A high power laser reliability test system

Abstract

A high-power laser reliability test system, the core power device of the high-power laser is thermally mounted on a high heat flux density cold plate in a small closed cavity, the input optical fiber is connected to the front-stage light source through the cavity wall sealing flange, and the output optical fiber is connected to the mounting seat at the front end of the light absorption cavity through the cavity wall sealing flange. During the test, the high-energy laser is reflected by the light cone and absorbed by the light absorption cavity, and a small amount of diffuse reflected return light is detected and displayed by the photoelectric detector and the digital display component through the energy attenuator and the optical fiber connector. The small closed cavity is externally connected to a cooling unit and an exhaust and charging system, and there is an infrared observation window on the top, which is externally connected to an infrared observer. The present invention provides a simple, reliable, efficient and visible solution for high-power laser reliability testing, which has the advantages of simple and compact structure, low cost and high efficiency. It is particularly suitable for reliability testing of high-power lasers developed in vacuum, low-pressure and other working environments, as well as photothermal mechanism analysis of power devices, process assessment and other applications.

Description

Technical Field

[0001] The present invention relates to the technical field of high-power fiber lasers, and in particular to a high-power laser reliability testing system, which can be applied to reliability verification of high-power lasers with high instantaneous power and high heat generation working in vacuum, low pressure and other environments. Background Art

[0002] With the development of high-power laser technology, the output power of lasers continues to increase. High-power fiber lasers have gradually gained favor in engineering applications due to their compact structure, high electro-optical conversion efficiency, good output beam quality, modular cascade expansion and other advantages. The output power of fiber lasers has now exceeded 10,000 watts. The traditional method to verify the reliability of high-power lasers is usually to place the entire laser into a large environmental simulation tank for reliability assessment in vacuum, low pressure, high and low temperature environments. This method conducts a comprehensive assessment of the entire product, with a long pre-preparation cycle, large engineering workload, and high testing costs. With the continuous increase in laser output power, the thermal physical effects of the core components inside the laser are more significant, and the reliability of the product has been greatly challenged. When the product has a high reliability risk, comprehensive and repeated large-scale reliability testing of the product itself will bring risks and hidden dangers such as long testing cycles, slow technology iterations, and high R&D costs.

[0003] Laser power devices are an effective guarantee for the reliability of high-power lasers. For example, pump LD, forward and reverse beam combiners, filters, gratings, etc. are important components of fiber lasers. The stability, reliability, and consistency of their performance parameters are the limiting factors for the engineering reliability of high-power fiber lasers. Therefore, in the development stage of high-power lasers, especially when working in vacuum, low-pressure environments, with short development cycles, low technology maturity, and high product reliability requirements, it is particularly important to be able to efficiently and quickly identify and verify the laser reliability test system.

[0004] The development and application of high-power fiber lasers have the following problems:

[0005] (1) Laser power devices commonly used in high-power fiber lasers have large internal heat consumption when working, especially when used in specific environments, such as vacuum, low pressure, etc. Combined with the coupling of multiple physical fields such as working temperature, the differences in process parameters in various links inside the device will lead to large differences in product performance, which has a great impact on the reliability of high-power lasers. The laser is verified in a vacuum tank as a whole. If damage occurs, the laser needs to be disassembled and repaired as a whole and needs to be tested and verified again. The cycle is long, the cost is high, and it is difficult to accurately locate the problem area of ​​the product. A simple and efficient reliability testing system is urgently needed.

[0006] (2) As the output optical power of single-fiber lasers continues to increase, the instantaneous heat inside the power device continues to increase. The heat dissipation condition and capacity after installation are closely related to the thermal physical properties, temperature gradient and temperature rise curve inside the device. The product failure is usually completed in a short time. At present, the traditional testing method is to attach thermistors to the surface of the internal laser device based on the principle of thermal conduction temperature measurement. Temperature conduction has a certain lag and gradient, which is not conducive to the testing of short-term working processes, and the physical state of the device cannot be observed in real time. A simple, stable and visual reliability test system can take real-time temperature shots, output power and parameter monitoring, and compare and analyze data for the entire process of the device's instantaneous operation. It is particularly important for reliability evaluation in the research and development stage of high-power lasers.

