Device and method for testing full-angle vacuum laser damage threshold of picosecond laser optical elements

Abstract

A full-angle vacuum laser damage threshold test device and method for picosecond laser optical elements, including an optical element fixing system, a picosecond laser system for damage, a picosecond laser damage monitoring system and a laser protection module; in the device, the online CCD imaging system related to the vacuum environment and the optical element to be tested are placed at a fixed angle, and the part that needs to be adjusted is limited to an air environment with a relatively large degree of adjustment freedom. By using a rotating and up-and-down moving polarizer, the full-angle laser damage test of the picosecond laser optical element in a vacuum environment is conveniently realized, avoiding the problem of inconvenient adjustment in the vacuum environment. The method adopts a spot superposition test method in the test area, and combines multi-pulse irradiation to examine the stability of the damage, which can accurately evaluate the energy density that the optical element can safely withstand under the application of picosecond lasers.

Description

Technical Field

[0001] The invention relates to a laser damage threshold test of a picosecond laser optical element, and in particular to a full-angle vacuum laser damage threshold test device and method for a picosecond laser optical element. Background Art

[0002] Driven by the demand for fast ignition of laser fusion, the development of high-energy picosecond petawatt large-scale laser devices has been actively carried out at home and abroad since the 1990s. The development of picosecond petawatt laser devices towards high energy has brought great tests and challenges to the ability of optical components to resist laser damage. The evaluation of the ability of optical components to resist picosecond laser damage has important practical value for the optimization of optical component preparation process and its safe application in laser systems. Compared with the common nanosecond laser damage test, the picosecond optical component laser damage test has its own particularity. Short-pulse picosecond laser has a high peak power. Focusing in the air may cause air breakdown and nonlinear self-focusing effects, which will affect the actual energy irradiated to the optical component and the accuracy of the spot measurement. Therefore, the vacuum environment is one of the conditions that must be considered in the picosecond laser damage test. However, the vacuum system greatly affects the flexible adjustment of the external optical system, which requires a comprehensive design of the overall optical path to meet the full-angle vacuum laser damage threshold test requirements of optical components for picosecond lasers. Summary of the invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, a full-angle vacuum laser damage threshold test device and method are proposed in view of the current situation that the working angles of picosecond laser optical elements are basically 70°, 45°, and 23°. The device and method are simple and convenient and can accurately evaluate the picosecond laser damage resistance of optical elements. Among them, 70° corresponds to the working angle of the diffraction element, 45° corresponds to the working angle of the reflection element, and 23° corresponds to the working angle of the transmission element.

[0004] The technical solution of the present invention is as follows:

[0005] A full-angle vacuum laser damage threshold test device for picosecond laser optical elements, characterized in that it includes: an optical element fixing system, a picosecond laser system for damage, a picosecond laser damage monitoring system and a laser protection module;

[0006] The optical element fixing system comprises a circular vacuum cavity, an optical element fixing device located in the circular vacuum cavity, and a two-dimensional adjustment mechanism for controlling the position of the optical element, wherein the optical element fixing device is used to fix the optical element to be measured so that the normal direction of the optical element to be measured is 45° clockwise with the horizontal direction; a 70° incident light pipe, a 63° diffraction light pipe, a 45° incident light pipe, a 45° reflected light pipe, a 23° incident light pipe, and a 23° transmitted light pipe are respectively provided on the circular vacuum cavity, which are 70°, 63°, 45°, and 23° with the normal of the optical element;

[0007] The picosecond laser system for damage comprises a picosecond laser, an energy regulator, a shutter, a half-wave plate, a polarizer, a first 45° reflector, a second focusing lens, a second 45° reflector, a fourth focusing lens and a third focusing lens;

[0008] The picosecond laser damage monitoring system comprises a computer, a first single-sided anti-reflection film, a second single-sided anti-reflection film, an energy meter, a first focusing lens, a beam quality analyzer located at the focal position of the first focusing lens, and an online CCD imaging system located in the normal direction of the optical element to be measured and connected to the circular vacuum cavity, wherein the computer is respectively connected to the energy regulator, the shutter, the energy meter, the beam quality analyzer, the polarizer, the online CCD imaging system and the optical element fixing device;

[0009] The laser protection module includes a first absorption cell, a second absorption cell, a third absorption cell, and a fourth absorption cell, which are respectively placed in the transmission light direction of the polarizer and the exit positions of the 63° diffraction light pipe, the 45° reflection light pipe, and the 23° transmission light pipe;

