A high-power laser mirror device

Abstract

The application discloses a strong laser mirror device, comprising: an ultrahigh-precision rotating table and a reflecting component; the reflecting component is fixedly connected to the upper side of the ultrahigh-precision rotating table through a connecting rod and can rotate axially along with the rotation of the ultrahigh-precision rotating table; the reflecting component comprises a mirror, a mirror body base for accommodating the mirror and a pressing plate for fixing the mirror. The strong laser mirror device disclosed by the application effectively inhibits the mirror surface thermal deformation of the mirror under strong laser irradiation, further reduces the thermal deformation of the mirror on the basis of the existing strong laser mirror, and further improves the laser damage threshold of the mirror.

Description

Technical Field

[0001] This invention relates to the technical field of laser applications, and more particularly to a high-power laser reflector device. Background Technology

[0002] High-power lasers have wide applications in industry, military, and space science. As a component of a high-power laser optical system, the reflector inevitably absorbs some light energy during reflection, causing a non-uniform temperature rise and resulting in thermal deformation of the mirror surface. This thermal deformation alters the beam propagation direction and degrades beam quality. Therefore, improving the design of high-power laser reflectors to mitigate thermal deformation is crucial for the application of high-power lasers.

[0003] Currently, the main methods for reducing the thermal deformation of mirror surfaces include water cooling, air cooling, and phase change refrigeration. These methods utilize heat absorption by the mirror to dissipate into the heat sink, thereby reducing the mirror's temperature rise and thus reducing thermal deformation. However, the thermal resistance between the heat sink and the mirror surface cannot be eliminated, and the energy absorbed by the mirror is generally non-uniformly distributed. Due to this thermal resistance, the mirror will experience a non-uniform temperature rise, resulting in thermal deformation. In addition, there are methods to reduce mirror surface thermal deformation through structural design, such as designing the back of the mirror as a protrusion or perforating the outer perimeter of the back. This method of compensating for thermal deformation using special mirror structures can achieve significant results to some extent, but its structure is often designed for a specific spot parameter, limiting its applicability. Furthermore, thermal compensation around the mirror can also reduce mirror surface thermal deformation to some extent, but this increases heat dissipation power and has limited effectiveness. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a high-power laser reflector device that effectively suppresses mirror thermal deformation under high-power laser irradiation. It further reduces the thermal deformation of the reflector based on existing high-power laser reflectors and simultaneously increases the laser damage threshold of the reflector.

[0005] Specific technical solutions include:

[0006] A high-power laser reflector device includes: an ultra-high precision rotating stage and a reflector;

[0007] The reflector is fixedly connected to the top of the ultra-high precision rotary table via a connecting rod, and can rotate axially as the ultra-high precision rotary table rotates;

[0008] The reflector includes a reflector, a base for housing the reflector, and a pressure plate for fixing the reflector.

[0009] The strong laser mirror device disclosed in the application rotates with the rotation of the rotation table surface of the ultra-high precision rotation table during the laser irradiation process, and the rotation axis is the central axis of the mirror surface, so that the position of the light spot is unchanged and the transmission direction of the irradiated laser is unchanged during the rotation process. Compared with the conventional constant position irradiation, the irradiation area is shifted after a short time of irradiation during the rotation process of the mirror, and the energy absorbed by the irradiation area will be smaller than that in the case of constant position irradiation, and the thermal deformation will also be smaller.

[0010] The strong laser mirror device disclosed in the application further comprises a cooling part;

[0011] When air cooling is used, the cooling part comprises a heat sink and a cold head;

[0012] The heat sink is arrayed and arranged on the back surface of the mirror body base;

[0013] The cold head is parallel and close to the mirror;

[0014] The cold head comprises a copper cold head block, a rubber heat insulation pad, a cold head fixing sleeve, a thermoelectric refrigerator and a thermoelectric refrigerator heat sink;

[0015] The rubber heat insulation pad is wrapped around the outer surface of the copper cold head block, and the copper cold head block wrapped with the rubber heat insulation pad is fixedly arranged in the cold head fixing sleeve, so that the heat leakage of the copper cold head block is fully insulated.

[0016] The thermoelectric refrigerator is fixed above the copper cold head block and can be connected to an external direct current power supply for power supply refrigeration; the hot end of the thermoelectric refrigerator is further fixed with a thermoelectric refrigerator heat sink; preferably, the thermoelectric refrigerator heat sink is fixed by using heat-conducting silica gel.