[0007] (3) The current high-power laser power meter generally realizes the absorption and measurement of incident laser energy based on the heat measurement method. It uses the thermo-optical effect and the reflection and absorption principles to convert laser energy into thermal energy, and arranges multiple thermocouples on the absorber structure for temperature acquisition. According to the temperature gradient distribution, the power data is obtained by correcting the absorption coefficient. Its measurement accuracy and response speed are closely related to the test accuracy of the thermistor, the correction coefficient, whether the light is fully absorbed, etc. It is usually large in size and complex in structure, and cannot meet the needs of multi-channel simultaneous testing.

[0008] The above factors bring great risks and uncertainties to the development cycle, cost, and technology iteration of high-power lasers. Especially when working in vacuum and low-pressure environments, the reliability risks of laser operation need to be eliminated in advance. Therefore, it is urgent to develop a simple, efficient, and visual high-power laser reliability test system. Summary of the invention

[0009] The purpose of the present invention is to solve the above-mentioned technical and engineering application problems, and to provide a simple, efficient, and visual high-power laser reliability test system, which can perform online reliability detection of core components in the early stage of the high-power fiber laser development process when the technology maturity is low, the process stability is poor, and the reliability is low, especially when working in a vacuum or low-pressure environment. The present invention has the advantages of low cost, high efficiency, safety and reliability, visualization, full-process monitoring, and cascade expansion.

[0010] The technical solution of the present invention is as follows:

[0011] A high-power laser reliability test system, comprising a working condition simulation unit, a photothermal treatment detection unit, and a circulating cooling unit;

[0012] The working condition simulation unit is used to simulate the working conditions of the core power device in the high-power laser under a harsh working environment and monitor the thermal physical state of the device;

[0013] The photothermal processing detection unit is used to collect the laser energy emitted during the operation of the high-power laser and convert it into heat, while monitoring the changes and fluctuations of the instantaneous optical power of the high-power laser in real time;

[0014] The circulating cooling unit adopts a circulating flow heat dissipation method to keep the core power devices and the photothermal treatment detection unit in the high-power laser in a normal working temperature environment at all times;

[0015] It consists of a small sealed cavity, an input optical fiber, a high heat flux density cold plate, a high-power laser device, a vacuum electrical connector, a voltage-stabilized power supply, an observation window mirror assembly, an infrared camera observer, an optical fiber output connector, an optical fiber mounting seat, an optical fiber connector, an energy attenuator, a reflection light cone, an optical fiber vacuum flange, a sealing flange, a pressure gauge, a gas cylinder, a vacuum valve, a vacuum gauge, a solenoid valve, a mechanical pump, a sealing connector, a cooling pipeline, an output optical fiber, a water cooling unit, an output optical fiber sealing flange, a photoelectric detector, a digital acquisition display assembly, a low-voltage power supply, a light absorption cavity, and a light absorption cavity cold plate; inside the small sealed cavity, the high-power laser device is heat-conductingly installed with the high heat flux density cold plate, the high heat flux density cold plate is heat-insulatedly installed with the small sealed cavity, the input optical fiber of the high-power laser device is connected to the front-stage light source through the optical fiber vacuum flange, and the output optical fiber is connected to the optical fiber output connector through the optical fiber sealing flange and connected to the optical fiber mounting seat of the photothermal treatment detection unit. Among them, the optical fiber output connector can be a bare optical fiber head or a connector expanded by an end cap. The output high-power laser energy is absorbed by the light-absorbing cavity after being reflected by the light cone. A small amount of diffuse reflected light inside is absorbed by the photodetector through the energy attenuator and the optical fiber connector. The data is collected and displayed through the digital acquisition and display component. A cooling pipeline is used inside the small closed cavity to connect the high heat flux density cold plate to the sealing joint on the cavity wall, and connected to the external cooling unit to form a heat dissipation circuit. The external vacuum valve, vacuum gauge, solenoid valve, and mechanical pump form an exhaust circuit; the external vacuum valve, barometer, pressure reducing valve, and gas cylinder form a boost circuit. It is connected to the voltage-stabilized power supply through a vacuum electrical connector to power the internal laser device. The external infrared camera observation instrument monitors the internal high-power laser device in real time through the observation window mirror assembly on its upper cover.

