adjustment connecting plate, wherein:

[0008] Ball grooves are provided at positions corresponding to the inner sides of the fixed adjustment connecting plate and the movable adjustment connecting plate, and steel balls are installed between the ball grooves, and the steel balls make a gap between the fixed adjustment connecting plate and the movable adjustment connecting plate; a plurality of telescopic springs are evenly distributed between the fixed adjustment connecting plate and the movable adjustment connecting plate;

[0009] On the movable adjustable connecting plate, a first adjusting screw and a second adjusting screw are respectively arranged on the upper part of the steel ball in the vertical direction and the side surface in the horizontal direction, respectively used to adjust the spacing of the movable adjustable connecting plate at the position relative to the fixed adjustable connecting plate; the arrangement positions of the first adjusting screw, the second adjusting screw and the position of the steel ball form a right triangle;

[0010] An L-shaped mounting plate is fixed on the outer side surface of the movable adjustable connecting plate, and a crystal fixing seat is arranged on the mounting plate. The frequency doubling crystal is assembled in the crystal slot on the crystal fixing seat, and the frequency doubling crystal is fixed by a crystal fixing cover; wherein, the crystal fixing seat is perpendicular to the movable adjustable connecting plate and parallel to the fixed base.

[0011] Furthermore, the diameter of the steel ball is greater than the sum of the depths of the ball grooves on the fixed adjustment connecting plate and the movable adjustment connecting plate. The existence of the gap allows the movable adjustable connecting plate to have a certain rotation adjustment space relative to the fixed adjustment connecting plate.

[0012] Furthermore, the ball groove is a spherical groove, which is matched with the outer surface of the steel ball; the ball groove is arranged at a lower corner of the fixed adjustment connecting plate and the movable adjustment connecting plate.

[0013] Furthermore, the two ends of the telescopic spring are respectively assembled in through holes symmetrically opened on the fixed adjustment connecting plate and the movable adjustment connecting plate, and are respectively fixed in the grooves at the ends of the through holes through spring fixing rods.

[0014] Furthermore, a threaded hole is provided on the movable adjustable connecting plate, and a first adjusting screw and a second adjusting screw are assembled into the threaded hole. When the movable adjustable connecting plate is parallel to the fixed adjusting connecting plate, it is an initial state. In the initial state, the front ends of the first adjusting screw and the second adjusting screw are in elastic contact with the fixed adjusting connecting plate.

[0015] Furthermore, grooves are respectively provided on the contact parts of the fixed adjustment connecting plate with the first adjustment screw and the second adjustment screw. In the initial state, the front ends of the first adjustment screw and the second adjustment screw are respectively located in the corresponding grooves, and the telescopic spring is configured to be in a stretched state in this state.

[0016] Furthermore, the first adjusting screw is located above the steel ball. Rotating the first adjusting screw clockwise or counterclockwise will cause the upper part of the movable adjusting connecting plate to deflect away from or toward the fixed adjusting connecting plate with the steel ball as a fulcrum. At this time, the working surface of the frequency doubling crystal corresponds to the deflection direction of the movable adjusting connecting plate, and the resulting inclination is an up and down deflection relative to the incident crystal surface; the second adjusting screw is located on the side of the steel ball in the horizontal direction, so the inclination caused by adjustment is a left and right deflection relative to the incident crystal surface; through alternating adjustment of the first adjusting screw and the second adjusting screw, the angle of the working surface of the frequency doubling crystal can be accurately adjusted to the required angle.

[0017] A method for adjusting the angle of a laser frequency doubling crystal using the device comprises the following steps:

[0018] Step 1: Wrap the frequency doubling crystal with tin foil and place it in the crystal slot on the crystal holder. Tighten the crystal fixing cover with screws to fix the frequency doubling crystal.

