General multi-pass pumping angle prism optical resonant cavity of solid laser

Abstract

The invention relates to the technical field of laser light source equipment in metal welding / cutting integrated equipment, in particular to a universal multi-pass pumping angle prism optical resonant cavity of a solid laser, which comprises a front-back through resonant cavity cooling sleeve, a front plate is connected to the front end of the resonant cavity cooling sleeve, and a rear plate is connected to the rear end of the resonant cavity cooling sleeve. The front plate is connected with a pump light mechanical diaphragm and a gain medium cooling pointer in a penetrating mode, the rear end of the resonant cavity cooling sleeve is connected with a rear plate, a laser mechanical diaphragm is arranged on the rear plate, and an angle edge and a parabolic mirror are arranged in the resonant cavity cooling sleeve and used for pumping and reflecting pump light. According to the invention, a plurality of outer ring angle edges and inner ring angle edges are arranged in the resonant cavity cooling sleeve, and the parabolic mirror is arranged in the resonant cavity cooling sleeve, so that the reflection times in the resonant cavity cooling sleeve are increased, and meanwhile, the light spot size is increased by increasing the pump light reflection angle on the parabolic mirror, so that the pump light energy density in the light spot is effectively reduced; and the absorption of the gain crystal to the pump light is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of laser light source devices in metal welding / cutting integrated devices, and particularly to a general multi-pass pumping corner prism optical resonator for solid-state lasers (mainly disk lasers) and an operation method thereof. Background Art

[0002] In 1994, GIESEN A first proposed the concept of a disk laser, making the laser crystal into a large and thin circular disk. The disk crystal has a large diameter-to-thickness ratio and is cooled by impinging water cooling, greatly improving the heat dissipation efficiency and significantly increasing the average power output of the disk laser. Due to the characteristics of the disk laser such as small thermal lens effect, high output power, good beam quality, high optical-optical conversion efficiency, and power serial expansion, it has important application prospects in the fields of industry, national defense, medical treatment, etc. In industrial applications, it is mainly used for the processing of metal plates, the welding of non-ferrous metals, the welding or cutting applications of aluminum alloys and copper alloys. Especially in the laser welding application scenarios with relatively strict requirements for power and beam divergence quality, the disk laser is the best choice of laser light source. However, in existing disk lasers, due to the relatively thin thickness of the gain medium, usually only 100μm - 200μm, the absorption efficiency of the pump light is relatively low. If only single-pass or double-pass pumping is used, the absorption efficiency of the gain medium for the pump light will be very low, unable to meet the requirements of the disk laser for the optical-optical conversion efficiency. Summary of the Invention

[0003] Aiming at the technical problem that the single-pass absorption efficiency of the above disk laser is low and cannot meet the requirements of the disk laser for the optical-optical conversion efficiency, in order to increase the absorption of the pump light by the gain crystal in the disk laser, the most effective method is to increase the number of pumping reflections and thus increase the number of absorption times.

[0004] Technical idea: Starting from the problems of the existing technology, the present application provides a general multi-pass pumping corner prism optical resonator for solid-state lasers, which realizes multiple pumping reflections of the pump light in the resonator cooling sleeve through multiple corner prisms, thereby increasing the absorption of the pump light by the gain crystal, and further improving the cooling efficiency through the gain medium cooling pointer to avoid the problem that the temperature of the gain crystal is too high due to increased light absorption and affects the beam quality.

[0005] To achieve the above technical idea, the technical solution adopted by the present invention is: The present application provides a general multi-pass pumping corner prism optical resonator for a solid-state laser, which includes a resonator cooling sleeve that penetrates through the front and back. The front end of the resonator cooling sleeve is connected to a front plate, and a pump light mechanical diaphragm and a gain medium cooling pointer are installed through the front plate. The rear end of the resonator cooling sleeve is connected to a rear plate, and a laser mechanical diaphragm is provided on the rear plate. A corner prism and a parabolic mirror are arranged inside the resonator cooling sleeve.

[0006] Further, an annular groove for adhesively fixing a cooling copper pipe is formed on the outer wall of the resonator cooling sleeve. The front end of the resonator cooling sleeve is connected to a gas distribution valve by screws, and a plurality of threaded holes are provided on the gas distribution valve.

