CN110487726B - Fixed-point laser damage threshold evaluation system - Google Patents
Fixed-point laser damage threshold evaluation system Download PDFInfo
- Publication number
- CN110487726B CN110487726B CN201910874468.6A CN201910874468A CN110487726B CN 110487726 B CN110487726 B CN 110487726B CN 201910874468 A CN201910874468 A CN 201910874468A CN 110487726 B CN110487726 B CN 110487726B
- Authority
- CN
- China
- Prior art keywords
- laser
- workpiece
- damage
- ccd camera
- computer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0106—General arrangement of respective parts
- G01N2021/0112—Apparatus in one mechanical, optical or electronic block
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
- G01N2021/8854—Grading and classifying of flaws
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
- G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques
Landscapes
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- Pathology (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Immunology (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Signal Processing (AREA)
- Laser Beam Processing (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
The invention relates to a fixed-point laser damage threshold evaluation system.A laser emitting device is sequentially provided with Nd, a YAG laser, a spatial filter, a beam expander and a conical mirror; the beam collimation feedback adjusting system is provided with X, Y directional rotatable feedback mirrors, an attenuator, a wave plate, a spectroscope I, a spectroscope II, an energy meter, a focusing lens I, a light spot screen, a CCD camera I, a focusing lens II, an X-direction piezoelectric controller and a Y-direction piezoelectric controller; an energy meter is arranged below the spectroscope I, a focusing lens I, a light spot screen and a CCD camera I are arranged below the spectroscope II, the energy meter and the CCD camera I are connected with a computer, and the computer is respectively connected with an X-direction rotatable feedback mirror and a Y-direction rotatable feedback mirror through an X-direction piezoelectric controller and a Y-direction piezoelectric controller; the adjustable fixture is arranged on the three-dimensional moving platform through the fixture supporting platform, and the three-dimensional moving platform is connected with the computer through the three-way motion controller; the CCD camera II is used for observing and recording the microscopic morphology of the workpiece test area before and after laser irradiation and feeding the microscopic morphology back to the computer.
Description
Technical Field
The invention relates to a laser damage testing system, in particular to a fixed-point laser damage threshold evaluation system.
Background
In a high-power/energy laser fusion device, a large number of optical elements are needed, and under the irradiation of strong laser, laser-induced damage is easy to occur on the surfaces of the optical elements, and the damage points become key factors for inhibiting the output power and the service life of a laser fusion system. Therefore, the strength of the Laser damage resistance of the optical element is an important index for measuring the performance of the Laser fusion device, and an accurate and reliable Laser-induced Damage threshold (LIDT) evaluation system needs to be developed.
When mechanical defects such as indentation, scratch, micro-crack, etc. or chemical defects such as metal particles, salt deposition particles, etc. are present on the surface of the element, the damage performance of the element is degraded. In order to evaluate and calibrate the damage threshold of these defects, accurate spot testing of the defects is required to explore the types and sizes of defects that adversely affect the damage performance of the components. In the laser damage testing process, due to the influence of the laser on the factors such as thermal deformation, environmental vibration, air disturbance and the like of the laser, the emitted laser beam often generates beam drift, bending and shaking in the transmission process, and the instability of the beam seriously influences the collimation of the emitted laser, so that the accuracy of the point testing position is influenced. In the process of performing a point-to-point test on a specific defect position on a component surface by using an existing laser damage testing system, a severe deviation of a laser damage point often occurs, that is, the damage point does not appear at a test target (defect) position.
The current common method is that after a damage point is observed on a computer screen, the appearance position of the actual damage point is manually circled on the screen, then a workpiece moving platform is adjusted to move the defect to be detected of the workpiece to the circled position, and the laser damage test is carried out again. Due to the uncontrollable and non-repetitive laser offset direction and angle, the above process is sometimes tried several times to hit the damage point at the designated defect position, so the method is time-consuming and labor-consuming and has many uncertainties. In addition, the judgment of the occurrence of the damage in the existing laser damage testing process is based on the observation of the shape difference of the testing positions of the element before and after laser irradiation by a tester, so that the judgment of whether the damage occurs or not is easily influenced by subjective factors of the tester, and meanwhile, small damage points which are difficult to identify by naked eyes are easily ignored, so that the accuracy of the damage performance testing result is influenced. In summary, in order to fully grasp the overall performance of the laser fusion device, it is important to accurately evaluate the laser damage threshold at the surface defect of the element.
Disclosure of Invention
The invention aims to provide a fixed-point laser damage threshold evaluation system which can effectively inhibit the drift of light beams in the laser damage test process, can quickly determine the specific position and the size of a damage point and realize the fixed-point test of the laser damage threshold of the specific position on the surface of a workpiece with different shapes and sizes.
