Device for testing service life of optical element in vacuum environment and accelerated measurement method

Abstract

The invention relates to a device for testing the service life of an optical element in a vacuum environment and an accelerated measurement method, and the device comprises a control system, a laser, a light beam transmission and control system, a light beam monitoring system, a damage monitoring system, a vacuum target chamber and a sample positioning and moving platform, the light beam enters the vacuum target chamber to irradiate the sample after passing through the light beam transmission and control system, and the damage monitoring system is used for monitoring sample change in real time to judge whether damage is generated; in the laser irradiation process, a wedge-shaped plate is adopted to sample a laser beam, then spatial distribution, time distribution and energy of light beam pulses are measured in real time through a light beam monitoring system, and a control system controls function implementation of all components, test process operation, data acquisition and processing and the like. According to the device and the test method, the damage threshold and the service life of the optical element under vacuum and different components can be measured, accelerated measurement of the service life test can be realized, and the measurement efficiency is improved.

Description

Technical Field

[0001] The invention relates to accelerated measurement of damage threshold and life test of optical elements, in particular to a measurement method under vacuum and specific air component environment. Background Art

[0002] With the gradual expansion of the application field of space satellites and the continuous increase in the demand for space technology, space lasers are constantly developing towards long life, high power, high repetition rate and high precision detection. Optical components are an indispensable part of laser systems and equipment. With the continuous development of laser technology, the output power of laser systems is getting higher and higher, and the requirements for the resistance of optical components to laser damage are also getting higher and higher. At the same time, the existence of high vacuum, high-energy particle radiation, solar radiation, biological contamination, gas escape, extreme temperature changes and other harsh environmental factors in space also put forward higher requirements for optical components. Studies have shown that pollutants in vacuum environments, ultraviolet radiation in sunlight and various space particle radiations will affect the optical properties and resistance to laser damage of optical components. Therefore, the damage test of space components has requirements such as vacuum environment and air composition, which has certain particularities.

[0003] Another feature of space laser systems is that they cannot replace components. The life of optical components determines the operating life of the laser system and even the entire space system to a certain extent. Therefore, space optical components attach great importance to operating life, and the life test of optical components is of great significance. However, since space systems usually require a long operating life, the cumulative number of irradiation pulses can reach 10 9 Direct life testing is extremely time-consuming, so accelerated testing of component life has been taken seriously, and some research has been conducted with certain results.

[0004] The current accelerated test is mainly conducted through the number of pulses and the energy density of the irradiation pulses. In the multi-pulse damage test, it was found that with the increase in the number of irradiation pulses, the damage threshold of the component decreased significantly, but the rate of decrease gradually slowed down and stabilized after the number of pulses reached a certain number. Therefore, a certain number of thresholds can be used to predict the life of the component without completing the full number of pulse irradiations; using the irradiation pulse energy to improve efficiency is also relatively intuitive. The increase in pulse energy corresponds to a decrease in the number of pulses required to produce damage, thereby improving test efficiency.

[0005] Although these two methods have improved the efficiency of life test to a certain extent, there are still some problems. For the use of changes in the number of irradiation, the number of pulses required for the damage threshold to reach stability is usually still large, and if the number of test pulses differs too much from the actual number of pulses used, the test confidence may be reduced, and changes in pulse energy may cause changes in the damage mechanism, thereby deviating from the fitting model and forming measurement errors. Therefore, in the field of accelerated life test of optical components, further research and optimization are still needed. Summary of the invention

[0006] In order to solve the deficiencies of the above-mentioned prior art methods and devices, the present invention provides an optical element life test device and an accelerated measurement method in a vacuum environment, which realizes accelerated aging test by adjusting the number, energy and frequency of irradiation pulses.

[0007] The solution of the present invention is as follows:

[0008] On the one hand, the present invention provides an optical element life test device in a vacuum environment, which is characterized in that the device includes: a laser, a beam transmission and control system, a wedge plate, a beam monitoring system, a vacuum target chamber, a sample positioning and motion platform, a damage monitoring system, a control system and other components.