[0010] The laser output by the picosecond laser passes through the energy regulator, shutter and half-wave plate in sequence, and then enters the first single-sided anti-reflection film. The transmitted light transmitted through the first single-sided anti-reflection film enters the polarizer, and the polarizer is controlled by a computer to achieve up and down movement or angle rotation;

[0011] The energy regulator is used to change the energy of the laser transmitted in the optical path, the shutter is used to control the on and off of the laser in the optical path, the half-wave plate is used to convert the laser in the optical path into a vertically polarized laser, the first single-sided anti-reflection film is placed at a small angle for laser sampling, the polarizer has an extinction ratio of ≥100:1 at a working angle of 56° to 57.5°, and the laser is irradiated to the optical element to be measured at incident angles of 70°, 45°, and 23° by rotating and moving up and down;

[0012] When the normal direction of the polarizer forms a counterclockwise angle of -57.5° with the incident laser, the first emission light reflected by the polarizer sequentially passes through the first 45° reflector, the second focusing lens and the 70° incident light pipe to irradiate the surface of the optical element to be measured, and the diffracted light diffracted by the optical element to be measured passes through the 63° diffraction light pipe and is absorbed by the second absorption cell;

[0013] When the normal direction of the polarizer forms a clockwise angle of 56° with the incident laser, the second emission light reflected by the polarizer sequentially irradiates the surface of the optical element to be measured through the second 45° reflector, the fourth focusing lens and the 23° incident light pipe, and the transmitted light transmitted through the optical element to be measured is absorbed by the fourth absorption cell through the 23° transmitted light pipe;

[0014] When the polarizer moves upward out of the light path, the transmitted light transmitted through the first single-sided anti-reflection film sequentially irradiates the surface of the optical element to be measured through the third focusing lens and the 45° incident light pipe, and the reflected light reflected by the optical element to be measured is absorbed by the third absorption cell through the 45° reflected light pipe;

[0015] The reflected light reflected by the first single-sided anti-reflection film is incident on the second single-sided anti-reflection film, the transmitted light transmitted by the second single-sided anti-reflection film is incident on the energy meter, and the emitted light reflected by the second single-sided anti-reflection film is focused by the first focusing lens and then incident on the beam quality analyzer.

[0016] The second single-sided antireflection film and the first single-sided antireflection film are placed parallel to each other, and the front surfaces of the first single-sided antireflection film and the second single-sided antireflection film are not coated, and the rear surfaces are coated with antireflection films.

[0017] The focal lengths of the first focusing lens, the second focusing lens, the third focusing lens, and the fourth focusing lens are consistent.

[0018] A method for performing picosecond laser damage testing using the full-angle vacuum laser damage threshold testing device for picosecond laser optical elements comprises the following steps:

[0019] ① The computer controls the polarizer to select one of three states according to the test requirements: rotate to -57.5°, 56°, or move upward out of the light path;

[0020] ② The computer controls the picosecond laser to emit light at the optimal fixed frequency to evacuate the circular vacuum cavity;

[0021] ③ The computer controls the energy regulator to adjust the laser energy so that the initial laser energy density irradiating the optical element to be measured does not exceed the picosecond intrinsic damage threshold of the optical element to be measured;

[0022] ④ The computer sets the motion trajectory and horizontal motion speed of the optical element fixture so that the laser spot irradiated on the optical element to be tested is within 1 cm 2 The test area is overlapped by 90% of the peak energy density;

[0023] ⑤ The computer controls the shutter to open, and at the same time controls the energy meter and the beam quality analyzer to collect energy data E and spot data A in real time, and obtains the energy density F = E × N / A of the current test, where N is the splitting ratio, which is equal to the ratio of the energy irradiated to the optical element to be tested at the same time to the energy collected by the energy meter;

[0024] ⑥ A computer-controlled online CCD imaging system diagnoses in real time whether the optical element to be tested is damaged.