[0017] Preferably, the thermoelectric refrigerator heat sink is selected from a plate-fin heat sink.

[0018] Preferably, the cold head is fixed on a precision tilt table, and is fixedly connected to a test table through a tilt table connecting rod. The height and inclination angle of the cold head can be adjusted by fine-tuning the screws under the precision tilt table, so that the cold head is parallel and close to the mirror.

[0019] When the laser irradiation absorption power is large or the laser irradiation time is long, preferably, the cooling part further comprises a fan and a fan bracket for fixing the fan.

[0020] The lower half of the fan completely covers the heat sink array at the air outlet, and the heat sink array can be fully blown and cooled;

[0021] The upper half of the fan completely covers the thermoelectric refrigerator heat sink at the air outlet, and the air outlet direction is parallel to the plate-fin direction of the plate-fin heat sink.

[0022] Preferably, the heat sink is selected from a needle column type and is uniformly arranged on the back of the mirror base. With the needle column type heat sink, the wind blocking area along the fan blowing direction is basically unchanged during rotation, which does not affect the flow of air, and due to the rotation of the heat sink, the disturbance to the air is further enhanced, which is beneficial to heat dissipation.

[0023] Preferably, one side of the mirror is a cold head, and the other side without shielding area is a laser irradiation area, and the included angle of the cold head to the laser irradiation area along the rotation direction is <180°. When the mirror rotates, the irradiation area first passes through the cold head for cooling, and then passes through the laser irradiation after less than half a rotation, which is beneficial to obtain smaller temperature rise and thermal deformation.

[0024] Further, when the laser irradiation absorption power is small or the laser irradiation time is short, the heat sink can be replaced by phase change energy storage cooling, which further simplifies the device.

[0025] When the laser irradiation absorption power is further increased, the cooling part can be replaced by water cooling.

[0026] When water cooling is used, the cooling part includes a slip ring device and a connecting water pipe, and the inside of the mirror base is further provided with a flow channel;

[0027] The connecting water pipe is in communication with the slip ring device and the back of the mirror base, respectively.

[0028] The slip ring device includes a stator and a rotor, the stator is sleeved outside the rotor, and the stator and the rotor are respectively provided with water inlet / outlet;

[0029] The inner diameter of the slip ring device is greater than the diameter of the connecting rod, the slip ring device is sleeved on the connecting rod, and the stator is fixed by the external clamping structure.

[0030] Preferably, the diameter of the mirror is greater than the sum of the laser irradiation spot diameter and the maximum length of the cold head, so that the mirror has sufficient reflection area for reflection.

[0031] Preferably, the rotation speed of the ultra-high precision rotary table is 0-15 rad / s, and can be selected from 0.5 rad / s, 1 rad / s, 2 rad / s, 3 rad / s, 4 rad / s, 5 rad / s, 6 rad / s, 7 rad / s, 8 rad / s, 9 rad / s, 10 rad / s, 11 rad / s, 12 rad / s, 13 rad / s, 14 rad / s, 15 rad / s and any value in the range, and further preferably 1-10 rad / s.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] (1) The method of changing the laser irradiation position by rotating the mirror adopted by the present application is suitable for the conventional strong laser mirror, and can further reduce the temperature rise and thermal deformation of the mirror on this basis.

[0034] (2) The mirror device designed by the present application can further improve the laser damage threshold of the mirror on the basis of the conventional strong laser mirror, thereby expanding the application range of the mirror.

[0035] (3) The mirror device designed by the present application is not designed for specific laser beam parameters, and has universality. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Structure diagram of the air-cooled strong laser mirror device prepared for Example 1;

[0037] Figure 2 Enlarged view of the cold head area in the strong laser mirror device prepared for Example 1;

[0038] Figure 3 Maximum temperature rise of the strong laser mirror device prepared by using Example 1 under three working conditions of no rotation and no refrigeration, rotation and no refrigeration, and rotation and refrigeration changes with time;

[0039] Figure 4 When the laser irradiation lasts for 10s, the maximum temperature rise and thermal deformation PV value of the strong laser mirror device prepared by using Example 1 under the working condition of rotation and refrigeration change with the rotation speed;

[0040] Figure 5 Structure diagram of the water-cooled strong laser mirror device prepared for Example 2;

[0041] Figure 6 When the laser irradiation lasts for 10s, the maximum temperature rise and thermal deformation PV value of the strong laser mirror device prepared by using Example 2 under the working condition of rotation change with the rotation speed;