[0009] The device structure is as follows: the laser outputs the laser pulse required for the test, which enters the vacuum target chamber to irradiate the sample after passing through the beam transmission and control system, and completes the laser pulse energy, polarization state and light plate size adjustment in this process; the test sample is clamped on the sample positioning and motion platform system and placed in the vacuum target chamber; the damage monitoring system images the test area in real time and records and analyzes the changes to determine whether damage occurs; during the laser irradiation process, the laser beam is sampled by the wedge plate and the spatial distribution, time distribution and energy of the beam pulse are measured and recorded in real time by the beam monitoring system, and the control system controls the functions of all components and the operation of the test process, data acquisition and processing, etc.

[0010] The vacuum target chamber can create and maintain a low-pressure environment, and at the same time, an atmosphere injection port is provided to allow different atmospheres to be filled in.

[0011] The laser output pulse frequency is adjustable.

[0012] The control system controls the laser, the beam transmission and control system, the beam monitoring system, the vacuum target chamber, the sample positioning and motion platform, the damage monitoring system component functions and test process operation, data acquisition and processing, etc.

[0013] On the other hand, the present invention also provides a method for accelerating the life measurement of an optical element, wherein the method comprises the following steps:

[0014] ① According to the test angle required by the sample to be tested, the sample positioning and motion platform are fixed and the sample is clamped; in an atmospheric environment, the laser is turned on to allow the light beam to pass through the beam transmission and control system and the wedge plate, and finally irradiate the sample to be tested, and the sample test position is moved to the convergence point of the laser beam.

[0015] ② Move the sample positioning and motion platform so that the test light spot is located at the edge of the sample to be tested, increase the energy of the measuring beam to damage the sample to be tested, and calibrate the damage monitoring system with the damaged area as the target so that the damaged area can be clearly observed.

[0016] ③ Adjust the beam transmission and control system to adjust the energy of the main beam to the minimum, adjust the wedge plate to allow the split beam to enter the beam monitoring system, and measure and record the spatial distribution, temporal distribution and energy of the beam pulse in real time.

[0017] ④ According to the actual operating environment of the sample, including ambient air pressure, air composition, irradiation laser wavelength, pulse frequency and total number of irradiation pulses, set the test parameters, block the laser light outlet and pre-run the test process, paying attention to whether the sample operation path, beam monitoring system, damage monitoring system, etc. meet the test requirements; after the pre-run is problem-free, close all the hatches of the vacuum chamber and start to evacuate to the set vacuum degree. If there is an air composition requirement, inject the corresponding gas from the vacuum atmosphere injection port.

[0018] ⑤ Test and calculate the corresponding damage threshold according to the S-on-1 test process in the ISO11254 standard. On the basis of keeping other parameters unchanged, increase the laser output pulse frequency and repeat the S-on-1 process to obtain a series of damage thresholds and their corresponding irradiation frequencies; establish a coordinate system with the irradiation frequency as the horizontal axis and the damage threshold as the vertical axis, and mark the obtained damage threshold in the coordinate system. According to the threshold change law, select a linear or exponential model to fit and obtain the corresponding relationship between the damage thresholds at different frequencies;

[0019] ⑥ Determine the highest test frequency based on the laser output pulse frequency characteristics and perform S-on-1 test to obtain the damage threshold at this frequency. The damage threshold under the actual operating parameters of the component can be obtained from the corresponding relationship, thereby completing the aging assessment.

[0020] After the measurement is completed, the laser is paused, the vacuum chamber is inflated, and steps ③, ④, and ⑤ are repeated after the sample is replaced to proceed to the next round of testing.

