A device and method for testing the growth threshold of laser-induced damage in optical elements

Abstract

The application discloses a kind of optical element laser damage growth threshold testing device and method, the application is based on the modulation of incident spot after damage and transmittance, the light field modulation and energy loss effect neglected in traditional test method due to damage are analyzed, the functional damage growth threshold in the damage growth process of optical element is obtained, so as to avoid the evaluation of traditional test method, only considering damage area growth, and ignoring the influence of damage on element device and the functional influence of element itself, the testing device and test method of the application not only improve test precision, but also provide a new evaluation system for optical element damage threshold test in high-power laser device, and provide more corresponding damage information.

Description

Technical Field

[0001] This invention relates to the field of optical testing technology, and in particular to a testing device and method for the laser damage growth threshold of optical components. Background Technology

[0002] Damage to optical components has always been a bottleneck technology restricting the development of high-power laser devices. Optical component damage is divided into structural damage and functional damage. Structural damage is the initial damage that occurs to optical components under laser irradiation conditions. Most of this type of damage does not affect the safe operation of the optical system. Functional damage, however, develops gradually from initial damage under subsequent energies, eventually affecting the safe operation of the entire optical path. Therefore, in high-power laser devices, functional damage is more dangerous and requires greater attention. Traditional testing methods for damage growth use damage size as the basis. For example, studies on damage growth on the surface of fused silica show that the damage diameter on the fused silica surface increases exponentially with the number of pulses under the same energy density irradiation. After reaching a certain damage size, the damage size stops growing. The incident laser energy density and the corresponding number of pulses at this point are used as the damage growth threshold for the fused silica surface. However, in high-power laser devices, damage often hasn't reached its final size. Due to light field modulation caused by scattering and absorption of subsequent pulsed laser light, as well as energy loss, the damage morphology not only causes significant losses in laser energy transmission but, more importantly, poses a risk of damage to downstream components, posing a substantial threat to the safe operation of high-power laser devices. Therefore, traditional damage growth threshold testing methods are insufficient to obtain effective data for the operation of high-power laser devices.

[0003] Because existing methods for testing the laser damage growth threshold of optical components lack data analyzing the impact of damage growth on the safe operation of high-power laser devices and providing corresponding guidance, there is a need to invent a testing device and method for the laser damage growth threshold of optical components. This is of great significance for studying the damage characteristics of optical component materials and ensuring the safe operation of high-power lasers. Summary of the Invention

[0004] In view of this, the present invention provides a testing device and method for the laser damage growth threshold of optical components, which solves the technical problem that the test data obtained by traditional optical component laser damage growth threshold testing methods lacks the analysis of the impact of damage growth on the safe operation of high-power laser devices and corresponding guidance significance, thus making it difficult to obtain effective data for the operation of high-power laser devices.

[0005] The device and testing method for determining the laser damage growth threshold of optical elements of the present invention monitor the incident light field modulation and energy loss during the damage growth process in real time, and combine this with the critical parameter index (the boundary condition of the damage growth threshold) which is more important in high-power laser devices, thereby obtaining a damage growth threshold that is more instructive for the safe operation of high-power laser devices.

[0006] To achieve the above-mentioned objectives, the technical solution provided by this invention patent is as follows:

[0007] A testing device for the laser damage growth threshold of optical components includes a laser, an attenuation system, a test optical path, and a detection optical path.

[0008] The laser is used to generate incident laser light directed toward the optical element;

[0009] The attenuation system is used to adjust the laser energy of the incident laser so that it causes initial damage to the rear surface of the optical element when it irradiates the optical element through the test optical path.

[0010] The optical axes of the test optical path and the detection optical path are coaxial. The test optical path is used to measure the laser energy density of the incident laser that causes initial damage to the rear surface of the optical element.

[0011] The detection optical path is used to monitor in real time the spot modulation and energy loss of optical elements as damage on the rear surface of the optical element increases during repeated laser irradiation.