[0025] ⑦ When the computer detects that the optical element to be measured moves to the last position coordinate of the motion track set in ④, the optical element to be measured stops moving and closes the shutter;

[0026] ⑧Computer statistics of 1cm 2 The number of damage points D and their location coordinates in the test area. 2 If there is no damage point in the test area, proceed to step 9; if the current 1cm 2 If a damage point appears in the test area, the computer controls the optical element to be tested to locate the damage point in sequence according to the recorded damage point position coordinates and controls the shutter so that S pulses irradiate the located damage point. At the same time, the online CCD imaging system performs real-time diagnosis. If the damage point does not change, the damage point is determined to be stable, otherwise, the damage point is determined to be unstable, until all damage points have completed S pulse irradiation.

[0027] ⑨ moving the optical element to be tested to the next test area, the computer adjusting the energy regulator according to the damage of the tested area to reduce or increase the laser energy irradiating the optical element to be tested (123), repeating ④ to ⑧ until the test of the optical element to be tested is completed, the online CCD imaging system stops diagnosis, the picosecond laser is turned off, and the circular vacuum cavity is deflated;

[0028] ⑩ Draw a curve showing the change of the number of damage points D with the energy density F, and give the stability of the damage points of the optical element to be tested.

[0029] The technical effects of the present invention are:

[0030] ① The online CCD imaging system and the optical element to be measured related to the vacuum environment of the present invention are placed at a fixed angle, and the part that needs to be adjusted is restricted to the air environment with relatively large adjustment freedom. The laser incident angle is changed by changing the optical path in the air environment, thereby avoiding the problem of inconvenience in adjusting the vacuum environment.

[0031] ② The present invention utilizes conventional optical elements, such as a 45° reflector, a polarizing plate, etc., to realize automatic adjustment of the incident angle of the test laser in a vacuum environment, and the optical path is simple and convenient to implement.

[0032] ③The present invention is in 1cm 2 The spot superposition test in the test area, combined with multi-pulse irradiation of the damage point, can accurately evaluate the energy density that the optical component can safely withstand under the application of picosecond laser.

[0033] ④The device is easy to adjust and can conveniently realize the testing of different incident angles of picosecond laser in a vacuum environment, meeting the full-angle testing requirements of optical components for picosecond laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the optical path diagram of the full-angle vacuum laser damage threshold test device for picosecond laser optical components. In the figure, 101 is a picosecond laser, 102 is an energy regulator, 103 is a shutter, 104 is a half-wave plate, 105 is a first single-sided anti-reflection film, 106 is an adjustable polarizer that can be moved up and down and rotated, 107 is a first absorption cell, 108 is a second single-sided anti-reflection film, 109 is a first focusing lens, 110 is an energy meter, 111 is a beam quality analyzer, 112 is a computer, 113 is a first 45° reflector, 114 is a second focusing lens, 115 is a 70° incident light pipe, 116 is a 45° reflector, 117 is a 70° incident light pipe, 118 is a 45° reflector, 119 is a 45° reflector, 120 is a 45° reflector, 121 is a 45° reflector, 122 is a 45° reflector, 123 is a 45° reflector, 124 is a 45° reflector, 125 is a 45° reflector, 126 is a 45° reflector, 127 is a 45° reflector, 128 is a 45° reflector, 129 is a 45° reflector, 130 is a 45° reflector, 131 is a 45° reflector, 132 is a 45° reflector, 133 is a 45° reflector, 134 is a 45° reflector, 135 is a 45° reflector, 136 is a 45° reflector, 137 is a 45° reflector, 138 is a 45° reflector, 13 16—63° diffraction light duct, 117—second absorption cell, 118—third focusing lens, 119—45° incident light duct, 120—second 45° reflecting mirror, 121—fourth focusing lens, 122—23° incident light duct, 123—optical element to be measured, 124—circular vacuum cavity, 125—online CCD imaging system, 126—45° reflected light duct, 127—third absorption cell, 128—23° transmitted light duct, 129—fourth absorption cell.

[0035] Figure 2 This is a schematic diagram showing that the normal direction of the polarizer forms a counterclockwise angle of -57.5° with the incident laser.

[0036] Figure 3 This is a schematic diagram showing that the normal direction of the polarizer forms a clockwise angle of 56° with the incident laser.

[0037] Figure 4 Each 1cm 2 Schematic diagram of light spot superposition in the test area.

[0038] Figure 5 This is a data processing diagram for picosecond laser damage threshold test. DETAILED DESCRIPTION

[0039] The present invention is further described below with reference to examples and drawings, but the protection scope of the invention shall not be limited thereto.