[0021] Due to the adoption of the above scheme, the present invention has the following advantages:

[0022] This device has a vacuum target chamber, and the test of space operating components can be carried out in a vacuum environment; the vacuum target chamber has a reserved inflation interface, which can be used to inject different atmospheres to simulate the actual operating environment, and is equipped with a residual gas analyzer for measurement and analysis, which can be used to study the damage characteristics of different atmosphere environments.

[0023] This device uses high-repetition-rate lasers to accelerate the aging test of space optical components and improve the test efficiency. The device has the following advantages: 1. It simulates real working conditions, including vacuum and air composition, so as to more accurately simulate the performance of optical components under actual use conditions; 2. It uses the irradiation laser frequency to improve the measurement efficiency and effectively solve the pain points of current life and aging tests; 3. It comprehensively examines the influence of frequency factors on life, and provides guidance and experimental basis for giving full play to component performance and improving material properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the optical element life test device under vacuum environment of the present invention.

[0025] In the figure, 101 is a laser, 102 is a beam transmission and control system, 103 is a wedge, 104 is a beam monitoring system, 105 is a vacuum target chamber, 106 is a sample positioning and motion platform, 107 is a damage monitoring system, and 108 is a control system.

[0026] Specific implementation cases

[0027] The present invention is further described below with reference to the implementation examples shown in the accompanying drawings, but this should not limit the scope of protection of the invention.

[0028] An optical element life test device in a vacuum environment, comprising:

[0029] A laser (101) is used to output laser pulses required for testing. The laser has the characteristic of adjustable pulse frequency;

[0030] The beam transmission and control system (102) is responsible for adjusting the energy, polarization state and spot size of the laser pulse to ensure that the laser beam can accurately irradiate the sample to be tested;

[0031] A wedge plate (103) for sampling the laser beam so as to measure the spatial distribution, temporal distribution and energy of the beam pulse in real time through a beam monitoring system;

[0032] A beam monitoring system (104) monitors and records various parameters of the laser beam in real time to ensure the accuracy and reliability of the test;

[0033] The vacuum target chamber (105) creates and maintains a low-pressure environment and has an atmosphere injection port, which can be filled with different atmospheres to simulate different actual operating environments;

[0034] The sample positioning and motion platform (106) is used to fix and move the sample to be tested to ensure that the test light spot can be accurately positioned at the specified position of the sample;

[0035] A damage monitoring system (107) is used to image the test area in real time and record and analyze changes to determine whether damage has occurred;

[0036] The control system (108) controls the functions of all components and the operation of the test process, and is responsible for data collection and processing.

[0037] The laser (101) outputs the laser pulse required for the test, and after being adjusted by the beam transmission and control system (102), enters the vacuum target chamber (105) to irradiate the sample. The test sample is clamped on the sample positioning and motion platform (106) and placed in the vacuum target chamber (105); the damage monitoring system (107) images the test area in real time and records and analyzes the changes in the test area during the laser pulse radiation to determine whether damage occurs; during the laser irradiation process, the laser beam is sampled by the wedge plate (103) and the spatial distribution, time distribution and energy of the beam pulse are measured in real time by the beam monitoring system (104); the control system (108) controls the functions of all components and the operation of the test process, data collection and processing, etc.

[0038] A method for testing the life of an optical element in a vacuum environment comprises the following steps:

[0039] ① According to the test angle required by the sample to be tested, the sample is positioned and fixed on the motion platform (106) and the sample is clamped;

[0040] In an atmospheric environment, the laser (101) is turned on, the light beam passes through the light beam transmission and control system (102) and the wedge plate (103), and finally irradiates the sample to be tested, and the sample test position is moved to the laser beam convergence point.

[0041] ② Move the sample positioning and motion platform (106) so that the test light spot is located at the edge of the sample to be tested, increase the energy of the measuring beam and irradiate the sample to be tested to cause damage, and calibrate the damage monitoring system (107) with the damaged area as the target so that the damaged area can be clearly observed.