[0012] Preferably, the test optical path is provided with a first beam splitter, a second beam splitter, a first electrically driven displacement platform, a lens, a third beam splitter, a third electrically driven displacement platform, and optical elements arranged sequentially along the beam emission direction. The incident laser generated by the laser is attenuated by the attenuation system and then incident on the first beam splitter, where it is split into two beams. One beam is transmitted into the test optical path as the test light, and the other beam is reflected into the detection optical path as the detection light.

[0013] A first energy meter for measuring the energy of the test optical path is provided on one side of the second beam splitter. A first baffle is provided on the first electric displacement platform. A first CCD camera for recording the size of the laser focal spot on the test optical path is provided on one side of the third beam splitter. The first energy meter, the first electric displacement platform, the third electric displacement platform and the first CCD camera are connected to a computer via a data cable.

[0014] Preferably, the splitting ratio of the first and third beam splitters is less than 1:99 to ensure that the detection optical path does not affect damage growth during operation.

[0015] Preferably, a first reflecting mirror, a second electrically driven displacement platform, and a second reflecting mirror are sequentially arranged along the exit direction of the light beam in the detection optical path, and a second baffle is provided on the second electrically driven displacement platform.

[0016] The detection light entering the detection optical path is reflected by the first and second reflectors and then incident on the third beam splitter. After being reflected by the third beam splitter, it strikes the optical element placed on the third electric displacement platform. A fourth electric displacement platform is set behind the optical element. A second CCD camera for recording the effect of the damage point on the modulation of the detection light and a second energy meter for recording the effect of the damage point on the energy transmittance of the detection light are installed on the fourth electric displacement platform. The second CCD camera, the second energy meter, the second electric displacement platform and the fourth electric displacement platform are connected to the computer via a data cable.

[0017] Preferably, the movement range of the first, second, third, and fourth electric displacement platforms is greater than the size of the test spot and the detection spot, and the error is less than 10 μm.

[0018] Preferably, the attenuation system includes a half-wave plate and a polarizer.

[0019] A method for testing the laser damage growth threshold of optical components, specifically including the following steps:

[0020] S1, adjust the optical axis of the test optical path and the optical axis of the detection optical path to be coaxial;

[0021] S2, open the test optical path and block the detection optical path. Use the test light on the test optical path to irradiate the rear surface of the optical element. Use the first energy meter to measure the beam splitting energy Q1 of the test optical path when the rear surface of the optical element shows initial damage. Use the first CCD camera to measure the laser focal spot size S on the test optical path. Use the beam splitting energy Q1 of the test optical path and the laser focal spot size S to calculate the laser energy density F of the incident laser when the rear surface of the optical element shows initial damage.

[0022] S3, block the test light path and open the detection light path. Use the detection light on the detection light path to irradiate the initial damage point position on the back surface of the optical element. Use the second CCD camera to measure the spot contrast M on the back surface of the optical element and use the second energy meter to measure the energy Q3 of the detection light path. Calculate the splitting ratio N based on the energy Q3 of the detection light path and the splitting energy Q1 of the test light path.

[0023] S4. Repeat step S3. Use an incident laser with laser energy density F to perform multiple irradiation tests on a single location on the back surface of the optical element. Stop the test when the spot contrast M and / or splitting ratio N on the back surface of the optical element reach the boundary condition of the damage growth threshold. Use the laser energy density F and the number of laser irradiations as the damage growth threshold of the optical element.

[0024] Preferably, the specific steps of S2 are as follows:

[0025] The computer controls the first electric displacement platform to move the first baffle outside the test optical path, thereby opening the test optical path, and at the same time controls the second electric displacement platform to move the second baffle into the detection optical path, thereby blocking the detection optical path;

[0026] The computer controls the laser to emit incident laser light, and the laser energy of the incident laser is gradually adjusted by the attenuation system. When the rear surface of the optical element is initially damaged, the beam splitting energy Q1 of the test optical path is measured by the first energy meter, and the laser focal spot size S of the test optical path is measured by the first CCD camera.