[0019] Step 2, fix the crystal holder with the frequency doubling crystal installed on the L-shaped mounting plate, and fix the mounting plate on the movable adjustable connecting plate, so that the crystal holder is perpendicular to the movable adjustable connecting plate;

[0020] Step 3, assemble the steel balls in the ball grooves on the movable adjustable connecting plate and the fixed adjustable connecting plate, and screw in the first adjusting screw and the second adjusting screw, so that the ends of the first adjusting screw and the second adjusting screw are located in the corresponding grooves on the fixed adjustable connecting plate, and keep the fixed adjustable connecting plate parallel to the movable adjustable connecting plate, and then install each telescopic spring respectively, and use the spring fixing rod to fix the ends of each telescopic spring to the through holes on the fixed adjustable connecting plate and the movable adjustable connecting plate respectively;

[0021] Step 4, fix the fixed adjustment connecting plate to the fixed plate on the base, and ensure that the crystal fixing seat is parallel to the fixed base; after installation, fine-tune the first adjustment screw and the second adjustment screw to make the movable adjustment connecting plate and the fixed adjustment connecting plate parallel;

[0022] Step 5, the frequency doubling crystal starts to work, with its working surface perpendicular to the incident direction of the fundamental frequency light, and the measured laser power after frequency doubling is observed;

[0023] Step 6, adjusting the first adjusting screw and the second adjusting screw to change the incident angle of the incident laser to adjust the frequency doubling efficiency.

[0024] Compared with the prior art, the present invention has the following technical features:

[0025] Most existing frequency doubling crystal devices cannot adjust the incident angle of the fundamental frequency light when the laser turns on the frequency doubling crystal to work, and the laser needs to be turned off to adjust it, resulting in extremely low frequency doubling efficiency and a long adjustment time. The device of the present invention solves these problems well, using steel balls to form a balance axis, using adjustment screws to achieve deflection, and achieving the same deflection of the frequency doubling crystal connected to the adjustment connecting plate. The fundamental frequency light incident angle can still be adjusted when the laser is working, achieving the second type of frequency doubling more efficiently, and greatly improving the frequency doubling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure decomposition of the device of the present invention;

[0027] Figure 2 A schematic diagram of adjusting the first adjusting screw to deflect the frequency doubling crystal downward;

[0028] Figure 3 A schematic diagram of adjusting the first adjusting screw to deflect the frequency doubling crystal upward;

[0029] Figure 4 The schematic diagram of adjusting the second adjusting screw to make the frequency doubling crystal deflect to the left;

[0030] Figure 5 Schematic diagram of adjusting the second adjustment screw to deflect the frequency doubling crystal to the right.

[0031] Explanation of the numbers in the figure: 1 fixed base, 2 fixed adjustment connecting plate, 3 movable adjustment connecting plate, 4 spring fixing rod, 5 telescopic spring, 6 steel ball, 7 first adjustment screw, 8 crystal fixing cover, 9 frequency doubling crystal, 10 crystal fixing seat, 11 mounting plate, 12 second adjustment screw. DETAILED DESCRIPTION

[0032] As mentioned in the previous background technology, laser frequency doubling technology is that the fundamental frequency light is incident on the working surface of the frequency doubling crystal, and a nonlinear effect occurs to produce light with twice the frequency. Therefore, the incident angle of the fundamental frequency light is extremely important. However, the angle of the working surface of the frequency doubling crystal is difficult to change after the clamp is fixed. Manually adjusting the clamp when the laser is working is dangerous. The idea of ​​the present invention to solve this problem is that when the laser is working, there is no need to adjust the tightness of the clamp screws to adjust the angle of the working surface of the frequency doubling crystal. Instead, the deflection of the frequency doubling crystal is achieved by adjusting the adjustment screws at two different positions on the connecting plate. The deflection includes the deflection of the up and down and left and right axes, ensuring more efficient and safer realization of crystal frequency doubling.

[0033] See also Figures 1 to 5The present invention provides a laser frequency doubling crystal angle adjustable device, comprising a fixed base 1, a fixed plate vertically arranged on the fixed base 1, a fixed adjustment connecting plate 2 arranged on the side of the fixed plate by M4 screws, and a movable adjustment connecting plate 3 arranged on one side of the fixed adjustment connecting plate 2, wherein:

