A long-spot, high-uniformity integrating mirror and system

Abstract

This invention discloses a long-spot high-uniformity integrating mirror and system, belonging to the field of laser processing. It includes a mirror body and a reflecting mirror surface. The reflecting mirror surface comprises multiple rotating sub-surfaces sharing a common rotation axis, with the generatrices of each rotating sub-surface connected end-to-end. These multiple rotating sub-surfaces are used to uniformly project proportionally incident laser beams onto the target spot, thereby ensuring that horizontally incident light, after reflection by the integrating mirror surface, forms a uniform rectangular spot on the working surface. This invention, through the design of the reflecting mirror's generatrices, significantly improves the uniformity of large-width uniformized spots and also enhances the uniformity of small-width spots, effectively improving the processing quality during laser processing and solving the problem of decreased spot uniformity due to left-right energy asymmetry when generating long spots.

Description

Technical Field

[0001] This invention belongs to the field of laser processing, and more specifically, relates to a long-spot, high-uniformity integrating mirror and system. Background Technology

[0002] In many laser processing applications, it is common to use a reflective integrating mirror to shape the incident Gaussian beam into a uniform rectangular spot. Reflective integrating mirrors can be fabricated using copper substrates or other materials, and can also be water-cooled on the back. They are suitable for high-power laser processing; the uniform rectangular spot has a more regular shape and more uniform energy compared to a Gaussian spot.

[0003] Traditional integrating mirrors have a rotation generatrix composed of multiple straight or curved segments. These curved surfaces reflect the light beam into a defined area, forming a uniform spot through multiple superpositions. However, each curved surface of the integrating mirror directly reflects light within its area, corresponding to the spot boundary, but the reflection conditions within the curved surface and the spot itself do not correspond. Furthermore, due to the inherent structural limitations of the integrating mirror, one side is closer to the light source and farther from the working surface, while the other side is closer to the working surface and farther away. Therefore, when the reflected spots are superimposed, one side of the uniform spot has higher energy than the other. The longer the uniform spot, the more pronounced the non-uniformity becomes. In precision machining applications, the unevenness of a long spot results in inconsistent energy distribution across the processing area, significantly impacting the quality of laser processing.

[0004] Therefore, if the problem of unevenness in generating long, uniform light spots in traditional integrating mirrors can be solved, it will be of great value to the application of integrating mirrors. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a long spot high uniformity integrating mirror and system. Its purpose is to solve the technical problem of the decrease in spot uniformity due to the energy asymmetry on the left and right sides when generating a long spot by designing the structure of the reflecting mirror surface so that the laser beam is projected completely uniformly on the target spot.

[0006] To achieve the above objectives, according to one aspect of the present invention, a long-spot high-uniformity integrating mirror is provided, comprising: a mirror body and a reflecting mirror surface;

[0007] The reflecting mirror surface includes multiple rotating sub-surfaces sharing a common rotation axis, with the generatrices of each rotating sub-surface connected end to end;

[0008] Multiple rotating sub-surfaces are used to uniformly project equally incident laser beams onto the target spot, so that the horizontally incident light is reflected by the integrating mirror and a uniform rectangular spot is obtained on the working surface.

[0009] Preferably, the generatrix of the rotating subsurface is concave-convex symmetrical, the mirror surface is symmetrically divided in the middle, and the shape of the generatrix of the reflecting mirror is that the concave and convex shapes alternate from the midpoint of the generatrix to the right, and also alternate from the midpoint to the left.

[0010] Preferably, the generatrix of the rotating subsurface has a convex structure.

[0011] Preferably, the generatrix of the rotating subsurface has a concave structure.

[0012] Preferably, the design method for the rotating subsurface includes the following steps:

[0013] Assume the equation of the generatrix of the subsurface is y = f(x), with the same direction as y = -x, the starting point of the generatrix is ​​A(xa, ya), the height of the generatrix is ​​h, the length of the generated spot is l, the spot is symmetrically distributed on both sides of the y-axis, the working distance is fw, and the coordinates of the two endpoints of the spot are... There is a random point P(xp, yp) on the generatrix. The ray reflected from point P hits a spot at position Q(xq, -fw). Solve for:

[0014]

[0015]

[0016]

[0017] The equation of the generatrix of the subsurface can then be obtained, where k1 is the slope of point P on the generatrix, k2 is the slope of the axis of light reflected to point P, and k3 is the slope of the light beam after reflection at P.

