An optical system for high-power adjustable ring-shaped focusing spot

Abstract

This invention discloses an optical system for a high-power adjustable annular focusing spot, comprising a zoom beam expander, a total reflection mirror, a conical lens, and a replaceable focusing lens group arranged sequentially from the object side to the image side. The zoom beam expander includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical path propagation direction. The first lens is a biconvex lens with positive optical power; the second lens is a biconcave lens with negative optical power; the third lens is a concave-convex lens with negative optical power; and the fourth lens is a plano-convex lens with positive optical power. The replaceable focusing lens group consists of focusing lenses with focal lengths of F12.5, F30, and F50. The focusing lens with a focal length of F12.5 includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the optical path propagation direction; the focusing lens with a focal length of F30 includes a tenth lens; and the focusing lens with a focal length of F50 includes an eleventh lens. This invention achieves continuously adjustable annular spot width and graded adjustable annular spot inner diameter, both of which are independently controllable.

Description

Technical Field

[0001] This invention relates to an optical system for a high-power adjustable ring-shaped focusing spot, belonging to the technical field of focusing ring-shaped focusing spot systems. Background Technology

[0002] In laser processing, laser cavitation, material surface modification, and precision manufacturing, the annular focused laser beam, due to its uniform energy distribution and relatively low central intensity, can effectively improve the heating uniformity of materials and reduce problems such as local overheating, spatter, and defects. It has become an important beam type for improving processing quality. With the increasing prevalence of high-power laser applications, the need for flexible and precise control over the size, width, and energy distribution of the annular laser beam on the working surface is becoming increasingly prominent. Summary of the Invention

[0003] The purpose of this invention is to provide an optical system for a high-power adjustable annular focusing spot. By continuously adjusting the aperture of the incident laser beam through a variable magnification beam expander, the ring width of the annular spot can be continuously adjusted. By replacing the focusing lens with different focal lengths, the inner diameter of the annular spot can be adjusted in stages. The two are independently controlled and do not interfere with each other, thus solving the problems of coupling, complex structure, and inconvenient operation in traditional annular spot adjustment.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] An optical system for a high-power adjustable ring-shaped focusing spot includes a zoom beam expander, a total reflection mirror, a conical lens, and a replaceable focusing lens group arranged sequentially from the object side to the image side.

[0006] The zoom beam expander includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical path propagation direction;

[0007] The first lens is a biconvex lens with positive optical power; the second lens is a biconcave lens with negative optical power.

[0008] The third lens is a concave-convex lens with positive optical power; the fourth lens is a plano-convex lens with positive optical power.

[0009] The replaceable focusing lens group consists of focusing lenses with focal lengths of F12.5, F30, and F50 respectively;

[0010] The focusing lens with a focal length of F12.5 includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the direction of light propagation;

[0011] The sixth lens is a biconcave lens with negative optical power; the seventh lens is a meniscus lens with positive optical power and its convex surface curved towards the image side; the eighth lens is a biconvex lens with positive optical power; and the ninth lens is a biconvex lens with positive optical power.

[0012] The focusing lens with a focal length of F30 includes a tenth lens, which is a plano-convex lens with positive optical power.

[0013] The focusing lens with a focal length of F50 includes an eleventh lens, which is a plano-convex lens with positive optical power.

[0014] The aforementioned optical system for high-power adjustable annular focusing spot achieves continuous adjustment of the annular spot width and graded adjustment of the annular spot inner diameter. The two are independently controlled and do not interfere with each other, solving the problems of coupling, complex structure, and inconvenient operation in traditional annular spot adjustment.

[0015] The aforementioned variable magnification beam expander is a continuous variable magnification beam expander with an adjustable magnification range of 0.5-2X. It is used to linearly control the beam diameter incident on the annular spot generating unit, thereby achieving continuous adjustment of the outer diameter d2 of the annular spot.

[0016] The first lens, second lens, third lens, fourth lens and focusing lens mentioned above are all made of silicon dioxide.