[0034] Ball grooves are provided at positions corresponding to the inner sides of the fixed adjustment connecting plate 2 and the movable adjustment connecting plate 3, and steel balls 6 are installed between the ball grooves, and the steel balls 6 make a gap between the fixed adjustment connecting plate 2 and the movable adjustment connecting plate 3; specifically, the diameter of the steel ball 6 is greater than the sum of the depths of the ball grooves on the fixed adjustment connecting plate 2 and the movable adjustment connecting plate 3, for example, the depth of the ball groove is 3mm, and the diameter of the steel ball 6 is 10mm, then after the steel ball 6 is assembled, when the fixed adjustment connecting plate 2 is parallel to the movable adjustment connecting plate 3, the gap between the two is 4mm; the existence of the gap allows the movable adjustment connecting plate 3 to have a certain rotation adjustment space relative to the fixed adjustment connecting plate. Wherein, the ball groove is a spherical groove, which is adapted to the outer surface of the steel ball 6. In one example, the fixed adjustment connecting plate 2 and the movable adjustment connecting plate 3 are rectangular plates or triangular plates of the same size, and the ball groove is arranged at a lower corner of the rectangular plate.

[0035] There are multiple telescopic springs 5 ​​evenly distributed between the fixed adjustment connecting plate 2 and the movable adjustment connecting plate 3; specifically, the two ends of the telescopic spring 5 are respectively assembled in the through holes symmetrically opened on the fixed adjustment connecting plate 2 and the movable adjustment connecting plate 3, and are respectively fixed in the grooves at the ends of the through holes by the spring fixing rods 4, so as to realize the installation of each telescopic spring 5. The function of the telescopic spring 5 is to provide extension force to the entire device, especially when the thread depth of the adjustment screw is reduced, the force of the telescopic spring 5 returning to the original state is used to make the movable adjustment connecting plate 3 deviate in the direction close to the fixed adjustment connecting plate 2; therefore, when the fixed adjustment connecting plate 2 is parallel to the movable adjustment connecting plate 3, since the force provided by the adjustment screw and the extension force provided by the telescopic spring 5 are a kind of force balance, the entire system structure is in a static equilibrium state at this time.

[0036] On the movable adjustable connecting plate 3, the first adjusting screw 7 and the second adjusting screw 12 are respectively arranged on the upper part of the steel ball 6 in the vertical direction and the side surface in the horizontal direction, respectively used to adjust the spacing of the movable adjustable connecting plate 3 at the position relative to the fixed adjustable connecting plate; the arrangement position of the first adjusting screw 7 and the second adjusting screw 12 and the connection line of the position of the steel ball 6 form a right triangle. Specifically, the movable adjustable connecting plate 3 is provided with a threaded hole, and the first adjusting screw 7 and the second adjusting screw 12 are assembled into the threaded hole. When the movable adjustable connecting plate 3 is parallel to the fixed adjustable connecting plate 2, it is the initial state. In the initial state, the front ends of the first adjusting screw 7 and the second adjusting screw 12 are in elastic contact with the fixed adjustable connecting plate 2. The elastic contact here means that the fixed adjustment connecting plate 2 is provided with grooves on the contact parts with the first adjustment screw 7 and the second adjustment screw 12, and in the initial state, the front ends of the first adjustment screw 7 and the second adjustment screw 12 are respectively located in the corresponding grooves, and the telescopic spring 5 is configured to be in a stretched state in this state; then when the first adjustment screw 7 and the second adjustment screw 12 are rotated clockwise, due to the cooperation with the threaded holes on the movable adjustable connecting plate 3, the movable adjustable connecting plate 3 at the position of the first adjusting screw 7 and the second adjusting screw 12 will be offset in the direction away from the fixed adjustment connecting plate 2, that is, it will rotate relative to the steel ball 6, and the telescopic spring 5 will be further stretched at this time; similarly, in the initial state, when the first adjusting screw 7 and the second adjusting screw 12 are rotated counterclockwise, under the action of the elastic force of the telescopic spring 5, the movable adjustable connecting plate 3 will be pulled toward the fixed adjustment connecting plate 2.

[0037] An L-shaped mounting plate 11 is fixed to the outer side surface of the movable adjustable connecting plate 3, and a crystal fixing seat 10 is arranged on the mounting plate 11. The frequency doubling crystal 9 is assembled in the crystal slot on the crystal fixing seat 10, and the frequency doubling crystal 9 is fixed by a crystal fixing cover 8; wherein, the crystal fixing seat 10 is perpendicular to the movable adjustable connecting plate 3 and parallel to the fixed base 1.