The technical scheme of the invention is as follows: a fixed-point laser damage threshold evaluation system is provided with a laser emitting device, a beam collimation feedback adjustment system, a three-coordinate motion control system and a damage judgment device, wherein the laser emitting device is sequentially provided with Nd, a YAG laser, a spatial filter, a beam expander and a conical mirror; the beam collimation feedback adjusting system is provided with an X-direction rotatable feedback mirror, a Y-direction rotatable feedback mirror, an attenuator, a wave plate, a spectroscope I, a spectroscope II, an energy meter, a focusing lens I, a light spot screen, a CCD camera I, a focusing lens II, an X-direction piezoelectric controller and a Y-direction piezoelectric controller; an energy meter is arranged below the spectroscope I and used for reading a laser energy numerical value in real time, a focusing lens I, a light spot screen and a CCD camera I are arranged below the spectroscope II, a laser beam is focused on the light spot screen by the focusing lens I and the actual position of a light spot is detected by the CCD camera I, the energy meter and the CCD camera I are connected with a computer, the computer is respectively connected with an X-direction rotatable feedback mirror and a Y-direction rotatable feedback mirror through an X-direction piezoelectric controller and a Y-direction piezoelectric controller, and the rotation angles of the X-direction rotatable feedback mirror and the Y-direction rotatable feedback mirror are controlled and adjusted by the computer; the three-dimensional motion control system is provided with an adjustable clamp, a clamp supporting table, a spring, a three-dimensional moving platform, an X-axis motion controller, a Y-axis motion controller and a Z-axis motion controller, wherein the adjustable clamp is arranged above the clamp supporting table and used for clamping a workpiece to be measured and is connected with the clamp supporting table through the spring, the clamp supporting table is fixed on the three-dimensional moving platform, the three-dimensional moving platform is connected with a computer through the X-axis motion controller, the Y-axis motion controller and the Z-axis motion controller, and the X-axis motion controller, the Y-axis motion controller and the Z-axis motion controller are controlled by the computer to drive the three-dimensional moving platform, the adjustable clamp and the workpiece to be measured to move three-dimensionally; the damage judging device comprises a CCD camera II with a long-focus microscope, the CCD camera II is used for observing and recording the microscopic appearance of a workpiece testing area before and after laser irradiation and feeding the microscopic appearance back to a computer, the computer utilizes image processing software to analyze the appearance change of the workpiece surface testing area before and after the laser damage testing, if pixel points near the testing area are obviously changed and exceed the size tolerance, the laser induced damage is judged to occur at the position, the size of the damage point is defined according to the change value of the pixel points, the accuracy and the reliability of damage judgment are guaranteed, and the quantitative evaluation of the size of the damage point is realized.
Further, the emitted laser of the Nd-YAG laser forms moire fringes through a spatial filter, a beam expander and a cone mirror to achieve primary collimation of the emitted laser, the specific position of a laser spot on a spot screen is detected through a CCD camera I, the offset of the laser beam in the X direction and the Y direction is determined and fed back to a computer, the X-direction piezoelectric controller and the Y-direction piezoelectric controller are controlled through an algorithm to respectively drive the X-direction rotatable feedback mirror and the Y-direction rotatable feedback mirror to rotate to required angles, and therefore the laser spot is adjusted to the coordinate origin of the spot screen, and collimation adjustment of the laser beam is achieved.
Furthermore, the adjustable clamp is divided into a left part and a right part, a rubber clamping strip is arranged on the inner side of the adjustable clamp at a certain interval, and a workpiece to be measured is placed in the adjustable clamp and is positioned and clamped through contact with the rubber clamping strip.
Furthermore, the adjustable clamp realizes telescopic adjustment along the wedge-shaped guide groove by means of the bottom spring through the left part and the right part according to the size of the workpiece to be measured, so that the workpiece to be measured is positioned and clamped.
Furthermore, the adjustable clamp can clamp a round workpiece with the workpiece size of phi 20-phi 100mm or a polygonal workpiece with the opposite side distance of 20-100 mm, and the thickness of the workpiece ranges from 5mm to 25mm, so that the workpieces with multiple shapes and sizes can be fixed.
Furthermore, the adjustable fixture and the workpiece are driven by the three-dimensional moving platform to realize feeding along the X direction, the Y direction and the Z direction, wherein the Y direction and the Z direction move to change the specific position of the region to be measured on the surface of the workpiece, the X direction moves to ensure that the region to be measured of the workpiece is always positioned at the focal position of the focusing lens II, laser irradiation on the rear surface of the workpiece in the laser test process is ensured, and the laser damage fixed-point test of any position of the surface of the workpiece with a plane, a wedge surface and a curved surface is realized by means of the driving of the three-dimensional moving platform.
Furthermore, the microscope multiplying power adjustable range of the CCD camera II is multiplied by 0.7 to multiplied by 4.5, and the field range is 0.5-3 mm.