[0042] In the figure, 1 is an ultra-high precision rotary table, 2 is a connecting rod, 3 is a heat sink, 4 is a mirror, 5 is a pressing plate, 6 is a mirror body base, 7 is a cold head, 8 is a precision tilt table, 9 is a tilt table connecting rod, 10 is a fan support, 11 is a fan, 12 is a screw, 21 is a slip ring device, 22 is a connecting water pipe, 23 is a water cooling connector, 24 is an inlet / outlet, 101 is a rotary table base, 102 is a rotary table surface, 201 is a stator, 202 is a rotor, 701 is a cold head fixing sleeve, 702 is a thermoelectric refrigerator, 703 is a thermoelectric refrigerator heat sink, 704 is a copper cold head block, 705 is a rubber heat insulation pad, and 706 is a polycarbonate screw. DETAILED DESCRIPTION

[0043] The application will be further described in detail below with reference to the accompanying drawings and embodiments, but the embodiments of the application are not limited thereto.

[0044] Embodiment 1

[0045] As shown in the drawings, the air-cooled strong laser mirror device disclosed in the embodiment comprises an ultra-high precision rotary table, a reflecting element and a cooling part. Figures 1-2 The ultra-high precision rotary table 1 comprises a rotary table base 101 and a rotary table surface 102, and the rotary table surface 102 can be controlled to rotate by the rotary table base 101.

[0046] The reflecting element comprises a mirror 4, a pressing plate 5 and a mirror body base 6; the mirror 4 is placed in a groove in the middle of the mirror body base 6, and is tightly positioned by the pressing plate 5, and the three are tightly fixed by screws 12.

[0047] The reflecting element is fixedly connected with the ultra-high precision rotary table 1 through a connecting rod 2, the connecting rod 2 is located at the center of the reflecting element, the upper end of the connecting rod 2 is tightly screwed into a threaded hole in the middle of the back of the mirror body base 6, and the lower end is fixed to the rotary table surface 102 of the ultra-high precision rotary table 1 by screws.

[0048] The cooling part comprises a cold head 7, a heat sink 3 and a fan assembly.

[0049] The cold head 7 is arranged above the mirror 4, the cold head 7 is tightly fixed on a precision tilting table 8, and is fixed on a test table through a tilting table connecting rod 9; the height and the inclination angle of the cold head 7 can be adjusted by adjusting the screws below the precision tilting table 8, so that the cold head 7 is parallel to and close to the mirror 4.

[0050] Further, the cold head 7 comprises a copper cold head block 704, a rubber heat insulation pad 705, a cold head fixing sleeve 701, a thermoelectric cooler 702, a thermoelectric cooler heat sink 703 and a polycarbonate screw 706; the copper cold head block 704 is sleeved in the cold head fixing sleeve 701 after the outer surface of the copper cold head block 704 is surrounded by a circle of rubber heat insulation pads 705, and is fixed around by the polycarbonate screw 706, the thermoelectric cooler 702 is pasted on the copper cold head block 704 by heat-conducting silicone, and can be connected to an external direct-current power supply for power supply and refrigeration, the hot end of the thermoelectric cooler 702 is pasted and arranged with the thermoelectric cooler heat sink 703 by heat-conducting silicone, and the thermoelectric cooler heat sink 703 adopts a plate-fin heat sink.

[0051] One side of the mirror 4 is provided with the cold head 7, and the other side without the shielding area is a laser irradiation area, and the included angle of the cold head 7 to the laser irradiation area along the rotation direction is <180°, when the mirror 4 rotates, the irradiation area first passes through the cold head 7 for cooling, and then passes through the laser irradiation area after less than half a rotation, which is beneficial to obtain smaller temperature rise and thermal deformation.

[0052]

[0053] ​The heat sink 3 is arranged on the back of the mirror base 6 in the reflector, is a uniform array of heat sinks fixed on the back of the mirror base 6, and is a pin column heat sink, which can ensure that the wind blocking area along the fan blowing direction is basically unchanged during rotation, does not affect the flow of air, and further enhances the disturbance of air due to the rotation of the heat sink 3, which is beneficial to heat dissipation.

[0054] The fan assembly includes a fan 11 and a fan bracket 10, the fan 11 is fixed on the fan bracket 10 by screws, and the fan bracket 10 is fixed on the test bench by screws.