[0038] The thread of the first adjusting screw 7 and the second adjusting screw 12 is inserted into the threaded hole of the movable adjusting connecting plate 3 to different degrees, which will cause the movable adjusting connecting plate 3 to tilt to different degrees. The tilt of the movable adjusting connecting plate 3 will cause the frequency doubling crystal 9 fixed on the mounting plate 11 to tilt. Figure 2 and Figure 3 As shown, in the initial state, since the first adjusting screw 7 is located above the steel ball 6, rotating the first adjusting screw 7 clockwise or counterclockwise will cause the upper part of the movable adjusting connecting plate 3 to deflect away from or toward the fixed adjusting connecting plate 2 with the steel ball 6 as the fulcrum. At this time, the working surface of the frequency doubling crystal 9 corresponds to the deflection direction of the movable adjusting connecting plate 3, that is, the resulting tilt is an up-and-down deflection relative to the incident crystal surface. The same principle applies, Figure 3 and Figure 4 As shown, the second adjusting screw 12 is located on the side of the steel ball 6 in the horizontal direction, so the inclination caused by adjustment is a left-right deflection relative to the incident crystal surface; in actual use, through the alternating adjustment of the first adjusting screw 7 and the second adjusting screw 12, the working surface angle of the frequency doubling crystal 9 can be accurately adjusted to the desired angle.

[0039] The principle of the 9-angle adjustment of the frequency doubling crystal in this device is:

[0040] A steel ball 6 is used as a rotation fulcrum, and the supporting force of the two adjusting screws and the extension force of the telescopic spring 5 keep the device in a balanced state in the initial state. When the first adjusting screw 7 and the second adjusting screw 12 are in operation, due to the presence of the steel ball 6, the spacing between the movable adjustable connecting plate 3 and the fixed adjustable connecting plate 2 at the bottom where the steel ball 6 is located is unchanged, but the spacing between the two positions where the adjusting screws are located will increase or decrease due to the change in force, thereby achieving the deflection of the movable adjustable connecting plate 3 relative to the fixed adjustable connecting plate 2; Case 1: If the thread insertion depth of the adjusting screw is increased, because the fixed adjustable connecting plate 2 is fixed, the part of the movable adjustable connecting plate 3 where the adjusting screw is located will deviate in the opposite direction relative to the movable adjustable connecting plate 3 due to the force of the adjusting screw, with the steel ball 6 as the fulcrum; Case 2: When the thread insertion depth of the adjusting screw is reduced, the force of the adjusting screw on the movable adjustable connecting plate 3 is reduced. Since the telescopic spring 5 is in an extended state, the movable adjustable connecting plate 3 will be pulled during the recovery process of the telescopic spring 5, so that it will deviate in the direction close to the fixed adjustable connecting plate 2.

[0041] Based on the above device, the method for adjusting the angle of the laser frequency doubling crystal 9 of the present invention comprises the following steps:

[0042] Step 1, wrap the frequency doubling crystal 9 with tin foil and place it in the crystal slot on the crystal fixing seat 10, and tighten the crystal fixing cover 8 with screws to fix the frequency doubling crystal 9.

[0043] Step 2, fix the crystal holder 10 with the frequency doubling crystal 9 installed on the L-shaped mounting plate 11, and fix the mounting plate 11 on the movable adjustable connecting plate 3, so that the crystal holder 10 is perpendicular to the movable adjustable connecting plate 3.

[0044] Step 3, assemble the steel ball 6 in the ball grooves on the movable adjustable connecting plate 3 and the fixed adjustable connecting plate 2, and screw in the first adjusting screw 7 and the second adjusting screw 12, so that the ends of the first adjusting screw 7 and the second adjusting screw 12 are located in the corresponding grooves on the fixed adjustable connecting plate 2, and keep the fixed adjustable connecting plate 2 and the movable adjustable connecting plate 3 parallel, and then install each telescopic spring 5 respectively, and use the spring fixing rod 4 to fix the ends of each telescopic spring 5 to the through holes on the fixed adjustable connecting plate 2 and the movable adjustable connecting plate 3.

[0045] Step 4, fix the fixed adjustment connecting plate 2 to the fixed plate on the base, ensure that the crystal fixing seat 10 is parallel to the fixed base 1; after installation, fine-tune the first adjustment screw 7 and the second adjustment screw 12 to make the movable adjustment connecting plate 3 and the fixed adjustment connecting plate 2 parallel.