[0017] From the object side to the image side, the two sides of the first lens are the first object side and the first image side, respectively; the two sides of the second lens are the second object side and the second image side, respectively; the two sides of the third lens are the third object side and the third image side, respectively; and the two sides of the fourth lens are the fourth object side and the fourth image side, respectively.

[0018] To improve imaging performance, the radius of curvature of the first object-side surface is 559.968±0.003mm, and the radius of curvature of the first image-side surface is -43.232±0.003mm; the radius of curvature of the second object-side surface is -21.0238±0.003mm, and the radius of curvature of the second image-side surface is 21.0238±0.003mm; the radius of curvature of the third object-side surface is -63.38±0.003mm, and the radius of curvature of the third image-side surface is -52.098±0.003mm; the radius of curvature of the fourth object-side surface is ∞ (infinity), and the radius of curvature of the fourth image-side surface is -86.137±0.003mm.

[0019] The center thickness of the first lens is 5±0.02mm; the center thickness of the second lens is 3±0.02mm; the center thickness of the third lens is 6.7±0.02mm; and the center thickness of the fourth lens is 4.5±0.02mm.

[0020] During the process of changing the magnification of the zoom lens from 0.5X to 2X, the center spacing between the first and second lenses changed from 56.32±0.02mm to 35.05±0.02mm; the center spacing between the second and third lenses changed from 32.66±0.02mm to 83.86±0.02mm; and the center spacing between the third and fourth lenses was 0.6±0.02mm.

[0021] The aforementioned total reflection mirror is a 45° total reflection mirror. The 45° total reflection mirror is positioned on the side away from the beam expander, reflecting the laser emitted from the beam expander into the fifth lens cone.

[0022] The center-to-center distance between the fourth lens and the total reflection mirror is 65±0.02mm.

[0023] The flat side of the conical lens faces the zoom beam expander group and serves as the beam input end, while the cone tip side serves as the beam output end. The conical lens is used to shape the collimated and expanded laser beam into a ring-shaped spot.

[0024] From the object side to the image side, the two sides of the cone lens are the fifth object side and the fifth image side, respectively. The fifth object side is a plane, and the fifth image side is a cone with a cone angle of 140~179°.

[0025] The center thickness of the aforementioned conical lens is 5~10mm; the center distance between the total reflection mirror and the conical lens is 65mm.

[0026] The aforementioned conical lens is made of silicon dioxide. The conical lens is considered the fifth lens.

[0027] The aforementioned replaceable focusing lens group consists of three different focusing lenses with focal lengths of F12.5, F30, and F50, respectively, corresponding to cases where the inner diameter of the annular focusing spot is φ100um, φ250um, and φ400um.

[0028] When the inner diameter of the fixed annular spot is φ100um, a focusing lens with a focal length of F12.5@532nm is selected; when the inner diameter of the fixed annular spot is φ250um, a focusing lens with a focal length of F30@532nm is selected instead of the focusing lens with a focal length of F12.5@532nm; when the inner diameter of the fixed annular spot is φ400um, a focusing lens with a focal length of F50@532nm is selected instead of the focusing lens with a focal length of F30@532nm.

[0029] The sixth, seventh, eighth, and ninth lenses mentioned above are all made of silicon dioxide.

[0030] From the object side to the image side, the two sides of the sixth lens are the sixth object side and the sixth image side, the two sides of the seventh lens are the seventh object side and the seventh image side, the two sides of the eighth lens are the eighth object side and the eighth image side, and the two sides of the ninth lens are the ninth object side and the ninth image side.

[0031] To ensure the adjustment effect, the radius of curvature of the sixth object side is -25±0.003mm, and the radius of curvature of the sixth image side is 25±0.003mm; the radius of curvature of the seventh object side is -150.53±0.003mm, and the radius of curvature of the seventh image side is -21.5±0.003mm; the radius of curvature of the eighth object side is 42.24±0.003mm, and the radius of curvature of the eighth image side is -42.24±0.003mm; the radius of curvature of the ninth object side is 20.2mm, and the radius of curvature of the ninth image side is -230.69±0.003mm.

[0032] The signs of the radii of curvature of the sixth to ninth lenses mentioned above are the signs before they were reversed by the total reflection mirror. Table 2 shows the signs after the reversal.