The invention has the beneficial effects that:
the invention provides a fixed-point laser damage threshold evaluation system which can avoid damage test position deviation caused by laser beam drift or jitter and is accurate and reliable in judgment and identification of laser damage points. The device principle is reliable, and the structure is perfect, and the simple operation can accurately realize the fixed point laser damage test of optical element surface target position, realizes the ration and the accurate aassessment of laser damage point, and this system is applicable to the laser damage threshold evaluation of many sizes, multiform form work piece, has stronger engineering application and worth.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a schematic view of an adjustable clamp of the present invention for clamping and positioning a workpiece;
FIG. 3 illustrates the operation of the present invention in testing different positions on the surface of a workpiece;
FIG. 4 is a comparison graph of the local topography of a workpiece before and after laser damage testing according to the present invention;
the code numbers of the main components in fig. 1-4 are given below:
YAG laser 1-Nd, space filter 2, beam expander 3, cone mirror 4, rotatable feedback mirror 5-X, rotatable feedback mirror 6-Y, attenuator 7, wave plate 8, spectroscope I9, spectroscope II10, spectroscope II 11, energy meter 12, focusing lens I13, facula screen 14, CCD camera I, focusing lens II15, piezoelectric controller 16-X, piezoelectric controller 17-Y, adjustable clamp 18, rubber clamp strip 18-1, clamp support table 19-1, wedge guide groove 19-1, spring 20, three-dimensional moving platform 21, workpiece 22, motion controller 23-X, motion controller 24-Y, motion controller 25-Z, motion controller 26-CCD camera II, 27-computer.
Detailed Description
The invention is further described with reference to the following figures and examples.
Example (b): as shown in fig. 1 to 4, a fixed-point laser damage threshold evaluation system mainly comprises an Nd, a YAG laser 1, a spatial filter 2, a beam expander 3, a cone mirror 4, an X-direction rotatable feedback mirror 5, a Y-direction rotatable feedback mirror 6, an attenuator 7, a wave plate 8, a beam splitter I9, a beam splitter II10, an energy meter 11, a focusing lens I12, a spot screen 13, a CCD camera I14, a focusing lens II15, an X-direction piezoelectric controller 16, a Y-direction piezoelectric controller 17, an adjustable clamp 18, a rubber clamping strip 18-1, a clamp support platform 19, a wedge-shaped guide groove 19-1, a spring 20, a three-dimensional moving platform 21, a workpiece to be measured 22, an X-axis motion controller 23, a Y-axis motion controller 24, a Z-axis motion controller 25, a CCD camera II26, a computer 27 and the like.
A YAG laser 1, a spatial filter 2, a beam expander 3 and a cone mirror 4 are sequentially arranged to form a laser emitting device; the X-direction rotatable feedback mirror 5, the Y-direction rotatable feedback mirror 6, the attenuator 7, the wave plate 8, the spectroscope I9, the spectroscope II10, the energy meter 11, the focusing lens I12, the light spot screen 13, the CCD camera I14 and the focusing lens II15 are sequentially arranged to form a light beam collimation feedback adjusting system; an energy meter 11 is arranged below a spectroscope I9 and used for reading a laser energy value in real time, a focusing lens I12, a light spot screen 13 and a CCD camera I14 are arranged below a spectroscope II10, the focusing lens I12 focuses a laser beam on the light spot screen 13 and detects the actual position of a light spot by using a CCD camera I14, the energy meter 11 and the CCD camera I14 are connected with a computer 27, the computer 27 is respectively connected with an X-direction rotatable feedback mirror 5 and a Y-direction rotatable feedback mirror 6 through an X-direction piezoelectric controller 16 and a Y-direction piezoelectric controller 17, and the computer 27 controls and adjusts the rotating angles of the X-direction rotatable feedback mirror 5 and the Y-direction rotatable feedback mirror 6; the adjustable clamp 18, the clamp supporting platform 19, the spring 20, the three-dimensional moving platform 21, the X-axis motion controller 23, the Y-axis motion controller 24 and the Z-axis motion controller 25 form a three-dimensional motion control system, the adjustable clamp 18 is arranged above the clamp supporting platform 19 and used for clamping a workpiece 22 to be measured and is connected with the clamp supporting platform 19 through the spring 20, the clamp supporting platform 19 is arranged on the three-dimensional moving platform 21, the three-dimensional moving platform 21 is connected with the computer 27 through the X-axis motion controller 23, the Y-axis motion controller 24 and the Z-axis motion controller 25, and the computer 27 controls the X-axis motion controller 23, the Y-axis motion controller 24 and the Z-axis motion controller 25 to drive the three-dimensional moving platform 21, the adjustable clamp 18 and the workpiece 22 to be measured to move three-dimensionally; the CCD camera II26 with a long-focus microscope and the computer 27 form a damage judging device, the CCD camera II26 is used for observing and recording the microscopic appearance of a workpiece testing area before and after laser irradiation and feeding the microscopic appearance back to the computer, the computer 27 utilizes image processing software to analyze the appearance change of the workpiece surface testing area before and after laser damage testing in real time, if pixel points near the testing area are obviously changed and exceed the size tolerance, the laser induced damage is judged to occur at the position, the size of a damage point is defined according to the change value of the pixel points, the accuracy and the reliability of damage judgment are ensured, and the quantitative evaluation of the size of the damage point is realized.