[0018] Preferably, the integrating mirror is made of a highly reflective metallic material.

[0019] Preferably, the surface of the reflective mirror is coated with a high-reflectivity film.

[0020] According to another aspect of the present invention, a long-spot high-uniformity integrating mirror system is provided, including the long-spot high-uniformity integrating mirror as described above, and further including a laser beam emitting device, a reflective collimating parabolic mirror and a working surface;

[0021] The reflective collimating parabolic mirror is arranged along the laser beam emission direction of the laser beam emitting device; the long-spot high-uniformity integrating mirror is arranged along the reflection beam direction of the reflective collimating parabolic mirror, and the mirror body of the long-spot high-uniformity integrating mirror is parallel to the laser beam reflected by the reflective collimating parabolic mirror; the working surface is arranged in the beam emission direction of the long-spot high-uniformity integrating mirror.

[0022] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0023] 1. The long-spot high-uniformity integrating mirror and system proposed in this invention greatly improves the uniformity of wide-width homogenized light spots through the design of the generatrix of the reflecting mirror surface, and can also improve the uniformity of small-width light spots to a certain extent, effectively improving the processing quality during laser processing.

[0024] 2. The long-spot high-uniformity integrating mirror and system proposed in this invention uses an integrating mirror with a larger range of incident beam sizes and reflects the high-energy part in the middle of the incident Gaussian beam to both sides of the beam spot. In this way, a relatively good uniform beam size can be obtained even with an incident beam that is close to one pitch width.

[0025] 3. The long-spot high-uniformity integrating mirror and system proposed in this invention has a high-reflectivity film coated on the reflecting mirror surface of the integrating mirror, which improves the smoothness and reflectivity of the reflecting mirror surface.

[0026] 4. The long-spot high-uniformity integrating mirror and system proposed in this invention do not impose specific requirements on the size and position of the incident spot.

[0027] 5. The long-spot, high-uniformity integrating mirror and system proposed in this invention can be used for processing applications of kilowatt and megawatt-level high-power lasers, greatly expanding the application fields. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the long-spot high-uniformity integrating mirror of the present invention;

[0029] Figure 2 This is a schematic diagram of the reflection between the endpoints and midpoints of the subsurface when a traditional integrating mirror generates a large-width light spot.

[0030] Figure 3 This is a simulation diagram of generating a large-width light spot using a traditional integrating mirror.

[0031] Figure 4 This is a diagram showing the effect of a large-width light spot test experiment using a traditional integrating mirror.

[0032] Figure 5 This is a schematic diagram of the generatrix principle of the convex sub-surface of the long-spot high-uniformity integrating mirror of the present invention;

[0033] Figure 6 This is a schematic diagram of the generatrix principle of the concave sub-surface of the long-spot high-uniformity integrating mirror of the present invention;

[0034] Figure 7 This is a schematic diagram of the high uniformity integrating mirror system for life-growth light spots according to an embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of the concave-convex curved surface integrating mirror used in Embodiment 1 of the present invention;

[0036] Figure 9 This is the light spot pattern obtained from simulation in Embodiment 1 of the present invention;

[0037] Figure 10 This is the energy distribution diagram of the light spot obtained by simulation in Embodiment 1 of the present invention;

[0038] Figure 11 This is a schematic diagram of the principle of the fully concave curved surface integrating mirror used in Embodiment 2 of the present invention;

[0039] Figure 12 This is a schematic diagram of the principle of the fully convex curved surface integrating mirror used in Embodiment 3 of the present invention.

[0040] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-laser beam emitting device; 2-long spot high uniformity integrating mirror; 21-mirror body; 22-reflecting mirror surface; 3-reflective collimating parabolic mirror; 4-working surface. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0042] This invention provides a long-spot, high-uniformity integrating mirror, comprising: a mirror body 21 and a reflecting mirror 22. The reflecting mirror 22 is composed of multiple rotating sub-surfaces sharing a common rotation axis, with the generatrices of each rotating sub-surface connected end-to-end. By solving for the rotation generatrices of each sub-surface, each rotating sub-surface projects a proportionally incident laser beam completely and uniformly onto the target spot. After horizontally incident light is reflected by this integrating mirror, a uniform rectangular spot can be obtained on the working surface.