[0046] Step 5, the frequency doubling crystal 9 starts to work, with its working surface perpendicular to the incident direction of the fundamental frequency light, and the measured laser power after frequency doubling is observed.

[0047] Step 6, adjusting the first adjusting screw 7 and the second adjusting screw 12, so as to change the incident angle of the incident laser to adjust the frequency doubling efficiency.

[0048] Example:

[0049] In one embodiment of the present invention, the dimensions of the movable adjustable connecting plate and the fixed adjustable connecting plate are both 60*60*7mm; a spherical ball groove with a depth of 3mm that can accommodate a steel ball with a diameter of 10mm is provided at the inner corner of the movable adjustable connecting plate. The ball groove is on a diagonal line of the movable adjustable connecting plate and is 15mm away from the nearest diagonal point; the movable adjustable connecting plate is rotated so that the ball groove is located on the lower right side, and the same ball groove processing is performed on the corresponding position on the fixed adjustable connecting plate.

[0050] A cylindrical cut-out groove with a depth of 1mm is processed above and on the side of the ball groove of the fixed adjustment connecting plate. The groove is located on the diagonal line and is 7mm away from the diagonal point. A threaded hole is opened at the corresponding position of the movable adjustment connecting plate.

[0051] The adjusting screws used in the scheme are all hexagonal headless top screws M6*10mm, which meet the use conditions. When the movable adjustable connecting plate and the fixed adjustable connecting plate are parallel, the adjustable spacing between the two plates is 4mm. According to the right triangle calculation formula, the angle can be calculated to be ±5.5 degrees.

[0052] The frequency doubling crystal used in this case is 6*6*10mm, so it can be understood that the deflection angle of the crystal working surface can be adjusted to ±5.5 degrees left and right, and ±5.5 degrees up and down. During the operation of the laser, the incident angle of the crystal working surface is adjusted to achieve the best frequency doubling angle and realize the ideal output power.

[0053] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A laser frequency doubling crystal angle adjustable device, characterized in that: The invention comprises a fixed base (1), a fixed plate is vertically arranged on the fixed base (1), a fixed adjustment connecting plate (2) is arranged on the side of the fixed plate, and a movable adjustment connecting plate (3) is arranged on one side of the fixed adjustment connecting plate (2), wherein: Ball grooves are provided at positions corresponding to the inner side surfaces of the fixed adjustable connecting plate (2) and the movable adjustable connecting plate (3), and steel balls (6) are installed between the ball grooves. The steel balls (6) create a gap between the fixed adjustable connecting plate (2) and the movable adjustable connecting plate (3); a plurality of telescopic springs (5) are evenly distributed between the fixed adjustable connecting plate (2) and the movable adjustable connecting plate (3); On the movable adjustable connecting plate (3), a first adjusting screw (7) and a second adjusting screw (12) are respectively arranged on the upper part of the steel ball (6) in the vertical direction and the side surface in the horizontal direction, and are respectively used to adjust the spacing between the movable adjustable connecting plate (3) at the position relative to the fixed adjustable connecting plate (2); the arrangement positions of the first adjusting screw (7), the second adjusting screw (12) and the position of the steel ball (6) form a right triangle; An L-shaped mounting plate (11) is fixed on the outer side surface of the movable adjustable connecting plate (3); a crystal fixing seat (10) is provided on the mounting plate (11); a frequency doubling crystal (9) is mounted in a crystal slot on the crystal fixing seat (10), and the frequency doubling crystal (9) is fixed by a crystal fixing cover (8); wherein the crystal fixing seat (10) is perpendicular to the movable adjustable connecting plate (3) and parallel to the fixed base (1); The first adjusting screw (7) is located above the steel ball (6). The first adjusting screw (7) is rotated clockwise or counterclockwise, so that the upper part of the movable adjusting connecting plate (3) will deflect in a direction away from or close to the fixed adjusting connecting plate (2) with the steel ball (6) as a fulcrum. At this time, the working surface of the frequency doubling crystal (9) corresponds to the deflection direction of the movable adjusting connecting plate (3), and the resulting inclination is an up-and-down deflection relative to the incident crystal surface. The second adjusting screw (12) is located on the side of the steel ball (6) in the horizontal direction, so the resulting inclination during adjustment is a left-and-right deflection relative to the incident crystal surface. By alternately adjusting the first adjusting screw (7) and the second adjusting screw (12), the working surface angle of the frequency doubling crystal (9) can be accurately adjusted to a desired angle.