The system can be applied to two damage threshold evaluation modes of R:1 and 1:1, and the working process of the system is mainly described by taking fixed-point laser damage test of the rear surface of the workpiece as an example because the rear surface of the workpiece is easier to generate laser-induced damage compared with the front surface. 1 Damage test by gradually increasing laser energy density (in J/cm)2The energy gradient is determined according to the surface to be measured) irradiates the point to be measured on the rear surface of the workpiece until damage occurs, and the laser energy density when the damage occurs is defined as the R:1 laser damage threshold of the point to be measured. In a 1:1 test mode, dozens of points to be tested are selected on the rear surface of a workpiece, each point to be tested is irradiated by using different laser energy, incident laser energy is sequenced from low to high and is divided into a plurality of energy intervals, a damage probability curve is obtained by counting the laser damage probability (the ratio of the number of test points with laser damage to the total number of irradiated test points) of the workpiece in each energy interval, then according to the specification of a zero probability damage method in ISO11254, the corresponding laser energy density with the damage probability of 0 is obtained by linearly fitting the damage probability curve, and the laser energy density is defined as the 1:1 damage threshold of the workpiece.
As shown in FIG. 1, the system firstly fixes a workpiece 22 to be measured in an adjustable fixture 18 above a fixture support platform 19, and the adjustable fixture 18 can flexibly adjust the distance between the left part and the right part according to the size of the workpiece 22 so as to clamp and position the workpiece 22. The three-dimensional moving platform 21 is controlled by the computer 27 to realize three-dimensional movement of the workpiece 22 along the X-axis, the Y-axis and the Z-axis, so as to ensure that the laser beam can focus on a specified position of a defect to be detected on the rear surface of the workpiece 22 to be detected, for example, a position of a defect such as a specific scratch, a crack, a contaminant particle, etc., and a specific adjustment process of the spatial position of the workpiece 22 is illustrated in fig. 3.
After the position of the workpiece 22 is adjusted, alignment adjustment of the laser beam is performed to prepare for spot laser damage testing. YAG laser 1 sends out the laser for the ultraviolet laser (351/355nm) of nanosecond pulsewidth, form no diffraction light by laser 1, spatial filter 2, beam expander 3 and conical mirror 4, utilize the bessel function halo that no diffraction light forms, does not change with the propagation distance as the reference axis, realize the primary collimation of outgoing laser through the moire fringe that the ring grating iteration produced. The ultraviolet laser after primary collimation enters a light beam collimation feedback regulation system, namely, the laser beam firstly reflects from the X-direction rotatable feedback mirror 5 to enter the Y-direction rotatable feedback mirror 6, and then sequentially passes through the attenuator 7, the wave plate 8, the spectroscope I9, the spectroscope II10 and the focusing lens II15 after reflecting from the Y-direction rotatable feedback mirror 6, and the laser beam is irradiated on a region to be measured on the rear surface of the workpiece 22 after being focused by the focusing lens II 15. In the initial state, the X-direction rotatable feedback mirror 5 and the Y-direction rotatable feedback mirror 6 are both at the tilt angle of 45 ° as shown in the figure, so that the reflection and propagation of the laser beam are smoothly achieved, and both are rotatable about the Y-axis and the X-axis, respectively. The splitting ratio of the beam splitter I9 to the beam splitter II10 is 1:1, and the energy meter 11 is connected with the beam splitter I9 and used for reading and recording the laser energy density emitted by the laser 1 in real time. In addition, the beam splitter II10 is connected with the focusing lens I12, the spot screen 13 and the CCD camera I14 in sequence, the laser beam is split by the beam splitter II10 and focused on the spot screen 13 through the focusing lens I12, the specific position of the laser spot on the spot screen 13 is detected by the CCD camera I14, if the laser beam does not drift during the propagation process, the laser spot is just focused on the coordinate origin of the spot screen 13, and if the laser beam drifts parallel lines during the propagation process, the laser spot still focuses on the coordinate origin of the spot screen 13 due to the focusing action of the focusing lens I12, so the laser offset measured on the spot screen 13 is mainly caused by the angular drift during the laser transmission process. During laser damage testing, a laser beam is finally focused by the focusing lens II15 and then irradiated to a to-be-tested area on the rear surface of the to-be-tested workpiece 22, namely the focusing action of the focusing lens II15 also compensates for parallel line drift in the laser beam propagation process, so that the feedback and adjustment of the laser drift in the system mainly focus on the angle drift in the laser beam propagation process. According to the specific position of the laser spot on the spot screen 13 measured by the CCD camera I14, the offset of the laser beam in the X direction and the Y direction is determined and fed back to the computer 27, the two-dimensional angular drift component of the laser beam is determined through analysis and calculation, the X-direction piezoelectric controller 16 is respectively controlled through an algorithm to drive the X-direction rotatable feedback mirror 5 to rotate for a certain angle around the Y axis, the Y-direction piezoelectric controller 17 is controlled to drive the Y-direction rotatable feedback mirror 6 to rotate for a certain angle around the X axis, the laser beam is rotated towards the direction of reducing the angular drift, and the laser spot is adjusted to be placed at the original point of the spot screen 13, namely the collimation adjustment of the laser beam is completed.