[0027] The laser energy density F of the incident laser when initial damage occurs on the rear surface of the optical element is calculated based on the beam splitting energy Q1 of the test optical path and the laser focal spot size S.

[0028] Preferably, the specific steps in S3 for measuring the contrast M of the detection optical path spot for damage points on the rear surface of the optical element using the second CCD camera are as follows:

[0029] The laser spot at the initial damage point on the surface of the optical element is measured using a second CCD camera. The energy distribution of the laser spot after passing the damage point is obtained based on the laser spot on the rear surface of the optical element.

[0030] The strongest light intensity H and the average light intensity A of the light spot are obtained based on the energy distribution of the light spot after passing through the damage point.

[0031] The contrast ratio M of the light spot on the surface after the test optical path passes through the optical element is calculated based on the strongest light intensity H and the average light intensity A of the light spot.

[0032] The beneficial effects of this invention are:

[0033] 1. This invention utilizes a damage growth detection optical path to monitor the light spot modulation and energy loss during the damage growth process in real time. Simultaneously, it uses the critical modulation of the optical field (1.3) and the critical decrease in transmittance (10%) in a high-power laser device as boundary conditions for the damage growth threshold. This simulates the impact of optical component damage on the high-power laser device, solving the problem that traditional damage growth threshold testing methods only focus on the growth of damage size while ignoring the impact on the overall safe operation of the high-power laser device. This provides a more instructive component damage growth threshold for the safe operation of high-power laser devices.

[0034] 2. This invention can test the damage growth threshold of optical elements made of any material, size, or function, and has high applicability.

[0035] 3. This invention takes the effect of damage growth on optical field modulation and energy loss as the research object. It can not only obtain the impact of damage growth on the safe operation of high-power laser devices, but also obtain the corresponding physical mechanisms of damage growth for different components and different damage growth stages, providing more and more reliable information for studying the damage characteristics and physical mechanisms of materials. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the test method for the laser damage growth threshold of optical elements according to the present invention.

[0038] Figure 2 This is a schematic diagram of the structure of the laser damage growth threshold testing device for optical elements of the present invention.

[0039] Figure 3 This is a circuit connection principle block diagram of the laser damage growth threshold testing device for optical elements of the present invention.

[0040] Figure 4 These are the light spot contrast test results in the embodiments of the present invention.

[0041] The meanings of the labels in the diagram are as follows:

[0042] 1 - Laser, 2 - Half-wave plate, 3 - Polarizer, 4 - First beam splitter, 5 - Second beam splitter, 6 - First energy meter, 7 - First baffle, 8 - First electric displacement platform, 9 - Lens, 10 - Third beam splitter, 11 - First CCD camera, 12 - First mirror, 13 - Second baffle, 14 - Second electric displacement platform, 15 - Second mirror, 16 - Test sample, 17 - Third electric displacement platform, 18 - Second energy meter, 19 - Second CCD camera, 20 - Fourth electric displacement platform, 21 - Computer, 22 - First data output card, 23 - Second data output card, 24 - Third data output card, 25 - Fourth data output card, 26 - Fifth data output card. Detailed Implementation

[0043] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0044] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0045] The present application will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0046] In the description of this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "a plurality of" refers to two or more. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] During the damage growth process of optical components, due to their special and complex physical and energy level structures, they have an elusive influence on subsequent incident lasers. Therefore, in high-power laser devices, these damage growths directly affect the optical field modulation and energy attenuation of subsequent incident lasers, thus making a precise laser damage growth threshold for optical components one of the important parameters for the safe and effective operation of high-power laser devices.

[0048] This invention provides a testing device and method for determining the laser damage growth threshold of optical components. By real-time monitoring of the modulation and energy loss of the detection optical field, and combining this with the boundary conditions for the safe and efficient operation of high-power lasers, the damage growth threshold for high-power laser devices is obtained. This invention not only helps to find the component damage growth threshold for the safe and efficient operation of high-power laser devices, but also provides more assistance in studying the physical mechanisms of component damage.

