A method and device for fast, real-time measurement of optical thin film laser damage threshold

Abstract

The present application belongs to the technical field of optical thin film laser damage measurement, and discloses a method and device for fast and real-time measurement of optical thin film laser damage threshold, which is based on the method for determining the optical thin film laser damage threshold by measuring the change of surface thermal reflectivity during the laser damage process. During the laser irradiation process, the temperature of the thin film surface will change, and the thermal reflectivity of the thin film surface will change with the change of the surface temperature; during the laser damage process, the temperature of the thin film surface will sharply increase, thus the thermal reflectivity of the thin film surface will also sharply increase, and the optical thin film laser damage threshold can be determined by measuring the relative change of the thin film surface reflectivity. The present application can quickly and real-timely determine the laser damage threshold of the optical thin film.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical thin film laser damage measurement, and in particular relates to a method and a device for quickly and in real time measuring the laser damage threshold of an optical thin film. Background Art

[0002] In high-power laser systems, high-damage-threshold, high-intensity thin films are key components of the entire system, making it essential to determine the laser damage threshold of optical thin films. Currently, the international standard ISO11254-1 is used to measure the damage threshold of optical thin films. The basic method is to determine the probability of film damage at different laser energy densities. The resulting damage probability and the corresponding laser energy density are then linearly fitted to determine the laser damage threshold.

[0003] While this method can accurately determine the laser damage threshold of optical thin films, it is time-consuming because it requires measuring the probability of damage at different laser energy densities. It also generally requires a high-precision optical microscope to determine whether the sample is damaged and the probability of damage at a certain laser energy density. Furthermore, the post-processing of the damage curve data is cumbersome.

[0004] Through the above analysis, the problems and defects of the existing technology are as follows:

[0005] Existing methods require measuring the probability of damage at different laser energy densities, which is time-consuming and generally requires a high-precision optical microscope to determine whether a sample is damaged and the probability of damage at a certain laser energy density. Furthermore, the post-processing of the damage curve data is cumbersome. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a method and device for quickly and in real time measuring the laser damage threshold of an optical thin film.

[0007] The present invention is implemented as follows: a method for rapidly and in real time measuring the laser damage threshold of an optical thin film, comprising:

[0008] Step 1: Start the pump laser, collimate the laser, and properly adjust the 45-degree turning angle, the half-reflecting half-mirror, and the position of the lens so that the laser output is vertically irradiated on the sample to be tested;

[0009] Step 2: Adjust the lens position by moving the lens adjustment structure so that the laser output has a suitable spot size on the sample to be tested;

[0010] Step 3: Start the detection laser and adjust the optical path so that the detection laser of the detection laser and the pump laser are irradiated on the sample to be tested at a certain angle. Start the energy meter and CCD online damage monitoring system, adjust the energy meter, Si avalanche photodiode detector and oscilloscope, set the energy of the pump laser to gradually change from small to large, and measure the thermal reflection signal on the sample surface at the same time.

[0011] Furthermore, as the energy density of the pump laser increases, the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film.

[0012] Another object of the present invention is to provide a device for rapidly and in real time measuring the laser damage threshold of an optical thin film, comprising:

[0013] Pump laser 1, which is used to excite the sample surface; laser 2, which is used to collimate the optical path; and laser 3, which is used to detect the optical path. Lasers 2 and 3 can be the same laser; the sample to be tested is located on a computer-controlled mobile platform, and a Si avalanche photodiode detector and an oscilloscope are used to measure the thermal reflection signal.

[0014] On the output optical path of the pump laser 1, a shutter 3 for controlling the number of output laser pulses, a beam splitter 5, and a laser energy attenuator 4 consisting of a rotatable half-wave plate and a polarizer are arranged.

[0015] Furthermore, the energy attenuator is connected to the computer via a communication line.

[0016] Furthermore, the laser light output by the pump laser 1 is attenuated by an attenuator and then irradiated onto a sample 15 to be tested on a movable platform through a focusing lens 10. An energy meter 5 is provided on the reflected light path of the spectroscope to measure the laser energy output by the pump laser 1. A 45-degree turning mirror is provided on the output light path of the laser 2 to collimate the optical path of the pump laser 1.

[0017] Furthermore, a beam splitter 11 is provided on the output optical path of the laser 3 to split the detection beam into two beams, one of which is passed through a Si avalanche photodiode detector 13 to measure the energy of the reflected detection laser;

[0018] The other beam is reflected by the reflector 12 onto the sample to be measured. The instantaneous thermal reflection signal on the sample surface is measured by another Si avalanche photodiode detector 14 and recorded by the oscilloscope 16 .