[0033] To balance imaging performance and structural stability, the center thickness of the sixth lens is 2±0.02mm; the center thickness of the seventh lens is 7±0.02mm; the center thickness of the eighth lens is 7±0.02mm; the center thickness of the ninth lens is 7±0.02mm; the center spacing between the cone lens and the sixth lens is 20±0.02mm; the center spacing between the sixth lens and the seventh lens is 17±0.02mm; the center spacing between the seventh lens and the eighth lens is 1±0.02mm; and the center spacing between the eighth lens and the ninth lens is 1±0.02mm.

[0034] From the object side to the image side, the two sides of the tenth lens are the tenth object side and the tenth image side, respectively. To ensure the adjustment effect, the radius of curvature of the tenth object side is ∞, and the radius of curvature of the tenth image side is -13.753±0.003mm.

[0035] The sign of the radius of curvature of the tenth lens mentioned above is the sign before it was reversed by the total reflection mirror. Table 3 shows the signs after the reversal.

[0036] To balance imaging performance and structural stability, the center thickness of the tenth lens is 10.47±0.02mm; the material is silicon dioxide; and the center spacing between the conical lens and the tenth lens is 60±0.02mm.

[0037] From the object side to the image side, the two sides of the eleventh lens are the eleventh object side and the eleventh image side, respectively. The radius of curvature of the eleventh object side is -23±0.003mm, and the radius of curvature of the eleventh image side is ∞.

[0038] The sign of the radius of curvature of the eleventh lens mentioned above is the sign before it was reversed by the total reflection mirror. Table 4 shows the signs after the reversal.

[0039] To balance imaging performance and structural stability, the center thickness of the eleventh lens is 5.82±0.02mm; the material is silicon dioxide; and the center spacing between the conical lens and the eleventh lens is 60mm.

[0040] The aforementioned replaceable focusing lens group allows for independent adjustment of the inner diameter d1 of the annular spot by replacing focusing lenses with different focal lengths.

[0041] The laser used for the high-power adjustable ring focusing optical system adopts a 532nm laser band, a 7ns pulse width, a collimated incident beam of 6mm, and a power of 500W. The laser, a variable magnification beam expander, a 45° total reflection mirror, a conical lens, and a replaceable focusing lens group are arranged sequentially from the object side to the image side.

[0042] Lasers are used to emit laser light.

[0043] A 6mm incident diameter, 500W pulsed laser is used for beam emission. After being expanded to φ3mm-φ12mm by a laser beam expander, the beam is incident on a conical lens. The conical lens creates a ring beam distribution, which is then incident on a focusing lens. Finally, the ring beam is focused at a depth of 15-20mm underwater, ensuring that the inner diameter d1 of the ring spot is φ100um, φ250um, and φ400um respectively, and the ratio of the inner and outer diameters of the ring spot is 0.4 < d2 / d1 < 0.8. Finally, detection and analysis are performed.

[0044] The aforementioned variable magnification beam expander is used to continuously adjust the incident laser aperture, thereby changing the ring width of the annular spot; by replacing the focusing lens with different focal lengths, the inner diameter of the annular spot can be independently adjusted; the ring beam shaping is achieved by using an axial cone mirror structure, which is simple in structure, has high power tolerance, and reliable in adjustment method, and can meet the needs of precise control of the size of the annular focused spot in high-power laser processing.

[0045] Any techniques not mentioned in this invention are based on existing technologies.

[0046] This invention relates to an optical system for a high-power adjustable ring-shaped focusing spot, which enables independent adjustment of the inner and outer diameters of the ring-shaped focusing spot. It features a simple structure, high stability, and high adjustment precision; it is compatible with various ring generation units, making it highly versatile; and it is suitable for high-power laser processing scenarios. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the optical path of an adjustable annular spot system when the inner diameter of the annular spot is φ100um.

[0048] Figure 2The image shows the light trails of different ring widths when the annular spot adjustable system of the present invention is expanded to an incident diameter of φ3mm-φ5.4mm.

[0049] Figure 3 This is a schematic diagram of the optical path of an adjustable ring spot system when the inner diameter of the ring spot is φ250um.