[0049] To obtain a precise laser damage growth threshold for optical components, this invention specifically designs a testing device for the laser damage growth threshold of optical components, such as... Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of the testing device.

[0050] The testing device for the laser damage threshold of optical components of the present invention includes a laser 1, an attenuation system, a test optical path, and a detection optical path.

[0051] The laser 1 is used to generate incident laser light directed toward the optical element 16.

[0052] The attenuation system is used to adjust the laser energy of the incident laser so that when it irradiates the rear surface of the optical element 16 through the test optical path, it causes initial damage to the rear surface of the optical element 16.

[0053] The optical axes of the test optical path and the detection optical path are coaxial. The test optical path is used to measure the laser energy density of the incident laser that causes initial damage to the rear surface of the optical element 16.

[0054] The detection optical path is used to monitor in real time the spot modulation and energy loss during the process of continuous damage growth on the back surface of the optical element 16 when it is repeatedly irradiated by laser.

[0055] Specifically, along the beam emission direction, the test optical path is sequentially arranged with a first beam splitter 4, a second beam splitter 5, a first electrically driven displacement platform 8, a lens 9, a third beam splitter 10, a third electrically driven displacement platform 17, and an optical element 16. A first energy meter 6 for measuring the beam splitting energy of the test optical path is disposed on one side of the second beam splitter 5. A first baffle 17 is disposed on the first electrically driven displacement platform. A first CCD camera 11 for recording the size of the laser focal spot on the test optical path is disposed on one side of the third beam splitter 10. The optical element 16 is disposed on the third electrically driven displacement platform 17, and the focal point of the lens 9 is located on the rear surface of the optical element 16.

[0056] The incident laser beam generated by the laser is attenuated and then incident on the first beam splitter 4, where it is split into two beams. One beam is transmitted as the test beam and enters the test optical path, while the other beam is reflected as the detection beam and enters the detection optical path. In other words, the incident laser beam generated by the laser is split into a damage test beam and a threshold detection beam by the first beam splitter 4.

[0057] The test light entering the test optical path passes through the second beam splitter 5, lens 9, and third beam splitter 10 and then hits the rear surface of the optical element 16. The first CCD camera 11 can measure the size S of the laser focal spot on the test optical path, and the first energy meter 6 can measure the energy Q1 of the test optical path beam splitter.

[0058] The energy of the main optical path of the test optical path, Q2, can be calculated from the energy of the split optical path Q1. Q2 = Q1 / K, where K is the splitting ratio between the split optical path and the main optical path of the test optical path.

[0059] The laser energy density F of the incident laser during the test is calculated based on the energy Q2 of the main optical path and the size S of the laser focal spot on the test optical path, where F = Q2 / S.

[0060] The detection optical path is provided with a first reflector 12, a second electric displacement platform 14, and a second reflector 15 arranged sequentially along the output direction of the light beam. A second baffle 13 is provided on the second electric displacement platform 14.

[0061] The detection light entering the detection optical path is reflected by the first reflector 12 and the second reflector 15 and then incident on the third beam splitter 10. After being reflected by the third beam splitter 10, it hits the optical element 16 on the third electric displacement platform 17. The fourth electric displacement platform 20 is equipped with a second CCD camera 19 for recording the effect of the damage point on the modulation of the detection light and a second energy meter 18 for recording the effect of the damage point on the energy transmittance of the detection light.

[0062] The testing device for the laser damage threshold of optical elements of the present invention further includes a computer, which is connected to the laser 1 via a first driving card 22, to the first electric displacement platform 8 via a second driving card 23, to the third electric displacement platform 17 via a third driving card 24, and to the fourth electric displacement platform 20 via a fourth driving card 25.

[0063] The first energy meter 6, the first electric displacement platform 8, the first CCD camera 11, the second electric displacement platform 14, the third electric displacement platform 17, and the fourth electric displacement platform 20 are all connected to the computer via data cables.

[0064] The test optical path and the detection optical path are adjusted to be coaxial by adjusting the first beam splitter 4, the first reflector 12, the second reflector 15 and the third beam splitter 10.

