CN112548324A

CN112548324A - Laser welding method and apparatus for laser welding

Info

Publication number: CN112548324A
Application number: CN201910911051.2A
Authority: CN
Inventors: 冯学明
Original assignee: Branson Ultrasonics Shanghai Co Ltd
Current assignee: Branson Ultrasonics Shanghai Co Ltd
Priority date: 2019-09-25
Filing date: 2019-09-25
Publication date: 2021-03-26

Abstract

The invention relates to a laser welding method, which comprises the following steps: generating a laser beam with Gaussian energy distribution; the generated laser beam is optically converted into a parallel beam, wherein the energy of the parallel beam is in Gaussian distribution; shaping the parallel light beams with the energy in Gaussian distribution into parallel light beams with the energy in uniform distribution; and focusing the parallel light beams with uniformly distributed energy to the welding position. The invention also relates to an apparatus for laser welding using the above method. The invention can reduce the welding defects caused by uneven heating, simplify the equipment for laser welding and weld under the condition of not changing the relative position between the equipment and the welding part.

Description

Laser welding method and apparatus for laser welding

Technical Field

The present invention relates to the field of laser welding, and more particularly, to a laser welding method and an apparatus for laser welding.

Background

This section provides background information related to the present invention, and such information does not necessarily constitute prior art.

Laser welding has been used in the welding of metals and plastics, and utilizes the characteristics of high laser energy and reduced attenuation during propagation to focus laser on the welding part of the welded part, heat and melt the welding part with the laser energy, compress and hold the melted welding part, and weld together after cooling.

However, most of the lasers emit a gaussian beam, that is, the energy distribution of the cross section of the laser beam follows a gaussian function, so that the energy density at the center of the spot is much higher than the energy density at the edge of the spot, which causes the temperature at the center of the spot to be much higher than the temperature at the edge of the spot, further causes the temperature of a molten pool formed on a welding portion receiving the laser beam to be uneven, and finally causes the properties of the material at the welding portion to be changed due to the excess temperature at the center of the spot, and the following conditions occur:

in the welding of thermoplastics, the material is denatured, decomposed, and vaporized, and the appearance is yellowish, scorched, bubble-included, bulge, warpage, and weld breakage, which results in uneven strength of the welded structure, residual welding stress, or sharp reduction in welding strength.

In the welding of metal plate materials, the crystal grains of the materials are coarse, and decomposition (decarburization) and vaporization phenomena occur, and appearance is represented by inclusion, warping, and inter-bead fracture, thereby causing non-uniformity of the strength of the welded structure, residual welding stress, or rapid reduction of the welding strength.

There is known an apparatus for laser welding comprising a fiber laser, a collimator, a movable mirror and a focusing lens, wherein a shaping diffractive optical element may be disposed between the collimator and the movable mirror to shape a beam of a gaussian profile into a uniform beam. Although the shaping diffraction optical element can redistribute the energy of the laser beam, the laser can be refracted, reflected and transmitted when passing through the shaping diffraction optical element, thereby generating the loss of the energy of the beam and increasing the temperature of the shaping diffraction optical element; meanwhile, since the diffraction phenomenon is distributed in space, diffraction spots with different uniformity are formed due to different spatial positions.

In addition, because the focusing lens is positioned behind the reflecting mirror, the size of a focusing light spot is changed at the center and the edge, so that the method is only suitable for welding in a small breadth; meanwhile, since the focal length cannot be changed, this arrangement is only suitable for performing a welding operation on a relatively nearly planar welding portion, and cannot perform a welding operation on a welding portion of a three-dimensional configuration.

Therefore, it is desirable to provide a laser welding method and a laser welding apparatus for implementing the method, which can form a uniform spot of a laser beam to reduce poor welding caused by uneven heating and minimize energy loss in shaping the laser beam. Furthermore, an increasing number of applications require laser welding apparatuses capable of performing welding operations on three-dimensionally configured weld sites. In addition, there is a need to find an apparatus for laser welding that can accomplish welding without changing the relative position between the weld member and the laser welding apparatus, thereby achieving miniaturization of the entire laser welding apparatus.

Disclosure of Invention

This summary is provided to introduce a general summary of the invention, and not a comprehensive disclosure of the full scope of the invention or all of its features.

The invention aims to provide a laser welding method with small energy loss and uniform energy distribution.