[0007] It should be noted that the threaded holes are divided into two types with different hole diameters.

[0008] Specifically, a groove for installing a cooling copper pipe is formed on the front end face of the front plate, and a plurality of quick connectors are penetrated through the front plate.

[0009] Furthermore, a cooling pointer mechanical diaphragm is installed on the front plate by screws. A quick connection socket and a plurality of air blowing ports are provided on the cooling pointer mechanical diaphragm, and a gain medium cooling pointer and a gain medium are sleeved inside the cooling pointer mechanical diaphragm.

[0010] In detail, the gain medium cooling pointer includes a cooling pointer housing, a threaded sleeve, a cooling pointer bushing, a plurality of cooling pointers, an internal nut, and an external nut; In the above technical solution, the head end of the cooling pointer housing is threadedly connected to the external nut and the internal nut, and the tail end is fixedly connected to the threaded sleeve. The cooling pointer housing is sleeved outside the cooling pointer bushing; the tail end of the cooling pointer bushing is in threaded fit with the threaded sleeve, and a gain medium is arranged in front of the cooling pointer bushing. The gain medium is sleeved with an internal nut; the internal nut is sleeved inside the external nut, and the external nut is sleeved inside the cooling pointer mechanical diaphragm; a plurality of pointer through holes are formed on the cooling pointer bushing, and each pointer through hole is connected to a cooling pointer.

[0011] Further, the gain medium includes a gain crystal and a diamond heat sink, and the gain crystal is bonded to the front end face of the diamond heat sink.

[0012] The cooling pointer bushing is composed of a bushing column platform structure in the front section and a bushing column body structure in the rear section. There is a gap between the front part and the rear part, and a side hole is formed through the cooling pointer bushing at the gap.

[0013] Further explanation: the inner diameter of the pointer through hole opened on the front cooling pointer bushing is twice the outer diameter of the cooling pointer, which is used to allow the return cooling water to pass through the side hole opened on the cooling pointer bushing and flow to the cooling pointer housing for secondary cooling. The inner diameter of the pointer through hole opened on the rear cooling pointer bushing matches the outer diameter of the cooling pointer.

[0014] The cooling water supplied to the back of the diamond heat sink through the cooling pointer will be squeezed back into the gap around the cooling pointer and the cooling pointer bushing after cooling the back of the diamond heat sink. Since the gap is smaller than the inner diameter of the cooling pointer, the cooling water will be squeezed into the space between the end of the cooling pointer and the back of the diamond heat sink at a relatively high pressure to form a turbulent distribution and a stable heat cycle, thereby better removing the heat from the rear end face of the diamond heat sink.

[0015] Specifically, the corner edges include an outer circle corner edge and an inner circle corner edge, both of which are bonded to the rear end surface of the front plate, and the cooling pointer mechanical aperture extends to the center position of the inner circle corner edge.

[0016] In particular, there are multiple outer circle corner edges and inner circle corner edges, and the multiple outer circle corner edges and inner circle corner edges are bonded to form two annular structures.

[0017] Furthermore, the parabolic mirror is fixed by abutting against a spring through a top screw arranged on the resonant cavity cooling sleeve, the spring is located in a spring groove opened on the wall of the resonant cavity cooling sleeve, a spring cover is arranged at the spring groove port, and the spring cover is fixed to the resonant cavity cooling sleeve by screws.

[0018] Furthermore, a laser emission through hole is provided at the center of the parabolic mirror, and the laser emission through hole corresponds to the position of the laser mechanical aperture.

[0019] In detail, the rear plate is also provided with an air outlet, and a filter element is arranged in the air outlet.