[0042] ③ Adjust the beam transmission and control system (102) to adjust the energy of the main beam to the minimum, adjust the wedge plate (103) to allow the split beam to enter the beam monitoring system (104) and adjust the system so that it can accurately measure and record the spatial distribution, temporal distribution and energy of the beam pulse.

[0043] ④ Set the test parameters according to the actual operating environment of the sample (including ambient air pressure, air composition, irradiation laser wavelength, pulse frequency and total number of irradiation pulses, etc.); block the laser light outlet and pre-run the test process to check whether the sample operation path, beam monitoring system, damage monitoring system, etc. meet the test requirements; after the pre-run is problem-free, close all the doors of the vacuum chamber and start to evacuate to the set vacuum degree. If there is an air composition requirement, inject the corresponding gas from the vacuum atmosphere injection port.

[0044] ⑤ Test and calculate the corresponding damage threshold according to the S-on-1 process in the ISO11254 standard; gradually increase the laser output pulse frequency and repeat the S-on-1 process while keeping other parameters unchanged, thereby obtaining a series of damage thresholds and their corresponding irradiation frequencies; establish a coordinate system with the irradiation frequency as the horizontal axis and the damage threshold as the vertical axis, and mark the obtained damage threshold in the coordinate system, and select a linear or exponential model to fit the corresponding relationship between the damage thresholds at different frequencies according to the threshold change law;

[0045] ⑥ Determine the highest test frequency based on the laser output pulse frequency characteristics and perform S-on-1 test to obtain the damage threshold at this frequency. The damage threshold under the actual operating parameters of the component can be obtained from the corresponding relationship, thereby completing the aging assessment.

[0046] After the measurement is completed, the laser (101) is paused, the vacuum chamber is inflated, and steps ③, ④, and ⑤ are repeated after the sample is replaced to proceed to the next round of testing.

[0047] Example: See Figure 1 , Figure 1 This is a schematic diagram of the structure of the optical element life test device in a vacuum environment. The figure consists of a laser, a beam transmission and control system, a wedge plate, a beam monitoring system, a vacuum target chamber, a sample positioning and motion platform, a damage monitoring system, and a control system.

[0048] As can be seen from the figure, the optical element life test device under vacuum environment of the present invention comprises:

[0049] The laser uses the PXn400-1-SLM model product of Edgewave Germany, with an output frequency adjustable between 1Hz and 10KHz, and a maximum pulse energy of 40mJ. The output beam enters the beam transmission and control system, and then passes through the wedge plate into the vacuum target chamber to irradiate the sample; the test sample is clamped on the sample positioning and motion platform system, and the sample positioning and motion platform is a device that moves the sample fixture to be tested in the horizontal and vertical directions with an XZ two-position mobile motor. The motor movement stroke is 100mm, which is sufficient to cover all areas of the test sample; the sample positioning and motion platform system is placed in the vacuum target chamber, and the target chamber is equipped with Stanford's RGA300 residual gas analyzer to monitor the residual gas components in the target chamber in real time; The damage monitoring system uses scattered light method and image method to check whether damage occurs, that is, the test area is illuminated by the HN050L-EC model He-Ne laser of Thorlabs, the light passing through the sample is received by the PDA36a model photoelectric detector of Thorlabs, and the test area is imaged in real time by the Aca2040 model CCD of Basler, and recorded and analyzed, and the change of the test area during the laser pulse radiation is judged to judge whether damage occurs; during the laser irradiation process, the laser beam is sampled by the wedge plate and then enters the beam monitoring system, and the beam monitoring system uses the J-25MT-10KHz and J-50MT-10KHz energy meters of Coherent, the beam quality analyzer of LaserCam HRⅡ and the UPD-35-UVIR-P model fast photoelectric probe of ALPHALAS with the RTM3004 oscilloscope to measure the spatial distribution, time distribution and energy of the beam pulse in real time, and the control system controls all component functions and the operation of the test process, data acquisition and processing, etc.