[0019] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0020] First, the advantage of the present invention is that it overcomes the shortcomings of the above-mentioned technologies. It is based on measuring the real-time changes of the thermal reflection signal of the optical film during the laser damage process. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film, providing a fast and real-time optical film damage threshold measurement method.

[0021] (1) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0022] The present invention proposes a method for determining the damage threshold of an optical film based on the laser damage mechanism of the optical film, filling the gap in the industry in determining the laser damage threshold based on the use of light scattering technology or microscopic imaging technology.

[0023] (2) The technical solution of the present invention overcomes technical prejudice:

[0024] The present invention overcomes the use of light scattering technology or microscopic imaging technology to detect the laser damage threshold of optical components, and instead proposes a method for determining the damage threshold of optical films based on the laser damage mechanism of optical films. At the same time, the method adopted by the present invention can assist in analyzing the laser damage mechanism and process of optical films.

[0025] Second, the technical problems solved by the technical solution of the present invention in industrial applications are:

[0026] 1. Low efficiency of laser damage threshold measurement in existing technologies

[0027] Traditional laser damage threshold measurement methods usually require multiple experiments and rely on offline analysis. They are complex and time-consuming to operate, making it difficult to meet the needs of rapid measurement.

[0028] The present invention can quickly determine the laser damage threshold of the optical film by real-time monitoring of the thermal reflection signal on the sample surface combined with the gradual change in the energy of the pump laser, thereby greatly improving the measurement efficiency.

[0029] 2. Insufficient detection accuracy in existing technologies

[0030] Traditional methods have limited monitoring accuracy for laser energy and sample status, especially in capturing tiny signals and regulating energy density, which can easily lead to measurement errors.

[0031] The present invention adopts an energy meter, a Si avalanche photodiode detector and an oscilloscope to monitor the changes of the thermal reflection signal in real time, ensuring the high sensitivity and accuracy of the measurement process and significantly improving the detection accuracy.

[0032] 3. Problems with spot control and energy uniformity in existing technologies

[0033] In existing technologies, it is difficult to precisely adjust the spot size and energy distribution, resulting in uneven laser energy distribution on the sample surface, affecting the reliability of the test results.

[0034] The present invention optimizes the light spot size and achieves uniform energy distribution through the lens movement adjustment structure, effectively avoiding data errors caused by improper light spot control.

[0035] The significant technical advancements achieved by the present invention are:

[0036] 1. Fast and real-time detection capabilities

[0037] The present invention can obtain the laser damage threshold of the sample in real time through online thermal reflection signal monitoring and gradual increase of pump laser energy, without the need for complex multiple experiments and offline analysis. The measurement efficiency is significantly improved compared with traditional methods, meeting the demand for efficient detection in modern industry.

[0038] 2. Improved detection accuracy and reliability

[0039] This method uses highly sensitive detection equipment and an optimized optical path design to effectively capture the subtle changes in the heat reflection signal during laser damage, ensuring accurate damage threshold measurements. Furthermore, by gradually adjusting and accurately recording the energy density, the results are more stable and reliable.

[0040] 3. One-stop solution for optical film performance evaluation

[0041] The present invention integrates multiple functional modules such as optical path adjustment, spot optimization, gradual energy control, and real-time thermal reflection monitoring, providing a one-stop laser damage threshold measurement solution from sample preparation to data output, significantly reducing the complexity and operational threshold of the measurement system.

[0042] 4. Wide range of industrial applicability

[0043] The present invention is applicable to various types of optical films, including laser lenses, filters, anti-reflection films, etc., and is widely used in optical material manufacturing, laser equipment research and development, and quality control of high-power optical systems, providing related industries with an efficient testing tool.

[0044] 5. Intelligent measurement to reduce human intervention

[0045] Through automated optical path adjustment, energy control, and data acquisition, the present invention achieves intelligent measurement of laser damage threshold, significantly reduces errors caused by human intervention and subjective judgment, and improves the repeatability and consistency of the experiment.

[0046] The present invention solves the problems of inefficiency, insufficient precision and complex operation in existing laser damage threshold measurement technologies. Through real-time thermal reflection monitoring, precise energy regulation and spot optimization, it significantly improves detection efficiency, accuracy and applicability, and provides an efficient and reliable solution for optical film performance evaluation and laser system quality control. It has important industrial application value and technological advancement significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of a method for rapidly and real-timely measuring the laser damage threshold of an optical thin film provided by an embodiment of the present invention.