[0043] Furthermore, to ensure that each rotating subsurface uniformly transmits the laser beam onto the target spot, the subsurface design includes the following steps:

[0044] Assume the equation of the generatrix of the subsurface is y = f(x), with an approximate direction similar to y = -x. The starting point of the generatrix is ​​A(xa, ya), the height of the generatrix is ​​h, the length of the generated spot is l, the spot is symmetrically distributed on both sides of the y-axis, the working distance is fw, and the coordinates of the two endpoints of the spot are... There is a random point P(xp, yp) on the generatrix. The ray reflected from point P hits a spot at position Q(xq, -fw). Solve for:

[0045]

[0046]

[0047]

[0048] If the desired subsurface generatrix is ​​concave, the equation of the subsurface generatrix can be obtained by solving the differential equations of equations (1) and (3); if the desired subsurface generatrix is ​​convex, the equation of the subsurface generatrix can be obtained by solving the differential equations of equations (2) and (3). After the equation of the generatrix is ​​obtained, the endpoint of the subsurface generatrix is ​​determined by passing through the generatrix height, and this endpoint is used as the starting point for solving the next subsurface generatrix. The equations of the generatrixes of other subsurfaces are obtained in the same way.

[0049] like Figure 1 The diagram shown is a schematic of a long-spot, high-uniformity integrating mirror proposed in this invention. This reflective homogenizing mirror includes a mirror body 21 and a reflecting mirror surface 22. The mirror body 21 is cylindrical, and the generatrix of the reflecting mirror surface 22 is formed by rotating a smooth curve composed of alternating concave and convex curves around a rotation axis.

[0050] Figures 2-4 Traditional integrating mirrors reflect light directly from the region boundary to the light spot boundary, but the reflection conditions inside the curved surface and inside the light spot are not correspondingly correlated. Figure 2 This is a schematic diagram showing the reflection positions of the two ends and the midpoint of the generatrix of the subsurface when a traditional integrating mirror generates a large-width light spot. Figure 2 It is quite obvious that the energy inside the homogenized spot generated by the traditional integrator is generally biased towards the side of the integrator that is closer to the working surface; Figure 3 This is a simulation diagram of generating a wide spot using a traditional integrating mirror. It can be seen intuitively that the energy non-uniformity of the wide spot generated by the traditional integrating mirror is as follows: the wider the spot, the worse its uniformity. Figure 4 This is a schematic diagram of the processing when using a traditional integrating mirror to conduct a large-spot experiment. The actual processing effect of the side with higher energy is quite different from that of the side with lower energy.

[0051] like Figure 5 , Figure 6 The figure shows a schematic diagram illustrating the principle of energy reflection from a single subsurface generatrix of the long-spot, high-uniformity integrating mirror of the present invention. Figure 5 For convex generatrices, Figure 6 Both types of concave generatrices can reflect parallel incident light beams onto the light spot completely and uniformly.

[0052] The present invention also proposes a long spot high uniformity integrating mirror system, including a long spot high uniformity integrating mirror 2, a laser beam emitting device 1, a reflective collimating parabolic mirror 3, and a working surface 4;

[0053] The reflective collimating parabolic mirror 3 is arranged along the laser beam emission direction of the laser beam emitting device 1; the long-spot high-uniformity integrating mirror 2 is arranged along the reflection beam direction of the reflective collimating parabolic mirror 3, and the mirror body 21 of the long-spot high-uniformity integrating mirror 2 is parallel to the laser beam reflected by the reflective collimating parabolic mirror 3; the working surface 4 is arranged in the beam emission direction of the long-spot high-uniformity integrating mirror 3.