The laser after the beam collimation adjustment can perform fixed point damage test on the specific position of the rear surface of the workpiece 22 to be tested, and in the process of the damage test, the CCD camera II26 with the long-focus microscope can timely and accurately judge whether damage occurs or not, wherein the magnification adjustable range of the microscope is multiplied by 0.7 to multiplied by 4.5, and the size of the field of view is 0.5-3 mm. Before and after each laser irradiation on the test point, the microscopic morphology of the test area obtained by the CCD camera II26 connected with the test point is directly observed through the screen of the computer 27 and automatically analyzed by image processing software, and the morphologies of the same test area before and after the laser irradiation are compared to judge whether the damage occurs or not. The principle of discriminating and evaluating laser damage on the surface of a workpiece before and after laser irradiation is described in detail with reference to fig. 4. In the R:1 damage testing process, if the workpiece testing position is judged to have laser damage, recording the real-time laser energy density measured by the energy meter 11 at the moment through the computer 27, and defining the real-time laser energy density as the R:1 laser damage threshold value of the point; in the 1:1 damage testing process, no matter whether laser-induced damage occurs after laser irradiation, the real-time laser energy density value measured by the energy meter 11 needs to be recorded by the computer 27, whether damage occurs under the energy is marked, and then the corresponding laser energy density with the damage probability of 0 is obtained by combining with ISO11254 standard linear fitting, and is defined as the 1:1 damage threshold of the workpiece.
Fig. 2 is a schematic diagram of the adjustable clamp 18 for clamping and positioning the workpiece 22 to be measured. The adjustable clamp 18 is divided into a left part and a right part, rubber clamping strips 18-1 are arranged on the inner side of the adjustable clamp at a certain interval, and a workpiece 22 to be measured is placed in the adjustable clamp 18 and is positioned and clamped by contacting with the rubber clamping strips 18-1. The bottom of the adjustable clamp 18 is connected with a clamp support platform 19 through four sections of springs 20, and the four sections of springs 20 are all arranged in a wedge-shaped guide groove 19-1 of the clamp support platform 19. When the workpiece 22 to be measured is not placed, the spring 20 is in a preliminary compression state due to the contact limit of the inner surfaces of the lower parts of the left and right parts of the adjustable clamp 18. When a workpiece 22 to be measured is placed in, the distance between the left part and the right part of the adjustable clamp 18 is determined by the size of the workpiece 22, under the action of the elastic restoring force of the spring 20, the rubber clamping strips 18-1 at the inner sides of the left part and the right part of the adjustable clamp 18 are in close fit contact with the left side surface and the right side surface of the workpiece 22, and the lower surface of the workpiece 22 is in fit contact with the upper surface of the adjustable clamp 18 or the upper surface of the clamp supporting platform 19, so that the positioning and clamping of the workpieces with different shapes and sizes are realized. The clamp can clamp workpieces with the size of phi 20-phi 100mm (circular) or the opposite side distance of 20-100 mm (polygonal), and the thickness range of the workpieces is 5-25 mm.
As shown in fig. 3, a workpiece with a curved surface is taken as an example to illustrate the working principle when testing the laser damage threshold at different positions on the surface of the workpiece 22 to be tested. Before the damage test is started, the focal length of the CCD camera II26 is adjusted to enable the focal point of the CCD camera II26 to be accurately intersected with the focal point of the focusing lens II15, and in the laser damage test process, the horizontal position of the workpiece 22 is adjusted in time, so that the lens focal point of the CCD camera II26 is always focused on the focal point of the focusing lens II15 and the position to be tested on the rear surface of the workpiece 22, and therefore the appearance change of a test area is observed in time before and after laser irradiation, and whether damage occurs or not is accurately judged. In the initial state, the center position of the lower surface of the jig support table 19 and the center position of the upper surface of the three-dimensional moving platform 21 are both located 55mm directly below the intersection of the focal point of the CCD camera II26 and the focal point of the focusing lens II15, and the thickness of the jig support table 19 is 5mm, and the center position of the lower surface of the jig support table 19 in the initial state is defined as the initial origin of coordinates (0,0,0) of the three-dimensional moving platform 21. The computer 27 controls the X-direction motion controller 23, the Y-direction motion controller 24 and the Z-direction motion controller 25 to adjust the three motion directionsThe position of the table 21 is moved to feed the jig support table 19, the jig 18, and the workpiece 22 in three directions, i.e., the X direction, the Y direction, and the Z direction. As shown in FIG. 3 (a), it is necessary to measure the rear surface T of a curved work piece of φ 100mm1And T2Laser damage threshold at two locations. Measurement of T1The point process is shown in FIG. 3 (b), and T is shown in FIG. 3 (a)1The Y-direction and Z-direction positions of the points are the same as the focal point coordinate of the focusing lens II15 in the initial state, namely Y1＝0，Z155, it is not necessary to adjust the Y-direction and Z-direction positions of the workpiece 22, and T is a curved surface on the rear surface of the workpiece 