Processing head for microjet laser machining

Abstract

The application discloses a machining head for microjet laser processing, and relates to the technical field of microjet laser processing. The machining head comprises an objective lens, a window sheet, a water cavity and a nozzle, and the objective lens, the window sheet, the water cavity and the nozzle are coaxially arranged in sequence along a first direction. The objective lens comprises a lens barrel and first double cemented lenses, second double cemented lenses and a positive meniscus lens which are coaxially arranged in sequence in the lens barrel. The lens barrel comprises a first port and a second port, and the first direction is the direction from the first port to the second port. The spherical aberration generated by the combination of the first double cemented lenses, the second double cemented lenses, the positive meniscus lens and the window sheet satisfies a first preset range, and the chromatic aberration generated satisfies a second preset range. Thus, the chromatic aberration of blue light and green light can be corrected, and the applicability of the objective lens is improved.

Description

[0001] Processing head for microfluidic laser processing Technical Field

[0002] This application relates to the field of microfluidic laser processing technology, and more particularly to a processing head for microfluidic laser processing. Background Technology

[0003] With the rapid development of laser technology, blue laser technology has become increasingly mature, and its application in precision industrial processing is becoming more and more widespread. Against this backdrop, application solutions combining blue lasers with microfluidic processing technology have emerged.

[0004] However, current mainstream microfluidic laser processing technologies generally use green lasers with a wavelength of 0.532 μm as the light source. The accompanying processing head optical system, especially the core focusing objective, is specifically optimized for this particular wavelength. This processing head optical system cannot be used in the shorter wavelength 0.470 μm blue light band. Applying it to the blue light band would result in significant degradation of the focused spot quality due to severe chromatic aberration, thus preventing the achievement of efficient and precise processing results. Therefore, existing microfluidic laser processing systems cannot be directly adapted to blue lasers, which greatly limits the application of blue lasers in the field of microfluidic processing. Summary of the Invention

[0005] The main objective of this application is to provide a processing head for microfluidic laser processing, which can eliminate aberrations in both blue and green wavelength lasers and improve the applicability of the objective lens.

[0006] To achieve the above objectives, this application provides a processing head for microfluidic laser processing, including an objective lens, a window, a water cavity, and a nozzle, wherein the objective lens, the window, the water cavity, and the nozzle are coaxially arranged sequentially along a first direction;

[0007] The objective lens includes a lens barrel and a first cemented doublet, a second cemented doublet, and a positive meniscus lens, which are coaxially disposed inside the lens barrel along a first direction. The lens barrel includes a first port and a second port, and the first direction is the direction from the first port toward the second port.

[0008] The spherical aberration generated by the combination of the first cemented doublet lens, the second cemented doublet lens, the positive meniscus lens, and the window plate satisfies a first preset range, and the chromatic aberration generated satisfies a second preset range.

[0009] Optionally, the first cemented doublet lens includes a first portion and a second portion, the first portion being a biconcave lens and the second portion being a biconvex lens; the second cemented doublet lens includes a third portion and a fourth portion, the third portion being a biconvex lens and the fourth portion being a biconcave lens; the second portion of the first cemented doublet lens and the third portion of the second cemented doublet lens are disposed opposite to each other, and the first portion of the first cemented doublet lens and the fourth portion of the second cemented doublet lens are disposed opposite to each other.

[0010] Optionally, the refractive index of the first portion of the first cemented doublet lens is 1.7234, the Abbe number is 37.992, and the center thickness is 3 mm; the refractive index of the second portion of the first cemented doublet lens is 1.5618, the Abbe number is 64.199, and the center thickness is 10 mm; the radius of curvature of the first surface of the first cemented doublet lens is 119.12 mm, the radius of curvature of the second surface of the first cemented doublet lens is 27 mm, and the radius of curvature of the third surface of the first cemented doublet lens is -47.98 mm.

[0011] Optionally, the refractive index of the third portion of the second cemented doublet lens is 1.67, the Abbe number is 51.738, and the center thickness is 8 mm; the refractive index of the fourth portion of the second cemented doublet lens is 2.0007, the Abbe number is 25.426, and the center thickness is 3 mm; the radius of curvature of the first surface of the second cemented doublet lens is 42.01 mm, the radius of curvature of the second surface of the second cemented doublet lens is -57.33 mm, and the radius of curvature of the third surface of the second cemented doublet lens is 110.07 mm.

[0012] Optionally, the positive meniscus lens has a refractive index of 1.8348, an Abbe number of 42.725, and a center thickness of 7 mm; the radius of curvature of the first surface of the positive meniscus lens is 16.11 mm, and the radius of curvature of the second surface of the positive meniscus lens is 35.40 mm.

[0013] Optionally, the first and second portions of the first cemented doublet lens have the same coefficient of thermal expansion, and the third and fourth portions of the second cemented doublet lens have the same coefficient of thermal expansion.

[0014] Optionally, the objective lens further includes a retaining ring, a first spacer, and a second spacer; the retaining ring is disposed between the first port of the lens barrel and the first cemented doublet lens for fixing the first cemented doublet lens; the first spacer is disposed between the first cemented doublet lens and the second cemented doublet lens for fixing the first cemented doublet lens and the second cemented doublet lens; the second spacer is disposed between the second cemented doublet lens and the positive meniscus lens for fixing the positive meniscus lens.

[0015] Optionally, the window is connected to the second port of the objective lens barrel; the nozzle has a through hole along the first direction; the objective lens is used to focus the light beam into the water cavity and the through hole, and the light beam includes a light beam with a wavelength of a first band and a second band.

[0016] Optionally, the window has a refractive index of 1.4585 and an Abbe number of 67.821.

[0017] Optionally, the first band is 0.470 μm and the second band is 0.532 μm.

[0018] The processing head for microfluidic laser processing disclosed in this application comprises a first cemented doublet lens, a second cemented doublet lens, a positive meniscus lens, and a window. Both the first and second cemented doublet lenses can provide positive spherical aberration, negative chromatic aberration, negative spherical aberration, and positive chromatic aberration. The positive meniscus lens provides both positive spherical aberration and negative chromatic aberration, and the window provides positive spherical aberration, negative spherical aberration, and negative chromatic aberration. By combining the first cemented doublet lens, the second cemented doublet lens, the positive meniscus lens, and the window, the spherical aberration generated by each component can be canceled, ensuring that the spherical aberration meets a first preset range. Similarly, the chromatic aberration generated by each component can also be canceled, ensuring that the chromatic aberration meets a second preset range. This achieves aberration correction of the beam and improves the applicability of the objective lens. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a processing head for microfluidic laser processing according to an embodiment of this application;

[0020] Figure 2 This is a Seidel diagram of an example processing head optical system of this application;

[0021] Figure 3 This is a fan-shaped diagram of an example processing head optical system of this application;

[0022] Figure 4 This is a dot diagram of an example processing head optical system of this application;

[0023] Figure 5 This is a modulation transfer function diagram of an example processing head optical system of this application;

[0024] Figure 6 This is a color focus shift diagram of an example processing head optical system of this application;

[0025] In the figure, 100 is the objective lens; 110 is the first cemented doublet; 120 is the second cemented doublet; 130 is the positive meniscus lens; 140 is the lens barrel; 150 is the retaining ring; 160 is the first spacer; 170 is the second spacer; 200 is the window; 300 is the water cavity; 400 is the nozzle; and 500 is the metal component.

[0026] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] In high-end precision manufacturing fields, such as micro-nano fabrication, semiconductor dicing, and brittle material processing, microjets laser processing technology has become a key process due to its advantages such as small heat-affected zone, high processing accuracy, and no pollution. The core of this technology lies in coupling a laser beam through a specially designed processing head into a micron-scale water jet to form an energy carrier, thereby achieving "cold" processing of the workpiece.

[0029] Currently, the light source relied upon by microfluidic laser processing technology is mostly a 0.532µm green laser. Its entire optical transmission and focusing system, from lens coating to aberration correction of the objective lens, is specifically optimized around this fixed wavelength.

[0030] However, with breakthroughs and developments in blue semiconductor laser technology, blue lasers with a wavelength of approximately 0.470µm are attracting increasing attention due to their superior absorption efficiency and application potential in processing specific materials (such as highly reflective metals like copper and gold). However, introducing this novel light source into existing microfluidic processing systems faces compatibility challenges: focusing objectives designed specifically for green light exhibit significant degradation in focal energy density and spot quality when applied to the blue light band due to insurmountable chromatic aberration and spherical aberration, failing to meet the requirements of precision machining. Therefore, developing an optical system compatible with both important industrial wavelengths while maintaining excellent focusing performance has become an urgent need to advance this technology.

[0031] Therefore, this application provides a processing head for microfluidic laser processing. By using a combination of a first cemented doublet lens, a second cemented doublet lens, a positive meniscus lens, and a window, and by designing the relevant parameters of the first cemented doublet lens, the second cemented doublet lens, the positive meniscus lens, and the window, the spherical aberration and chromatic aberration of the objective lens can be brought close to zero, thereby achieving aberration correction for both blue and green laser beams and improving the applicability of the objective lens.

[0032] Figure 1This is a cross-sectional view of a processing head for microfluidic laser processing according to an embodiment of this application. For example... Figure 1 As shown, the processing head may include an objective lens 100, a window 200, a water cavity 300, and a nozzle 400, which are arranged coaxially in sequence along a first direction.

[0033] The objective lens 100 includes a lens barrel 140 and a first cemented doublet lens 110, a second cemented doublet lens 120, and a positive meniscus lens 130, which are coaxially arranged inside the lens barrel 140 along a first direction. The lens barrel 140 includes a first port and a second port, and the first direction is the direction from the first port to the second port. The spherical aberration generated by the combination of the first cemented doublet lens 110, the second cemented doublet lens 120, and the positive meniscus lens 130 satisfies a first preset range, and the chromatic aberration generated satisfies a second preset range.

[0034] First, it should be noted that the first preset range and the second preset range can be set by the staff according to actual needs. Both the first preset range and the second preset range are small numerical ranges that gradually approach zero.

[0035] In this embodiment, the lens barrel 140 can be a cylindrical structure, and its inner diameter can be precisely designed according to the size of the lens it accommodates to ensure that each lens assembly can be stably and accurately installed in a predetermined position. The interior of the lens barrel 140 may be provided with steps and threads, so that each assembly and lens can be stably and securely installed inside the lens barrel 140.

[0036] The lens barrel 140 can be made of a material with high strength, high rigidity, and low coefficient of thermal expansion, such as a special alloy, to reduce the impact of ambient temperature changes on the optical performance of the objective lens 100. During the manufacturing process of the lens barrel 140, precision machining techniques can be employed to ensure an extremely high level of smoothness on the inner wall of the lens barrel 140, avoiding light scattering caused by roughness of the inner wall and thus guaranteeing the imaging quality of the objective lens 100.

[0037] In this embodiment, the lens barrel 140 includes a first port and a second port, which are located at opposite ends of the lens barrel 140 along its axial direction. The diameter of the first port is larger than the diameter of the second port. A laser beam can enter the objective lens 100 through the first port, be focused by the objective lens 100, and exit through the second port. The first and second ports can also be used to connect to other components; for example, the first port can be connected to a laser, and the second port can be connected to a window 200.

[0038] It should be noted that the objective lens 100 of this embodiment is applicable to blue lasers with a wavelength of 0.470µm and green lasers with a wavelength of 0.532µm. Therefore, the objective lens 100 can be used with a blue laser or with a green laser.

[0039] In this embodiment, the first cemented doublet lens 110, the second cemented doublet lens 120, and the positive meniscus lens 130 can be arranged coaxially inside the lens barrel 140 in sequence along a first direction. The first direction is the direction from the first port to the second port, i.e., the direction of light propagation. It should be noted that a cemented doublet lens refers to a lens assembly formed by bonding two lenses together using a cementing process. This structure helps to correct chromatic aberration and spherical aberration, thereby improving image quality.

[0040] Furthermore, after combining the first cemented doublet 110, the second cemented doublet 120, the positive meniscus lens 130, and the window 200, based on the relevant parameter settings of the first cemented doublet 110, the second cemented doublet 120, the positive meniscus lens 130, and the window 200, the spherical aberration generated after combination is reduced and approaches zero, and the chromatic aberration generated after combination is also reduced and approaches zero. Thus, aberration correction is achieved for light beams of two wavelengths, 0.47µm and 0.532µm.

[0041] Continue to refer to Figure 1 In some embodiments, the first cemented doublet lens 110 includes a first portion and a second portion, the first portion being a biconcave lens and the second portion being a biconvex lens; the second cemented doublet lens 120 includes a third portion and a fourth portion, the third portion being a biconvex lens and the fourth portion being a biconcave lens; the second portion of the first cemented doublet lens 110 and the third portion of the second cemented doublet lens 120 are disposed opposite to each other, and the first portion of the first cemented doublet lens 110 and the fourth portion of the second cemented doublet lens 120 are disposed opposite to each other.

[0042] Specifically, both the first cemented doublet lens 110 and the second cemented doublet lens 120 are formed by cementing two lenses together. Therefore, both the first cemented doublet lens 110 and the second cemented doublet lens 120 can be divided into two parts. One lens in the first cemented doublet lens 110 is designated as the first part, and the other lens as the second part; one lens in the second cemented doublet lens 120 is designated as the third part, and the other lens as the fourth part.

[0043] The first portion of the first cemented doublet lens 110 is a biconcave lens, located near the first port of the lens barrel 140; the second portion of the first cemented doublet lens 110 is a biconvex lens, located below the first portion. The third portion of the second cemented doublet lens 120 is a biconvex lens, located below the first cemented doublet lens 110; the fourth portion of the second cemented doublet lens 120 is a biconcave lens, located below the third portion.

[0044] After the laser beam enters from the first port, it passes through the first and second portions of the first cemented doublet lens 110, the third and fourth portions of the second cemented doublet lens 120, and then through the positive meniscus lens 130 before exiting from the second port of the lens barrel 140.

[0045] In some embodiments, the first portion of the first cemented doublet lens 110 can be made of H-ZBAF21 material. The refractive index of the first portion of the first cemented doublet lens 110 can be 1.7234, the Abbe number can be 37.992, and the center thickness can be 3 mm. The second portion of the first cemented doublet lens 110 can be made of H-K9L material. The refractive index of the second portion of the first cemented doublet lens 110 can be 1.5618, the Abbe number can be 64.199, and the center thickness can be 10 mm.

[0046] Furthermore, along the first direction, the three surfaces of the first cemented doublet lens 110 are respectively designated as the first surface, the second surface, and the third surface of the first cemented doublet lens 110. The radius of curvature of the first surface of the first cemented doublet lens 110 is 119.12 mm, the radius of curvature of the second surface is 27 mm, and the radius of curvature of the third surface is -47.98 mm.

[0047] Based on the above parameters, the first surface of the first cemented doublet lens 110 can produce positive spherical aberration and negative chromatic aberration, the second surface of the first cemented doublet lens 110 can produce negative spherical aberration and positive chromatic aberration, and the third surface of the first cemented doublet lens 110 can produce positive spherical aberration and negative chromatic aberration.

[0048] In some embodiments, the materials of the first and second portions of the first cemented doublet lens 110 have the same coefficient of thermal expansion. Specifically, the coefficient of thermal expansion of the materials of both the first and second portions of the first cemented doublet lens 110 is 7.0 × 10⁻⁶. -6 Since the thermal expansion coefficients of the first and second parts are the same, the first doublet lens 110 will not be damaged when the temperature rises due to the inconsistency of the thermal expansion coefficients of the first and second parts.

[0049] In some embodiments, the third portion of the second cemented doublet lens 120 may be made of H-LAK67 material. The refractive index of the third portion of the second cemented doublet lens 120 is 1.67, the Abbe number is 51.738, and the center thickness is 8 mm. The fourth portion of the second cemented doublet lens 120 may be made of H-ZLAF90 material. The refractive index of the fourth portion is 2.0007, the Abbe number is 25.426, and the center thickness is 3 mm.

[0050] Furthermore, along the first direction, the three surfaces of the second cemented doublet lens 120 are respectively designated as the first surface, the second surface, and the third surface of the second cemented doublet lens 120. The radius of curvature of the first surface of the second cemented doublet lens 120 is 42.01 mm, the radius of curvature of the second surface is -57.33 mm, and the radius of curvature of the third surface is 110.07 mm.

[0051] Based on the above parameters, the first surface of the second cemented doublet 120 can produce negative spherical aberration and negative chromatic aberration, the second surface of the second cemented doublet 120 can produce negative spherical aberration and positive chromatic aberration, and the third surface of the second cemented doublet 120 can produce positive spherical aberration and negative chromatic aberration.

[0052] In some embodiments, the materials of the third and fourth portions of the second cemented doublet lens 120 have the same coefficient of thermal expansion. Specifically, the coefficient of thermal expansion of the materials of the third and fourth portions of the second cemented doublet lens 120 is both 7.0 × 10⁻⁶. -6 Since the thermal expansion coefficients of the materials in the third and fourth parts are the same, the second doublet lens 120 will not be damaged when the temperature rises due to the inconsistency of the thermal expansion coefficients of the materials in the third and fourth parts.

[0053] Continue to refer to Figure 1 In some embodiments, the refractive index of the positive meniscus lens 130 is 1.8348, the Abbe number is 42.725, and the center thickness is 7 mm; the radius of curvature of the first surface of the positive meniscus lens 130 is 16.11 mm, and the radius of curvature of the second surface of the positive meniscus lens 130 is 35.40 mm.

[0054] Specifically, the positive meniscus lens 130 can be made of H-ZLAF55D material. The refractive index of the positive meniscus lens 130 can be 1.8348, the Abbe number can be 42.725, and the center thickness can be 7mm. Further, along the first direction, the two surfaces of the positive meniscus lens 130 are respectively designated as the first surface and the second surface of the positive meniscus lens 130; the radius of curvature of the first surface of the positive meniscus lens 130 is 16.11mm, capable of producing positive spherical aberration and negative chromatic aberration; the radius of curvature of the second surface of the positive meniscus lens 130 is 35.40mm, capable of producing positive spherical aberration and negative chromatic aberration.

[0055] Continue to refer to Figure 1 In some embodiments, the objective lens 100 may further include a retaining ring 150, a first spacer 160, and a second spacer 170.

[0056] The pressure ring 150 is disposed between the first port of the lens barrel 140 and the first cemented doublet lens 110 for fixing the first cemented doublet lens 110; the first spacer 160 is disposed between the first cemented doublet lens 110 and the second cemented doublet lens 120 for fixing the first cemented doublet lens 110 and the second cemented doublet lens 120; and the second spacer 170 is disposed between the second cemented doublet lens 120 and the positive meniscus lens 130 for fixing the second cemented doublet lens 120 and the positive meniscus lens 130.

[0057] Specifically, the retaining ring 150 can be a metal ring with external threads. The retaining ring 150 can be pressed together with the internal threads of the lens barrel 140 through the external threads, so that the retaining ring 150 is installed inside the lens barrel 140. The upper and lower surfaces of the retaining ring 150 are both flat. The lower surface of the retaining ring 150 contacts the first surface of the first cemented doublet lens 110, thereby fixing the first cemented doublet lens 110 below the retaining ring 150 and inside the lens barrel 140.

[0058] The first spacer 160 can be a metal ring with a rectangular cross-section. The upper surface of the first spacer 160 contacts the third surface of the first cemented doublet lens 110, and the lower surface of the first spacer 160 contacts the first surface of the second cemented doublet lens 120. The first spacer 160 is used to fix the first cemented doublet lens 110 and the second cemented doublet lens 120, and to create an air gap between the first cemented doublet lens 110 and the second cemented doublet lens 120.

[0059] The second spacer 170 can be a metal ring with a pentagonal cross-section. The upper surface of the second spacer 170 is flat and contacts the third surface of the second cemented doublet lens 120. The lower inner side of the second spacer 170 is conical and tangent to the first surface of the positive meniscus lens 130. The upper inner side of the second spacer 170 is also conical, thus ensuring smooth passage of the edge beam. In this embodiment, the second spacer 170 is used to fix the second cemented doublet lens 120 and the positive meniscus lens 130, and to create an air gap between them.

[0060] Continue to refer to Figure 1 In some embodiments, the refractive index of the window 200 is 1.4585, the Abbe number is 67.821, and the window 200 is connected to the second port of the tube 140 of the objective lens 100.

[0061] Specifically, the window 200 can be a flat glass plate, and the material can be fused silica; the refractive index of the window 200 can be 1.4585, and the Abbe number can be 67.821. Further, along the first direction, the two surfaces of the window 200 are respectively designated as the first surface and the second surface of the window 200; the first surface of the window 200 can produce negative spherical aberration and positive chromatic aberration, and the second surface of the window 200 can produce positive spherical aberration and positive chromatic aberration. In this embodiment, the window 200 is used to protect the internal environment of the water cavity 300, preventing the liquid in the water cavity 300 from contaminating or corroding the objective lens 100.

[0062] Continue to refer to Figure 1 In some embodiments, the processing head may also include a metal device 500 for mounting the window 200 and the nozzle 400, the upper part of which is connected to the second port of the objective lens barrel 140.

[0063] In some embodiments, the water cavity 300 is a cavity enclosed by the window 200, the nozzle 400, and the metal device 500. The nozzle 400 is disposed below the water cavity 300, the upper surface of the nozzle 400 is flat, and a through hole is formed at the center along a first direction. The through hole is conical, and the upper diameter of the through hole is smaller than the lower diameter.

[0064] Table 1 shows the relevant data of the processing head, including the radius of curvature, thickness, material, and light-transmitting semi-aperture of each lens, window 200, and water cavity 300.

[0065] Table 1. Processing Head Data Sheet

[0066]

[0067] In practical applications, objective lens 100 is used to focus the light beam into water cavity 300 and through-hole; furthermore, high-pressure water can enter water cavity 300 from all sides and be ejected from through-hole at the center of the upper surface of nozzle 400, forming a high-pressure water jet. The laser focusing point coincides with the center of the through-hole on the upper surface, and the laser propagates through total internal reflection in the high-pressure water jet, forming a laser microjet. It should be noted that the light beam includes a first wavelength band and a second wavelength band; the first wavelength band is 0.470µm, and the second wavelength band is 0.532µm.

[0068] The following analysis further examines the principle of aberration elimination achieved by the processing head, referencing the specific structure and parameters of the aforementioned processing head used for microfluidic laser processing.

[0069] Figure 2 This is a Seidel diagram of an example processing head optical system according to this application. It should be noted that the processing head optical system consists of the first cemented doublet lens 110, the second cemented doublet lens 120, the positive meniscus lens 130, and the window 200 described above. Furthermore, Figure 2It was obtained using a laser with a wavelength of 0.5320 μm. Figure 2 The grid lines are spaced 0.05 mm apart, and the maximum aberration range is 0.5 mm.

[0070] Figure 2 In the diagram, apertures 2 to 11 are used to characterize the first, second, and third surfaces of the first cemented doublet lens 110, the first, second, and third surfaces of the second cemented doublet lens 120, the first and second surfaces of the positive meniscus lens 130, and the first and second surfaces of the window 200, respectively.

[0071] from Figure 2 As can be seen, the first surface of the first cemented doublet lens 110 (i.e., at aperture 2) can produce very small positive spherical aberration and very small negative chromatic aberration, the second surface of the first cemented doublet lens 110 (i.e., at aperture 3) can produce large negative spherical aberration and small positive chromatic aberration, and the third surface of the first cemented doublet lens 110 (i.e., at aperture 4) can produce large positive spherical aberration and small negative chromatic aberration.

[0072] Furthermore, the first surface of the second cemented doublet 120 (i.e., at aperture 5) can produce very small negative spherical aberration and very small negative chromatic aberration, the second surface of the second cemented doublet 120 (i.e., at aperture 6) can produce large negative spherical aberration and small positive chromatic aberration, and the third surface of the second cemented doublet 120 (i.e., at aperture 7) can produce very small positive spherical aberration and very small negative chromatic aberration.

[0073] Furthermore, the first surface of the positive meniscus lens 130 (i.e., at aperture 8) can produce a large positive spherical aberration and a small negative chromatic aberration, and the second surface of the positive meniscus lens 130 (i.e., at aperture 9) can produce a large positive spherical aberration and a small negative chromatic aberration.

[0074] Furthermore, the first surface of the window 200 (i.e., at aperture 10) can produce a large negative spherical aberration and a small positive chromatic aberration, while the second surface of the window 200 (i.e., at aperture 11) can produce a very small positive spherical aberration and a very small positive chromatic aberration.

[0075] When these positive and negative spherical aberrations are added together, they almost cancel each other out, resulting in a spherical aberration close to zero when the lenses are combined. Similarly, when these positive and negative chromatic aberrations are added together, they almost cancel each other out, resulting in a chromatic aberration close to zero when the lenses are combined.

[0076] Figure 3 This is an example of the optical sector plot of a processing head optical system according to this application. The optical sector plot can represent the aberrations of the optical system. Figure 3 The origin of the coordinate system represents the center point of the lens. For example... Figure 3As shown, regardless of whether the laser wavelength is 0.470µm or 0.532µm, the aberration increases closer to the lens edge. Specifically, the grid range in the figure is ±5µm. The maximum aberration for the 0.470µm wavelength laser is at the lens edge, and the aberration is less than ±3µm. The maximum aberration for the 0.532µm wavelength laser is also at the lens edge, and the aberration is less than ±1µm.

[0077] Figure 4 This is a dot plot of an example processing head optical system of this application. The dot plot is used to illustrate the dispersion pattern of the beam. Figure 4 The grid size is 10µm, the field of view is 1, the RMS radius (i.e., the speckle radius) is 0.987, the GEO radius (i.e., the geometric radius) is 2.504, the scaling scale is 10, and the reference is the principal ray. Figure 4 As shown, the RMS (average) radius of the diffuse spot of the 0.470µm and 0.532µm wavelength lasers is 1.052µm, indicating that the optical system has a good beam-focusing effect.

[0078] Figure 5 This is a modulation transfer function diagram of an example processing head optical system of this application. For example... Figure 5 As shown, the modulation function curve of the optical system (i.e., the lower curve in the figure) is very close to the diffraction limit, which indicates that the aberration of the optical system is very small.

[0079] Figure 6 This is a color shift map of an example processing head optical system according to this application. The color shift map is used to represent the axial chromatic aberration of the optical system. For example... Figure 6 As shown, the axial distance between the focal points of the 0.470µm and 0.532µm wavelength lasers is less than 4µm, which is much smaller than the focal depth of the optical system.

[0080] Therefore, the processing head of this application embodiment has an internal optical system that features a collaborative aberration correction design for two specific wavelengths: 0.47μm (blue light) and 0.532μm (green light), ensuring high-quality focused light spots in both wavelength bands. Thus, this processing head can be perfectly adapted to laser light sources of different wavelengths (blue light, green light, or combinations thereof), greatly expanding its application range.

[0081] Secondly, by employing cemented doublet lenses, the number of individual lens elements in the processing head is effectively reduced while ensuring excellent optical performance. This not only simplifies the optical structure and reduces manufacturing costs, but more importantly, it reduces installation errors during assembly, significantly improving the consistency and stability of the optical system.

[0082] Finally, by selecting materials with the same or similar coefficients of thermal expansion to manufacture cemented doublet lenses, the choice of materials ensures that the bonding interface will not generate internal stress due to the different degrees of expansion or contraction of the two materials when the optical system faces changes in ambient temperature. This fundamentally avoids lens cracking, deformation, or deterioration of optical performance caused by thermal stress, and greatly improves the long-term reliability of the system under complex working conditions.

[0083] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A processing head for microfluidic laser processing, characterized in that, It includes an objective lens, a window, a water cavity, and a nozzle, wherein the objective lens, the window, the water cavity, and the nozzle are arranged coaxially in sequence along a first direction; The objective lens includes a lens barrel and a first cemented doublet, a second cemented doublet, and a positive meniscus lens, which are coaxially disposed inside the lens barrel along the first direction. The lens barrel includes a first port and a second port, and the first direction is the direction from the first port toward the second port. Wherein, the spherical aberration generated by the combination of the first cemented doublet lens, the second cemented doublet lens, the positive meniscus lens and the window plate meets the first preset range, and the chromatic aberration generated meets the second preset range; The first cemented doublet lens includes a first portion and a second portion, wherein the first portion is a biconcave lens and the second portion is a biconvex lens; The second cemented doublet lens includes a third portion and a fourth portion, wherein the third portion is a biconvex lens and the fourth portion is a biconcave lens; The second portion of the first cemented doublet lens is disposed opposite to the third portion of the second cemented doublet lens, and the first portion of the first cemented doublet lens and the fourth portion of the second cemented doublet lens are disposed opposite to each other. The first portion of the first cemented doublet lens has a refractive index of 1.7234, an Abbe number of 37.992, and a center thickness of 3 mm. The second portion of the first cemented doublet lens has a refractive index of 1.5618, an Abbe number of 64.199, and a center thickness of 10 mm. The radius of curvature of the first surface of the first cemented doublet lens is 119.12 mm, the radius of curvature of the second surface of the first cemented doublet lens is 27 mm, and the radius of curvature of the third surface of the first cemented doublet lens is -47.98 mm. The refractive index of the third portion of the second cemented doublet lens is 1.67, the Abbe number is 51.738, and the center thickness is 8 mm. The fourth portion of the second cemented doublet lens has a refractive index of 2.0007, an Abbe number of 25.426, and a center thickness of 3 mm. The radius of curvature of the first surface of the second cemented doublet lens is 42.01 mm, the radius of curvature of the second surface of the second cemented doublet lens is -57.33 mm, and the radius of curvature of the third surface of the second cemented doublet lens is 110.07 mm.

2. The processing head for microfluidic laser processing according to claim 1, characterized in that, The positive meniscus lens has a refractive index of 1.8348, an Abbe number of 42.725, and a center thickness of 7 mm. The radius of curvature of the first surface of the positive meniscus lens is 16.11 mm, and the radius of curvature of the second surface of the positive meniscus lens is 35.40 mm.

3. The processing head for microfluidic laser processing according to claim 1, characterized in that, The materials of the first and second portions of the first cemented doublet lens have the same coefficient of thermal expansion, and the materials of the third and fourth portions of the second cemented doublet lens have the same coefficient of thermal expansion.

4. The processing head for microfluidic laser processing according to any one of claims 1 to 3, characterized in that, The objective lens also includes a pressure ring, a first spacer, and a second spacer; The pressure ring is disposed between the first port of the lens barrel and the first cemented doublet lens, and is used to fix the first cemented doublet lens. The first spacer is disposed between the first cemented doublet lens and the second cemented doublet lens to fix the first cemented doublet lens and the second cemented doublet lens; The second spacer is disposed between the second cemented doublet lens and the positive meniscus lens to fix the second cemented doublet lens and the positive meniscus lens.

5. The processing head for microfluidic laser processing according to any one of claims 1 to 3, characterized in that, The window is connected to the second port of the objective lens barrel; The nozzle has a through hole along the first direction; The objective lens is used to focus the light beam into the water cavity and the through hole, and the light beam includes light beams with wavelengths of the first band and the second band.

6. The processing head for microfluidic laser processing according to claim 5, characterized in that, The refractive index of the window is 1.4585, and the Abbe number is 67.

821.

7. The processing head for microfluidic laser processing according to claim 5, characterized in that, The first band is 0.470µm, and the second band is 0.532µm.

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