Ultraviolet nanosecond laser ultraprecise micro-polishing device

Abstract

The utility model relates to an ultraviolet nanosecond laser ultraprecise micro-polishing device, which belongs to the technical field of laser processing and comprises a support unit, a five-axis moving unit and a laser unit. The five-axis moving unit can achieve five-axis linkage and is used for conducting accurate positioning when laser polishing is conducted on the curved surface of the optical element, the laser focusing distance, namely the laser spot size, is kept unchanged all the time, and a machining area is perpendicular to a laser beam all the time. The laser regulation and control unit combines ultraviolet nanosecond laser, green indication laser and CCD online imaging, and can achieve rapid and accurate positioning and control of a machining area and real-time monitoring of the machining process. According to the utility model, high-efficiency, high-precision and high-quality laser polishing treatment on curved surfaces of various optical elements can be realized.

Description

Technical Field

[0001] This utility model belongs to the field of laser processing technology, and in particular relates to an ultraviolet nanosecond laser ultra-precision micro-polishing device. Background Technology

[0002] Laser micropolishing technology plays a crucial role in ultra-precision machining, especially in the manufacture of high-precision optical components. It performs fine processing on optical surfaces non-contactly, effectively avoiding physical damage to the workpiece during processing and achieving nanometer-level machining accuracy, meeting the high standards required for ultra-precision machining. Laser micropolishing can significantly improve the surface quality of optical components, thereby enhancing their optical performance. This technology is particularly suitable for fragile or complex-shaped optical components, avoiding the damage and deformation that may be caused by traditional mechanical polishing. Laser micropolishing has wide applicability, capable of handling a variety of materials including glass, plastics, and crystals, providing greater flexibility in the manufacture of optical components.

[0003] With the ever-increasing demands on the performance of optical systems, laser micropolishing technology has a promising future in high-resolution imaging, advanced laser systems, optical communication, and optical sensors, and is one of the key technologies driving the development of optical manufacturing technology to a higher level. However, most of the laser polishing equipment currently in widespread use is for large-area macroscopic polishing, whose main function is to polish rough metal surfaces to the micrometer level. Micropolishing of ultra-precision surfaces still heavily relies on expensive femtosecond lasers, making this technology difficult to popularize. Currently, there is a lack of relatively low-cost laser micropolishing equipment that can polish ultra-precision machined micrometer and submicrometer optical surfaces to the nanometer and sub-nanometer levels. Furthermore, when micropolishing curved surfaces, even slight changes in the shape and size of the laser spot will cause changes in the energy density of the laser on the material surface, which will affect the final polishing effect. Maintaining a constant shape and size of the laser spot is also a technical challenge.

[0004] Therefore, there is an urgent need for a new technical solution to address this problem. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide an ultraviolet nanosecond laser ultra-precision micro-polishing device to solve the current lack of a relatively low-cost laser micro-polishing device that can polish ultra-precision machined micron-level and submicron-level optical surfaces to nanon-level and sub-nanometer-level; and the technical problem of maintaining a constant shape and size of the laser spot when micro-polishing curved surfaces.

[0006] An ultraviolet nanosecond laser ultra-precision micro-polishing device includes a support unit, a five-axis moving unit, and a laser unit. The support unit includes a marble platform and a marble gantry vertically arranged on the upper part of the marble platform. The five-axis moving unit includes an X-axis slide, a Y-axis slide, a Z-axis slide, a cradle, and a turntable. The X-axis and Y-axis slides are both set on the marble platform and are perpendicular to each other in the horizontal plane. One end of the Y-axis slide is slidably connected to the X-axis slide. The Z-axis slide is arranged perpendicular to the marble platform, and its lower part is slidably connected to the Y-axis slide. The side of the Z-axis slide is slidably connected to a rotating shaft located at the lower part of the cradle. The cradle swings around the rotating shaft, and a turntable is located on the upper part of the cradle. The turntable rotates around a rotating shaft located in its middle, and a fixture is provided on the turntable. The workpiece to be processed is installed in the fixture.

[0007] The laser unit includes a laser focusing module and a laser control module;

[0008] The laser focusing module includes a protective cover, an aperture, and an objective lens; the protective cover is fixedly installed on the side of the upper beam of the marble gantry, and the aperture and objective lens are fixed inside the protective cover; the aperture is located at the incident end of the objective lens;

[0009] The laser control module includes an optical plate and a housing attached to the upper part of the optical plate. The housing is provided with an entrance hole. An ultraviolet nanosecond laser source is connected to the outside of the entrance hole.