Another object of the present invention is to provide a laser welding method which can adjust the focal length in the direction of the X-Y-Z axis, such as the length and width of the welded member, to perform three-dimensional welding according to the geometric configuration of the welded member, thereby achieving miniaturization of the laser welding apparatus as a whole.

Another object of the present invention is to provide an apparatus for laser welding, which can emit laser light for welding with uniform energy distribution.

Another object of the present invention is to provide an apparatus for laser welding that can perform three-dimensional welding with respect to the solid geometry of the welding site of a weld without changing the relative position between the apparatus and the weld.

According to an aspect of the present invention, there is provided a laser welding method, comprising the steps of:

generating a laser beam with Gaussian energy distribution;

the generated laser beam is optically transformed into a parallel beam, wherein the energy of the parallel beam is in Gaussian distribution;

shaping the parallel light beams with the energy in Gaussian distribution into parallel light beams with the energy in uniform distribution; and

the parallel light beams with uniformly distributed energy are focused to the welding position.

Further, the shaping step includes diverging the parallel light beams with the gaussian energy distribution, and converging the diverging light beams into parallel light beams with uniform energy distribution again.

Further, the focusing step includes adjusting a focal position of the parallel beams focused on the X-axis, the Y-axis, and/or the Z-axis to move the focal position along the welding path.

Further, the method also comprises the step of adjusting the spatial range of the focused parallel beams with the uniformly distributed energy, so that larger welding pieces can be welded.

Further, the method also comprises the step of changing the circular light spot formed by gathering the laser beam at the welding position into a linear or rectangular light spot.

Further, the method further comprises changing the orientation of the linear or rectangular spot.

Further, the method comprises the step of changing the circular light spot formed by gathering the laser beam at the welding position into an annular light spot.

According to another aspect of the present invention, there is provided an apparatus for laser welding, comprising:

the laser is used for generating a laser beam with Gaussian energy distribution;

the collimating mirror is used for optically transforming the generated laser beam into a parallel beam through the lens, and the energy of the parallel beam is also in Gaussian distribution;

the shaping mirror comprises at least one aspheric concave lens and at least one aspheric convex lens, the aspheric concave lens is used for diverging the parallel light beams with Gaussian energy distribution, the aspheric convex lens is used for converging the diverging light beams, and the parallel light beams with Gaussian energy distribution are shaped into parallel light beams with uniform energy distribution through the aspheric concave lens and the aspheric convex lens; and

the focusing system comprises at least one first lens, and the first lens is a convex lens and is used for focusing the parallel light beams to the welding position so as to focus the energy of the light beams onto a smaller area, so that the temperature of the welding position reaches the temperature required by melting;

the collimating lens, the shaping lens and the focusing system are sequentially arranged along the optical axis of the laser beam.

Further, the focusing system further comprises a second lens which is arranged in front of the first lens along the optical path, the second lens is a convex lens or a concave lens, and the focal length of the focusing system can be changed by changing the distance between the first lens and the second lens, so that the focal length of the focusing system is adjustable in the Z-axis direction.

Furthermore, the focusing system further comprises an X-axis reflector and a Y-axis reflector which are arranged behind the focusing mirror along the optical path, wherein the X-axis reflector and the Y-axis reflector can rotate along respective rotation axes, and the rotation axes of the X-axis reflector and the Y-axis reflector are orthogonal in a three-dimensional space, so that the emitted light beams are adjustable in the X-axis direction and the Y-axis direction.

Furthermore, a cylindrical mirror can be arranged between the shaping mirror and the focusing system, and the original round light spots can be changed into rectangular or linear light spots by the cylindrical mirror. Further, the cylindrical mirror can also be rotated around the optical axis to change the orientation of the rectangular or linear light spot.

Further, at least one of the aspherical concave lens and the aspherical convex lens of the shaping mirror may be movable along the optical axis to change the circular spot into a substantially annular spot.

Furthermore, the collimating lens is a Galileo collimating lens without a real focus, which is composed of a concave lens and a convex lens, so that the Keplerian collimating lens with the real focus is prevented from causing the gasification of dust and water vapor near the focus to cause the pollution of the mirror surface and influence the use.

According to the equipment and the method, the laser beam with the energy in Gaussian distribution is integrated into the laser beam with the energy uniformly distributed, and poor welding caused by local energy concentration is avoided.

In addition, since the shaping mirror is composed of only the aspherical concave lens and the aspherical convex lens, no diffraction phenomenon occurs, and thus energy loss of the laser beam is very small.