[0050] Figure 4 The image shows the beam traces of different ring widths when the annular beam adjustable system of the present invention is expanded to an incident beam of φ4.8mm-φ7.2mm.

[0051] Figure 5 This is a schematic diagram of the optical path of an adjustable ring spot system when the inner diameter of the ring spot is φ400um.

[0052] Figure 6 The image shows the light trails of different ring widths when the annular spot adjustable system of the present invention is expanded to an incident diameter of φ6mm-φ10.8mm.

[0053] Figure 7 A graph showing the relationship between the outer diameter of the annular laser spot and the incident laser aperture.

[0054] Figure 8 A graph showing the relationship between the inner diameter of the annular light spot and the focal length of the focusing lens;

[0055] In the diagram, 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the fourth lens, 5 is the cone lens, 6 is the sixth lens, 7 is the seventh lens, 8 is the eighth lens, 9 is the ninth lens, 10 is the tenth lens, and 11 is the eleventh lens. Detailed Implementation

[0056] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0057] Example 1

[0058] like Figure 1 As shown, a high-power adjustable ring-shaped focusing spot system includes a laser, a zoom beam expander, a 45° total reflection mirror, a conical lens, and a focusing lens arranged sequentially from the object side to the image side. In this case, to fix the inner diameter of the ring-shaped focusing spot at φ100µm, a focusing lens with a focal length of F12.5@532nm is selected.

[0059] This embodiment uses a 532nm laser band, a 7ns pulse width, a collimated incident light spot of φ6mm, and a power of 500W.

[0060] The zoom beam expander consists of four lenses, arranged sequentially from the object side to the 45° total reflection mirror: the first lens, the second lens, the third lens, and the fourth lens. The first lens is a biconvex lens with positive optical power; the second lens is a biconcave lens with negative optical power; the third lens is a meniscus lens with positive optical power and its convex surface curved towards the image side; and the fourth lens is a plano-convex lens with positive optical power.

[0061] From the object side to the 45° total reflection mirror, the two sides of the first lens are the first object side and the first image side, the two sides of the second lens are the second object side and the second image side, the two sides of the third lens are the third object side and the third image side, and the two sides of the fourth lens are the fourth object side and the fourth image side.

[0062] The radius of curvature of the first object side is 559.968 mm, and the radius of curvature of the first image side is -43.232 mm; the radius of curvature of the second object side is -21.0238 mm, and the radius of curvature of the second image side is 21.0238 mm; the radius of curvature of the third object side is -63.38 mm, and the radius of curvature of the third image side is -52.098 mm; the radius of curvature of the fourth object side is ∞, and the radius of curvature of the fourth image side is -86.137 mm.

[0063] The first lens, second lens, third lens, and fourth lens mentioned above are all made of silicon dioxide.

[0064] The center thickness of the first lens is 5mm; the center thickness of the second lens is 3mm; the center thickness of the third lens is 6.7mm; and the center thickness of the fourth lens is 4.5mm.

[0065] During the process of changing the magnification of the zoom lens from 0.5X to 2X, the center distance between the first image side and the second object side changes from 56.32mm to 35.05mm; the center distance between the second image side and the third object side changes from 32.66mm to 83.86mm; and the center distance between the third image side and the fourth object side remains fixed at 0.6mm.

[0066] Table 1 shows the optical dimensions of the zoom beam expander.

[0067] From the object side to the 45° total reflection mirror, the two sides of the first lens are, in order, the first object side S1 and the first image side S2; the two sides of the second lens are, in order, the second object side S3 and the second image side S4; the two sides of the third lens are, in order, the third object side S5 and the third image side S6; and the two sides of the fourth lens are, in order, the fourth object side S7 and the fourth image side S8. In the table, the “thickness or interval” corresponding to the object side of the lens is the center thickness of the corresponding lens, and the “thickness or interval” corresponding to the image side of the lens is the center interval between the corresponding lens and the next lens.

[0068] Table 1 Optical parameters of the zoom beam expander

[0069]

[0070] Depend on Figure 1 As shown, a 45° total reflection mirror is placed 65mm away from the fourth lens to reflect the light emitted from the beam expander by 45° and then into the conical lens.