[0040] See also Figure 1 A full-angle vacuum laser damage threshold test device for picosecond laser optical elements, characterized by comprising: an optical element fixing system, a picosecond laser system for damage, a picosecond laser damage monitoring system and a laser protection module;

[0041] The optical element fixing system comprises a circular vacuum cavity 124, an optical element fixing device located in the circular vacuum cavity 124, and a two-dimensional adjustment mechanism for controlling the position of the optical element. The optical element fixing device is used to fix the optical element 123 to be measured so that the normal direction of the optical element 123 to be measured is 45 degrees clockwise with the horizontal direction; a 70° incident light pipe 115 is provided on the circular vacuum cavity 124, and the angle α with the normal of the optical element 123 to be measured is equal to 70 degrees. , a 63° diffraction light conduit 116 having an angle β of 63° with the normal of the optical element 123 to be measured, a 45° incident light conduit 119 having an angle γ of 45° with the normal of the optical element 123 to be measured, a 45° reflected light conduit 126 having an angle χ of 45° with the normal of the optical element 123 to be measured, a 23° incident light conduit 122 having an angle θ of 23° with the normal of the optical element 123 to be measured, and a 23° transmitted light conduit 128 having an angle i of 23° with the normal of the optical element 123 to be measured;

[0042] The picosecond laser system for damage comprises a picosecond laser 101, an energy regulator 102, a shutter 103, a half-wave plate 104, a polarizer 106, a first 45° reflector 113, a second focusing lens 114, a second 45° reflector 120, a fourth focusing lens 121 and a third focusing lens 118;

[0043] The picosecond laser damage monitoring system comprises a computer 112, a first single-sided anti-reflection film 105, a second single-sided anti-reflection film 108, an energy meter 110, a first focusing lens 109, a beam quality analyzer 111 located at the focal position of the first focusing lens 109, and an online CCD imaging system 125 located in the normal direction of the optical element to be measured 123 and connected to the circular vacuum cavity 124. The computer 112 is respectively connected to the energy regulator 102, the shutter 103, the energy meter 110, the beam quality analyzer 111, the polarizer 106, the online CCD imaging system 125 and the optical element fixing device;

[0044] The laser protection module includes a first absorption cell 107, a second absorption cell 117, a third absorption cell 127, and a fourth absorption cell 129, which are respectively placed in the transmission light direction of the polarizer 106 and the exit positions of the 63° diffraction light duct 116, the 45° reflection light duct 126, and the 23° transmission light duct 128;

[0045] The laser output by the picosecond laser 101 passes through the energy regulator 102, the shutter 103 and the half-wave plate 104 in sequence, and then enters the first single-sided anti-reflection film 105. The transmitted light transmitted through the first single-sided anti-reflection film 105 enters the polarizer 106. The polarizer 106 is controlled by the computer 112 to achieve up and down movement or angle rotation.

[0046] The energy regulator 102 is used to change the energy of the laser transmitted in the optical path, the shutter 103 is used to control the on and off of the laser in the optical path, the half-wave plate 104 is used to convert the laser in the optical path into a vertically polarized laser, the first single-sided anti-reflection film 105 is placed at a small angle for laser sampling, the adjustable polarizer 106 has an extinction ratio of ≥100:1 at a working angle of 56° to 57.5°, and the laser is irradiated to the optical element to be measured 123 at incident angles of 70°, 45°, and 23° by moving up and down and rotating;

[0047] The second single-sided anti-reflection film 108 and the first single-sided anti-reflection film 105 are placed parallel to each other, and the front surfaces of the first single-sided anti-reflection film 105 and the second single-sided anti-reflection film 108 are not coated, and the rear surfaces are coated with anti-reflection films;

[0048] The reflected light reflected by the first single-sided anti-reflection film 105 is incident on the second single-sided anti-reflection film 108, the transmitted light transmitted by the second single-sided anti-reflection film 108 is incident on the energy meter 110, and the emitted light reflected by the second single-sided anti-reflection film 108 is focused by the first focusing lens 109 and then incident on the beam quality analyzer 111;

[0049] The focal lengths of the first focusing lens 109 , the second focusing lens 114 , the third focusing lens 118 , and the fourth focusing lens 121 are consistent.