[0065] Specifically, in this embodiment, the splitting ratio of the first beam splitter and the third beam splitter is less than 1:99 to ensure that the detection optical path will not affect the damage growth when it is working.

[0066] Specifically, in this embodiment, the wavelength of the laser emitted by laser 1 is 1064nm, 532nm, or 355nm, and the pulse width of the laser is adjustable from 10fs to 20ns.

[0067] Specifically, in this embodiment, the laser energy of the laser output by laser 1 is adjustable in the range of 2J to 100J, and the optical element can be any optical element.

[0068] Specifically, in this embodiment, the movement range of the first electric displacement platform 8, the second electric displacement platform 14, the third electric displacement platform 17, and the fourth electric displacement platform 20 is greater than the size of the test spot and the detection spot, and the error is less than 10μm.

[0069] This invention also provides a method for testing the laser damage growth threshold of optical components, specifically including the following steps:

[0070] S1. Adjust the first beam splitter 4, the first reflecting mirror 12, the second reflecting mirror 15 and the third beam splitter 10 to make the optical axis of the test optical path and the optical axis of the detection optical path coaxial.

[0071] S2, open the test optical path and block the detection optical path. Use the test light on the test optical path to perform irradiation test on the rear surface of the optical element 16. Use the first energy meter 6 to measure the beam splitting energy Q1 of the test optical path when the rear surface of the optical element 16 shows initial damage. Use the first CCD camera 11 to measure the laser focal spot size S on the test optical path. Use the beam splitting energy Q1 of the test optical path and the laser focal spot size S to calculate the laser energy density F of the incident laser when the rear surface of the optical element 16 shows initial damage.

[0072] Specifically, first, the optical element 16 is placed in the test optical path, and combined with the focal length of the focusing lens 9, the position to be measured on the optical element 16 is adjusted to the focal point of the focusing lens 9 using the third electric displacement platform 17.

[0073] Then, the computer controls the first electric displacement platform 8 to move the first baffle 7 outside the test optical path to open the test optical path, and at the same time controls the second electric displacement platform 14 to move the second baffle 13 onto the detection optical path to block the detection optical path.

[0074] Then, the computer controls the laser 1 to emit the incident laser, and uses the attenuation system to gradually adjust the laser energy of the incident laser. When the rear surface of the optical element 16 is initially damaged, the first energy meter 6 is used to measure the beam splitting energy Q1 of the test optical path at this time, and the first CCD camera 11 is used to measure the laser focal spot size S of the test optical path at this time.

[0075] The energy of the main optical path of the test optical path, Q2, can be calculated from the energy of the split optical path Q1. Q2 = Q1 / K, where K is the splitting ratio between the split optical path and the main optical path of the test optical path.

[0076] The laser energy density F of the incident laser during the test (i.e., the laser energy density F of the incident laser when the initial damage occurs on the rear surface of optical element 16) is calculated based on the energy Q2 of the main optical path of the test optical path and the size S of the laser focal spot on the test optical path. F = Q2 / S.

[0077] S3, the computer controls the first electric displacement platform 20 to place the first baffle 8 in the test optical path to block the test optical path, and at the same time controls the second electric displacement platform 14 to move the second baffle 13 outside the detection optical path to open the detection optical path.

[0078] The initial damage point location on the rear surface of the optical element 16 is irradiated using the detection light in the detection optical path. The spot contrast M on the rear surface of the optical element 16 is measured using the second CCD camera 19, and the detection optical path energy Q3 is measured using the second energy meter 18. The splitting ratio N is calculated based on the detection optical path energy Q3 and the splitting path energy Q1 of the test optical path, where N = Q3 / Q1.