[0020] In the above technical solution, a method for operating a solid-state laser universal multi-pass pumping corner prism optical resonator comprises the following steps: S1: The pump light is injected into the parabolic mirror in the cooling sleeve of the resonant cavity through the pump light mechanical aperture; S2: The incident pump light is reflected by the parabolic mirror to the end face of the gain medium. The pump light at the end face of the gain medium is reflected by the corner edge and then reflected to the parabolic mirror again. S3: The gain medium absorbs the pump light reflected by the parabolic mirror and converts the pump light into laser light, and the obtained laser light is emitted from the laser mechanical aperture; wherein the gain medium cooling finger cools the gain medium.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention forms a multiple reflection system based on the conjugation of corner cubes and parabolic mirrors by arranging a plurality of outer - ring corner cubes, inner - ring corner cubes, and parabolic mirrors in the resonant cavity cooling sleeve, reflecting the pump beam 44 to 46 times. By increasing the number of reflections in the resonant cavity cooling sleeve and increasing the laser reflection angle on the parabolic mirror to increase the spot size, compared with the existing multi - pass pumping resonant cavities on the market, it can effectively reduce the pump light energy density in the spot, and the maximum allowable damage threshold can reach 50 kW per square centimeter, thus allowing a lower probability of ablation to be ensured under low - cost and lower - damage - threshold optical components. According to the currently tested data, the probability of ablation can be reduced by 10%.

[0022] 2. The present invention improves the cooling efficiency to avoid the reduction of the optical - optical conversion efficiency caused by increased light absorption by pasting fixed cooling copper tubes on the outer wall of the resonant cavity cooling sleeve and the front end face of the front plate, pasting the corner cubes on the front plate, and fixing the parabolic mirror in the resonant cavity cooling sleeve with set screws and springs. The current operating cooling temperature is 28 to 29 degrees Celsius. This application can achieve a minimum cooling temperature of 25 degrees Celsius for the optomechanical part and maintain it within plus or minus 0.5 degrees Celsius under continuous operation for 1 hour. The present invention adopts standard buried - tube technology, eliminating the use of technologies such as mechanical drilling (deep holes) and friction welding, reducing costs and the possibility of seal use and failure leakage. Compared with the conventional solution of using deep - drilled holes in copper cooling blocks as cooling water channels, it eliminates the design of seals and seal grooves, mechanical processing, and special tooling costs, and the cost is 30% lower under step - by - step quotations.

[0023] 3. The present invention is connected with an air - distributing valve at the front end of the resonant cavity cooling sleeve by screws, thereby realizing the formation of a standard air - circulation drying module in the resonant cavity cooling sleeve, retaining the positive pressure formed by air circulation in the resonant cavity cooling sleeve, and further reducing the lens ablation and laser scattering caused by the invasion of particulate matter and humid gas into the cavity.

[0024] 4. The present invention fixes a pump - optical - mechanical diaphragm with a standard design on the front plate and a laser - mechanical diaphragm with a standard design on the rear plate to match different spot sizes. The mechanical diaphragm design includes air vents to improve the overall sealing performance of the resonant cavity cooling sleeve.

[0025] 5. The present invention realizes the adjustable fixation of the parabolic mirror through the standard - designed set screws and springs on the resonant cavity cooling sleeve, enabling the parabolic mirror to better reflect the pump light technology and improving the reflection efficiency. Under the condition of a single - resonant - cavity excitation of 8000 watts, when the power in the resonant cavity is measured without adjusting the parabolic mirror and the parabolic mirror, the power difference can reach up to 20%.