[0016] Preferably, the light spot incident on the reflected light cone can be directly output from a bare optical fiber output connector; or output through an optical fiber end cap, and corresponding reasonable design parameters are obtained through calculation.

[0017] Preferably, the window glass of the observation window mirror assembly is made of materials such as CaF2 and ZnSe, which have extremely low absorption rate to infrared wavelengths, and the front and back film layers are infrared high-transmittance films, which ensure the accuracy and stability of temperature measurement of the infrared camera observation instrument. At the same time, the glass material and the window flange are sealed by epoxy glue bonding or solder welding, which can effectively increase the observation range of the infrared window, reduce the thickness of the lens, and further reduce the cost compared with the traditional O-ring mirror pressure sealing method.

[0018] Preferably, the high heat flux cold plate can be an aluminum alloy or copper plate with internally processed water channels and welded, or a combination of a temperature-averaging plate and a water channel cold plate composed of a phase change material, or a flat heat pipe + external circuit cold plate with graphene applied externally. The design of separating the working cold plate from the small closed cavity increases the flexibility of the cold plate design, which is particularly important for the heat dissipation of instantaneous high-power devices, and can also avoid condensation and low heat dissipation efficiency caused by water passing through the small closed cavity.

[0019] Preferably, the high-power laser device is mounted on a high heat flux density cold plate by applying a certain torque through materials such as silver foil, indium foil, and thermal grease, which effectively reduces the installation stress caused by the poor surface flatness of the device and the cold plate structure while ensuring the thermal conductivity efficiency.

[0020] Preferably, the cooling pipeline includes double sealing rings, a threaded gland, a plunger joint, and a sealing bellows. The two ends of the sealing bellows are welded and sealed with the plunger joint, and the double sealing rings are installed in the radial groove of the plunger joint. When conducting a test, the plunger joint is inserted into the sealing joint and the threaded gland is pressed. The cooling pipeline is used for quick plug-in connection, which is simple and reliable to operate and can be used in vacuum, low pressure and other environments.

[0021] Preferably, the optical fiber output head is connected to the polyimide insulation layer on the front surface of the light absorbing cavity through an optical fiber mounting seat. After the laser energy is incident on the surface of the light cone, it is scattered to the inner surface of the light absorbing cavity. After multiple diffuse reflections and absorption inside, the residual return light energy is coupled to the photoelectric detector through the energy attenuator and the optical fiber connector, and intelligent operations such as recording and alarm are performed through the data acquisition and display module.

[0022] Preferably, the angle between the bottom surface of the light absorption cavity and the incident direction is greater than 90 degrees, and a triangular or trapezoidal spiral runway is set in the cavity, and the outer surface is sandblasted and black anodized. The incident laser is reflected and scattered multiple times in the cavity, and oscillates and absorbs in the spiral runway. This method effectively increases the light absorption area and light absorption efficiency of the light absorption cavity, and effectively avoids interference and damage to the laser core components, the main optical fiber melting point, etc. caused by the return light generated by the local concentration of the laser in the cavity when the power density of the incident laser spot is large. The laser absorption efficiency is effectively improved through synthetic parameter design;

[0023] Preferably, the reflected light cone can be made of a metal material with good thermal conductivity such as copper and oxygen-free copper, the surface of which is processed to a mirror surface by a diamond tool and then plated with 3-5um gold. It can also be a fused quartz material with a high reflectivity dielectric film of the corresponding matching wavelength plated on the surface.