Furthermore, in some embodiments of the invention, the focus of the laser beam may also be adjusted in the direction of the X-Y-Z axis to allow for accurate focused welding based on the spatial configuration of the weld.

In addition, in some embodiments of the present invention, the shape of the light spot may be controlled to form a circular, linear, rectangular, or annular light spot, for example, to meet different welding requirements.

Further, in some embodiments of the present invention, welding can also be performed without changing the relative position between the weld member and the laser welding apparatus, thereby simplifying the structure of the welding machine and achieving miniaturization of the welding machine.

Drawings

The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, which are given by way of example only and which are not necessarily drawn to scale. Like reference numerals are used to indicate like parts in the accompanying drawings, in which:

FIG. 1 shows a flow chart of a laser welding method according to the present invention;

fig. 2 shows a schematic light path diagram of an apparatus for laser welding according to a first embodiment of the present invention;

fig. 3 shows a schematic structural view of an apparatus for laser welding according to a first embodiment of the present invention;

FIG. 4 is a schematic diagram of the optical path of a shaping mirror according to the present invention, wherein an incident light ray with Gaussian energy distribution is shaped into a light ray with uniform energy distribution;

fig. 5 shows a schematic light path diagram of an apparatus for laser welding according to a second embodiment of the present invention; and

fig. 6 shows a schematic configuration of an apparatus for laser welding according to a second embodiment of the present invention.

Detailed Description

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. Corresponding components or parts are designated by the same reference numerals throughout the several views.

In the present invention, in order to better describe the characteristics of the laser beam, some characteristics of the laser beam are represented by different spot shapes, wherein the spot shape is a three-dimensional configuration, the bottom surface shape of the three-dimensional configuration represents the cross-sectional shape of the laser beam, and the height of each point in the bottom surface shape of the three-dimensional configuration represents the beam intensity or energy value of each corresponding point in the cross-sectional shape of the laser beam.

In this context, the term "optical path" refers to a path that the laser light passes through during propagation, and the path may be a straight line or a broken line; the term "optical axis" refers to the central axis of the "optical path" of the laser light, and accordingly, the "optical axis" may be a straight line or a polygonal line.

In fig. 1, a flow chart of a laser welding method according to the invention is shown. The method comprises the following steps:

generating a laser beam with Gaussian energy distribution;

forming a parallel beam by optically transforming the generated laser beam, wherein the energy of the parallel beam is in a Gaussian distribution, and the step is used for ensuring that the laser can propagate without divergence as much as possible and determining the incident angle of the beam;

the parallel light beams with the energy in Gaussian distribution are shaped into parallel light beams with the energy in uniform distribution, and furthermore, the shaping step can be carried out in a mode that the parallel light beams with the energy in Gaussian distribution are firstly diverged and the diverged light beams are converged into the parallel light beams with the energy in uniform distribution again; and

a parallel beam of evenly distributed energy is focused to the weld site to provide sufficient energy density for welding.

Further, in order to focus the focal point at a proper position, the focusing step includes adjusting the focal point position at which the parallel light beams are focused in the X-axis, the Y-axis, and/or the Z-axis, so that the focal point position is moved according to the welding path of the weldment. This adjustment process allows the focal point to be focused within a spatial range, and the focal point can be adjusted to the welding site as long as the welding site is placed within the spatial range. Further, in order to weld a larger weld, the spatial range in which the focus can be focused can also be adjusted.

In addition, in order to adjust the shape of the light spot to meet different welding requirements, the method further comprises changing the circular light spot into a linear or rectangular light spot and changing the orientation of the linear or rectangular light spot, or changing the circular light spot into an annular light spot.

How to implement the above method is described below by way of specific embodiments.

Fig. 2 shows a schematic light path diagram of an apparatus for laser welding according to a first embodiment of the present invention, and fig. 3 shows a schematic structural diagram of the apparatus for laser welding according to the first embodiment of the present invention.

Referring to fig. 2, a laser 1 emits a laser beam having gaussian energy distribution, the laser beam is guided to a collimator lens 3 through, for example, an optical fiber 2, the collimator lens 3 is disposed on an optical axis 100, and outputs a parallel beam along the optical axis 100.

The first spot shape BP of the laser beam output by the optical fiber 2 in FIG. 2₁The gaussian beam having a smaller spot radius (also referred to as a beam waist radius) is more likely to diverge according to the characteristics of the gaussian beam, and thus the laser beam output from the optical fiber 2 is more likely to diverge.