[0026] 6. The present invention relates to a gain crystal used in a high-power disk laser and its cooling pointer. The gain crystal is bonded to a diamond heat sink to achieve the best thermal conduction and cooling effect. A double-cavity gain medium cooling pointer with an adjustable distance of the cooling pointer is realized by the threaded fit between the tail end of the cooling pointer bushing and the threaded sleeve. When using Yb YAG as the gain crystal and the laser excitation power is 4000W, the cooling efficiency is the highest when the distance between the bushing of the cooling pointer and the back of the diamond is 2 mm. When the laser excitation power is 6000W, the cooling efficiency is the highest when the distance between the bushing of the cooling pointer and the back of the diamond is 1.5 mm. Among them, the double cooling cavities reduce the thermal convection caused by too large a temperature gradient in the cooling water. The adjustable distance gain medium cooling pointer ensures the adjustability of the cooling water flow rate to match the thermal coupling on the back of the heat sink under different laser powers, that is, the water cooling effect. Compared with the prior art, the present application has two technical effects: adjustable cooling distance to match different laser excitation powers and double-cavity cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0028] Figure 1 is a three-dimensional view of the overall structure of the present invention; Figure 2 is a three-dimensional view of a partial structure of the present invention; Figure 3 For the present invention Figure 2 rear three-dimensional view; Figure 4 For the present invention Figure 2 front three-dimensional view; Figure 5 For the present invention Figure 4 cross-sectional view taken along the A-A direction in the present invention; Figure 6 is a three-dimensional view of the resonant cavity cooling sleeve structure of the present invention; Figure 7 For the present invention Figure 2 exploded view; Figure 8 is a three-dimensional view of the cooling pointer mechanical diaphragm structure of the present invention; Figure 9 For the present invention Figure 8 front view; Figure 10 is a three-dimensional view of the parabolic mirror structure of the present invention; Figure 11Stereogram of the cooling pointer structure of the gain medium of the present invention; Figure 12 For the present invention Figure 11 Rear view; Figure 13 For the present invention Figure 12 Cross-sectional view taken along the B-B direction in the present invention; Figure 14 For the present invention Figure 13 Enlarged view of part A in the present invention; Figure 15 Diagram showing the positional relationship between the cooling pointer bushing and the gain medium of the present invention; Figure 16 Experimental demonstration diagram of the pump light focusing at the center position of the gain crystal of the present invention; Figure 17 Actual photo of the physical object of the present invention being tested on a solid laser platform; Figure 18 Physical diagram of the present invention.

[0029] In the figure: 1. Resonator cooling sleeve; 11. Annular groove; 12. Set screw; 13. Spring groove; 14. Spring; 15. Spring cover; 2. Front plate; 21. Pump light mechanical diaphragm; 22. Groove; 23. Quick interface; 24. Cooling pointer mechanical diaphragm; 25. Quick connection socket; 26. Blowing port; 3. Gain medium cooling pointer; 31. Cooling pointer housing; 32. Threaded sleeve; 33. Cooling pointer bushing; 34. Cooling pointer; 35. Inner nut; 36. Outer nut; 4. Gain medium; 41. Gain crystal; 42. Diamond heat sink; 5. Rear plate; 51. Laser mechanical diaphragm; 52. Air outlet; 6. Corner prism; 61. Outer ring corner prism; 62. Inner ring corner prism; 7. Parabolic mirror; 71. Laser emission through hole; 8. Air distribution valve; 81. Threaded hole. Detailed implementation mode

[0030] In order to enable those of ordinary skill in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "front end", "rear end", "inner side", "outer side", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0032] In the description of the present application, it should also be noted that, unless otherwise clearly specified and limited, the terms "arranged", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0033] The inventors have found through research that in existing disk lasers, due to the relatively thin thickness of the gain medium, usually only 100μm - 200μm, the absorption efficiency of pump light is relatively low. If only single-pass or double-pass pumping is used, the absorption efficiency of the gain medium for pump light will be very low, unable to meet the requirements of the disk laser for the light-light conversion efficiency.

[0034] Based on the above findings, the present application provides a general multi-pass pumped corner prism optical resonator for a solid-state laser, including a resonator cooling sleeve 1 that penetrates through the front and back. The front end of the resonator cooling sleeve 1 is connected to a front plate 2, and a pump light mechanical aperture 21 and a gain medium cooling pointer 3 are connected through the front plate 2. The rear end of the resonator cooling sleeve 1 is connected to a rear plate 5, and a laser mechanical aperture 51 is provided on the rear plate 5. And a corner prism 6 and a parabolic mirror 7 are arranged inside the resonator cooling sleeve 1. Embodiment

[0035] Referring to Figures 1 - 18 As shown, the present application provides a general multi-pass pumped corner prism optical resonator for a solid-state laser, including a resonator cooling sleeve 1 that penetrates through the front and back. The front end of the resonator cooling sleeve 1 is connected to a front plate 2, and a pump light mechanical aperture 21 is connected through the front plate 2. The rear end of the resonator cooling sleeve 1 is connected to a rear plate 5, and a laser mechanical aperture 51 is provided on the rear plate 5. And a corner prism 6 and a parabolic mirror 7 are arranged inside the resonator cooling sleeve 1. The corner prism 6 and the parabolic mirror 7 are used for pumping and reflecting the pump light.