[0024] Preferably, the reflected light cone angle is designed to be β<90°, in order to effectively suppress the range of diffuse reflection inside the absorber and reduce the influence of laser return light, the effective light coverage angle

[0025] Preferably, according to the modular design characteristics of the system, the number of devices installed on the corresponding intracavity cold plate and the aperture of the corresponding light and heat absorption device are cascaded and expanded, so that vacuum screening and testing of a large number of quantitative devices, online monitoring, etc. can be achieved.

[0026] In summary, compared with the prior art, the advantages of the present invention are:

[0027] 1. A high-power laser reliability test system of the present invention solves the problem of reliability verification in the development process of traditional high-power lasers. With the continuous improvement of output energy, new requirements are constantly put forward for product devices, processes and technologies. In the early stage, when the technical maturity and reliability are relatively low, the laser machine is easily damaged during the light emission process during reliability environmental testing, which brings high test costs, long iteration cycles, and difficulties in troubleshooting. A high-power laser reliability test system is provided, which can reduce the risk of whole machine testing and greatly improve the reliability of the product by conducting preliminary verification of the reliability of local core power devices such as pump LD, forward and reverse combiners, filters, gratings, etc.

[0028] 2. A high-power laser reliability test system of the present invention performs real-time, non-contact monitoring of the instantaneous working process of high-power devices. Compared with the use of thermistors for temperature acquisition in traditional measurements, it has good real-time performance and fast response speed, and can obtain the surface thermal gradient distribution of the working device. Combined with process parameters, numerical simulation, and performance test data, it can further explore the influence of its internal thermal physical mechanism on performance parameters, which is of great significance for the analysis of problems affecting product reliability.

[0029] 3. A high-power laser reliability test system of the present invention, whose photothermal absorption and detection unit can realize the efficient absorption of high-power lasers and the integration of power stability testing, is compared with the traditional laser absorber, which uses multiple thermocouples arranged on the absorber structure to collect temperature and obtain the temperature gradient distribution. The corresponding curve of the absorbed light power and temperature is obtained by the calibration method, thereby realizing the measurement of light power. Its measurement accuracy, reaction speed, response time are closely related to the thermal resistance of the heat conduction path. Usually, the device is large in size and complex in structure. After the output laser of the high-power device of the present invention is absorbed by the photothermal absorption unit, the internal part of the diffusely reflected light passes through the frosted glass of the energy attenuation component and the adjusted variable aperture diaphragm in turn to obtain the energy intensity matching the photodetector, thereby realizing the simultaneous absorption and energy monitoring of various power devices under different power ranges. It has the characteristics of simple and compact structure, high reliability, and can record the changes of light output performance parameters in real time.

[0030] 4. A high-power laser reliability test system of the present invention adopts a modular design method, is easy to operate and has good maintainability. By cascading the number of devices installed on the working cold plate in a small closed cavity and the absorption detection aperture of the corresponding light and heat absorption device, batch power device reliability testing can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to explain the technical solution of the present invention in detail and intuitively, the following is a brief description of the drawings required for use in the embodiments.

[0032] Figure 1 Shown is a schematic diagram of a high-power laser reliability testing system of the present invention.

[0033] Figure 2 Shown is a schematic diagram of an observation window component involved in an embodiment of the present invention.

[0034] Figure 3 Shown is a schematic diagram of the photothermal treatment detection unit in the present invention.

[0035] Figure 4 It is a schematic diagram of the structure and internal light path absorption in the absorption cavity involved in the embodiment of the present invention.

[0036] Figure 5 It is a schematic diagram showing the direct output of the optical fiber output head by the optical fiber in the present invention.

[0037] Figure 6 The figure shows a schematic diagram of the output of the optical fiber output head after beam expansion by the optical fiber end cap in an embodiment of the present invention.