The collimator lens 3 can increase the spot radius of the laser beam transmitted from the optical fiber 2 by lens optical conversion and output the laser beam as a parallel beam, for example, the second spot shape BP of the laser beam output by the collimator lens 3 in fig. 2₂Has a spot radius larger than the first spot shape BP₁The radius of the light spot of (a) is larger,the laser beam output by the collimator lens 3 is less likely to diverge. In general, the collimating lens 3 is a galilean collimating lens without a real focus composed of a concave lens and a convex lens, because the keplerian collimating lens with a real focus composed of a convex lens causes vaporization of fine dust and water vapor at the real focus, thereby causing pollution of the lens surface and affecting the use of the lens.

An adapter 8 may be provided along the light path behind the collimator lens 3, the adapter 8 being used to enhance the coupling strength of the coaxial coupling between the collimator lens 3 and the subsequent device. Obviously, in case the coupling strength is sufficient, the adapter 8 may be omitted.

In order to shape the parallel beam with gaussian energy distribution into a parallel beam with uniform energy distribution, a shaping mirror 4 is disposed along the optical path behind the adapter 8, as shown in fig. 2. The shaping mirror 4 includes at least one aspherical lens, preferably, an aspherical concave lens and an aspherical convex lens.

Referring to fig. 2 and 4, the shaping mirror 4 includes an aspherical concave lens 401 for diverging the parallel beam having gaussian distribution of energy, which is shaped to have the third spot shape BP through the aspherical concave lens 401 and the aspherical convex lens 402, and an aspherical convex lens 402 for converging the diverging beam₃The energy of the light source is uniformly distributed parallel beams.

Referring to fig. 4, an aspherical concave lens 401 has a first aspherical surface 403 and a first planar surface 404, and an aspherical convex lens 402 has a second aspherical surface 405 and a second planar surface 406, wherein the first aspherical surface 403 and the second aspherical surface 405 are disposed opposite to each other.

The parallel beams are represented by incident rays parallel to the optical axis 100, wherein the energy of the incident parallel beams is gaussian distributed, so the incident rays close to the optical axis 100 are dense, and the incident rays far from the optical axis 100 are sparse. The incident ray pencil passes straight through the first planar surface 404 into the aspheric concave lens 401; incident light rays then refractively deflect upon first aspheric surface 403 as they exit first aspheric surface 403, where the incident light rays closer to optical axis 100 are deflected at greater angles; then, the incident light is refracted and deflected again on the second aspheric surface 405 while passing through the second aspheric surface 405, forming an outgoing light parallel to the optical axis 100; finally, the emitted light rays are emitted straight through the second planar surface 406, which, as a whole, forms a parallel beam with uniformly distributed energy.

Therefore, the energy density of the light, that is, the energy distribution of the parallel light beam can be changed as long as the incident light is deflected by an appropriate angle using different curvatures with respect to the density of the incident light. The functions of the first aspheric surface 403 and the second aspheric surface 405 are disclosed in the prior art, and are well known in the art and will not be described herein.

Further, in order to change the spot formed on the welding site 6 from an originally circular spot to an annular spot, at least one of the aspherical concave lens 401 and the aspherical convex lens 402 may be moved along the optical axis 100. In the process of separating the aspheric concave lens 401 and the aspheric convex lens 402, the light is focused toward the periphery to form an annular light spot because the deflection angle of the incident light is larger closer to the optical axis 100.

In order to be able to focus the parallel light beams on the welding site 6, a focusing system 5 is further arranged along the optical path behind the shaping mirror 4, the focusing system 5 comprising at least one first lens 502, the at least one first lens 502 being a convex lens for converging the parallel light beams output by the shaping mirror 4 into a converging light beam having a fourth spot shape BP on the welding site 6₄Fourth spot shape BP₄Compare with the third spot shape BP₃With a smaller base radius and a larger height, the converging beam therefore has a larger energy per unit area of the weld site 6 in order to provide sufficient welding energy to melt the weld site 6.