[0048] Figure 2 This is a structural diagram of a device for rapidly and real-timely measuring the laser damage threshold of an optical thin film provided by an embodiment of the present invention.

[0049] Figure 3 This is a schematic diagram of the laser damage threshold of a sample measured using the method of the present invention provided in an embodiment of the present invention.

[0050] Figure 4 This is a graph of the laser damage threshold of a single-layer HfO2 film determined using ISO11254-1.

[0051] Figure 2 In: 1. Pump laser; 2. Collimated laser; 3. Detection laser; 4. Energy attenuator; 5. Spectrometer; 6. Energy meter; 7. Turning point; 8. Half-reflecting half-mirror; 9. Damage judgment device; 10. Focusing lens; 11. Beam splitter; 12. Reflector; 13. Photodiode detector; 14. Photodiode detector; 15. Sample to be tested; 16. Oscilloscope; 17. Computer. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0053] like Figure 1 As shown, an embodiment of the present invention provides a method for quickly and real-time measuring the laser damage threshold of an optical thin film, comprising the following steps:

[0054] S101, start the pump laser, collimate the laser, and properly adjust the 45-degree turning angle, the half-reflecting half-mirror, and the position of the lens so that the laser output is vertically irradiated on the sample to be tested;

[0055] S102, adjusting the lens position by moving the lens adjustment structure so that the laser output by the laser has a suitable spot size on the sample to be measured;

[0056] S103, start the detection laser, adjust the optical path so that the detection laser of the detection laser and the pump laser are irradiated on the sample to be tested at a certain angle, start the energy meter and CCD online damage monitoring system, adjust the energy meter and Si avalanche photodiode detector and oscilloscope, set the energy of the pump laser to gradually change from small to large, and measure the thermal reflection signal on the sample surface at the same time.

[0057] As the energy density of the pump laser provided in the embodiment of the present invention increases, the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film.

[0058] Figure 2 This is a schematic diagram of a device capable of rapidly and in real time measuring the laser damage threshold of an optical thin film. As can be seen from the figure, the present invention provides a device capable of rapidly and in real time measuring the laser damage threshold of an optical thin film. The device comprises a pump laser 1, which excites the sample surface; a laser 2, which is used to collimate the optical path and assist in monitoring damage; a laser 3 for detecting the optical path; a sample to be measured 15 placed on a mobile platform; two Si avalanche photodiode detectors 13 and 14; and an oscilloscope 16. The device comprises:

[0059] The optical path of the laser 1 output is sequentially arranged with a laser pulse control shutter 3, an energy attenuator 4, a beam splitter 5, a half-reflecting mirror 8, and a focusing lens 10. The laser light output by the laser 1 is vertically irradiated onto the sample 15 to be tested through the focusing lens 10. An energy meter 6 is provided in the reflected optical path of the beam splitter 5 to measure the laser energy of the laser 1. In the embodiment of the present invention, the laser 1 is an Nd:YAG laser that uses electro-optical Q-switching and outputs a basilar Gaussian laser with a wavelength of 1064 nm. Both lasers 1 and 2 are 639 nm continuous wave lasers. The energy attenuator 4 comprises a rotatable half-slope plate and an attenuator plate, which are computer-controlled to adjust the laser energy irradiated on the sample surface. The sample 15 to be tested is placed on a movable platform. This platform is precisely positioned within the sample test area by a computer-controlled two-dimensional stepping motor, with a single-step accuracy of 5 microns. The detection laser 3 and the pump laser 1 are irradiated at a certain angle on the sample to be tested 15. The laser is split into two beams by a beam splitter 11. A Si avalanche photodiode detector 13 is set on the reflection light path of the beam splitter 11 to measure the energy of the reflected detection laser. The other beam is reflected by a reflector 12 at a certain angle and irradiated onto the sample surface. The instantaneous thermal reflection signal on the sample surface is detected by a Si avalanche photodiode detector 14 and recorded by an oscilloscope 16. During the measurement process, the CCD online damage judgment device 9 is aligned with the irradiation point of the pump laser 1 on the sample surface at a certain angle, and relies on the scattering of the laser output by the laser 2 on the sample surface to determine whether damage has occurred and the probability of occurrence, which is compared with the method of the present invention. In the CCD online damage judgment device 9, the energy meter 6 and the oscilloscope are connected to the serial port of the computer 17 via a communication line. In this embodiment, the sample to be tested is a single-layer HfO2 thin film prepared by electron beam evaporation.