[0079] The specific steps for measuring the spot contrast M on the rear surface of the optical element 16 using the second CCD camera 19 are as follows: First, the computer controls the fourth electric displacement platform 20 to move the second CCD camera 19 into the detection optical path. The second CCD camera 19 measures the laser spot on the rear surface of the optical element 16. Based on the laser spot on the rear surface of the optical element 16, the energy distribution of the laser spot in the detection optical path after passing the damage point is obtained. Then, based on the energy distribution of the laser spot after passing the damage point, the strongest light intensity H and the average light intensity A of the spot are obtained. Based on the strongest light intensity H and the average light intensity A, the spot contrast M of the detection optical path passing the rear surface of the optical element 16 is calculated, where M = H / A.

[0080] S4. Repeat step S3. Use an incident laser with laser energy density F to perform multiple irradiation tests on a single position on the rear surface of the optical element 16. Stop the test when the spot contrast M and / or splitting ratio N of the detection optical path on the rear surface of the optical element 16 reach the boundary condition of the damage growth threshold. Use the laser energy density F and the number of laser irradiations as the damage growth threshold of the optical element.

[0081] In this embodiment, the boundary conditions for the damage growth threshold are that the spot contrast M on the rear surface of the optical element 16 does not exceed 1.3 and the splitting ratio N decreases by no more than 10%.

[0082] That is, when the spot contrast M obtained by the test after irradiating a single position on the rear surface of the optical element 16 with an incident laser with a laser energy density of F multiple times increases to 1.3, or the beam splitting ratio N decreases by 10%, the test must be stopped immediately. At this time, the laser energy density F and the number of laser irradiations are used as the damage growth threshold of the optical element.

[0083] This invention uses the modulation and transmittance of the incident light spot after damage as a basis to analyze the light field modulation and energy loss effects caused by damage, which are ignored in traditional testing methods. This allows for the determination of the functional damage growth threshold during the damage growth process of optical components. This avoids the problem of traditional testing methods that only consider the growth of the damage area while ignoring the impact of damage on the device and the functionality of the component itself. The testing device and method of this invention not only improve the testing accuracy but also provide a new evaluation system for the damage threshold testing of optical components in high-power laser devices and provide more relevant damage information.

[0084] The specific embodiments of the present invention will be illustrated below with examples.

[0085] Assume that the optical element under test 16 is a fused silica with a size of 10*10*10mm, the focal length of the focusing lens 9 is 500mm, and the laser 1 emits a Gaussian pulse laser with a diameter of 5mm, a pulse width of 10ns, and a maximum output energy of 10J.

[0086] The first electric displacement platform 8, the second electric displacement platform 14, the third electric displacement platform 17, and the fourth electric displacement platform 20 have a movement range of 50 mm and an error of 1 μm.

[0087] A method for testing the laser damage growth threshold of optical components, specifically including the following steps:

[0088] S1, adjust the first beam splitter 4, the first reflector 12, the second reflector 15 and the third beam splitter 10 to make the optical component damage growth test optical path and the detection optical path coaxial;

[0089] S2, the computer 21 uses the second drive card 23 to adjust the first electric displacement platform 8 to move the first baffle 7 outside the test optical path, and at the same time the computer uses the third drive card 24 to adjust the second electric displacement platform 14 to move the second baffle 13 inside the detection optical path to block the detection optical path.

[0090] The computer uses the first driver card 22 to make the laser emit a laser with an energy of 10J. The attenuation system composed of half-wave plate 2 and polarizer 3 is used to adjust the energy of the incident laser appropriately. The energy of the test optical path splitter is measured to be 0.02J using the second beam splitter 5 and the first energy meter 6, and then transmitted to the computer 21. Based on the energy of the test optical path splitter, the energy of the test optical path main optical path can be calculated to be 0.2J (0.2 / K, where K is the splitting ratio of the splitter and the main optical path, which is 10%).

[0091] Simultaneously, the size S of the focal spot in the test optical path was measured using the third beam splitter 10 and the first CCD camera 11, and it was found to be 0.4 mm. 2Therefore, the corresponding incident laser energy density during the test can be calculated to be 50 J / cm². 2 ;

[0092] S3, utilizing an incident laser energy density (also known as incident laser flux) of 50 J / cm². 2 The laser is used to irradiate a single location on the surface of the fused silica. When damage is found on the surface of the fused silica, the irradiation is stopped.