[0071] Depend on Figure 1 As shown, the conical lens 65mm away from the 45° total reflection mirror is considered the fifth lens. From the object side to the image side, the two surfaces of the conical lens are the fifth object-side surface S9 and the fifth image-side surface S10, respectively. The fifth object-side surface S9 is a plane, and the fifth image-side surface S10 is an odd-order aspherical surface. The diameter of the conical lens is 25.4mm, and the cone angle (apex angle) of the conical surface (the fifth image-side surface) is 179° (α is 0.5°). The center thickness of the conical lens is 5.1mm, and the material used for the conical lens is silicon dioxide. The center distance between the conical lens and the F12.5@532nm focusing lens is 20mm.

[0072] A focusing lens with a focal length of F12.5@532nm includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the optical path propagation direction; the sixth lens is a biconcave lens with negative optical power; the seventh lens is a meniscus lens with positive optical power and its convex surface curved towards the image side; the eighth lens is a biconvex lens with positive optical power; and the ninth lens is a biconvex lens with positive optical power.

[0073] From the object side to the image side, the focusing lenses are arranged such that the two sides of the sixth lens are the sixth object side and the sixth image side, the two sides of the seventh lens are the seventh object side and the seventh image side, the two sides of the eighth lens are the eighth object side and the eighth image side, and the two sides of the ninth lens are the ninth object side and the ninth image side.

[0074] The radius of curvature of the sixth object side is -25mm, and the radius of curvature of the sixth image side is 25mm; the radius of curvature of the seventh object side is -150.53mm, and the radius of curvature of the seventh image side is -21.5mm; the radius of curvature of the eighth object side is 42.24mm, and the radius of curvature of the eighth image side is -42.24mm; the radius of curvature of the ninth object side is 20.2mm, and the radius of curvature of the ninth image side is -230.69mm. The signs of the radii of curvature of the sixth to ninth lenses mentioned above are the signs before they were reversed by the total reflection mirror. Table 2 shows the signs after the reversal.

[0075] The sixth, seventh, eighth, and ninth lenses mentioned above are all made of silicon dioxide.

[0076] The center thickness of the sixth lens is 2mm; the center thickness of the seventh lens is 7mm; the center thickness of the eighth lens is 7mm; and the center thickness of the ninth lens is 7mm.

[0077] The center distance from the side of the sixth image to the side of the seventh object is 17mm; the center distance from the side of the seventh image to the side of the eighth object is 1mm; the center distance from the side of the eighth image to the side of the ninth object is 1mm; the center distance from the side of the ninth image to the water surface is 5mm, and the annular focusing spot is finally focused 16.3mm below the water surface.

[0078] From the 45° total reflection mirror to the image side, the two sides of the sixth lens are the sixth object side S11 and the sixth image side S12, the two sides of the seventh lens are the seventh object side S13 and the seventh image side S14, the two sides of the eighth lens are the eighth object side S15 and the eighth image side S16, the two sides of the ninth lens are the ninth object side S17 and the ninth image side S18, and S19 represents the water surface; the "thickness or interval" corresponding to the object side of the lens is the center thickness of the corresponding lens, and the "thickness or interval" corresponding to the image side of the lens is the center interval between the corresponding lens and the next lens.

[0079] The parameters of the conical lens and the F12.5@532nm focusing lens are shown in Table 2.

[0080] Table 2 Optical parameters of the conic lens and focusing lens

[0081]

[0082] Note: After passing through the reflecting mirror, the radii of curvature of each lens are reversed.

[0083] like Figure 2 As shown, this embodiment uses a 532nm laser wavelength, a 7ns pulse width, an incident collimated beam with a φ6mm incident spot, and a power of 500W. A focusing lens with an F12.5mm@532nm aperture is selected. Figure 2 In the diagram, a, b, and c represent adjusting the magnification of the beam expander from 0.5X to 0.9X, the incident aperture from φ3mm to φ5.4mm, the inner diameter d1 of the annular focused spot being φ100um, the outer diameter d2 changing from φ128um to φ146um, and the ratio of the inner and outer diameters of the annular spot being 0.4 < d2 / d1 < 0.8.