[0055] The lower half of the fan 11 completely covers the heat sink 3 at the air outlet, which can fully blow and dissipate heat for the heat sink 3; the upper half of the fan 11 and the thermoelectric cooler heat sink 703 are fixed, and the thermoelectric cooler heat sink 703 is located at the centrifugal position of the reflector 4, and the plate fin direction is parallel to the air outlet direction of the fan, so that sufficient air blowing and heat dissipation can be achieved.

[0056] The size of the reflector 4 used in the embodiment is φ100mm*5mm, the material is SiC, the absorption power is 50W, the waist radius of the Gaussian light beam is 15mm, the distance between the light spot center and the center of the reflector 4 is 30mm, the refrigeration power density is 0.2 times at the center of the Gaussian light beam, the refrigeration area of the cold head 7 is a radius of 20mm, the refrigeration center is 30mm away from the centrifugal position, and the angle between the refrigeration center and the light spot center is (π-1) rad.

[0057] Working principle: for a conventional static reflector, the light irradiation area is always heated by absorbing heat during the entire irradiation process. For the rotating reflector disclosed in the application, the rotary table base 101 can control the rotary table 102 to rotate, the reflector is axially rotated with the rotary table 102, the area irradiated by light on the reflector 4 absorbs heat during light irradiation, and the area will soon rotate away from the light irradiation position with the rotation of the reflector 4, so the total heat absorbed by the area is much smaller than that of the static reflector, and the area is cooled during rotation, and then rotates to the light irradiation area for light reflection. Therefore, during the rotation of the reflector, the temperature rise and thermal deformation will be smaller than that of the static reflector.

[0058] The wind-cooled high-power laser reflector device disclosed in the embodiment is studied under three working conditions of no rotation and no refrigeration, rotation and no refrigeration, and rotation and refrigeration (rotation speed is 3 rad / s), and the maximum temperature rise with time is studied, as shown in Figure 3 .

[0059] As shown in Figure 3It can be seen that the rotation of the mirror 4 has obvious effect on reducing the temperature rise. During the process of 5-300s, the temperature rise is 35%-69% of that without rotation. The temperature rise can be further reduced to 18%-23% of that without rotation after applying the refrigeration area, and the laser damage threshold can be increased by 5 times.

[0060] The wind-cooled strong laser mirror device disclosed in the embodiment has almost no change in the thermal deformation PV value during the irradiation time of 5-300s under the three working conditions of no rotation and no refrigeration, rotation and no refrigeration, and rotation and refrigeration (rotation speed of 3 rad / s), that is, after 5s, the mirror only has overall temperature rise, but the temperature gradient distribution no longer changes, and the thermal deformation is 0.0657 μm, 0.0377 μm and 0.0370 μm respectively. It can be seen that the rotation can reduce the thermal deformation by 43%.

[0061] The wind-cooled strong laser mirror device disclosed in the embodiment is used to study the change of the maximum temperature rise and the thermal deformation PV value of the mirror 4 with the rotation speed under the working condition of rotation and refrigeration when the laser irradiation lasts for 10s, as shown in Figure 4 .

[0062] It can be seen from Figure 4 that when the rotation speed is low, increasing the rotation speed has obvious effect on reducing the temperature rise and the thermal deformation. With the increase of the rotation speed, the effect of increasing the rotation speed gradually decreases, so a reasonable rotation speed can be selected in actual situation.

[0063] Embodiment 2

[0064] As shown in Figure 5 , the water-cooled strong laser mirror device disclosed in the embodiment includes an ultra-high precision rotary table, a reflecting member and a cooling part.

[0065] The ultra-high precision rotary table 1 includes a rotary table base 101 and a rotary table surface 102. The rotary table surface 102 can be controlled to rotate through the rotary table base 101.

[0066] The reflecting member includes a mirror 4, a pressing plate 5 and a mirror body base 6. The mirror 4 is placed in the groove in the middle of the mirror body base 6, and is tightly positioned by the pressing plate 5. The three are tightly fixed by screws 12. In the embodiment, the inside of the mirror body base 6 is provided with a flow channel.

[0067] The reflecting member is fixedly connected with the ultra-high precision rotary table 1 through a connecting rod 2. The upper end of the connecting rod 2 is tightly screwed into the threaded hole in the middle of the back of the mirror body base 6, and the lower end is fixed on the rotary table surface 102 of the ultra-high precision rotary table 1 through a screw.