[0093] The first baffle 8 is placed in the test optical path using the first electric displacement platform 8 to block the test optical path, while the second baffle 13 is moved outside the detection optical path using the second electric displacement platform 14.

[0094] Using the fourth drive card 26, the electric displacement platform 20 moves the second CCD camera 19 into the detection optical path, and obtains the corresponding spot contrast of 0.8 (less than 1.3). Then, the fourth electric displacement platform 20 moves the second energy meter 18 into the detection optical path, and obtains the detection optical path energy of 0.196J.

[0095] Based on the detection optical path energy of 0.196J and the splitting optical path energy of 0.02J, the corresponding decrease in the splitting ratio is calculated to be 4% (less than 10%).

[0096] S4, repeat S3, using an incident laser energy density of 50 J / cm². 2 Multiple irradiation tests were conducted on a single location on the surface of the fused silica using a laser. The test was stopped when the contrast ratio M first increased to 1.3, and the corresponding incident energy density was set to 50 J / cm². 2 The number of laser irradiations under the given conditions (i.e., the number of test shots – 5 shots) is used as the damage growth threshold for the back surface of the fused silica element.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A testing device for the laser damage growth threshold of optical components, characterized in that, The laser (1), the attenuation system, the test light path and the detection light path, The laser (1) is used to generate incident laser light to the optical element (16); The attenuation system is used to adjust the laser energy of the incident laser light to cause the initial damage of the front surface of the optical element (16) when the optical element (16) is irradiated by the test light path; The optical axes of the test light path and the detection light path are coaxial, and the test light path is used to measure the laser energy density of the incident laser light causing the initial damage of the back surface of the optical element (16); The detection light path is used to monitor the spot regulation and energy loss in the process of continuous growth of the damage of the back surface of the optical element (16) when the optical element (16) is irradiated by the laser multiple times. The first light splitting plate (4), the second light splitting plate (5), the first electric displacement platform (8), the lens (9), the third light splitting plate (10) and the optical element (16) are sequentially arranged on the test light path along the outgoing direction of the light beam, and the incident laser light generated by the laser is incident on the first light splitting plate (4) after the attenuation system, and is split into two beams by the first light splitting plate (4), one of which is transmitted into the test light path as test light, and the other is reflected into the detection light path as detection light, The first energy meter (6) for measuring the energy of the test light path is arranged on one side of the second light splitting plate (5), the first baffle (7) is arranged on the first electric displacement platform (8), the first CCD camera (11) for recording the size of the laser focal spot is arranged on one side of the third light splitting plate (10), and the first energy meter (6), the first electric displacement platform (8), the third electric displacement platform (17) and the first CCD camera (11) are connected with the computer through data lines; The first reflecting mirror (12), the second electric displacement platform (14) and the second reflecting mirror (15) are sequentially arranged on the detection light path along the outgoing direction of the light beam, and the second baffle (13) is arranged on the second electric displacement platform (14), The detection light entering the detection light path is reflected by the first reflecting mirror (12) and the second reflecting mirror (15), and then is incident on the third light splitting plate (10), and then is reflected by the third light splitting plate (10) and hits the optical element (16), and the fourth electric displacement platform (20) is arranged on the back side of the optical element (16), and the second CCD camera (19) for recording the influence of the damage point on the detection light regulation and the second energy meter (18) for recording the influence of the damage point on the energy transmittance of the detection light are installed on the fourth electric displacement platform (20), and the second electric displacement platform (14), the fourth electric displacement platform (20), the second CCD camera (19) and the second energy meter (18) are connected with the computer through data lines.

2. The apparatus for testing a growth threshold of a laser-induced damage of an optical element according to claim 1, wherein The light splitting ratios of the first light splitting plate (4) and the third light splitting plate (10) are both less than 1:99, so as to ensure that the detection light path will not affect the damage growth when working.