[0050] See also Figure 2 , the dotted line is the normal of the polarizer 106 and the first 45° reflector 113. When the counterclockwise angle i1 between the normal direction of the polarizer 106 and the incident laser is -57.5°, the first emitted light reflected by the polarizer 106 sequentially passes through the first 45° reflector 113, the second focusing lens 114 and the 70° incident light pipe 115 to irradiate the surface of the optical element to be measured 123, and the diffracted light diffracted by the optical element to be measured 123 passes through the 63° diffraction light pipe 116 and is absorbed by the second absorption cell 117.

[0051] See also Figure 3 , the dotted line is the normal of the polarizer 106 and the second 45° reflector 120. When the normal direction of the polarizer 106 forms a clockwise angle i2 of 56° with the incident laser, the second emission light reflected by the polarizer 106 sequentially irradiates the surface of the optical element to be measured 123 through the second 45° reflector 120, the fourth focusing lens 121 and the 23° incident light pipe 122, and the transmitted light transmitted through the optical element to be measured passes through the 23° transmitted light pipe 128 and is absorbed by the fourth absorption cell 129;

[0052] When the polarizer 106 moves out of the light path, the transmitted light transmitted through the first single-sided anti-reflection film 105 sequentially irradiates the surface of the optical element to be measured 123 through the third focusing lens 118 and the 45° incident light pipe 119, and the reflected light reflected by the optical element to be measured 123 passes through the 45° reflected light pipe 126 and is absorbed by the third absorption cell 127.

[0053] The method for performing picosecond laser damage testing using the full-angle vacuum laser damage threshold testing device for picosecond laser optical elements is characterized in that the method comprises the following steps:

[0054] ① The computer 112 controls the polarizer 106 to select one of three states according to the test requirements: rotate to -57.5°, 56°, or move upward out of the light path;

[0055] ② The computer 112 controls the picosecond laser 101 to emit light at an optimal fixed frequency to evacuate the circular vacuum cavity (124);

[0056] ③ The computer 112 controls the energy regulator 102 to adjust the laser energy so that the initial laser energy density irradiating the optical element 123 to be measured does not exceed the picosecond intrinsic damage threshold of the optical element 123 to be measured;

[0057] ④ The computer 112 sets the motion trajectory and horizontal motion speed of the optical element fixture so that the laser spot irradiated on the optical element 123 to be tested is within 1 cm 2 The test area is overlapped by 90% of the peak energy density;

[0058] ⑤ The computer 112 controls the shutter 103 to open, and controls the energy meter 110 and the beam quality analyzer 111 to collect energy data E and spot data A in real time, and obtains the energy density F of the current test = E × N / A, where N is the splitting ratio, which is equal to the ratio of the energy irradiated to the optical element 123 to be tested at the same time to the energy collected by the energy meter 110;

[0059] ⑥ The computer 112 controls the online CCD imaging system 125 to diagnose in real time whether the optical element 123 to be tested is damaged or not.

[0060] ⑦ When the computer 112 detects that the optical element 123 to be tested has reached the last position coordinate of the motion track set in ④, the optical element 123 to be tested stops moving and closes the shutter 103;

[0061] ⑧Computer statistics of 1cm 2 The number of damage points D and their location coordinates in the test area. 2 If there is no damage point in the test area, proceed to step 9; if the current 1cm 2 If a damage point appears in the test area, the computer 112 controls the optical element 123 to be tested to locate the damage point in sequence according to the recorded coordinates of the damage point and controls the shutter 103 so that S pulses irradiate the located damage point. Meanwhile, the online CCD imaging system 125 performs real-time diagnosis. If the damage point does not change, the damage point is determined to be stable. Otherwise, the damage point is determined to be unstable. The process continues until all damage points have been irradiated with S pulses. Then, step ⑨ is performed.

[0062] ⑨ Move the optical element 123 to be tested to the next test area. The computer 112 adjusts the energy regulator 102 according to the damage of the tested area to reduce or increase the laser energy irradiating the optical element 123 to be tested. Repeat ④ to ⑧ until the test of the optical element 123 to be tested is completed, the online CCD imaging system 125 stops diagnosis, the picosecond laser 101 is turned off, and the circular vacuum chamber 124 is deflated;

[0063] ⑩ Draw a curve showing the change of the number of damage points D with the energy density F, and give the stability of the damage points of the optical element 123 to be tested.

[0064] See also Figure 4 . Figure 4 Each ~1cm 2 The schematic position of the square test area on the surface of the optical element to be tested. One of the square test areas corresponds to an energy density, and the circle in the square test area represents the irradiation position of the test laser spot.