221A certain distance X is formed between the point and the center position of the upper surface of the three-dimensional moving platform 21 in the horizontal direction (X direction)1Therefore, it is necessary to adjust the horizontal position of the workpiece 22 by controlling the X-direction motion controller 23 through the computer 27, i.e. to drive the three-dimensional moving platform 21 to move the midpoint position of the upper surface horizontally to the left by X1Distance, at which point T to be measured is observed through the screen of computer 271When the lens of the CCD camera II26 is clearly visible, the point T to be measured is considered to be already measured1And adjusting the position to the focus of the focusing lens II15, and starting the Nd: YAG laser 1 to perform laser damage test. Measurement of T2The point process is shown in FIG. 3 (c), and T is shown in FIG. 3 (a)2The X-direction, Y-direction, and Z-direction positions of the points are all different from the focal point coordinates of the focusing lens II15 in the initial state. Thus, in measuring T2Before the laser damage threshold of the point, firstly, the computer 27 adjusts the Y-direction motion controller 24 and the Z-direction motion controller 25 to change the specific position of the region to be measured on the surface of the workpiece 22, i.e. the three-dimensional moving platform 21 is driven to make the midpoint position of the upper surface advance to-Y along the Y-direction and the Z-direction respectively2And (Z)2-55), when the Y-direction and Z-direction positions of the point to be measured are adjusted to correspond to the focal position of the focusing lens II 15. Then, the computer 27 controls the X-direction motion controller 23 to adjust the horizontal position of the workpiece 22, i.e. drives the three-dimensional moving platform 21 to move the midpoint position of the upper surface horizontally to the left by X2Distance, at which point T to be measured is observed through the screen of computer 272When the lens of the CCD camera II26 is clearly visible, the point T to be measured is considered to be already measured2Adjusted to the focal point of focusing lens II15Then, the Nd: YAG laser 1 can be started to carry out laser damage test. For a workpiece with a wedge-shaped surface, the principle of the test process is similar, the Y-direction motion controller 24 and the Z-direction motion controller 25 are controlled to change the specific position of the region to be tested on the surface of the workpiece 22 to be tested, and then the X-direction motion controller 23 is controlled to drive the workpiece 22 to be tested to horizontally move along the X direction according to the horizontal distance between the region to be tested and the focus of the CCD camera II26, so that the region to be tested is always located at the focus of the focusing lens II 15. For a workpiece with a plane surface shape, after the X-direction motion controller 23 is adjusted to focus laser on the rear surface of the workpiece 22 to be tested, in the laser damage test process, only the Y-direction motion controller 24 and the Z-direction motion controller 25 need to be controlled to adjust the specific position of the region to be tested on the surface of the workpiece 22, and the position of the workpiece 22 in the horizontal direction does not need to be adjusted. Therefore, the damage threshold evaluation system can be effectively applied to workpiece testing of planes, wedge surfaces and curved surfaces.
As shown in fig. 4, taking the measurement of the laser damage threshold at the scratch/microcrack on the rear surface of the workpiece as an example, a comparison graph of the local topography of the workpiece 22 to be tested before and after the laser damage test, which is acquired by the CCD camera II26, is shown. FIG. 4 (a) is a graph showing the local defect profile of the workpiece 22 measured by the CCD camera II26 before laser irradiation, and the image is inputted into the computer 27, and the scratch defect N before the damage test is analyzed by the image processing software00The pixel condition and the specific size of (a) in fig. 4 are the defect appearance of the same position of the rear surface of the workpiece 22 to be measured after laser irradiation with a certain energy, and the scratch defect N after laser irradiation is analyzed by using the image processing software in the computer 27 again01When N is the pixel condition and the specific size01And N00Judging the scratch defect N when the comparison pixel point has no obvious change00Laser induced damage has not occurred; when N is present01And N00When the comparison pixel point is obviously changed and exceeds the size tolerance, judging that the scratch defect N occurs at the position00Induced laser damage, i.e., defect-induced damage occurs as shown in fig. 4(b), the real-time laser energy density value read by the energy meter 11 at this time is recorded and defined as the laser damage threshold (in the R:1 test mode) or the laser energy density value of the induced damage of the workpiece 22 to be tested(1:1 in test mode), and adding N01And N00The size difference is defined as the size of the laser damage point, so that accurate assessment of the damage threshold and quantitative evaluation of the size of the damage point are realized.
The laser damage threshold evaluation system is reliable in principle and complete in structure, can effectively inhibit the drift of light beams in the laser damage testing process, can quickly determine the specific position and size of a damage point, and can be suitable for the fixed-point laser damage threshold evaluation of workpieces with multiple sizes and shapes. In addition, the design idea of the invention is also suitable for inhibiting laser splashing in the laser marking machine, and only the CCD camera II is required to be removed and the type and the parameters of the used laser are required to be changed into the required type and parameters.