[0038] Figure 7 Shown is a schematic diagram of the cooling pipeline structure involved in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the embodiments and the accompanying drawings, which are described in more detail and in detail, but the scope of protection of the present invention should not be limited by this. For those skilled in the art, several modifications and extensions can be made without departing from the spirit and scope of the present invention, so the scope of protection of the present invention should be based on the scope defined by the claims.

[0040] Figure 1 The present invention is a schematic diagram of a high-power laser reliability test system, as shown in the figure, comprising a small closed cavity 1, an input optical fiber 2, a high heat flux density cold plate 3, a high-power laser device 4, a vacuum electrical connector 5, a voltage-stabilized power supply 6, an observation window mirror assembly 7, an infrared camera observer 8, an optical fiber output connector 9, an optical fiber mounting seat 10, an optical fiber connector 11, an energy attenuation assembly 12, a reflection light cone 13, an optical fiber vacuum flange 14, a sealing flange 15, a pressure gauge 16, a gas cylinder 17, a vacuum valve 18, a vacuum gauge 19, a solenoid valve 20, a mechanical pump 21, a sealing joint 22, a cooling pipeline 23, an output optical fiber 24, a water cooling unit 25, an output optical fiber sealing flange 26, a photoelectric detector 27, a digital acquisition display assembly 28, a low-voltage power supply 29, a light absorption cavity 30 and a light absorption cavity cold plate 31.

[0041] The input optical fiber 2 of the front-stage laser is connected to the input end of the laser power device through the optical fiber sealing flange, wherein the optical fiber and the sealing flange are sealed by transparent low-refractive index silicone rubber, and the main part of the optical fiber in the cavity is coiled onto the working cold plate, and the bending radius R>90mm in the example; the output optical fiber of the power device passes through the optical fiber sealing flange, and is directly connected to the optical fiber mounting seat of the photothermal treatment detection unit after output. In the specific embodiment, a bare optical fiber connector and a connector after end cap expansion are used for testing.

[0042] As stated, Figure 3 As shown, in the embodiment, the light and heat absorption and detection of 4 power devices are carried out simultaneously. The optical fiber output connector 9 is installed on the optical fiber mounting seat 10 at the front end of the light absorption cavity 30. The output laser is coaxial with the light cone. Four energy attenuation components 12 and corresponding optical fiber connectors 11 are fixed next to it. After collecting the return light energy, it is coupled into the photodetector, and the output electrical signal is displayed and stored by the digital acquisition display component. The heat collected by the absorption cavity is circulated and dissipated by an external water cooling unit through the light absorption cavity cold plate 31. In the embodiment, a high-power laser device is selected as the beam combiner, and the output laser power is 4000W. The return light power detected by the front-stage light source is about 58mw.

[0043] The absorption cavity structure and the light path reflection and absorption process inside the absorption cavity are as follows: Figure 4As shown, when the light is outputting, inside the light absorbing cavity 30, the output laser is incident on the reflected light cone 13, process a; scattered by the reflected light cone 13, process b; then absorbed by the oscillation track groove on the inner surface of the light absorbing cavity 30, process c; part of the light is reflected to the side wall of the absorption cavity, process d; then absorbed by the oscillation track groove on the side wall and inner surface of the absorption cavity, process e; the residual light oscillates in the cavity, process f; triangular and trapezoidal tracks are set on the inner surface and measuring surface of the light absorbing cavity 30, with a peak-to-valley height of 1 mm and an angle of 60°.

[0044] The high-power laser device 4 and the high heat flux density cold plate 3 are installed with indium foil for heat conduction, and the high heat flux density cold plate 3 and the small closed chamber 1 are installed with glass fiber reinforced plastic pads for heat insulation. The high heat flux density cold plate 3 is connected to the sealing joint 22 on the small closed chamber 1 by a cooling pipeline 23, and forms an external heat dissipation circuit with the external cooling unit. The small closed chamber 1 is connected to the vacuum valve 18, vacuum gauge 19, solenoid valve 20, and mechanical pump 21 through the sealing flange 15 to form an exhaust circuit, and is connected to the pressure reducing valve and gas cylinder 17 through the vacuum valve 18 and pressure gauge 16 to form a boost circuit; and is connected to the voltage stabilized power supply 6 through the vacuum electrical connector 5 to power the internal laser device, as shown in the small closed chamber.