[0010] The optical plate is set on the top of the gantry. The optical plate is equipped with a first reflecting mirror, a second reflecting mirror, a dichroic mirror, a third reflecting mirror, an LED light source, a first semi-reflective lens, a second semi-reflective lens, an indicator light source, a beam expander collimator, a CCD camera, and a sleeve lens. The LED light source, the first semi-reflective lens, the second semi-reflective lens, the dichroic mirror, and the third reflecting mirror are arranged on the same optical axis.

[0011] The ultraviolet nanosecond laser is incident through the entrance hole, reflected by the first and second reflecting mirrors in sequence, and then reflected by the dichroic mirror and the third reflecting mirror in sequence. After the stray light is filtered out by the aperture, it is incident on the objective lens and focused to irradiate the surface of the workpiece.

[0012] The indicator light source emits a green laser beam, which is expanded and collimated by a beam expander and collimator in sequence, and then reflected by a first half-reflecting lens. At the same time, the white illumination beam emitted by the LED light source passes through the first half-reflecting lens, and together with the green laser beam, passes through a second half-reflecting lens and a dichroic mirror, is reflected by a third reflecting mirror, passes through an aperture, and is focused on the surface of the workpiece by an incident objective lens.

[0013] The reflected light generated by the LED light source beam on the surface of the workpiece passes sequentially through the objective lens, the aperture, and then through the third reflecting mirror. It is then reflected by the dichroic mirror, then through the second half-reflecting lens, and finally focused by the sleeve lens to form an image on the CCD camera, thus forming an imaging optical path.

[0014] The first semi-reflective lens, the second semi-reflective lens, the first reflector and the second reflector are adjusted to a fixed angle to make the imaging optical path, the green laser emitted by the indicator light source and the ultraviolet nanosecond laser coaxial;

[0015] In operation, the five-axis moving unit moves under the control of the CNC program, so that the Z-axis slide keeps the distance between the workpiece's processing area and the objective lens, i.e., the ultraviolet nanosecond laser focusing distance, unchanged, while keeping the workpiece's processing area perpendicular to the ultraviolet nanosecond laser beam.

[0016] The support unit also includes a bracket and a shock-absorbing air cushion. The bracket is fixedly installed on the lower part of the marble platform; the shock-absorbing air cushion is disposed between the marble platform and the bracket.

[0017] A right-angle bracket is provided at the connection point between the marble gantry and the laser unit, making the connection between the marble gantry and the laser unit more stable.

[0018] Through the above design scheme, this utility model can bring the following beneficial effects:

[0019] 1. This utility model uses ultraviolet nanosecond laser to micro-polish the surface of curved optical components. Ultraviolet laser has high photon energy, and compared with infrared laser used in traditional laser processing platforms, it has less thermal impact on the material surface and is easier to obtain higher surface quality after processing.

[0020] 2. Using ultraviolet nanosecond lasers to micro-polish the material surface reduces the cost compared to using femtosecond lasers.

[0021] 3. Through five-axis linkage, the workpiece can move along the XYZ direction and rotate along the rotation axis of the cradle or the rotation axis of the turntable, thereby realizing the polishing of complex curved surfaces of optical components. At the same time, the surface of the processing area can always be kept perpendicular to the laser beam and kept at a fixed distance to reduce the impact of spot deformation or defocus caused by the tilt of the processing area relative to the laser beam on the processing process.

[0022] 4. By using coaxial pointing laser and CCD camera imaging, precise positioning and focusing of the processing area can be achieved, which can significantly improve processing efficiency.

[0023] 5. This utility model combines ultraviolet nanosecond laser, green indicator laser and online imaging with CCD camera to achieve rapid and accurate positioning, control and real-time monitoring of the processing area and the processing process. It can achieve high-efficiency, high-precision and high-quality laser precision micro-polishing of the curved surfaces of various optical components. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0025] Figure 1 This is a schematic diagram of the structure of an ultraviolet nanosecond laser ultra-precision micro-polishing device according to the present invention;

[0026] Figure 2 This is a schematic diagram of the indicator optical path and imaging optical path in an ultraviolet nanosecond laser ultra-precision micro-polishing device of this utility model;

[0027] Figure 3 This is a schematic diagram showing the positional relationship between the aperture, the third reflecting mirror, and the objective lens in an ultraviolet nanosecond laser ultra-precision micro-polishing device according to this utility model.