Claims (7)
1. A fixed-point laser damage threshold evaluation system is provided with a laser emitting device, a beam collimation feedback adjustment system, a three-coordinate motion control system and a damage judgment device, and is characterized in that: the laser emitting device is sequentially provided with Nd, a YAG laser, a spatial filter, a beam expander and a cone mirror; the beam collimation feedback adjusting system is provided with an X-direction rotatable feedback mirror, a Y-direction rotatable feedback mirror, an attenuator, a wave plate, a spectroscope I, a spectroscope II, an energy meter, a focusing lens I, a light spot screen, a CCD camera I, a focusing lens II, an X-direction piezoelectric controller and a Y-direction piezoelectric controller; an energy meter is arranged below the spectroscope I and used for reading a laser energy numerical value in real time, a focusing lens I, a light spot screen and a CCD camera I are arranged below the spectroscope II, a laser beam is focused on the light spot screen by the focusing lens I and the actual position of a light spot is detected by the CCD camera I, the energy meter and the CCD camera I are connected with a computer, the computer is respectively connected with an X-direction rotatable feedback mirror and a Y-direction rotatable feedback mirror through an X-direction piezoelectric controller and a Y-direction piezoelectric controller, and the rotation angles of the X-direction rotatable feedback mirror and the Y-direction rotatable feedback mirror are controlled and adjusted by the computer; the three-dimensional motion control system is provided with an adjustable clamp, a clamp supporting table, a spring, a three-dimensional moving platform, an X-axis motion controller, a Y-axis motion controller and a Z-axis motion controller, wherein the adjustable clamp is arranged above the clamp supporting table and used for clamping a workpiece to be measured and is connected with the clamp supporting table through the spring, the clamp supporting table is fixed on the three-dimensional moving platform, the three-dimensional moving platform is connected with a computer through the X-axis motion controller, the Y-axis motion controller and the Z-axis motion controller, and the X-axis motion controller, the Y-axis motion controller and the Z-axis motion controller are controlled by the computer to drive the three-dimensional moving platform, the adjustable clamp and the workpiece to be measured to move three-dimensionally; the damage judging device comprises a CCD camera II with a long-focus microscope, the CCD camera II is used for observing and recording the microscopic appearance of a workpiece testing area before and after laser irradiation and feeding the microscopic appearance back to a computer, the computer utilizes image processing software to analyze the appearance change of the workpiece surface testing area before and after the laser damage testing, if pixel points near the testing area are obviously changed and exceed the size tolerance, the laser induced damage is judged to occur at the position, the size of the damage point is defined according to the change value of the pixel points, the accuracy and the reliability of damage judgment are guaranteed, and the quantitative evaluation of the size of the damage point is realized.
2. The fixed-point laser damage threshold evaluation system according to claim 1, wherein: YAG laser emits laser, moire fringes are formed by a spatial filter, a beam expander and a cone mirror to achieve primary collimation of the emitted laser, a CCD camera I is used for detecting the specific position of a laser spot on a spot screen, the offset of the laser beam in the X direction and the Y direction is determined and fed back to a computer, and an X-direction piezoelectric controller and a Y-direction piezoelectric controller are controlled through an algorithm to respectively drive an X-direction rotatable feedback mirror and a Y-direction rotatable feedback mirror to rotate to required angles, so that the laser spot is adjusted to the origin of coordinates of the spot screen, and collimation adjustment of the laser beam is achieved.
3. The fixed-point laser damage threshold evaluation system according to claim 1, wherein: the adjustable clamp is divided into a left part and a right part, a rubber clamping strip is arranged on the inner side of the adjustable clamp at a certain interval, and a workpiece to be measured is arranged in the adjustable clamp and is positioned and clamped through contact with the rubber clamping strip.
4. The fixed-point laser damage threshold evaluation system according to claim 3, wherein: the adjustable clamp realizes telescopic adjustment of the left part and the right part along the wedge-shaped guide groove by means of the bottom spring according to the size of the workpiece to be measured, so that the workpiece to be measured is positioned and clamped.
5. The fixed-point laser damage threshold evaluation system according to claim 4, wherein: the adjustable clamp can clamp a round workpiece with the workpiece size of phi 20-phi 100mm or a polygonal workpiece with the opposite side distance of 20-100 mm, and the thickness of the workpiece ranges from 5mm to 25mm, so that the workpieces with multiple shapes and sizes can be fixed.
6. The fixed-point laser damage threshold evaluation system according to claim 1, wherein the adjustable fixture and the workpiece are driven by a three-dimensional moving platform to realize feeding along X, Y and Z directions, wherein the Y and Z directions move to change the specific position of the region to be measured on the surface of the workpiece, and the X direction moves to ensure that the region to be measured of the workpiece is always located at the focal position of the focusing lens II, so as to ensure that laser irradiates the rear surface of the workpiece during laser testing, and the fixed-point laser damage test of any position of the surface of the workpiece with a plane, a wedge and a curved surface is realized by means of the driving of the three-dimensional moving platform.