[0045] As described above, the high heat flux density cold plate 3 is made of aluminum alloy with internally processed water channels, and the local heat dissipation efficiency of the device is improved through the design of water channels and flow resistance.

[0046] The reflection light cone 13 is made of oxygen-free copper material, and the cone surface is processed by a diamond tool to a mirror surface and then plated with gold for 3-5um, and then polished. The thickness of the gold layer after polishing is >1um. It is ensured that there are no scratches on the surface of the reflection light cone, and the reflection efficiency is guaranteed while the surface damage resistance threshold is improved, and the reflection efficiency is >99%.

[0047] The angle of the reflected light cone 13 is β=86°, D=25.4 mm. In order to effectively suppress the range of diffuse reflection inside the absorber and reduce the influence of laser return light, the effective light coverage angle is α=2°.

[0048] As stated, Figure 2 As shown, the observation window mirror assembly 7 is located at the top of the small closed cavity 1, the material of the window glass 7-1 is CaF2, the material of the window flange 7-2 is aluminum alloy, the window glass and the window flange are sealed by epoxy adhesive, the front and back surfaces of the window glass are coated with anti-reflection film with a transmittance of >99.9%, and the wavelength range covers 1030nm~1090nm.

[0049] As described above, the high-power laser device 4 is mounted on the high heat flux density cold plate 3 through indium foil and applying a certain torque. The flatness of the device mounting surface of the working cold plate is better than 0.02 mm. The thickness of the indium foil can be adjusted between 0.2 mm and 1 mm and the mounting torque can be adjusted between 0.5 Nm and 4 Nm to reduce the impact of the mounting stress introduced by the difference in surface flatness of the device and the cold plate structure on the device performance.

[0050] As stated, Figure 5 As shown, the light spot incident on the reflected light cone 13 can be directly output by the bare fiber output connector 9, and the output light spot diameter Dc, the light cone diameter D, the multimode fiber numerical aperture NA, the fiber far-field divergence angle θ0, and the working distance L satisfy the relationship: θ0 = arcsin (NA), D>D c +2L·tanθ0. The diameter of the reflected light cone 13 is D=25.4 mm, the numerical aperture of the multimode optical fiber is NA=0.22, the optical fiber divergence angle θ0=12.7°, and the working distance is L=30 mm;

[0051] As stated, Figure 6 As shown in another embodiment, the output light spot Dg after the optical fiber end cap 9-2 expands the beam, and the far-field divergence angle of the optical fiber end cap is θ, then: D>D g +2L·tanθ, output light spot Diameter D g =5mm, according to the end cap length and the radius of curvature, the divergence angle of the output end of the optical fiber end cap is θ=6.144°.

[0052] As described above, the diameter of the variable aperture inside the energy attenuation component 12 is selected to be 3 mm, the optical fiber connector is selected to be an FC optical fiber connector, and the photoelectric detector is selected to be a PIN tube, and then the output energy is monitored in real time through the data acquisition and display module.

[0053] As stated, Figure 7 As shown, the cooling pipeline 23 includes a double sealing ring 23-1, a threaded pressure cap 23-2, a plunger joint 23-3, and a sealing bellows 23-4; wherein, both ends of the sealing bellows 23-4 are welded and sealed with the plunger joint 23-3, and the double sealing ring 23-1 is installed in the radial groove of the plunger joint 23-3; when connecting the cooling pipeline, the plunger joint 23-3 is inserted into the sealing joint 22, and the threaded pressure cap 23-2 is tightened.