[0065] See also Figure 5 . Figure 5 A curve showing the change of damage points with energy density is given. Figure 5 The hollow triangles in the figure indicate that the 2 The damage point changes during multi-pulse irradiation, showing instability; the hollow circle indicates that the damage threshold of the picosecond laser optical element is 3J / cm 2 .

Claims

1. A full-angle vacuum laser damage threshold test device for picosecond laser optical elements, characterized in that: include: Optical component fixing system, picosecond laser system for damage, picosecond laser damage monitoring system and laser protection module; The optical element fixing system comprises a circular vacuum cavity (124), an optical element fixing device located in the circular vacuum cavity (124), and a two-dimensional adjustment mechanism for controlling the position of the optical element, wherein the optical element fixing device is used to fix the optical element (123) to be measured so that the normal direction of the optical element (123) to be measured forms a clockwise angle of 45° with the horizontal direction; a 70° incident light pipe (115), a 63° diffraction light pipe (116), a 45° incident light pipe (119), a 45° reflected light pipe (126), a 23° incident light pipe (122), and a 23° transmitted light pipe (128) are respectively provided on the circular vacuum cavity (124) at angles of 70°, 63°, 45°, and 23° with the normal of the optical element (123) to be measured; The picosecond laser system for damage treatment comprises a picosecond laser (101), an energy regulator (102), a shutter (103), a half-wave plate (104), a polarizing plate (106), a first 45° reflecting mirror (113), a second focusing lens (114), a third focusing lens (118), a second 45° reflecting mirror (120) and a fourth focusing lens (121); The picosecond laser damage monitoring system comprises a computer (112), a first single-sided anti-reflection film (105), a second single-sided anti-reflection film (108), an energy meter (110), a first focusing lens (109), a beam quality analyzer (111) located at the focal position of the first focusing lens (109), and an online CCD imaging system (125) located in the normal direction of the optical element to be measured (123) and connected to the circular vacuum cavity (124); the computer (112) is respectively connected to the energy regulator (102), the shutter (103), the energy meter (110), the beam quality analyzer (111), the polarizer (106), the online CCD imaging system (125) and the optical element fixing device; The laser protection module comprises a first absorption cell (107), a second absorption cell (117), a third absorption cell (127), and a fourth absorption cell (129), which are respectively placed in the transmission light direction of the polarizer (106) and at the exit positions of the 63° diffraction light duct (116), the 45° reflection light duct (126), and the 23° transmission light duct (128); The laser light output by the picosecond laser (101) passes through the energy regulator (102), the shutter (103) and the half-wave plate (104) in sequence, and then enters the first single-sided anti-reflection film (105). The transmitted light transmitted through the first single-sided anti-reflection film (105) enters the polarizing plate (106). The polarizing plate (106) is controlled by a computer (112) to achieve up and down movement or angle rotation. When the normal direction of the polarizing plate (106) forms a counterclockwise angle of -57.5° with the incident laser, the first emission light reflected by the polarizing plate (106) sequentially passes through the first 45° reflector (113), the second focusing lens (114) and the 70° incident light pipe (115) to irradiate the surface of the optical element to be measured (123), and the diffracted light diffracted by the optical element to be measured (123) passes through the 63° diffracted light pipe (116) and is absorbed by the second absorption cell (117); When the normal direction of the polarizing plate (106) forms a clockwise angle of 56° with the incident laser, the second emission light reflected by the polarizing plate (106) sequentially passes through the second 45° reflector (120), the fourth focusing lens (121) and the 23° incident light pipe (122) to irradiate the surface of the optical element to be measured (123), and the transmitted light transmitted through the optical element to be measured (123) passes through the 23° transmitted light pipe (128) and is absorbed by the fourth absorption cell (129); When the polarizing plate (106) moves out of the optical path, the transmitted light transmitted through the first single-sided anti-reflection film (105) sequentially passes through the third focusing lens (118) and the 45° incident light pipe (119) to irradiate the surface of the optical element to be measured (123), and the reflected light reflected by the optical element to be measured (123) passes through the 45° reflected light pipe (126) and is absorbed by the third absorption cell (127); The reflected light reflected by the first single-sided anti-reflection film (105) is incident on the second single-sided anti-reflection film (108), the transmitted light transmitted by the second single-sided anti-reflection film (108) is incident on the energy meter (110), and the emitted light reflected by the second single-sided anti-reflection film (108) is focused by the first focusing lens (109) and then incident on the beam quality analyzer (111).