[0060] Measurement process:

[0061] like Figure 3 As shown, the actual use process of the device is described in detail below. First, the sample 15 to be tested is placed on the sample platform to be tested. Then, the energy attenuator 4 in the output optical path of the laser 1 is controlled by a computer to control the output energy of the laser. The energy density of the pump laser 1 is set to a fixed value. After the continuous laser with a wavelength of 639nm is adjusted according to the above method, the oscilloscope 16 records the thermal reflection signal of the sample surface detected by the detector 14 in real time and transmits the data to the computer. The energy density of the pump laser is increased, and the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the minimum laser energy corresponding to the damage threshold of the optical film is obtained. The damage condition of the sample is determined by the CCD system 9. The damage threshold is determined by traditional methods and compared with the value obtained by the method of the present invention to determine the accuracy of the present invention in determining the damage threshold of the optical film.

[0062] 1. Pump laser excitation and optical path adjustment principle

[0063] The pump laser 1 is the core component of the device, responsible for providing high-energy laser pulses to excite the surface of the sample to be tested. The output laser pulse number is adjusted by a shutter 3 to ensure consistent laser pulse parameters for each test. A laser energy attenuator 4, consisting of a rotatable half-wave plate and polarizer, adjusts the output laser energy to accommodate the laser damage threshold range of different samples. The attenuated laser light is guided by a beam splitter 5. A portion of the laser light is measured by an energy meter to monitor the stability of the pump laser output. The remaining laser light is focused by a focusing lens 10 onto the surface of the sample to be tested on a mobile platform, ensuring concentrated laser energy and effective excitation.

[0064] 2. Laser optical path alignment and energy distribution principle

[0065] Laser 2 is used to collimate the optical path. A 45-degree deflection mirror is used to precisely calibrate the optical path, ensuring that the laser beam output by the pump laser propagates in a straight line and is focused onto the sample surface. Laser 3 is used to detect the optical path. The output beam is split into two beams by a beam splitter 11: one beam is used to measure the energy of the reflected laser light, while the other beam continues to reflect and irradiate the sample surface. The combined design of the beam splitter and deflection mirror ensures efficient energy distribution and path optimization of the laser beam, reducing energy loss in the optical system and improving measurement accuracy.

[0066] 3. Measurement and recording principle of thermal reflection signal

[0067] When the laser beam from the pump laser 1 strikes the sample surface, it absorbs energy and generates a thermal effect. The instantaneous thermal reflection signal from the sample surface is captured in real time by a Si avalanche photodiode detector 14, and the signal waveform is recorded by an oscilloscope 16. The amplitude and waveform of the reflection signal are directly related to the laser power and the sample material properties, and can be used to assess the laser damage threshold of the sample surface. By comparing the thermal reflection signals at different laser energy levels, the onset energy of laser damage can be quickly determined.

[0068] 4. Dual-detector collaborative measurement principle

[0069] The two beams split from the detection optical path are measured by two Si avalanche photodiode detectors. One beam directly measures the reflected energy of the probe laser, while the other beam, reflected from the sample surface, measures the thermal reflection signal. Data from both detectors is simultaneously acquired and transmitted to an oscilloscope, enabling real-time synchronization and comparative analysis of dual-channel measurement data. This collaborative measurement method improves the accuracy of correlation assessments between reflected energy and thermal reflection signals.

[0070] 5. Principle of mobile platform and sample position control

[0071] The sample to be tested is mounted on a computer-controlled mobile platform. The platform automatically moves the sample according to preset paths and adjustments to the laser beam path, ensuring the laser beam hits the target point. The platform's precise movement allows for multiple test points on the same sample, thereby mapping the laser damage threshold distribution on the sample surface. Centrally controlled by a computer, the mobile platform works in conjunction with the pump and probe lasers to achieve rapid, real-time sample testing.

[0072] 6. Data processing and real-time measurement principle of laser damage threshold

[0073] The device's core control system, connected to an oscilloscope and energy meter, collects real-time data on the pump laser output energy, reflected laser energy, and the sample's thermal reflection signal. This data is analyzed using a dedicated algorithm to calculate the laser's energy absorption and thermal effects on the sample surface. The laser damage threshold (LDT) is determined based on the reflected signal's changing trend. Significant changes in the sample's thermal reflection signal (such as a significant increase in signal amplitude or a sudden change in waveform) indicate the occurrence of laser damage. Based on this data, the system rapidly outputs a report on the sample's LDT.