[0028] In the diagram, 1-X-axis slide, 2-Y-axis slide, 3-Z-axis slide, 4-cradle, 5-turntable, 6-laser focusing module, 7-laser control module, 8-entry hole, 9-marble gantry, 10-marble platform, 11-shock-absorbing air cushion, 12-support, 13-first reflecting mirror, 14-second reflecting mirror, 15-dichroic mirror, 16-third reflecting mirror, 17-aperture, 18-objective lens, 19-LED light source, 20-first semi-reflective lens, 21-second semi-reflective lens, 22-indicator light source, 23-beam expander collimator, 24-CCD camera, 25-sleeve lens, 26-workpiece, 27-clamp, 28-optical plate, 29-right-angle support, 30-outer shell, 31-protective cover. Detailed Implementation

[0029] An ultraviolet nanosecond laser ultra-precision micro-polishing device includes a support unit, a five-axis moving unit, and a laser unit.

[0030] The support unit includes a bracket 12, a marble platform 10, a shock-absorbing air cushion 11, and a marble gantry 9. The marble platform 10 is mounted on the bracket 12; the shock-absorbing air cushion 11 is mounted between the marble platform 10 and the bracket 12; and the marble gantry 9 is vertically mounted on the marble platform 10.

[0031] The five-axis motion unit includes an X-axis slide 1, a Y-axis slide 2, a Z-axis slide 3, a cradle 4, and a turntable 5. The X-axis slide 1 and the Y-axis slide 2 are perpendicularly arranged on the marble platform 10 in a horizontal plane. The Z-axis slide 3 is arranged on the Y-axis slide 2, and the cradle 4 is arranged on the Z-axis slide 3. The turntable 5 is arranged on the cradle 4. A clamp 27 is arranged on the turntable 5. The workpiece 26 is installed in the clamp 27. Therefore, the workpiece 26 can move along the XYZ directions, swing along the rotation axis arranged at the lower part of the cradle 4, and rotate along the rotation axis arranged at the middle of the turntable 5.

[0032] The laser unit includes a laser focusing module 6, a right-angle bracket 29, and a laser control module 7. The laser focusing module 6 is installed on the side of the marble gantry 9, and the laser control module 7 is set on the top of the marble gantry 9. The laser control module 7 is connected to the side of the marble gantry 9 through the right-angle bracket 29 to improve stability.

[0033] The laser control module 7 includes an optical plate 28 and a housing 30 attached to the upper part of the optical plate 28. The housing 30 is provided with an entrance hole 8. An ultraviolet nanosecond laser source is connected to the outside of the entrance hole 8.

[0034] The optical plate 28 is set on the top of the gantry 9. The optical plate 28 is equipped with a first reflecting mirror 13, a second reflecting mirror 14, a dichroic mirror 15, a third reflecting mirror 16, an LED light source 19, a first semi-reflective lens 20, a second semi-reflective lens 21, an indicator light source 22, a beam expander collimator 23, a CCD camera 24, and a sleeve lens 25. The LED light source 19, the first semi-reflective lens 20, the second semi-reflective lens 21, the dichroic mirror 15, and the third reflecting mirror 16 are arranged on the same optical axis.

[0035] The laser focusing module 6 includes a protective cover 31, an aperture 17, and an objective lens 18. The protective cover 31 is located on one side of the gantry 9, and the aperture 17 and the objective lens 18 are located inside the protective cover 31.

[0036] After the ultraviolet nanosecond laser is incident, it is reflected by the first reflecting mirror 13 and the second reflecting mirror 14, and then reflected by the dichroic mirror 15 and the third reflecting mirror 16 and passed through the aperture 17. The diameter of the incident beam is controlled by adjusting the size of the aperture 17 and stray light is filtered out. Then it is incident on the objective lens 18. After the laser is focused by the objective lens 18, it irradiates the surface of the workpiece 26 to form a polishing optical path.