[0036] Furthermore, an annular groove 11 for adhesively fixing a cooling copper tube is formed on the outer wall of the resonator cooling sleeve 1.

[0037] Specifically, the resonant cavity cooling sleeve 1 is a cylindrical hollow mechanical sleeve, which is machined from blackened aluminum alloy or copper. The cooling copper pipe is fixed in the annular groove 11 by means of pipe pressing and bonding. Standard quick connectors are installed at both ends of the cooling copper pipe for connecting PU pipes. The PU pipes send cooling water in and out to form heat exchange. The stray light in the non-optical axis direction is absorbed by the resonant cavity cooling sleeve 1 and converted into heat energy, which is evenly distributed on the surface of the resonant cavity cooling sleeve 1. Further, the heat on the surface of the resonant cavity cooling sleeve 1 is conducted to the cooling copper pipe in the form of providing thermal coupling. Furthermore, the cold water circulation passes through the cooling copper pipe to take away the heat.

[0038] It should be noted that the cooling water temperature provided by the PU pipes sending cooling water in and out to form heat exchange is 28 - 29 °C, the water pressure is 3.5 - 4 bar, and the flow rate is 10 - 50 L / min for cooling the resonant cavity under different powers.

[0039] As an example, the pump light mechanical diaphragm 21 is used to filter the stray light part of the incident pump light.

[0040] Furthermore, an air outlet 52 is also provided on the rear plate 5, and a filter element is arranged in the air outlet 52.

[0041] Even further, a gas distribution valve 8 is connected to the front end of the resonant cavity cooling sleeve 1 by screws, and a plurality of threaded holes 81 are provided on the gas distribution valve 8.

[0042] Specifically, a groove 22 for installing the cooling copper pipe is formed on the front end face of the front plate 2, and a plurality of quick connectors 23 are penetrated and provided.

[0043] In detail, a cooling pointer mechanical diaphragm 24 is connected to the front plate 2 by screws. A quick connection socket 25 and a plurality of air blowing ports 26 are provided on the cooling pointer mechanical diaphragm 24.

[0044] As an example, the gas distribution valve 8 is made of galvanized or nickel-plated stainless steel. There is a relatively large-diameter threaded hole 81 and a plurality of relatively small-diameter threaded holes 81 perpendicular to it on the gas distribution valve 8. The relatively small-diameter threaded holes 81 are used to install PU or PVC air pipes. The air pipe installed in the relatively large-diameter threaded hole 81 is used to connect the air supply device, usually a blower, a dryer or an oxygen / nitrogen / other inert gas cylinder. And the air pipes installed on the plurality of relatively small-diameter threaded holes 81 are used to lead to the quick connectors 23 on the front plate 2 or the quick connection socket 25 provided on the cooling pointer mechanical diaphragm 24, and supply air to the closed space in the resonant cavity cooling sleeve 1.

[0045] In the above technical solution, the corner edge 6 includes an outer ring corner edge 61 and an inner ring corner edge 62. Both the outer ring corner edge 61 and the inner ring corner edge 62 are adhesively bonded to the rear end face of the front plate 2, and the cooling pointer mechanical diaphragm 24 extends to the central position of the inner ring corner edge 62.

[0046] Specifically, the inner ring corner edge 62 is formed by several pairs of corner edge pairs with opposite reflecting surfaces. The outer ring corner edge 61 is also formed by several pairs of corner edge pairs with opposite reflecting surfaces.

[0047] Further, the parabolic mirror 7 is abutted and fixed by a setscrew 12 and a spring 14 provided on the resonant cavity cooling sleeve 1. The spring 14 is located in a spring groove 13 opened on the wall of the resonant cavity cooling sleeve 1. A spring cover 15 is provided at the port of the spring groove 13, and the spring cover 15 is fixedly connected to the resonant cavity cooling sleeve 1 by screws. Specifically, a laser emission through hole 71 is opened at the center of the parabolic mirror 7, and the laser emission through hole 71 corresponds to the laser mechanical diaphragm 51.