3. The apparatus for testing a growth threshold of a laser-induced damage of an optical element according to claim 1, wherein The optical axes of the test light path and the detection light path are adjusted to be coaxial by adjusting the first light splitting plate (4), the first reflecting mirror (12), the second reflecting mirror (15) and the third light splitting plate (10).

4. The apparatus for testing a growth threshold of a laser-induced damage of an optical element according to claim 1, wherein The moving ranges of the first, second, third and fourth electric displacement platforms (8, 14, 17 and 20) are all greater than the sizes of the test and detection light spots, and the errors are all less than 10 μm.

5. The apparatus for testing a growth threshold of a laser-induced damage of an optical element according to claim 1, wherein The attenuation system comprises a half-wave plate (2) and a polarizer (3).

6. A method for testing the growth threshold of laser-induced damage in optical elements based on the apparatus of any one of claims 1-5, characterized in that, Specifically comprising the following steps: S1, adjusting the optical axis of the test light path and the optical axis of the detection light path to be coaxial; S2, opening the test light path and blocking the detection light path, irradiating the rear surface of the optical element (16) with the test light on the test light path for irradiation testing, measuring the energy Q1 of the light path of the test light path when the initial damage occurs on the rear surface of the optical element (16) by using the first energy meter (6), measuring the laser focal spot size S on the test light path by using the first CCD camera (11), and calculating the laser energy density F of the incident laser when the initial damage occurs on the rear surface of the optical element (16) by using the energy Q1 of the light path of the test light path and the laser focal spot size S. S3, blocking the test light path and opening the detection light path, irradiating the damage point position on the rear surface of the optical element (16) with the detection light on the detection light path for irradiation testing, and measuring the spot contrast M of the rear surface of the optical element (16) by using the second CCD camera (19), measuring the energy Q3 of the detection light path by using the second energy meter (18), and calculating the splitting ratio N according to the energy Q3 of the detection light path and the energy Q1 of the light path of the test light path. S4, repeating steps S2-S3, and irradiating a single position on the rear surface of the optical element (16) with the incident laser with the laser energy density F for multiple times, and stopping the testing when the spot contrast M and / or the splitting ratio N of the detection light path passing through the rear surface of the optical element (16) reaches the boundary condition of the damage growth threshold, and taking the laser energy density F and the laser irradiation times as the damage growth threshold of the optical element.

7. The method of testing the growth threshold of laser-induced damage in optical elements as recited in claim 6, wherein, The specific steps of S2 are: The computer controls the first electric displacement platform (8) to move the first baffle (7) to the outside of the test light path to open the test light path, and controls the second electric displacement platform (14) to move the second baffle (13) to the detection light path to block the detection light path; The computer controls the laser (1) to emit the incident laser, and gradually adjusts the laser energy of the incident laser by using the attenuation system, measures the energy Q1 of the light path of the test light path when the initial damage occurs on the rear surface of the optical element (16) by using the first energy meter (6), and measures the laser focal spot size S on the test light path at this time by using the first CCD camera (11); The laser energy density F of the incident laser when the initial damage occurs on the rear surface of the optical element (16) is calculated according to the energy Q1 of the light path of the test light path and the laser focal spot size S.

8. The method of testing the growth threshold of laser-induced damage in optical elements as recited in claim 6, wherein, The specific steps of measuring the spot contrast M of the rear surface of the optical element (16) by using the second CCD camera (19) in S3 are: The laser spot on the rear surface of the optical element (16) is measured by using the second CCD camera (19), and the energy distribution of the laser spot after passing through the damage point is obtained according to the laser spot after the detection light path passes through the damage point on the rear surface of the optical element (16); The laser spot on the rear surface of the optical element (16) is measured by using the second CCD camera (19), and the energy distribution of the laser spot after passing through the damage point is obtained according to the laser spot after the detection light path passes through the damage point on the rear surface of the optical element (16); According to the light spot energy distribution of the laser spot after passing through the damage point, the strongest light intensity H and the average light intensity A of the light spot are obtained; According to the strongest light intensity H and the average light intensity A of the light spot, the light spot contrast M of the rear surface of the optical element (16) is calculated.

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