[0084] Example 2

[0085] like Figure 3As shown, the adjustable ring-shaped focusing spot system includes a laser, a zoom beam expander, a 45° total reflection mirror, a conical lens, and a focusing lens arranged sequentially from the object side to the image side. In this case, to adjust the inner diameter of the ring-shaped focusing spot to φ250µm, a focusing lens with a focal length of F30@532nm is selected. Unless otherwise specified in this example, the parameters of the laser, zoom beam expander, 45° total reflection mirror, and conical lens are the same as in Example 1.

[0086] Among them, the focusing lens with a focal length of F30@532nm has only one lens, which is the tenth lens. The tenth lens is a plano-convex lens with positive optical power.

[0087] From the 45° total reflection mirror to the image side, the two sides of the tenth lens are the tenth object-side surface S20 and the tenth image-side surface S21, respectively. The radius of curvature of the tenth object-side surface is ∞, and the radius of curvature of the tenth image-side surface is -13.753 mm. The sign of the aforementioned radius of curvature of the tenth lens is the sign before it was reversed by the total reflection mirror. Table 3 shows the signs after the reversal.

[0088] The center thickness of the tenth lens is 10.47 mm; the material is silicon dioxide.

[0089] The center distance from the side of the fifth image to the side of the tenth image is 60mm; the center distance from the side of the tenth image to the water surface S19 is 16mm, and the annular focusing spot is finally focused 18.5mm below the water surface.

[0090] The parameters of the F30@532nm focusing lens are shown in Table 3.

[0091] Table 3 F30@532nm Focusing Lens Parameters

[0092]

[0093] Note: After passing through the reflecting mirror, the signs of the radii of curvature of each lens are reversed. In the table, the "thickness or spacing" corresponding to the object side of the lens is the center thickness of the corresponding lens, and the "thickness or spacing" corresponding to the opposite side of the lens is the center spacing between the corresponding lens and the next lens.

[0094] like Figure 4 As shown, this embodiment uses a 532nm laser wavelength, a 7ns pulse width, an incident collimated beam with a φ6mm incident spot, and a power of 500W. A focusing lens with an F30mm@532nm aperture is selected. Figure 4 In the diagram, a, b, and c represent adjusting the magnification of the beam expander from 0.8X to 1.2X, the incident aperture from φ4.8mm to φ7.2mm, the inner diameter d1 of the annular focused spot being φ250um, the outer diameter d2 changing from φ320um to φ625um, and the ratio of the inner and outer diameters of the annular spot being 0.4 < d2 / d1 < 0.8.

[0095] Example 3

[0096] like Figure 5 As shown, the adjustable ring-shaped focusing spot system includes a laser, a zoom beam expander, a 45° total reflection mirror, a conical lens, and a focusing lens arranged sequentially from the object side to the image side. In this example, to adjust the inner diameter of the ring-shaped focusing spot to φ400µm, a focusing lens with a focal length of F50@532nm is selected. Unless otherwise specified, the parameters for the laser, zoom beam expander, 45° total reflection mirror, and conical lens are the same as in Example 1.

[0097] Among them, the focusing lens with a focal length of F50@532nm has only one lens, which is the eleventh lens. The eleventh lens is a plano-convex lens with positive optical power.

[0098] From the 45° total reflection mirror to the image side, the two sides of the eleventh lens are the eleventh object-side surface S22 and the eleventh image-side surface S23, respectively. The radius of curvature of the eleventh object-side surface S22 is ∞, and the radius of curvature of the eleventh image-side surface S23 is -23 mm. The signs of the aforementioned eleventh lens radii of curvature are the signs before they are reversed by the total reflection mirror. Table 4 shows the signs after the reversal.

[0099] The center thickness of the eleventh lens is 5.82 mm; the material is silicon dioxide.

[0100] The center distance from the side of the fifth image to the side of the eleventh object is 60mm; the center distance from the side of the eleventh image to the water surface S19 is 38mm, and the ring-shaped focusing spot is finally focused 16mm below the water surface.