Claims

1. A high power laser reliability test system, characterized in that: It includes working condition simulation unit, photothermal treatment detection unit and circulating cooling unit; The working condition simulation unit is used to simulate the working conditions of the core power device in the high-power laser under a harsh working environment and monitor the thermal physical state of the device; The photothermal processing detection unit is used to collect the laser energy emitted during the operation of the high-power laser and convert it into heat, while monitoring the changes and fluctuations of the instantaneous optical power of the high-power laser in real time; The circulating cooling unit adopts a circulating flow heat dissipation method to keep the core power devices and the photothermal treatment detection unit in the high-power laser in a normal working temperature environment at all times; The working condition simulation unit comprises: a small sealed cavity (1), an input optical fiber (2), a high heat flux density cold plate (3), a sealed electrical connector (5), a voltage-stabilized power supply (6), an observation window mirror assembly (7), an infrared camera observer (8), a sealed joint (22), and a cooling pipeline (23); The high heat flux cold plate (3) is thermally insulated and installed in the small closed cavity (1), N high-power laser devices (4) are distributed on the high heat flux cold plate (3), and the high heat flux cold plate (3) is connected to a sealing joint (22) via two cooling pipes (23), and passes through the small closed cavity (1) to an external circulating cooling unit for heat dissipation; The small closed chamber (1) is externally connected to a vacuum valve (18), a vacuum gauge (19), a solenoid valve (20), and a mechanical pump (21) through a sealing flange (15) to form an exhaust circuit, and is externally connected to a vacuum valve (18), a barometer (16), a pressure reducing valve, and a gas cylinder (17) to form a pressure boosting circuit; The input optical fiber (2) of the high-power laser device (4) extends to the outside of the small-sized sealed cavity (1) through the input optical fiber sealing flange (14) and is connected to the front-stage light source; the output optical fiber (24) of the high-power laser device (4) extends to the outside of the small-sized sealed cavity (1) through the output optical fiber sealing flange (26) and is connected to the photothermal absorption detection unit; The cable of the high-power laser device (4) passes through the small closed cavity (1) via a sealed electrical connector (5) and is externally connected to a voltage-stabilized power supply (6); The small sealed chamber (1) is in the shape of a small flat rectangular parallelepiped, and an observation window mirror assembly (7) is provided on the top for the infrared camera observer (8) to monitor the thermal physical state of the high-power laser device (4).

2. The high power laser reliability test system according to claim 1, characterized in that: The photothermal absorption detection unit comprises a light absorption cavity cold plate (31), a data acquisition display component (28), a low-voltage power supply (29), N photoelectric detectors (27), N light absorption cavities (30) and optical fiber mounting seats (10) thereof, an optical fiber connector (11), an energy attenuation component (12) and a reflection light cone (13); N light absorbing cavities (30) are distributed on the light absorbing cavity cold plate (31) for providing cooling and heat dissipation for the light absorbing cavity (30); the light absorbing cavity cold plate (31) is externally connected to a cooling unit (25) via two pipelines to form a circulating heat dissipation loop; a reflecting light cone (13) is provided in the light absorbing cavity (30); The laser light transmitted by the high-power laser device (4) through the output optical fiber (24) is incident on the light absorption cavity (30), and is absorbed by the light absorption cavity (30) after being reflected by the reflection light cone (13); a portion of the diffusely reflected return light is attenuated by the energy attenuation component (12), and then coupled to the photodetector (27) through the optical fiber connector (11), and converted into an electrical signal and transmitted to the data acquisition display component (28); The low-voltage power supply (29) is connected to the photoelectric detector (27) and the data acquisition and display component (28) respectively.

3. The high power laser reliability testing system according to claim 2, characterized in that: The light spot incident on the reflected light cone (13) is outputted from the optical fiber output connector (9), and the output light spot diameter D c , light cone diameter D, multimode fiber numerical aperture NA, fiber far-field divergence angle θ0, working distance L satisfy the relationship: θ0 = arcsin (NA), D>D c +2L·tanθ0; or the output light spot D expanded by the optical fiber end cap (9-2) g , the far-field divergence angle of the fiber end cap is θ, then: D>D g +2L·tanθ.