[0048] As an example, the parabolic mirror 7 is a large-aperture aspherical parabolic mirror with an emission through hole 71 at the center. The emission through hole 71 is used for the laser generated after the gain medium 4 absorbs the pump light, and the aspherical surface of the parabolic mirror 7 is used to conjugate with the opposite corner edge 6 to produce the effect of multi-pass pumping reflection. The reflectivity of the corner edge 6 and the parabolic mirror 7 for the pump light at the wavelength of the pump light should exceed 99.5%. Embodiment

[0049] On the basis of Embodiment 1, with reference to Figure 12 、 14 as shown, a gain medium cooling pointer 3 and a gain medium 4 are sleeved inside the cooling pointer mechanical diaphragm 24.

[0050] Further, the gain medium cooling pointer 3 includes a cooling pointer housing 31, a threaded sleeve 32, a cooling pointer bushing 33, a plurality of cooling pointers 34, an inner nut 35, and an outer nut 36. The head end of the cooling pointer housing 31 is threadedly connected with the outer nut 36 and the inner nut 35, the tail end is fixedly connected with the threaded sleeve 32, and a cooling pointer bushing 33 is sleeved inside the cooling pointer housing 31. The tail end of the cooling pointer bushing 33 is in threaded cooperation with the threaded sleeve 32. A gain medium 4 is arranged in front of the cooling pointer bushing 33, and the gain medium 4 is sleeved with an inner nut 35. The inner nut 35 is sleeved with an outer nut 36, and the outer nut 36 is sleeved inside the cooling pointer mechanical diaphragm 24. A plurality of pointer through holes are opened on the cooling pointer bushing 33, and each pointer through hole is connected with a cooling pointer 34.

[0051] As an example, the gain medium 4 includes a gain crystal 41 and a diamond heat sink 42, and the gain crystal 41 is bonded to the front end face of the diamond heat sink 42.

[0052] Specifically, the process of bonding the gain crystal 41 to the front end face of the diamond heat sink 42 is as follows: 1. Taking Yb YAG with a doping ratio of 8% as the gain crystal as an example, first, the Yb YAG crystal is thinned into a double-plane thin crystal of about 100 μm by grinding and polishing, and the plane surface is processed to a specified aperture value by polishing.

[0053] 2. Taking diamond as the heat sink as an example, first, the surface of the diamond for bonding is processed into a curved surface with a certain curvature by turning and milling, and then the surface profile is processed to ensure the surface roughness PV value. Subsequently, the surface not used for bonding is metallized or coated with a copper film / gold film to ensure that this surface does not transmit any wavelength of laser, and the back surface of the diamond has a broad-spectrum reflection for laser.

[0054] 3. Coat the processed Yb YAG gain crystal. One side is coated with a matched transmission film for the pump light angle AOI and the vertical angle of the excitation laser, and the other side is coated with a matched transmission film for the pump light angle AOI. Low-stress coating must be used to prevent the influence of the stress generated by coating on the surface profile.

[0055] 4. Cold weld and bond the processed diamond and gain crystal. The solder specifically used is indium metal. The specific operation is as follows: an indium ball or a 500-μm-thick film-shaped indium solder can be placed on the diamond surface, and the coated gain crystal is placed above the solder. A glass standard ball with a curvature is used to press the crystal sheet downward. When the pressure reaches 100 to 150 bar, the indium solder starts to flow and forms a 30-μm-thick welding layer to complete the bonding of the gain crystal and the diamond.

[0056] It should be noted that the cooling pointer housing 31 is a hollow cavity structure, and there is a gap between the cooling pointer bushing 33 and the cooling pointer housing 31. In addition, side holes are drilled through the outer wall of the cooling pointer bushing 33. Cooling water enters the conical cavity of the cooling pointer bushing 33 and then enters the cooling pointer 34 and is sprinkled on the back surface of the diamond heat sink 42 for heat exchange.

[0057] Specifically, the tail end of the cooling pointer bushing 33 is threadedly engaged with the threaded sleeve 32, thereby enabling the rotation of the cooling pointer 34. By rotation, the distance between the cooling pointer bushing 33 and the surface of the diamond heat sink 42 can be controlled, directly controlling the flow rate and velocity of the cooling water, and ultimately controlling the cooling amount of the water on the back of the diamond heat sink 42. In addition, the double-chamber design can ensure that the cooling water has passed through the return water before being sprayed onto the diamond heat sink 42, that is, the return flow between the cooling pointer 34 and the multiple pointer through-holes provided on the cooling pointer bushing 33 indirectly heats and reduces the excessive temperature difference that may occur between the inlet and return of the cooling water, thereby avoiding the influence of the thermal stress difference in the gain crystal 41 caused by the excessive temperature gradient on the surface profile of the gain crystal 41.