[0074] The operating principle described above encompasses key steps such as pump laser excitation, optical path adjustment, thermal reflection signal measurement, dual-detector collaboration, mobile platform sample control, and data analysis. Through these designs and methods, the device can rapidly and accurately measure the laser damage threshold of optical thin films, providing a highly effective tool for the evaluation and application of high-energy laser materials.

[0075] Figure 4 This is a graph of the laser damage threshold of a single-layer HfO2 film determined using ISO11254-1.

[0076] Example 1: Measurement of laser damage threshold for reflective optical films

[0077] Test device structure:

[0078] 1. Pump laser: Nd:YAG laser (wavelength 532nm), pulse width 10ns, repetition frequency 10Hz, peak power adjustable range 50-500mJ.

[0079] 2. Energy attenuator: It consists of a rotatable half-wave plate and a polarizer, which adapts the damage threshold range of different thin film materials by adjusting the laser energy.

[0080] 3. Focusing lens: The focal length is 100mm, used to focus the pump laser onto the surface of the sample to be measured. The focus spot diameter is about 200μm.

[0081] 4. Detection light path: A He-Ne laser (wavelength 633nm) is used as the detection light source, which is divided into two beams by a beam splitter; one beam is used to measure the reflected energy, and the other is used to measure the thermal reflection signal of the sample surface.

[0082] 5. Detector and recording equipment: Two Si avalanche photodiode detectors are connected to an oscilloscope to collect the reflected laser signal and thermal reflection signal waveforms in real time.

[0083] Testing process:

[0084] 1. Install the reflective optical film sample on a computer-controlled mobile platform and accurately adjust the sample position through the computer so that the laser spot irradiates the test point.

[0085] 2. Gradually increase the output power of the pump laser and make fine adjustments through the energy attenuator, and record the changes in the thermal reflection signal under different laser energies.

[0086] 3. Determine the critical point where the laser energy reaches the film damage threshold by comparing the waveform changes of the reflected signal and the thermal reflected signal.

[0087] 4. After the test is completed, the multi-point test results are plotted as an optical film damage threshold distribution diagram to evaluate the laser damage resistance of the film material.

[0088] Example 2: Measurement of laser damage threshold for transmissive optical films

[0089] Test device structure:

[0090] 1. Pump laser: Use Ti:Sapphire femtosecond laser (wavelength 800nm), pulse width 50fs, peak power 10-100mJ.

[0091] 2. Energy attenuator: Contains an attenuator set and a mechanical shutter to ensure that the laser output energy is stable and adjustable.

[0092] 3. Sample fixing platform: The transmissive optical film is installed in the sample frame on the platform, which can achieve ±5° inclination adjustment to facilitate optical path alignment.

[0093] 4. Detection optical path: A spectroscope is used to split the detection laser into two beams. One beam passes directly through the sample to measure the transmission signal, and the other beam is used for the reflection optical path to measure the thermal signal on the sample surface.

[0094] 5. Detector and data acquisition equipment: InGaAs photodetector and Si avalanche photodiode detector are configured respectively, and the transmission signal and thermal signal are recorded by oscilloscope respectively.

[0095] Testing process:

[0096] 1. Install the transmissive optical film and adjust the inclination of the sample frame so that the laser light path passes through the sample vertically.

[0097] 2. Adjust the power output of the pump laser, gradually increase the laser energy, and record the changes in the transmission signal and thermal reflection signal through the detection optical path.

[0098] 3. When the amplitude of the thermal reflection signal increases significantly and the transmission signal drops suddenly, it is determined that the sample has been damaged by laser, and the laser energy value at this time is recorded.

[0099] 4. Use a mobile platform to perform multi-point measurements on different areas of the film and analyze the laser damage threshold distribution of the transmissive optical film at different locations.

[0100] Notable features of both embodiments:

[0101] 1. Example 1 is for reflective films and uses the mutation characteristics of the thermal reflection signal to accurately determine the damage threshold; Example 2 combines the changes in the transmission signal and is suitable for evaluating the damage performance of transmissive films.

[0102] 2. Both embodiments use dual detectors and a computer-controlled mobile platform to ensure the efficiency of multi-point measurement and the accuracy of data, providing a comprehensive evaluation tool for the laser damage performance of optical films.

[0103] The present invention first activates the pump laser and collimator laser. By properly adjusting the positions of the 45-degree deflecting mirror, half-reflecting mirror, and lens, the laser beam is ensured to be perpendicular to the surface of the sample being measured. This optical path adjustment process utilizes precision optical components to achieve high-quality beam control, providing precise laser irradiation conditions for subsequent measurements of optical thin film damage thresholds. Furthermore, vertical laser incidence minimizes optical path errors, improving experimental repeatability and reliability.