[0037] The indicator light source 22 emits a green laser beam, which is expanded and collimated by the beam expander collimator 23 and reflected by the first semi-reflective lens 20. At the same time, the LED light source 19 emits a white illumination beam, which passes through the first semi-reflective lens 20 and together with the green laser beam, passes through the second semi-reflective lens 21 and the dichroic mirror 15, is reflected by the third reflecting mirror 16, passes through the aperture 17, and is focused on the surface of the workpiece 26 by the incident objective lens 18, forming an indicator light path.

[0038] The reflected light generated by the LED light source 19 on the surface of the workpiece 26 passes through the objective lens 18 and the aperture 17, is reflected by the third reflecting mirror 16, passes through the dichroic mirror 15, is reflected by the second semi-reflective lens 21, and is focused by the sleeve lens 25 to form an image on the CCD camera 24, thus forming an imaging optical path.

[0039] Before operation, an ultraviolet nanosecond laser is introduced into the laser control module 7 through the entrance aperture 8. After the laser is incident, it is reflected by the first reflector 13 and the second reflector 14, and then reflected by the dichroic mirror 15 and the third reflector 16 before passing through the aperture 17. The diameter of the incident beam is controlled by adjusting the size of the aperture 17 and stray light is filtered out. Then it is incident on the objective lens 18. After being focused by the objective lens 18, the laser irradiates the surface of the fixture 27.

[0040] Then, the indicator light source 22 is turned on, and the indicator light source 22 emits a green laser beam. The beam is expanded and collimated by the beam expander collimator 23, and reflected by the first semi-reflective lens 20. At the same time, the LED light source 19 emits a white illumination beam, which passes through the first semi-reflective lens 20, and together with the green laser beam, passes through the second semi-reflective lens 21 and the dichroic mirror 15, is reflected by the third reflecting mirror 16, passes through the aperture 17, and is focused on the surface of the fixture 27 by the incident objective lens 18.

[0041] The reflected light generated by the LED light source 19 on the surface of the fixture 27 passes through the objective lens 18 and the aperture 17, is reflected by the third reflecting mirror 16, passes through the dichroic mirror 15, is reflected by the second semi-reflective lens 21, and is focused by the sleeve lens 25 to form an image on the CCD camera 24.

[0042] By adjusting the angles of the first semi-reflective lens 20, the second semi-reflective lens 21, the first reflector 13, and the second reflector 14, the imaging optical path, the green laser emitted by the indicator light source 22, and the ultraviolet nanosecond laser are ensured to be coaxial, and the imaging focal plane, the focal plane of the indicator light source 22 after focusing, and the focal plane of the ultraviolet nanosecond laser are made to coincide. In this way, the ultraviolet nanosecond laser processing area can be determined by the green indicator light spot, and the status of the processing area can be observed in real time through the image formed by the CCD camera 24.

[0043] Turn off the incident ultraviolet nanosecond laser, fix the workpiece 26 to be processed on the fixture 27, manually control the X-axis 1 and Y-axis 2 to move to the processing position by focusing the green laser spot on the surface of the workpiece 26 through the indicator light source 22, manually control the Z-axis 3 to focus through the image of the CCD camera 24, and set the current position as the machine tool zero point.

[0044] Input the CNC program, turn on the incident ultraviolet nanosecond laser source, and link the five axes of the X-axis slide 1, Y-axis slide 2, Z-axis slide 3, cradle 4 and turntable 5 to control the laser spot to move on the surface of workpiece 26 according to the processing trajectory set in the program, and process the surface of workpiece 26. X-axis slide 1 and Y-axis slide 2 are responsible for controlling the processing area, Z-axis slide 3 is responsible for keeping the distance between the processing area of ​​workpiece 26 and objective lens 18, i.e., the laser focusing distance, unchanged, and cradle 4 and turntable 5 are responsible for keeping the processing area perpendicular to the laser beam.

[0045] This invention utilizes a multi-axis linkage motion platform combined with indicator light and real-time imaging of the processing area to perform precise positioning and processing on complex curved surfaces, achieving high-precision, high-quality, and high-efficiency polishing of the curved surfaces of optical components.