[0058] Specifically, after the gain crystal 41 of the low-energy band electrons absorbs the pump light, it is excited to jump to the high-energy band and then falls back, emitting photons and oscillating to form a laser with a fixed wavelength. The gain crystal 41 is attached to the diamond heat sink 42 for heat conduction by means of cold welding or bonding with UV glue.

[0059] In particular, the cooling pointer 34 directly cools the back of the diamond heat sink 42 through a PVC plastic pipe to supply cold water, thereby indirectly cooling the gain crystal 41.

[0060] As an example, the gain crystal 41 is a rod laser gain crystal or a disk laser gain crystal.

[0061] For a laser with an excitation wavelength of 1030 nm, the disk laser gain crystal itself is a Yb YAG or Yb LuAG crystal, the doping concentration of yttrium ions is 7% - 15% (depending on the engineering requirements for the absorption efficiency and optical-optical conversion efficiency of the laser gain crystal). The front diameter is 17 - 25 mm, the thickness is about 90 - 150 μm, and the side curvature radius is 3 - 4 m to adapt to the resonator lengths of different powers. The end face of the disk laser gain crystal facing the pump light is coated with an antireflection film, and the transmittance for the pump light with a wavelength of 940 nm should exceed 99.6%. The back of the disk laser gain crystal has a reflective film, the reflectivity for the pump light with a wavelength of 940 nm should exceed 99.5%, and the reflectivity for the laser with a wavelength of 1030 nm should exceed 99.8%.

[0062] It should be noted that the disc laser gain crystal material is not limited to Yb YAG, Yb LuAG, or Nd YAG. Other solid gem materials doped with different ions can also be used as crystal substrates to excite lasers of different wavelengths. For example, Nd:YAG, Er:YAG, Yb:Lu2O3, DyTb∶LuLiF4, Er:GGG, Ce:YAG, CTH:YAG, Nd:YLF, Nd:YVO, or other scintillation crystals. The excitable wavelengths include but are not limited to 1064nm, 1070nm, etc., and can also include yellow light, blue light, green light, and ultraviolet light.

[0063] This application mainly describes a 44 - 46 - time multiple - reflection system based on the conjugation of the corner cube 6 and the parabolic mirror 7. This design focuses on increasing the number of reflections within the resonator cooling sleeve 1 and increasing the laser reflection angle on the parabolic mirror 7 to increase the spot size.

[0064] During the specific application process, the pump light enters the parabolic mirror 7 inside the resonator cooling sleeve 1 through the pump - light mechanical aperture 21, is reflected towards the gain crystal 41 in front of the cooling pointer 34, and then is reflected back to the parabolic mirror 7 again, which is considered as one pumping process.

[0065] The incident pump light will be reflected towards the corresponding corner cube 6 after one pumping process, then the reflection direction is rotated and it is reflected back to the parabolic mirror 7 to start a new pumping process, that is, it is reflected towards the end face of the gain medium 4. The parabolic mirror 7 is used to reflect the pump light reflected from the corner cube 6. A Zemax simulation of the pumping process in the resonator is carried out to ensure that in each pumping process, the pump light is focused at the center position of the gain crystal 41 to achieve the best absorption efficiency, as Figure 16 shown.

[0066] In each pumping process, the gain medium 4 absorbs the pump light reflected by the parabolic mirror 7, converts the pump light into laser light, and the obtained laser light is emitted from the laser mechanical aperture 51; among them, the gain - medium cooling pointer 3 cools the gain medium 4.