2. The full-angle vacuum laser damage threshold test device for picosecond laser optical elements according to claim 1, characterized in that: The first single-sided anti-reflection film (105) and the second single-sided anti-reflection film (108) are placed parallel to each other, and the front surfaces of the first single-sided anti-reflection film (105) and the second single-sided anti-reflection film (108) are not coated, while the rear surfaces are coated with anti-reflection films.

3. The full-angle vacuum laser damage threshold test device for picosecond laser optical elements according to claim 1, characterized in that: The focal lengths of the first focusing lens (109), the second focusing lens (114), the third focusing lens (118), and the fourth focusing lens (121) are consistent.

4. The full-angle vacuum laser damage threshold test device for picosecond laser optical elements according to any one of claims 1 to 3, characterized in that: The energy regulator (102) is used to change the energy of the laser transmitted in the optical path, the shutter (103) is used to control the on and off of the laser in the optical path, the half-wave plate (104) is used to convert the laser in the optical path into vertically polarized laser, and the first single-sided anti-reflection film (105) is placed at a small angle for laser sampling.

5. The full-angle vacuum laser damage threshold test device for picosecond laser optical elements according to any one of claims 1 to 3, characterized in that: The polarizer (106) has an extinction ratio of ≥100:1 at a working angle of 56° to 57.5°, and can be rotated and moved up and down to allow the laser to irradiate the optical element (123) to be measured at incident angles of 70°, 45°, and 23°.

6. A method for testing the picosecond laser damage threshold using the full-angle vacuum laser damage threshold testing device for picosecond laser optical elements according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: ① The computer (112) controls the polarizer (106) to select one of three states according to the test requirements: rotate to -57.5°, 56°, or move upward out of the light path; ② The computer (112) controls the picosecond laser (101) to emit light at an optimal fixed frequency to evacuate the circular vacuum cavity (124); ③ The computer (112) controls the energy regulator (102) to regulate the laser energy so that the initial laser energy density irradiating the optical element (123) to be measured does not exceed the picosecond intrinsic damage threshold of the optical element (123) to be measured; ④ The computer (112) sets the motion trajectory and horizontal motion speed of the optical element fixing device so that the laser spot irradiated on the optical element to be measured (123) is within 1 cm 2 The test area is overlapped by 90% of the peak energy density; ⑤ The computer (112) controls the shutter (103) to open, and at the same time controls the energy meter (110) and the beam quality analyzer (111) to collect energy data E and spot data A in real time, and obtains the energy density F of the current test = E × N / A, wherein N is the splitting ratio, which is equal to the ratio of the energy irradiated to the optical element (123) to be tested to the energy collected by the energy meter (110) at the same time; ⑥ The computer (112) controls the online CCD imaging system (125) to diagnose in real time whether the optical element (123) to be tested is damaged; ⑦ When the computer (112) detects that the optical element (123) to be tested has reached the last position coordinate of the motion track set in ④, the optical element (123) to be tested stops moving and the shutter (103) is closed; ⑧The computer (112) counts the 1cm 2 The number of damage points D and their location coordinates in the test area: If the current 1cm 2 If there is no damage point in the test area, proceed to step 9; if the current 1cm 2 If a damage point appears in the test area, the computer (112) controls the optical element (123) to be tested to locate the damage point in sequence according to the recorded damage point position coordinates and controls the shutter (103) so that S pulses irradiate the located damage point, and at the same time the online CCD imaging system (125) performs real-time diagnosis. If the damage point does not change, the damage point is determined to be stable; otherwise, the damage point is determined to be unstable, until all damage points have completed S pulse irradiation, and then proceed to step 9; ⑨ moving the optical element to be tested (123) to the next test area, the computer (112) adjusting the energy regulator (102) according to the damage of the tested area to reduce or increase the laser energy irradiating the optical element to be tested (123), repeating ④ to ⑧ until the test of the optical element to be tested (123) is completed, the online CCD imaging system (125) stops diagnosis, the picosecond laser (101) is turned off, and the circular vacuum chamber (124) is deflated; ⑩ Draw a curve showing the change of the number of damage points D with the energy density F, and give the stability of the damage points of the optical element (123) to be tested.

Images