4. The high power laser reliability testing system according to claim 1, characterized in that: The circulating cooling unit comprises a cooling unit (25), a filter and corresponding connecting pipelines; The two pipelines of the cooling unit (25) are connected to the sealing joint (22) on the small closed chamber (1) after passing through the filter to form a cooling loop; the other two cooling pipelines are connected to the light absorption chamber cold plate (31) to form another cooling loop.

5. The high power laser reliability testing system according to claim 1, characterized in that: The cooling pipeline (23) comprises a double sealing ring (23-1), a threaded gland (23-2), a plunger joint (23-3), and a sealing bellows (23-4); The two ends of the sealing bellows (23-4) are welded and sealed to the plunger joint (23-3), and the double sealing ring (23-1) is installed in the radial groove of the plunger joint (23-3); when the pipeline is connected, the plunger joint (23-3) is inserted into the sealing joint (22), and the threaded gland (23-2) is pressed tightly.

6. The high power laser reliability testing system according to claim 1, characterized in that: The infrared camera observation instrument (8) is made of a material with good infrared wavelength transmittance, such as CaF2, ZnSe, etc., which has an extremely low absorption rate for infrared wavelengths, thereby ensuring the accuracy and stability of the temperature measurement of the infrared camera observation instrument; the glass material and the window flange are sealed by epoxy glue bonding or solder welding, which can effectively increase the observation range of the infrared window, reduce the lens thickness, and further reduce the cost compared to the traditional O-ring mirror pressure sealing method.

7. A high power laser reliability testing system according to claim 1, characterized in that The high heat flux density cold plate (3) is an aluminum alloy or copper plate with a water channel processed inside and welded, or a combination of a temperature equalizing plate and a water channel cold plate composed of a phase change material, or a flat heat pipe + external loop cold plate coated with graphene, which can effectively simulate the actual heat dissipation environment when the laser is working.

8. A high power laser reliability testing system according to claim 1, characterized in that The high-power laser device can be installed on a high heat flux density cold plate by applying a certain torque through silver foil, indium foil, and thermal conductive silicone grease materials. On the basis of ensuring thermal conductivity efficiency, the installation stress caused by the poor surface flatness of the device and the cold plate structure is effectively reduced.

9. A high power laser reliability testing system according to claim 2, characterized in that The energy attenuation component (12) used in the photothermal treatment detection unit is composed of a variable aperture component and frosted glass, wherein the variable aperture component can adjust the aperture of the light exit hole to attenuate the scattered light power in the small closed cavity (1) to the detectable range of the rear photoelectric detector.

10. A high power laser reliability testing system according to claim 2, characterized in that The bottom surface of the light absorbing cavity (30) includes an angle greater than 90 degrees with the incident direction, and a triangular or trapezoidal spiral track is arranged in the cavity, and the surface is sandblasted and black anodized; multiple reflections and scatterings of the incident laser in the cavity effectively increase the light absorbing area and light absorbing efficiency of the light absorbing cavity, and avoid interference and damage to the laser power device, the main optical fiber melting point, etc. caused by the return light generated by the local concentration of the laser in the cavity when the power density of the incident laser spot is large.

11. A high power laser reliability testing system according to claim 2, characterized in that The reflected light cone (13) is made of a metal material with good thermal conductivity such as copper or oxygen-free copper, the surface of which is processed to a mirror surface by a diamond tool, plated with 3-5um gold, and then polished; or it is made of fused quartz material, the surface of which is plated with a high reflectivity dielectric film of a corresponding matching wavelength.

12. A high power laser reliability testing system according to claim 2, characterized in that The reflected light cone (13) is designed to have an angle β < 90°, and an effective light coverage angle

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