[0068] The cooling unit includes a slip ring device 21, a connecting water pipe 22, and a water-cooling connector 23. The connecting water pipe 22 is connected to the back of the mirror base 6 through the water-cooling connector 23; and is connected to the slip ring device 21 through the water-cooling connector 23.

[0069] The slip ring device 21 includes a stator 201 and a rotor 202. The stator 201 is fitted over the rotor 202 and has inlet / outlet ports 24 for connecting to a water chiller to provide chilled water circulation. The rotor 202 also has inlet / outlet ports and is connected to a connecting water pipe 22. The stator 201 is fitted onto a connecting rod 2, clamped with a ring clamp, and fixed to the test bench by a fixing rod (not shown in the figure). When the connecting rod 2 rotates the reflector, it also rotates the connecting water pipe 22, thereby rotating the rotor 202.

[0070] Using the water-cooled high-power laser reflector device disclosed in this embodiment, the changes in the maximum temperature rise and thermal deformation PV value of the reflector 4 under rotating conditions during laser irradiation for 10 seconds were studied. Figure 6 As shown.

[0071] Depend on Figure 6 It is evident that at lower speeds, increasing the speed significantly reduces temperature rise and thermal deformation. However, as the speed increases, the effect of increasing the speed gradually diminishes. Therefore, a reasonable speed should be selected in practical situations.

[0072] The above-described embodiments are preferred embodiments, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A high-power laser reflector device, characterized in that, The strong laser mirror device comprises an ultra-high precision rotary table and a reflecting member. The reflecting member is fixedly connected to the upper side of the ultra-high precision rotary table through a connecting rod and can rotate axially with the rotation of the ultra-high precision rotary table. The reflecting member comprises a mirror, a mirror body base for accommodating the mirror, and a pressing plate for fixing the mirror. The strong laser mirror device further comprises a cooling part. The cooling part comprises a heat sink and a cold head. The heat sink is arranged in an array on the back of the mirror body base. The cold head is parallel to and close to the mirror. The cold head comprises a copper cold head block, a rubber heat insulation pad, a cold head fixing sleeve, a thermoelectric cooler, and a thermoelectric cooler heat sink. The rubber heat insulation pad is wrapped around the outer surface of the copper cold head block. The copper cold head block wrapped with the rubber heat insulation pad is fixed in the cold head fixing sleeve. The thermoelectric cooler is fixed above the copper cold head block and can be connected to an external direct current power supply for power supply and refrigeration. The hot end of the thermoelectric cooler is further fixed with a thermoelectric cooler heat sink. One side of the mirror is a cold head, and the other side is a laser irradiation area without shielding. The angle between the cold head and the laser irradiation area in the rotation direction is less than 180°.

2. The strong laser mirror device according to claim 1, wherein the ultra-high precision rotary table comprises a rotary table base and a rotary table surface, and the rotary table surface is controlled to rotate by the rotary table base.

3. The strong laser mirror device according to claim 1, wherein the cooling part comprises a slip ring device and a connecting water pipe, and the mirror body base further comprises a flow channel. The connecting water pipe is in communication with the slip ring device and the back of the mirror body base, respectively.

4. The strong laser mirror device according to claim 1, wherein the heat sink is arranged in an array, and the heat sink is selected from needle column type and uniformly arranged on the back of the mirror body base.

5. The high-power laser mirror apparatus of claim 1, wherein The thermoelectric cooler heat sink is selected from a plate-fin type heat sink.

6. The high-power laser mirror apparatus of claim 1, wherein, The cooling part further comprises a fan and a fan bracket for fixing the fan. The cold head is fixed on a precision elevation table, and the elevation table connecting rod is fixedly connected to the test table.

7. The strong laser mirror device according to claim 3, wherein the slip ring device comprises a stator and a rotor, the stator is sleeved outside the rotor, and the stator and the rotor are respectively provided with water inlets / outlets. The inner diameter of the slip ring device is greater than the diameter of the connecting rod, the slip ring device is sleeved on the connecting rod, and the stator is clamped and fixed by an external clamping structure.

8. The high-power laser mirror apparatus of claim 1, wherein, The diameter of the mirror is greater than the sum of the laser irradiation spot diameter and the maximum length of the cold head.

9. The high-power laser mirror apparatus of claim 1, wherein, The rotation speed of the ultra-high precision rotary table is 0-15 rad / s.

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