7. The fixed-point laser damage threshold evaluation system according to claim 1, wherein: the microscope multiplying power adjustable range of the CCD camera II is multiplied by 0.7 to multiplied by 4.5, and the field range is 0.5-3 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910874468.6A CN110487726B (en) | 2019-09-17 | 2019-09-17 | Fixed-point laser damage threshold evaluation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910874468.6A CN110487726B (en) | 2019-09-17 | 2019-09-17 | Fixed-point laser damage threshold evaluation system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110487726A CN110487726A (en) | 2019-11-22 |
| CN110487726B true CN110487726B (en) | 2021-11-19 |
Family
ID=68557344
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910874468.6A Active CN110487726B (en) | 2019-09-17 | 2019-09-17 | Fixed-point laser damage threshold evaluation system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110487726B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112222645A (en) * | 2020-08-24 | 2021-01-15 | 梅林� | Focusing adjusting device and method for online punching of thin rod object |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102608019A (en) * | 2012-03-23 | 2012-07-25 | 中国矿业大学 | Device and method for measuring laser irradiation optical thin film damage threshold in high-temperature environment |
| CN103926057A (en) * | 2013-11-14 | 2014-07-16 | 中国电子科技集团公司第十一研究所 | Laser damage resistance testing system |
| CN109186958A (en) * | 2018-09-19 | 2019-01-11 | 西安工业大学 | A kind of coaxial laser damage threshold test device of more light and implementation method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6727460B2 (en) * | 2002-02-14 | 2004-04-27 | Troitski | System for high-speed production of high quality laser-induced damage images inside transparent materials |
-
2019
- 2019-09-17 CN CN201910874468.6A patent/CN110487726B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102608019A (en) * | 2012-03-23 | 2012-07-25 | 中国矿业大学 | Device and method for measuring laser irradiation optical thin film damage threshold in high-temperature environment |
| CN103926057A (en) * | 2013-11-14 | 2014-07-16 | 中国电子科技集团公司第十一研究所 | Laser damage resistance testing system |
| CN109186958A (en) * | 2018-09-19 | 2019-01-11 | 西安工业大学 | A kind of coaxial laser damage threshold test device of more light and implementation method |
Non-Patent Citations (2)
| Title |
|---|
| Laser induced damage characteristics of fused silica optics treated by wet chemical processes;Hui Ye et al;《Applied Surface Science》;20150908;全文 * |
| 光学元件磨削加工亚表面损伤检测研究;胡陈林等;《人工晶体学报》;20141130;第43卷(第11期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110487726A (en) | 2019-11-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101733561B (en) | Method for quickly and precisely adjusting focal plane in laser trimming membrane resistance | |
| JP6046033B2 (en) | Flexible beam delivery system for high power laser systems | |
| JP2007517408A5 (en) | ||
| CN105855696B (en) | Laser focal beam spot localization method and device | |
| CN103364176B (en) | A kind of laser damage threshold test macro | |
| JP2013171042A (en) | Non-contact determination device of edge shape of thin disk-like object | |
| CN111060294B (en) | Comprehensive test platform for fluorescence microscope objective | |
| US10415785B2 (en) | Sunlight focusing analysis device for vehicle lamp lens, and method for using same | |
| WO2011017572A2 (en) | Laser modules and processes for thin film solar panel laser scribing | |
| CN105499789A (en) | Method for quantifying laser focus and focus quantifying device | |
| CN103264225A (en) | Laser butt welding process parameter optimization method and device | |
| CN110487726B (en) | Fixed-point laser damage threshold evaluation system | |
| CN110238521A (en) | A kind of collimator lattice structure laser accurate welder and method | |
| CN112264722A (en) | Laser micropore machining equipment and machining method suitable for thin-wall parts | |
| CN202916206U (en) | Device for measuring and evaluating laser-induced damage resisting capacity of film | |
| CN102091974B (en) | Installing and adjusting method for high-speed lathe machining property on-machine measuring device | |
| CN104748674A (en) | Focus monitoring device and method | |
| Zeilmann et al. | Effects of cutting power, speed and assist gas pressure parameters on the surface integrity cut by laser | |
| JP2011230179A (en) | Method for adjusting optical axis of laser machining apparatus | |
| CN104776804A (en) | Optical camera adjustment method and device on basis of non-contact type micro distance measurement | |
| CN102494712B (en) | Method and device for detecting loading process and attenuation law of laser shock wave | |
| CN202216766U (en) | Collimated light beam detection device | |
| CN113910052A (en) | Integrated device and method for in-situ repair and monitoring of fused quartz optical element in whole process | |
| CN116160120B (en) | Machining method and machining system for improving abrasion resistance of tenon tooth mortises of turbine blades | |
| JPS58202751A (en) | Ultrafine cutting work for large-aperture metal mirror |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |