Laser Engraving Machine

Abstract

The application discloses a laser etching machine, comprising a first laser light source for emitting a first laser with a cross-sectional shape of a strip, a second laser light source for emitting a second laser with a cross-sectional shape of a strip, and a light combiner, wherein the first laser and the second laser are incident to the light combiner, the light combiner is used for combining the first laser and the second laser, and the first laser and the second laser are combined in a manner that the polarization directions are perpendicular to each other. The technical scheme can improve the energy density of the spot center of the laser etching machine.

Description

Technical Field

[0001] This invention relates to the field of laser engraving technology, and in particular to a laser engraving machine. Background Technology

[0002] Existing laser engraving machines typically shape the laser beam into a square spot, minimizing its size to achieve higher energy density. This is because higher energy density allows for the engraving of a wider variety of materials, resulting in higher engraving efficiency. However, this traditional method of increasing energy density by reducing spot size has limitations. Optical devices are constrained by the diffraction limit and manufacturing precision, leading to significant aberrations in extremely small spots. This prevents some light from focusing onto the focal plane, resulting in lower energy density. To broaden the application range and increase engraving efficiency, a laser engraving machine with higher energy density is needed. Summary of the Invention

[0003] The main objective of this invention is to provide a laser engraving machine that aims to increase the energy density at the center of the laser spot.

[0004] To achieve the above objectives, the present invention proposes a laser engraving machine comprising: a first laser source for emitting a first laser with a strip-shaped cross-section; a second laser source for emitting a second laser with a strip-shaped cross-section; and a beam combiner, wherein the first laser and the second laser are incident on the beam combiner, and the beam combiner is used to combine the first laser and the second laser; and the first laser and the second laser are combined in a manner where their polarization directions are mutually orthogonal.

[0005] Optionally, the beam combiner is configured as a polarization beam combiner, and the cross-sections of the first laser and the second laser after beam combining are cross-shaped.

[0006] Furthermore, the laser engraving machine also includes a first collimating lens and a second collimating lens. The first collimating lens is disposed in the optical path between the first laser source and the polarization combining device; the second collimating lens is disposed in the optical path between the second laser source and the polarization combining device.

[0007] Furthermore, the laser engraving machine also includes a first lens barrel and a second lens barrel, wherein the first laser source and the first collimating lens are disposed at both ends of the first lens barrel; and the second laser source and the second collimating lens are disposed at both ends of the second lens barrel.

[0008] Optionally, the first and second lens barrels are configured as cylindrical lens barrels, and the ratio of the diameter to the axial length of the first and second lens barrels is greater than or equal to 2·tan20° and less than or equal to 2·tan30°.

[0009] Furthermore, the laser engraving machine also includes a focusing lens, which is disposed on the light-emitting side of the polarization combining device.

[0010] Optionally, the polarization combining device is configured as a polarization beam splitter; the laser engraving machine satisfies the following constraint:

[0011] 0.8·l1≤D1≤1.02·l1;

[0012] D1≤D2≤1.15·l1;

[0013] D2≤W1≤1.05·D2;

[0014] W1≤H1≤1.05·W1;

[0015] Wherein, l1 is the optical path from the light-emitting surface of the first laser source to the light-incident surface of the first collimating lens, and the optical path from the light-emitting surface of the second laser source to the light-incident surface of the second collimating lens; D1 is the effective surface diameter of the first collimating lens and the second collimating lens; D2 is the diameter of the focusing lens; W1 is the length of the polarizing beam splitter in the optical axis direction; and H1 is the height of the polarizing beam splitter in the direction perpendicular to the optical axis.

[0016] Optionally, the laser engraving machine satisfies the following constraint:

[0017]

[0018] Wherein, D is the diameter of the light spot on the engraving surface of the laser engraving machine; l2 is the optical path from the focusing lens to the focused light spot of the laser engraving machine; l1 is the optical path from the light emitting surface of the first laser source to the light emitting surface of the first collimating lens; the light emitting surfaces of the first laser source and the second laser source are configured as squares, and a is the length of the long side of the light emitting surfaces of the first laser source and the second laser source.

[0019] Furthermore, the laser engraving machine also includes a first galvanometer and a second galvanometer, wherein the first galvanometer is disposed on the light-emitting side of the focusing lens; and the second galvanometer is disposed on the light-emitting side of the first galvanometer.

[0020] Optionally, the laser engraving machine satisfies the following constraint:

[0021]

[0022] 0.8·(D f -2·l3·tanθ)≤b1≤1.1·(D f -2·l3·tanθ);

[0023]

[0024] 0.8·(D f -2·l4·tanθ)≤b2≤1.1·(D f -2·l4·tanθ);

[0025] Wherein, D is the diameter of the laser spot on the engraving surface of the laser engraving machine; l is the distance from the focal point of the laser engraving machine to the focusing lens; l2 is the optical path from the focusing lens to the focused spot of the laser engraving machine; θ is the angle between the line connecting the effective edge of the focusing lens and the focused spot of the laser engraving machine and the optical axis; D f l1 is the effective aperture of the focusing lens; l2 is the distance from the focusing lens to the first galvanometer; l3 is the optical path from the focusing lens to the second galvanometer; the first galvanometer is rectangular in shape, a1 is the length of the long side of the first galvanometer, and b1 is the length of the short side of the first galvanometer; the second galvanometer is rectangular in shape, a2 is the length of the long side of the second galvanometer, and b2 is the length of the short side of the second galvanometer.

[0026] In this invention, it is not necessary to homogenize and shape the laser spot emitted by the laser source into a square or dot shape, but to maintain the strip shape of the first and second lasers. This reduces the number of devices required for homogenization and shaping, such as collimating devices, homogenizing devices, and shaping devices. In addition, the laser spots of the first and second lasers are both Gaussian spots with a higher energy ratio in the middle. Thus, after the first and second lasers are combined by a beam combiner in a mutually orthogonal polarization direction, the middle of the resulting combined spot is a superposition of the high energy ratio regions of the two lasers, thereby increasing the energy density at the center of the laser engraving machine's spot. In particular, this increase in energy density is not achieved by shrinking the spot size, but by reducing the aberrations of the combined spot. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0028] Figure 1 This is a first-view structural schematic diagram of an embodiment of the laser engraving machine of the present invention;

[0029] Figure 2 for Figure 1 A structural schematic diagram from a second perspective of the embodiment;

[0030] Figure 3 for Figure 1 The engraving spot produced in the Chinese embodiment.

[0031] Explanation of icon numbers:

[0032]

[0033]

[0034] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0037] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0038] This invention proposes a laser engraving machine.

[0039] In an embodiment of the present invention, reference is made to Figure 1 and Figure 2 The laser engraving machine includes:

[0040] The first laser source 11 is used to emit a first laser with a strip-shaped cross-section.

[0041] The second laser source 12 is used to emit a second laser with a strip-shaped cross-section; and

[0042] A beam combiner is used to combine the first laser and the second laser into a single beam; and the first laser and the second laser are combined in a manner in which their polarization directions are mutually orthogonal.

[0043] The first laser source 11 and the second laser source 12 can be configured as semiconductor lasers (LDs). In this case, the first laser source 11 and the second laser source 12 do not require shaping, and the emitted laser spot is strip-shaped. Alternatively, the first laser source 11 and the second laser source 12 can be configured as gas lasers, with the emitted spot being elliptical. Since an ellipse has a major axis and a minor axis, it can also be understood as being strip-shaped. The first laser source 11 and the second laser source 12 can also have built-in shaping lenses, such as cylindrical lenses or aspherical lenses, to compress the emitted laser spot in a direction perpendicular to the optical axis, making it strip-shaped. In summary, the technical solution of the present invention does not require additional homogenization and shaping of the first and second lasers, thereby reducing the number of devices required for additional homogenization and shaping. It should be noted that the strip shape can be rectangular, elliptical, or even a rhombus with unequal diagonal lengths. In conclusion, the difference in size of the laser spot in two orthogonal directions can be interpreted as being strip-shaped.

[0044] The beam combiner can be a semi-reflective membrane or a wedge, etc., all of which can be used to overlap the optical paths of the two first lasers and the second laser. In the technical solution of the present invention, the beams of the first laser and the second laser are both Gaussian beams, with a higher energy ratio in the middle. Thus, after the first laser and the second laser are combined in a mutually orthogonal polarization direction using the beam combiner, the middle of the resulting beam is a superposition of the high energy ratio regions of the two lasers, thereby increasing the energy density at the center of the laser engraving machine's beam. In particular, this increase in energy density is not achieved by reducing the beam size, but by reducing the aberrations of the beam combined.

[0045] The shape of the light spot can be obtained through various methods. For example, a grayscale image of the light spot can be captured (where grayscale represents light intensity), and a grayscale threshold can be calculated using existing algorithms. Pixels with grayscale values ​​below the threshold are considered background points, while the set of pixels with grayscale values ​​above the threshold is taken as the shape of the light spot. Alternatively, the shape of the light spot can be determined by plotting a light intensity-position relationship function. Half of the maximum laser intensity is taken as the threshold intensity, and the set of all points in the light intensity-position relationship function with intensity greater than the threshold intensity is taken as the shape of the light spot. The statement that "after the first and second lasers are combined by a beam combiner, they intersect and partially overlap in cross-section" refers to the state of the light spot shape obtained through the above methods (or other existing technologies).

[0046] refer to Figure 1 and Figure 2Optionally, the beam combiner is configured as a polarization beam combiner 20, and the cross-sections of the first laser and the second laser after beam combining are cross-shaped (e.g., ...). Figure 3 (As shown). The polarization combining device 20 has a good light combining effect, mainly reflected in less light energy loss (when the incident light is exactly in the polarization direction corresponding to the polarization combining device 20), thus improving the efficiency of the laser engraving machine.

[0047] The polarization beam combining device 20 can be optionally a polarized beam splitter (PBS), a reflective polarizer (as opposed to an absorptive polarizer), etc.

[0048] refer to Figure 1 and Figure 2 Furthermore, the laser engraving machine also includes a first collimating lens 31 and a second collimating lens 32. The first collimating lens 31 is disposed in the optical path between the first laser source 11 and the polarization beam combiner 20; the second collimating lens 32 is disposed in the optical path between the second laser source 12 and the polarization beam combiner 20. The first collimating lens 31 can collimate the first laser, reducing the beam divergence angle, and can also modulate the transmission direction of the first laser, allowing the first laser to enter the beam combiner at an angle more suitable to the beam combiner. Similarly, the second collimating lens 32 can also be used to collimate the second laser or modulate the transmission direction of the second laser. In addition, by replacing the first collimating lens 31 and the second collimating lens 32, the size and energy density of the final high-energy region of the light spot can be different to adapt to different application scenarios. Both the first collimating lens 31 and the second collimating lens 32 can be spherical lenses.

[0049] refer to Figure 1 and Figure 2 Furthermore, the laser engraving machine also includes a first lens barrel 41 and a second lens barrel 42. The first laser source 11 and the first collimating lens 31 are disposed at both ends of the first lens barrel 41; the second laser source 12 and the second collimating lens 32 are disposed at both ends of the second lens barrel 42. The first lens barrel 41 and the second lens barrel 42 respectively prevent stray light from being generated or affected in the optical path of the first laser from the first laser source 11 to the first collimating lens 31 and in the optical path of the second laser from the second laser source 12 to the second collimating lens 32, thereby improving the stability of the laser engraving machine.

[0050] refer to Figure 1 and Figure 2Optionally, the first lens barrel 41 and the second lens barrel 42 are configured as cylindrical lens barrels, and the ratio of the diameter to the axial length of the first lens barrel 41 and the second lens barrel 42 is greater than or equal to 2·tan20° and less than or equal to 2·tan30°. When the ratio of the diameter to the axial length of the first lens barrel 41 or the second lens barrel 42 is too large, the barrel wall is too close to the laser, which may affect the laser transmission; when the ratio of the diameter to the axial length of the first lens barrel 41 or the second lens barrel 42 is too small, it may not be sufficient to weaken the influence of stray light. When the ratio of the diameter to the axial length of the first lens barrel 41 or the second lens barrel 42 is within the above-mentioned range, the above-mentioned defects can be overcome.

[0051] refer to Figure 1 and Figure 2 Furthermore, the laser engraving machine also includes a focusing lens 50, which is disposed on the light-emitting side of the polarizing beam combiner 20. The focusing lens 50 can focus the beam of the first and second lasers combined onto its focal plane, thereby modulating the beam size and the laser engraving distance. The beam size can be controlled by changing the focusing lens 50. Additionally, the focusing lens 50 can be an even-order aspherical lens.

[0052] refer to Figure 1 and Figure 2 Optionally, when the polarizing beam combiner 20 is configured as a polarizing beam splitter, the laser engraving machine satisfies the following constraint:

[0053] 0.8·l1≤D1≤1.02·l1;

[0054] D1≤D2≤1.15·l1;

[0055] D2≤W1≤1.05·D2;

[0056] W1≤H1≤1.05·W1;

[0057] Wherein, l1 is the optical path from the light-emitting surface of the first laser source 11 to the light-incident surface of the first collimating lens 31, and the optical path from the light-emitting surface of the second laser source 12 to the light-incident surface of the second collimating lens 32; D1 is the effective surface diameter of the first collimating lens 31 and the second collimating lens 32; D2 is the diameter of the focusing lens 50; W1 is the length of the polarizing beam splitter in the optical axis direction; H1 is the height of the polarizing beam splitter in the direction perpendicular to the optical axis. When the laser engraving machine satisfies the above constraints, the utilization rate of the laser can be improved, thereby increasing the efficiency of the laser engraving machine. W1 can be the length of the polarizing beam splitter in the optical axis direction of the first laser source 11, or the length in the optical axis direction of the second laser source 12; both can satisfy the above constraints, or only one can satisfy them. H1 can be the height of the polarizing beam splitter in the direction perpendicular to the optical axes of both the first laser source 11 and the second laser source 12.

[0058] refer to Figure 1 and Figure 2 Optionally, the laser engraving machine satisfies the following constraint:

[0059]

[0060] Where D is the diameter of the laser spot on the engraving surface of the laser engraving machine; l2 is the optical path from the focusing lens 50 to the focused laser spot of the laser engraving machine; l1 is the optical path from the emitting surface of the first laser source 11 to the incident surface of the first collimating lens 31; the emitting surfaces of the first laser source 11 and the second laser source 12 are configured as squares, and a is the length of the longer side of the emitting surfaces of the first laser source 11 and the second laser source 12. By maintaining the above constraints, the focusing lens 50 can perform near-ideal imaging of the laser spot after the first and second lasers are combined, thereby reducing the increase in light spread and concentrating the energy.

[0061] refer to Figure 1 and Figure 2 Furthermore, the laser engraving machine also includes a first galvanometer 61 and a second galvanometer 62. The first galvanometer 61 is disposed on the light-emitting side of the focusing lens 50; the second galvanometer 62 is disposed on the light-emitting side of the first galvanometer 61.

[0062] The first galvanometer 61 and the second galvanometer 62 can vibrate along their respective axes, thereby controlling the focusing position of the laser spot and enabling the laser engraving machine to perform laser engraving on different positions. Typically, the vibration axes of the first galvanometer 61 and the second galvanometer 62 are perpendicular to each other.

[0063] refer to Figure 1 and Figure 2 Optionally, the laser engraving machine satisfies the following constraint:

[0064]

[0065] 0.8·(D f -2·l3·tanθ)≤b1≤1.1·(D f -2·l3·tanθ);

[0066]

[0067] 0.8·(D f -2·l4·tanθ)≤b2≤1.1·(D f -2·l4·tanθ);

[0068] Where D is the diameter of the laser spot on the engraving surface of the laser engraving machine; l is the distance from the focal point of the laser engraving machine to the focusing lens 50; l2 is the optical path from the focusing lens 50 to the focused spot of the laser engraving machine; θ is the angle between the line connecting the effective edge of the focusing lens 50 and the focused spot of the laser engraving machine and the optical axis; D fl is the effective surface diameter of the focusing lens 50; l3 is the distance from the focusing lens 50 to the first galvanometer 61; l4 is the optical path from the focusing lens 50 to the second galvanometer 62; the first galvanometer 61 is rectangular in shape, a1 is the length of the long side of the first galvanometer 61, and b1 is the length of the short side of the first galvanometer 61; the second galvanometer 62 is rectangular in shape, a2 is the length of the long side of the second galvanometer 62, and b2 is the length of the short side of the second galvanometer 62. When using the first galvanometer 61 and the second galvanometer 62, l can be the optical path from the focal point of the laser engraving machine to the focusing lens 50. When using the first galvanometer 61, θ can be the angle between the line connecting the effective surface edge of the focusing lens 50 and the virtual image of the focused spot of the laser engraving machine formed by the first lens and the optical axis. Without loss of generality, the galvanometer can rotate about an axis parallel to its short side, because this provides sufficient incident surface for the incident spot (preventing the incident spot from failing to enter the galvanometer). While maintaining the above limitations, the surface area of ​​the first galvanometer 61 or the second galvanometer 62 can be kept as small as possible, allowing them to rotate within a wider angle while ensuring complete laser incidence. In general, reducing the surface area of ​​the first galvanometer 61 and the second galvanometer 62 (resulting in lighter weight and higher speed movement) improves the efficiency of the laser engraving machine; simultaneously, increasing the rotation angle of the first galvanometer 61 and the second galvanometer 62 allows for a wider range of laser engraving position adjustment.

[0069] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A laser engraving machine, characterized in that, include: The first laser source is used to emit a first laser beam with a strip-shaped cross-section. The second laser source is used to emit a second laser with a strip-shaped cross-section. as well as A beam combiner is used to combine the first laser and the second laser into a beam; and the first laser and the second laser are combined in a manner where their polarization directions are mutually orthogonal. The beam combiner is configured as a polarization beam combiner, and the cross-sections of the first laser and the second laser after beam combining are cross-shaped. The laser engraving machine further includes a first collimating lens and a second collimating lens. The first collimating lens is disposed in the optical path between the first laser source and the polarization combining device; the second collimating lens is disposed in the optical path between the second laser source and the polarization combining device. The laser engraving machine also includes a focusing lens, which is disposed on the light-emitting side of the polarization combining device; The laser engraving machine satisfies the following constraint: in, The diameter of the laser spot on the engraving surface of the laser engraving machine; The optical path from the focusing lens to the focused spot of the laser engraving machine; The optical path length from the emitting surface of the first laser source to the incident surface of the first collimating lens; the emitting surfaces of the first laser source and the second laser source are configured as square. It is the length of the longer side of the light-emitting surface of the first laser source and the second laser source.

2. The laser engraving machine as described in claim 1, characterized in that, The laser engraving machine also includes a first lens barrel and a second lens barrel, wherein the first laser source and the first collimating lens are disposed at both ends of the first lens barrel; and the second laser source and the second collimating lens are disposed at both ends of the second lens barrel.

3. The laser engraving machine as described in claim 2, characterized in that, The first and second lens barrels are configured as cylindrical lens barrels, and the ratio of the diameter to the axial length of the first and second lens barrels is greater than or equal to... and less than or equal to .

4. The laser engraving machine as described in claim 1, characterized in that, The polarization beam combining device is configured as a polarization beam splitter. The laser engraving machine satisfies the following constraint: ； ； ； ； in, The optical path length from the light-emitting surface of the first laser source to the light-incident surface of the first collimating lens, and the optical path length from the light-emitting surface of the second laser source to the light-incident surface of the second collimating lens; The effective surface diameters of the first collimating lens and the second collimating lens; The diameter of the focusing lens; The length of the polarizing beam splitter along the optical axis; The height of the polarizing beam splitter in the direction perpendicular to the optical axis.

5. The laser engraving machine as described in claim 1, characterized in that, The laser engraving machine also includes a first galvanometer and a second galvanometer. The first galvanometer is disposed on the light-emitting side of the focusing lens, and the second galvanometer is disposed on the light-emitting side of the first galvanometer.

6. The laser engraving machine as described in claim 5, characterized in that, The laser engraving machine satisfies the following constraint: ； ； ； ； in, The diameter of the laser spot on the engraving surface of the laser engraving machine; The distance from the focal point of the laser engraving machine to the focusing lens; The optical path from the focusing lens to the focused spot of the laser engraving machine; The angle between the line connecting the effective edge of the focusing lens and the focused spot of the laser engraving machine and the optical axis; The effective aperture diameter of the focusing lens; The distance from the focusing lens to the first galvanometer; The optical path length from the focusing lens to the second galvanometer mirror; the first galvanometer mirror is rectangular in shape. Let the length of the longer side of the first galvanometer be denoted as . The length of the shorter side of the first galvanometer; the second galvanometer is rectangular in shape. Let the length of the longer side of the second galvanometer be denoted as . is the length of the shorter side of the second galvanometer.

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