In one embodiment, to achieve a change in focal length in the Z-axis, the focusing system 5 may also have a second lens 501. The second lens 501 may be disposed in front of the first lens 502 along an optical path and may move in the direction of the optical axis 100. The second lens 501 may be a convex lens or a concave lens, and in this embodiment, the second lens 501 is a convex lens. By moving the second lens 501 to change the distance between the first lens 502 and the second lens 501, the focal length of the converging light beam can be changed, and the focal position can be adjusted on the Z-axis according to the spatial configuration of the weldment. It should be understood that the change in focal length may also be achieved by moving first lens 502. In this embodiment, it is still necessary to change the relative positions between the weld members and the laser welding apparatus in the X-axis and the Y-axis for welding, but it is possible to cope with the case where the weld is in a three-dimensional configuration by adjusting the focal position in the Z-axis without providing a displacement device in the Z-axis.

In another embodiment, the focusing system 5 may also have an X-axis mirror 503 and a Y-axis mirror 504. The X-axis mirror 503 and the Y-axis mirror 504 are disposed behind the focusing mirror 502 along the optical path and are rotatable along respective rotation axes OX and OY, the rotation axes OX and OY of the X-axis mirror 503 and the Y-axis mirror 504 are orthogonal in a three-dimensional space, and the converging light beam output from the focusing mirror 502 is reflected by the X-axis mirror 503 and the Y-axis mirror 504 and projected onto the welding site 6. The X-axis mirror 503 and the Y-axis mirror 504 thus arranged have two benefits:

on the one hand, the position of the output beam in the X-axis and Y-axis of the welding site 6 is made adjustable by adjusting the X-axis mirror 503 and the Y-axis mirror 504 in a rotational manner. Therefore, by moving the output beam in the X axis and the Y axis, the welding member does not need to be moved to match the welding. However, during the rotation of the X-axis mirror 503 and the Y-axis mirror 504, since the focal lengths cannot be changed simultaneously, and the actual coverage of the focal points is a spherical surface, when the rotation angle is too large, the converging light is scattered at the planar welding portion, so that the welding portion does not reach the required welding temperature. Therefore, this method of welding by only positional adjustment in the X-axis and the Y-axis without changing the relative position between the weld and the laser welding apparatus allows use only on a smaller weld.

On the other hand, when welding, different operation modes are selected according to actual conditions, for example, when a welding seam is wide, in addition to traveling along the welding path (welding seam), the welding seam needs to slightly swing back and forth in the transverse direction so as to increase the welding width. In order to realize the operation of the welding trajectory, in the present embodiment, the X-axis mirror 503 and the Y-axis mirror 504 are automatically controlled by a driver, such as a motor, to rotate within a rotation angle within ± 3 ° according to the welding parameters, and such rotation actually appears in a state of small swing, which may help to simulate different operation modes to realize different welding widths and welding depths.

In addition, in fig. 2, although the X-axis mirror 503 is disposed in front of the Y-axis mirror 504 along the optical path, the positions of the two may be interchanged.

In yet another embodiment, the focusing system 5 has both the second lens 501, the first lens 502, the X-axis mirror 503, and the Y-axis mirror 504. In this case, in addition to adjusting the focal position in the Z-axis and simulating various operation modes, the light beam can be focused in a continuous three-dimensional spatial range, which depends on the focal length, the adjustment range of the focal length, and the swing ranges of the X-axis mirror 503 and the Y-axis mirror 504. Therefore, the spatial range in which the parallel light beams can be focused can be expanded by changing the curvature of the second lens 501 or the first lens 502 to increase the focal length, increasing the moving range of the second lens 501 to increase the adjustment range of the focal length, increasing the mirror surface areas of the X-axis mirror 503 and the Y-axis mirror 504 to obtain a larger swingable angle, or the like. Thus, when the spatial range of the focal point is sufficiently large, or when the three-dimensional spatial range of the focal point covers the entire welding path, the controller can focus the light beam on the welding part of the welding member and weld along the welding path by controlling the driver according to the welding path to drive the movement of the Z-axis dynamic mirror 501 and the rotation of the X-axis mirror 503 and the Y-axis mirror 504 without changing the relative position between the welding member and the laser welding apparatus, and thus components for changing the relative position between the welding member and the laser welding apparatus can be omitted, thereby achieving the miniaturization of the entire laser welding apparatus.

Fig. 5 shows a schematic light path diagram of an apparatus for laser welding according to a second embodiment of the present invention, and fig. 6 shows a schematic structural diagram of an apparatus for laser welding according to a second embodiment of the present invention, wherein the apparatus includes a laser 1, a collimating mirror 3, a shaping mirror 4, a cylindrical mirror 7, and a focusing system 5.