[0067] It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A solid-state laser universal multi-pass pumping corner prism optical resonator, comprising a resonator cooling sleeve (1) extending from front to back, characterized in that: The front end of the resonant cavity cooling sleeve (1) is connected to a front plate (2), a pump optical mechanical aperture (21) and a gain medium cooling pointer (3) are installed through the front plate (2), the rear end of the resonant cavity cooling sleeve (1) is connected to a rear plate (5), a laser mechanical aperture (51) is arranged on the rear plate (5), and an angle edge (6) and a parabolic mirror (7) are arranged inside the resonant cavity cooling sleeve (1).

2. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 1, characterized in that: An annular groove (11) for bonding and fixing the cooling copper tube is provided on the outer wall of the resonant cavity cooling sleeve (1), and a gas separation valve (8) is connected to the front end of the resonant cavity cooling sleeve (1) via screws, and a plurality of threaded holes (81) are provided on the gas separation valve (8).

3. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 2, characterized in that: A groove (22) for mounting a cooling copper tube is provided on the front end surface of the front plate (2), and a plurality of quick connectors (23) are provided through the front plate (2).

4. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 3, characterized in that: A cooling pointer mechanical diaphragm (24) is mounted on the front plate (2) by means of screws, a quick-connect socket (25) and a plurality of air blowing ports (26) are provided on the cooling pointer mechanical diaphragm (24), and a gain medium cooling pointer (3) and a gain medium (4) are sleeved inside the cooling pointer mechanical diaphragm (24).

5. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 4, characterized in that: The gain medium cooling pointer (3) comprises a cooling pointer housing (31), a threaded sleeve (32), a cooling pointer bushing (33), a plurality of cooling pointers (34), an inner nut (35) and an outer nut (36); The head end of the cooling pointer housing (31) is threadedly connected to the outer nut (36) and the inner nut (35), and the tail end is fixedly connected to the threaded sleeve (32), and the cooling pointer housing (31) is sleeved outside the cooling pointer bushing (33); The tail end of the cooling pointer bushing (33) is threadably matched with the threaded sleeve (32); a gain medium (4) is arranged in front of the cooling pointer bushing (33); and an inner nut (35) is arranged on the outer sleeve of the gain medium (4); The inner nut (35) is sleeved in the outer nut (36), and the outer nut (36) is sleeved in the cooling pointer mechanical aperture (24); The cooling pointer bushing (33) is provided with a plurality of pointer through holes, and each of the pointer through holes is connected to a cooling pointer (34).

6. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 5, characterized in that: The gain medium (4) comprises a gain crystal (41) and a diamond heat sink (42); the gain crystal (41) is bonded to the front end surface of the diamond heat sink (42).

7. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 6, characterized in that: The corner edge (6) comprises an outer corner edge (61) and an inner corner edge (62), the outer corner edge (61) and the inner corner edge (62) are both bonded to the rear end surface of the front plate (2), and the cooling pointer mechanical aperture (24) extends to the center position of the inner corner edge (62).

8. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 7, characterized in that: The parabolic mirror (7) is fixed by abutting against a spring (14) through a top screw (12) provided on the resonant cavity cooling sleeve (1); the spring (14) is located in a spring groove (13) on the wall of the resonant cavity cooling sleeve (1); a spring cover (15) is provided at the end of the spring groove (13); and the spring cover (15) is fixed to the resonant cavity cooling sleeve (1) by screws; A laser emission through hole (71) is provided at the centre of the parabolic mirror (7), and the laser emission through hole (71) corresponds to the position of the laser mechanical aperture (51).

9. The solid-state laser universal multi-pass pumping corner prism optical resonator according to claim 8, characterized in that: The rear plate (5) is also provided with an air outlet (52), and a filter element is provided in the air outlet (52).

10. The working principle of a solid-state laser universal multi-pass pumping corner prism optical resonator according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: The pump light is injected into the parabolic mirror (7) in the resonant cavity cooling sleeve (1) through the pump light mechanical aperture (21); S2: The incident pump light is reflected by the parabolic mirror (7) toward the end face of the gain medium (4), and the pump light at the end face of the gain medium (4) is reflected by the corner edge (6) and then reflected again to the parabolic mirror (7); S3: The gain medium (4) absorbs the pump light reflected by the parabolic mirror (7) and converts the pump light into laser light, and the obtained laser light is emitted from the laser mechanical aperture (51); wherein the gain medium cooling pointer (3) cools the gain medium (4).

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