Claims

1. An optical element life test device in a vacuum environment, characterized in that: include: A laser (101) is used to output laser pulses required for testing, and the output pulse frequency of the laser is adjustable; A beam transmission and control system (102) is used to adjust the energy, polarization state and spot size of the laser pulse and guide the adjusted laser pulse to the vacuum target chamber; a wedge plate (103), located in the beam transmission path, for sampling the laser beam for monitoring by a beam monitoring system; A beam monitoring system (104) for measuring and recording the spatial distribution, temporal distribution and energy of the laser beam pulse in real time; A vacuum target chamber (105) is used to create and maintain a low-pressure environment, and an atmosphere injection port is provided to allow different atmospheres to be filled in. The vacuum target chamber is provided with a sample positioning and motion platform (106) to fix and move the optical element to be measured; A damage monitoring system (107) is used to perform real-time imaging of the test area in the vacuum target chamber and record and analyze changes to determine whether damage has occurred; The control system (108) is used to control the laser, beam transmission and control system, beam monitoring system, vacuum target chamber, sample positioning and motion platform and damage monitoring system, and to collect and process data.

2. The optical element life test device under vacuum environment according to claim 1, characterized in that: The control system (108) is also used to set test parameters according to the actual operating environment of the sample, including ambient air pressure, air composition, irradiation laser wavelength, pulse frequency and total number of irradiation pulses; Block the laser light outlet and pre-run the test process to check whether the sample running path, beam monitoring system, damage monitoring system, etc. meet the test requirements; After the pre-run is complete, the vacuum target chamber is controlled to start evacuating to the set vacuum degree, and corresponding gases are injected from the vacuum atmosphere injection port as needed.

3. A method for measuring the life of an optical element by accelerating the optical element life test device under vacuum environment according to claim 1 or 2, characterized in that: The method comprises the following steps: ① According to the test angle required by the sample to be tested, the sample positioning and motion platform (106) is fixed and the sample is clamped; in an atmospheric environment, the laser (101) is turned on to irradiate the sample to be tested after the light beam passes through the light beam transmission and control system (102) and the wedge plate (103), and the sample test position is moved to the convergence point of the laser beam. ② Move the sample positioning and motion platform (106) so that the test light spot is located at the edge of the sample to be tested, increase the energy of the measuring light beam to cause damage to the sample to be tested, and calibrate the damage monitoring system (107) with the damaged area as the target so that the damaged area can be clearly observed. ③ Adjust the light beam transmission and control system (102) to adjust the energy of the main light beam to the minimum, adjust the wedge plate (103) to allow the split light beam to enter the light beam monitoring system (104) and adjust the system so that it can accurately measure and record the spatial distribution, time distribution and energy of the light beam pulse. ④ Set the test parameters according to the actual operating environment of the sample, block the laser light outlet and pre-run the test process to check whether the sample operation path, beam monitoring system and damage monitoring system meet the test requirements; after checking, close all the doors of the vacuum chamber and start to evacuate to the set vacuum degree, and inject the corresponding gas from the vacuum atmosphere injection port as needed; ⑤ Test and calculate the corresponding damage threshold according to the S-on-1 process in the ISO11254 standard; gradually increase the laser output pulse frequency while keeping other parameters unchanged and repeat the S-on-1 process to obtain a series of damage thresholds and their corresponding irradiation frequencies; A coordinate system is established with the irradiation frequency as the horizontal axis and the damage threshold as the vertical axis, and the obtained damage threshold is marked in the coordinate system. According to the threshold change law, a linear or exponential model is selected to fit the corresponding relationship between the damage thresholds at different frequencies; ⑥ Determine the highest test frequency based on the laser output pulse frequency characteristics and perform S-on-1 test to obtain the damage threshold at this frequency. The damage threshold under the actual operating parameters of the component can be obtained from the corresponding relationship, thereby completing the aging assessment.

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