2. The laser frequency doubling crystal angle adjustable device according to claim 1, characterized in that: The diameter of the steel ball (6) is greater than the sum of the depths of the ball grooves on the fixed adjustment connecting plate (2) and the movable adjustment connecting plate (3), and the existence of the gap allows the movable adjustment connecting plate (3) to have a certain rotation adjustment space relative to the fixed adjustment connecting plate.

3. The laser frequency doubling crystal angle adjustable device according to claim 1, characterized in that: The ball groove is a spherical groove, which is matched with the outer surface of the steel ball (6); the ball groove is arranged at a lower corner of the fixed adjustment connecting plate (2) and the movable adjustment connecting plate (3).

4. The laser frequency doubling crystal angle adjustable device according to claim 1, characterized in that: The two ends of the telescopic spring (5) are respectively mounted in through holes symmetrically opened on the fixed adjustment connecting plate (2) and the movable adjustment connecting plate (3), and are respectively fixed in the grooves at the ends of the through holes through spring fixing rods (4).

5. The laser frequency doubling crystal angle adjustable device according to claim 1, characterized in that: The movable adjustable connecting plate (3) is provided with a threaded hole, and the first adjusting screw (7) and the second adjusting screw (12) are assembled into the threaded hole. When the movable adjustable connecting plate (3) is parallel to the fixed adjustable connecting plate (2), it is in an initial state. In the initial state, the front ends of the first adjusting screw (7) and the second adjusting screw (12) are in elastic contact with the fixed adjustable connecting plate (2).

6. The laser frequency doubling crystal angle adjustable device according to claim 1, characterized in that: The fixed adjustment connecting plate (2) is provided with grooves at the contact parts with the first adjustment screw (7) and the second adjustment screw (12). When the movable adjustment connecting plate (3) is parallel to the fixed adjustment connecting plate (2), it is in an initial state. In the initial state, the front ends of the first adjustment screw (7) and the second adjustment screw (12) are respectively located in the corresponding grooves, and the telescopic spring (5) is configured to be in a stretched state in this state.

7. A method for adjusting the angle of a laser frequency doubling crystal using the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1, wrap the frequency doubling crystal (9) with tin foil and place it in the crystal slot on the crystal fixing seat (10), and tighten the crystal fixing cover (8) with screws to fix the frequency doubling crystal (9); Step 2, fix the crystal fixing seat (10) with the frequency doubling crystal (9) installed on the L-shaped mounting plate (11), and fix the mounting plate (11) on the movable adjustable connecting plate (3), so that the crystal fixing seat (10) is perpendicular to the movable adjustable connecting plate (3); Step 3, assemble the steel balls (6) in the ball grooves on the movable adjustable connecting plate (3) and the fixed adjustable connecting plate (2), and screw in the first adjusting screw (7) and the second adjusting screw (12), so that the ends of the first adjusting screw (7) and the second adjusting screw (12) are located in the corresponding grooves on the fixed adjustable connecting plate (2), and the fixed adjustable connecting plate (2) and the movable adjustable connecting plate (3) are kept parallel, and then each telescopic spring (5) is installed respectively, and the ends of each telescopic spring (5) are fixed to the through holes on the fixed adjustable connecting plate (2) and the movable adjustable connecting plate (3) respectively by using the spring fixing rod (4); Step 4, fix the fixed adjustment connecting plate (2) to the fixed plate on the base, and ensure that the crystal fixing seat (10) is parallel to the fixed base (1); after installation, fine-tune the first adjustment screw (7) and the second adjustment screw (12) to make the movable adjustment connecting plate (3) and the fixed adjustment connecting plate (2) parallel; Step 5, the frequency doubling crystal (9) starts to work, with its working surface perpendicular to the incident direction of the fundamental frequency light, and the measured laser power after frequency doubling is observed; Step 6, adjusting the first adjusting screw (7) and the second adjusting screw (12) to change the incident angle of the incident laser to adjust the frequency doubling efficiency.

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