[0101] The parameters of the F50@532nm focusing lens are shown in Table 4.

[0102] Table 4 F50@532nm Focusing Lens Parameters

[0103]

[0104] Note: After passing through the reflecting mirror, the signs of the radii of curvature of each lens are reversed. In the table, the "thickness or spacing" corresponding to the object side of the lens is the center thickness of the corresponding lens, and the "thickness or spacing" corresponding to the opposite side of the lens is the center spacing between the corresponding lens and the next lens.

[0105] like Figure 6 As shown, a focusing lens with an aperture of F50mm at 532nm was selected. Figure 6 In the diagram, a, b, and c represent the adjustment of the beam expander magnification from 1X to 1.8X, the incident aperture from φ6mm to φ10.8mm, the inner diameter d1 of the annular focused spot being φ400um, the outer diameter d2 changing from φ500um to φ1000um, and the ratio of the inner and outer diameters of the annular spot being 0.4 < d2 / d1 < 0.8.

[0106] like Figure 7 The diagram shows the relationship between the inner diameter of the annular focused spot and the focal length of the focusing lens. Changing the focal length of the focusing lens can independently adjust the inner diameter of the annular focused spot. When the focal length of the focusing lens is 12.5mm, the inner diameter of the annular focused spot is φ100um; when the focal length of the focusing lens is 30mm, the inner diameter of the annular focused spot is φ250um; and when the focal length of the focusing lens is 50mm, the inner diameter of the annular focused spot is φ400um.

[0107] like Figure 8 As shown in the figure, the relationship between the outer diameter of the annular spot and the incident laser aperture is as follows. It can be seen from the figure that when the incident laser aperture changes, the outer diameter of the annular focusing spot changes accordingly. By adjusting the continuously variable magnification beam expander, the incident laser aperture can be continuously controlled, so the outer diameter of the annular spot can be continuously adjusted with high precision. It is compatible with a variety of annular generation units and has strong versatility; it is suitable for high-power laser processing scenarios.

Claims

1. An optical system for a high-power adjustable ring-shaped focusing spot, characterized in that: It includes a zoom beam expander, a total reflection mirror, a conical lens, and a replaceable focusing lens group arranged sequentially from the object side to the image side; The zoom beam expander includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical path propagation direction; The first lens is a biconvex lens with positive optical power; the second lens is a biconcave lens with negative optical power. The third lens is a concave-convex lens with positive optical power; the fourth lens is a plano-convex lens with positive optical power. The replaceable focusing lens group consists of focusing lenses with focal lengths of F12.5, F30, and F50 respectively; The focusing lens with a focal length of F12.5 includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the direction of light propagation; The sixth lens is a biconcave lens with negative optical power; the seventh lens is a meniscus lens with positive optical power and its convex surface curved towards the image side; the eighth lens is a biconvex lens with positive optical power; and the ninth lens is a biconvex lens with positive optical power. The focusing lens with a focal length of F30 includes a tenth lens, which is a plano-convex lens with positive optical power. The focusing lens with a focal length of F50 includes an eleventh lens, which is a plano-convex lens with positive optical power.

2. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1, characterized in that: The variable magnification beam expander is a continuously variable magnification beam expander with an adjustable magnification range of 0.5-2X. It is used to linearly control the beam diameter incident on the annular spot generating unit, thereby achieving continuous adjustment of the outer diameter d2 of the annular spot.

3. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: The first lens, second lens, third lens, fourth lens, and focusing lens are all made of silicon dioxide.

4. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: From the object side to the image side, the two sides of the first lens are the first object side and the first image side, respectively; the two sides of the second lens are the second object side and the second image side, respectively; the two sides of the third lens are the third object side and the third image side, respectively; and the two sides of the fourth lens are the fourth object side and the fourth image side, respectively. The radius of curvature of the first object side is 559.968±0.003mm, and the radius of curvature of the first image side is -43.232±0.003mm; the radius of curvature of the second object side is -21.0238±0.003mm, and the radius of curvature of the second image side is 21.0238±0.003mm; the radius of curvature of the third object side is -63.38±0.003mm, and the radius of curvature of the third image side is -52.098±0.003mm; the radius of curvature of the fourth object side is ∞, and the radius of curvature of the fourth image side is -86.137±0.003mm.

5. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: The center thickness of the first lens is 5±0.02mm; the center thickness of the second lens is 3±0.02mm; the center thickness of the third lens is 6.7±0.02mm; and the center thickness of the fourth lens is 4.5±0.02mm. During the process of changing the magnification of the zoom lens from 0.5X to 2X, the center spacing between the first and second lenses changes from 56.32±0.02mm to 35.05±0.02mm; the center spacing between the second and third lenses changes from 32.66±0.02mm to 83.86±0.02mm; and the center spacing between the third and fourth lenses is 0.6±0.02mm.

6. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: The total reflection mirror is a 45° total reflection mirror; the center distance between the fourth lens and the total reflection mirror is 65±0.02mm; And / or, from the object side to the image side, the two sides of the cone lens are the fifth object side and the fifth image side, respectively. The fifth object side is a plane, and the fifth image side is a cone surface with a cone angle of 140~179°. And / or, the center thickness of the cone lens is 5~10mm; the material used for the cone lens is silicon dioxide; And / or, the center distance between the total reflection mirror and the conical lens is 65±0.02mm.

7. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: When the inner diameter of the fixed annular spot is φ100um, a focusing lens with a focal length of F12.5@532nm is selected; when the inner diameter of the fixed annular spot is φ250um, a focusing lens with a focal length of F30@532nm is selected; when the inner diameter of the fixed annular spot is φ400um, a focusing lens with a focal length of F50@532nm is selected.

8. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: From the object side to the image side, the two sides of the sixth lens are the sixth object side and the sixth image side, the two sides of the seventh lens are the seventh object side and the seventh image side, the two sides of the eighth lens are the eighth object side and the eighth image side, and the two sides of the ninth lens are the ninth object side and the ninth image side. The radius of curvature of the sixth object's side surface is -25±0.003mm, and the radius of curvature of the sixth image's side surface is 25±0.003mm; the radius of curvature of the seventh object's side surface is -150.53±0.003mm, and the radius of curvature of the seventh image's side surface is -21.5±0.003mm; the radius of curvature of the eighth object's side surface is 42.24±0.003mm, and the radius of curvature of the eighth image's side surface is -42.24±0.003mm; the radius of curvature of the ninth object's side surface is 20.2, and the radius of curvature of the ninth image's side surface is -230.69±0.003mm.

9. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: The center thickness of the sixth lens is 2±0.02mm; the center thickness of the seventh lens is 7±0.02mm; the center thickness of the eighth lens is 7±0.02mm; the center thickness of the ninth lens is 7±0.02mm. The center spacing between the cone lens and the sixth lens is 20±0.02mm; the center spacing between the sixth lens and the seventh lens is 17±0.02mm; the center spacing between the seventh lens and the eighth lens is 1±0.02mm; and the center spacing between the eighth lens and the ninth lens is 1±0.02mm.

10. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: From the object side to the image side, the two sides of the tenth lens are the tenth object side and the tenth image side, respectively. The radius of curvature of the tenth object's side surface is ∞, and the radius of curvature of the tenth image's side surface is -13.753±0.003mm; And / or, the center thickness of the tenth lens is 10.47±0.02mm; the center spacing between the cone lens and the tenth lens is 60±0.02mm.

11. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: From the object side to the image side, the two sides of the eleventh lens are the eleventh object side and the eleventh image side, respectively. The radius of curvature of the eleventh object side is -23±0.003mm, and the radius of curvature of the eleventh image side is ∞. And / or, the center thickness of the eleventh lens is 5.82±0.02mm; the center spacing between the cone lens and the eleventh lens is 60mm.

12. The optical system for a high-power adjustable ring-shaped focusing spot according to claim 1 or 2, characterized in that: The compatible laser uses a 532nm laser band, a 7ns pulse width, a collimated incident beam of 6mm, and a power of 500W. The laser, a variable magnification beam expander, a 45° total reflection mirror, a conical lens, and a replaceable focusing lens group are arranged sequentially from the object side to the image side.

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