[0054] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0055] Example 1:

[0056] This implementation example is an integrating mirror system with a long light spot and high uniformity, such as... Figure 7 As shown, the laser beam emitted from the laser beam emitting device 1 is collimated by the reflective collimating parabolic mirror 3, and reflected and collimated into a parallel Gaussian beam. After collimation, the incident direction of the beam must be parallel to the direction of the integrating mirror body, and then the beam is reflected onto the working surface 4. Figure 1 This is a schematic diagram of a wide-width reflecting integrator according to the first embodiment of the present invention. The integrator has a concave-convex symmetrical structure. The shape of the generatrix of the reflecting mirror is that the concave and convex shapes alternate from the midpoint to the right and from the midpoint to the left. Figure 8 This is a schematic diagram of the principle of alternating concave and convex generatrices on a reflecting mirror. By relying on the design of the sub-curved generatrices, the light beam reflected by a single sub-curved surface can be completely and uniformly hit within the light spot. Figure 9 To be Figure 1 The homogenized spot pattern obtained from the simulation of the designed long-spot, high-uniformity integrating mirror in Zemax is obtained. Figure 10 The above simulation shows the energy distribution of the homogenized light spot.

[0057] Example 2:

[0058] like Figure 11 The diagram shown is a schematic of a wide-width reflective integrator according to the second embodiment of the present invention. The integrator is composed of multiple sets of convex sub-surfaces, and the reflector is formed by rotating a generatrix composed of multiple convex curves around a rotation axis.

[0059] Example 3:

[0060] like Figure 12The diagram shown is a schematic of a wide-width reflective integrator according to the third embodiment of the present invention. The integrator is composed of multiple sets of concave sub-surfaces, and the reflector is formed by rotating a generatrix composed of multiple concave curves around a rotation axis.

[0061] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A long-spot, high-uniformity integrating mirror, characterized in that, include: Mirror body (21) and reflecting mirror (22); The reflecting mirror (22) includes multiple rotating sub-surfaces sharing a common rotation axis, with the generatrices of each rotating sub-surface connected end to end; Multiple rotating sub-surfaces are used to uniformly project equally incident laser beams onto the target spot, so that the horizontally incident light is reflected by the integrating mirror and a uniform rectangular spot is obtained on the working surface. The design method for the revolution subsurface includes the following steps: Assume the equation of the generatrix of the subsurface is , direction and The same applies; the starting point of the busbar is A. (xa, ya The height of the generatrix of the subsurface is... h The length of the generated light spot is l The light spots are symmetrically distributed in y The working distance on both sides of the shaft is fw The coordinates of the two ends of the light spot are , There is a random point P on the generatrix. xp,yp The light reflected from point P hits the spot at position Q. xq,-fw ), by solving: The equation of the generatrix of the subsurface can then be obtained, where k 1 is the slope of point P on the generatrix. k 2 is the slope of the axis of light reflected to point P. k 3 is the slope of the beam after it is reflected by P.

2. The long-spot high-uniformity integrating mirror according to claim 1, characterized in that, The generatrix of the rotating subsurface is concave-convex symmetrical, and the mirror surface is symmetrically divided in the middle. The shape of the generatrix of the reflecting mirror is that it alternates between concave and convex to the right from the midpoint of the generatrix, and also alternates between concave and convex to the left from the midpoint.

3. The long-spot high-uniformity integrating mirror according to claim 1, characterized in that, The generatrix of the revolution subsurface has a convex structure.

4. The long-spot high-uniformity integrating mirror according to claim 1, characterized in that, The generatrix of the rotating subsurface has a concave structure.

5. The long-spot high-uniformity integrating mirror according to claim 1, characterized in that, The integrating mirror (2) is made of a highly reflective metallic material.

6. The long-spot high-uniformity integrating mirror according to claim 1, characterized in that, The surface of the reflective mirror (22) is coated with a high-reflectivity film.

7. A long-spot, high-uniformity integrating mirror system, characterized in that, The system includes a long-spot high-uniformity integrating mirror (2) as described in any one of claims 1-6, and also includes a laser beam emitting device (1), a reflective collimating parabolic mirror (3), and a working surface (4). The reflective collimating parabolic mirror (3) is arranged along the laser beam emission direction of the laser beam emitting device (1); the long-spot high-uniformity integrator (2) is arranged along the reflection beam direction of the reflective collimating parabolic mirror (3), and the mirror body (21) of the long-spot high-uniformity integrator (2) is parallel to the laser beam reflected by the reflective collimating parabolic mirror (3); the working surface (4) is arranged in the beam emission direction of the long-spot high-uniformity integrator (2).

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