Claims

1. An ultraviolet nanosecond laser ultra-precision micro-polishing device, characterized in that: The system includes a support unit, a five-axis moving unit, and a laser unit. The support unit includes a marble platform (10) and a marble gantry (9) vertically arranged on the upper part of the marble platform (10). The five-axis moving unit includes an X-axis slide (1), a Y-axis slide (2), a Z-axis slide (3), a cradle (4), and a turntable (5). The X-axis slide (1) and the Y-axis slide (2) are both set on the marble platform (10) and are perpendicular to each other in the horizontal plane. One end of the Y-axis slide (2) is perpendicular to the X-axis slide (3). 1) Sliding connection; the Z-axis slide (3) is arranged perpendicularly to the marble platform (10), and the lower part of the Z-axis slide (3) is slidably connected to the Y-axis slide (2); the side of the Z-axis slide (3) is slidably connected to the rotating shaft provided at the lower part of the cradle (4); the cradle (4) swings around the rotating shaft, and a turntable (5) is provided at the upper part of the cradle (4); the turntable (5) rotates around the rotating shaft provided in its middle, and a fixture (27) is provided on the turntable (5); the workpiece (26) to be processed is installed in the fixture (27); The laser unit includes a laser focusing module (6) and a laser control module (7); The laser focusing module (6) includes a protective cover (31), an aperture (17), and an objective lens (18); the protective cover (31) is fixedly installed on the side of the upper beam of the marble gantry (9), and the aperture (17) and the objective lens (18) are fixed inside the protective cover (31); the aperture (17) is located at the incident end of the objective lens (18); The laser control module (7) includes an optical plate (28) and a housing (30) attached to the upper part of the optical plate (28). The housing (30) is provided with an entrance hole (8). An ultraviolet nanosecond laser source is connected to the outside of the entrance hole (8). The optical plate (28) is set on the top of the gantry (9). The optical plate (28) is equipped with a first reflector (13), a second reflector (14), a dichroic mirror (15), a third reflector (16), an LED light source (19), a first semi-reflective lens (20), a second semi-reflective lens (21), an indicator light source (22), a beam expander collimator (23), a CCD camera (24), and a sleeve lens (25). The LED light source (19), the first semi-reflective lens (20), the second semi-reflective lens (21), the dichroic mirror (15), and the third reflector (16) are arranged on the same optical axis. The ultraviolet nanosecond laser is incident through the entrance hole (8), and is reflected by the first reflector (13) and the second reflector (14) in sequence. After being reflected by the dichroic mirror (15) and the third reflector (16) in sequence, the stray light is filtered out by the aperture (17), and then it is incident on the objective lens (18) for focusing and then irradiates the surface of the workpiece (26). The indicator light source (22) emits a green laser beam, which is expanded and collimated by the beam expander collimator (23) in sequence, and then reflected by the first semi-reflective lens (20). At the same time, the white illumination beam emitted by the LED light source (19) passes through the first semi-reflective lens (20), and together with the green laser beam, passes through the second semi-reflective lens (21) and the dichroic mirror (15), and is reflected by the third reflecting mirror (16). It then passes through the aperture (17), the incident lens (18), and is focused on the surface of the workpiece (26). The reflected light generated by the LED light source (19) beam on the surface of the workpiece (26) passes through the objective lens (18), the aperture (17), and then is reflected by the third mirror (16), passes through the dichroic mirror (15), and then is reflected by the second semi-reflective lens (21), and is focused by the sleeve lens (25) to form an image on the CCD camera (24), thus forming an imaging optical path. The first semi-reflective lens (20), the second semi-reflective lens (21), the first reflector (13) and the second reflector (14) are adjusted to a fixed angle so that the imaging optical path, the green laser emitted by the indicator light source (22) and the ultraviolet nanosecond laser are coaxial. In the working state, the five-axis moving unit moves under the control of the CNC program, so that the Z-axis slide (3) keeps the distance between the processing area of ​​the workpiece (26) and the objective lens (18), i.e. the ultraviolet nanosecond laser focusing distance, unchanged, while keeping the processing area of ​​the workpiece (26) perpendicular to the ultraviolet nanosecond laser beam.

2. The ultraviolet nanosecond laser ultra-precision micro-polishing device according to claim 1, characterized in that: The support unit also includes a bracket (12) and a shock-absorbing air cushion (11). The bracket (12) is fixedly installed on the lower part of the marble platform (10). The shock-absorbing air cushion (11) is disposed between the marble platform (10) and the bracket (12).

3. The ultraviolet nanosecond laser ultra-precision micro-polishing device according to claim 1, characterized in that: A right-angle bracket (29) is provided at the connection between the side of the marble gantry (9) and the laser unit to make the connection between the marble gantry (9) and the laser unit more stable.

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