[0104] By adjusting the lens's position through a movable adjustment mechanism, the lens's position is adjusted to control the laser spot size on the sample surface to meet experimental requirements. Choosing the right spot size ensures uniform laser energy distribution across the sample surface, avoiding local overload or data errors caused by excessively large or small spots. This step ensures accurate and uniform laser irradiation and is crucial for accurately measuring the laser damage threshold of optical thin films.

[0105] The detection laser is activated so that it forms a fixed angle with the pump laser and irradiates the sample. Using an energy meter, a CCD online damage monitoring system, a Si avalanche photodiode detector, and an oscilloscope, the thermal reflection signal from the sample surface is monitored in real time. By adjusting the optical path to ensure the matching and stability of the detection and pump laser paths, highly sensitive detection of changes in the sample's thermal reflectivity is achieved. The design of the detection optical path enables rapid capture of minute changes in the sample's thermal reflection signal after exposure to the laser, providing real-time data support for damage threshold measurements.

[0106] By gradually increasing the energy density of the pump laser, the thermal reflection signal from the sample surface is observed in real time. When the laser energy reaches a certain value, the intensity of the thermal reflection signal from the sample surface stops changing, indicating that the sample has reached the damage threshold. The minimum laser energy recorded at this point is the damage threshold of the optical film. This method, combined with precise energy control and thermal reflection signal monitoring, can rapidly and in real time determine the laser damage threshold of optical films, providing an efficient and reliable detection method for evaluating thin film material properties.

[0107] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A device for rapid and real-time measurement of laser damage threshold of optical thin films, characterized in that: include: Pump laser, used to excite the surface of the sample to be tested; an energy attenuator, including a rotatable half-wave plate and a polarizer, for adjusting the laser energy output by the pump laser; A beam splitter is used to separate the optical path of the pump laser. One part of the optical path is used for sample excitation, and the other part of the optical path is connected to an energy meter to measure the laser energy. Focusing lens, used to focus the pump laser onto the surface of the sample to be measured; A computer-controlled mobile platform for mounting the sample to be tested, used to accurately locate the sample test point; A method for rapid, real-time measurement of laser damage threshold of optical thin films comprises the following steps: Step 1: Start the pump laser, collimate the laser, and properly adjust the 45-degree turning angle, the half-reflecting half-mirror, and the position of the lens so that the laser output is vertically irradiated on the sample to be tested; Step 2: Adjust the lens position by moving the lens adjustment structure so that the laser output has a suitable spot size on the sample to be tested; Step 3: Start the detection laser and adjust the optical path so that the detection laser and the pump laser are irradiated on the sample at a certain angle. Start the energy meter and CCD online damage monitoring system, adjust the energy meter, Si avalanche photodiode detector and oscilloscope, set the pump laser energy to gradually change from small to large, and measure the thermal reflection signal on the sample surface at the same time. As the energy density of the pump laser increases, the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film.

2. The device according to claim 1, wherein Also includes: A laser is used to collimate the optical path, and the collimated optical path adjusts the laser direction through a 45-degree turning mirror; A beam splitter is used to split the detection laser into two beams, which are respectively guided to a reflection energy measurement path and a thermal reflection signal measurement path.

3. The device according to claim 2, wherein The reflected energy measurement path includes: Si avalanche photodiode detector, used to measure the reflected energy of the detection laser; An oscilloscope is connected to the detector and is used to record energy data of the reflected laser signal.

4. The device according to claim 2, wherein The thermal reflection signal measurement path includes: Si avalanche photodiode detector, used to measure the instantaneous thermal reflection signal on the surface of the sample to be tested; A reflector, used to guide the detection laser to the surface of the sample to be measured; The oscilloscope is connected to the detector and is used to record the instantaneous thermal reflection signal of the sample surface.

5. The device according to claim 1, wherein The energy attenuator is connected to a computer via a communication line. The computer is used to control the dynamic adjustment of laser energy and work in conjunction with the mobile platform to achieve multi-point testing.

6. The device according to claim 1, wherein The mobile platform includes: Computer control module, used to accurately move the position of the sample to be tested according to the preset path; Sample fixing fixture, used to fix the sample to ensure test stability; Adjustable support frame, used to adjust the vertical or tilt angle between the sample and the laser beam path.

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