Referring to fig. 5 and 6, compared to the first embodiment, the second embodiment has a cylindrical mirror 7 disposed between the shaping mirror 4 and the focusing system 5, and forms a fifth spot shape BP after passing parallel light beams through the cylindrical mirror 7₅. The fifth light spot shape BP is different according to the curvature of the cylindrical mirror 7₅May be rectangular or linear. Accordingly, the sixth spot shape BP formed on the welding portion₆Is also rectangular or linear and has a smaller floor area and a larger height.

In addition, the cylindrical mirror 7 can also be rotated about the optical axis 100 to change the orientation of the rectangular or linear light spot.

Preferred embodiments according to various aspects of the present invention have been described above in connection with specific embodiments. It will be understood that the above description is intended to be illustrative and not restrictive, and that various changes and modifications may be suggested to one skilled in the art in view of the above description without departing from the scope of the invention. Such variations and modifications are also included in the scope of the present invention. Further, features used in one embodiment may also be used in other embodiments, where technology allows.

Claims

1. A method of laser welding, the method comprising the steps of:

generating a laser beam with Gaussian energy distribution;

forming the generated laser beam into a parallel beam through optical transformation, wherein the energy of the parallel beam is in Gaussian distribution;

and focusing the parallel light beams with the uniformly distributed energy to the welding position.

2. The method of claim 1, wherein the shaping step comprises diverging the parallel beam of gaussian distributed energy and reconverging the diverging beam into a parallel beam of uniform distributed energy.

3. The method of claim 1, wherein the focusing step comprises adjusting a focal position at which the parallel beams are focused in an X-axis, a Y-axis, and/or a Z-axis to move the focal position along the weld path.

4. The method of claim 1, further comprising adjusting a spatial extent to which the parallel beam of uniformly distributed energy can be focused.

5. The method of claim 1, further comprising transforming the circular spot formed by the focusing of the laser beam at the weld site into a linear or rectangular spot.

6. The method of claim 5, further comprising changing an orientation of the linear or rectangular spot.

7. The method of claim 1, further comprising varying the circular spot formed by focusing the laser beam at the weld site into an annular spot.

8. An apparatus for laser welding, comprising:

the collimating mirror is used for optically transforming the generated laser beam into a parallel beam through a lens, and the energy of the parallel beam is also in Gaussian distribution;

the shaping mirror comprises an aspheric lens used for shaping the parallel light beams with Gaussian energy distribution into parallel light beams with uniform energy distribution; and

the focusing system comprises at least one first lens, and the first lens is a convex lens and is used for focusing the parallel beams with uniformly distributed energy to a welding part;

9. The apparatus of claim 8, wherein the aspheric lens includes at least one aspheric concave lens for diverging the parallel beam of energy in a gaussian distribution and at least one aspheric convex lens for converging the diverging beam to form a parallel beam of energy in a uniform distribution.

10. The apparatus of claim 8, wherein the focusing system further comprises a second lens disposed in front of the first lens along the optical path, the second lens being either a convex lens or a concave lens, the second lens being movable along the optical axis.

11. The apparatus of claim 8, wherein the focusing system further comprises an X-axis mirror and a Y-axis mirror disposed behind the first lens along an optical path, wherein the X-axis mirror and the Y-axis mirror are rotatable along respective axes of rotation, the axes of rotation of the X-axis mirror and the Y-axis mirror being orthogonal in a volumetric space.

12. The apparatus of claim 8, wherein the focusing system further comprises a second lens disposed between the first lens and the shaping mirror, the second lens being either a convex lens or a concave lens, the second lens being movable along the optical axis, and an X-axis mirror and a Y-axis mirror disposed behind the first lens along an optical path; the X-axis reflector and the Y-axis reflector can rotate along respective rotation axes, and the rotation axes of the X-axis reflector and the Y-axis reflector are orthogonal in a three-dimensional space.

13. The apparatus of claim 8, wherein the apparatus further comprises a cylindrical mirror disposed between the shaping mirror and the focusing system.

14. The apparatus of claim 13, wherein the cylindrical mirror is rotatable about the optical axis.

15. The apparatus of claim 9, wherein at least one of the aspheric concave lens and the aspheric convex lens is movable along the optical axis.

16. The apparatus of claim 8, the collimating mirror being a solid focus-free Galileo collimating mirror comprised of a concave lens and a convex lens.