Wide-area high-gain laser homogenizing and beam expanding method and device

Abstract

The invention discloses a wide-area high-gain laser homogenizing and beam expanding method and device. The device comprises a first lens, a second lens and a third lens. The method comprises the following steps: acquiring Gaussian laser beams and performing first centralized processing through a convex lens to obtain first centralized Gaussian laser beams; converging the Gaussian laser beams in the first set through a convex lens to obtain Gaussian laser beams in a second set; and performing beam expanding and homogenizing treatment on the Gaussian laser beams in the second set, and outputting the flattop laser beams after beam expanding. According to the invention, the uniformity of the Gaussian beam in light intensity distribution can be improved, and the beam expanding distance and the expanding multiple of the original beam can be improved. The wide-area high-gain laser homogenizing and beam expanding method and device can be widely applied to the technical field of laser shaping.

Description

Technical Field

[0001] The present invention relates to the technical field of laser shaping, and in particular to a wide-area high-gain laser homogenization and beam expansion method and a device thereof. Background Art

[0002] A Gaussian beam is a laser beam with a special shape. Its beam characteristics have limited distribution range. Its focusing properties result in a higher intensity near the beam waist, while the intensity decreases sharply as the beam moves away from the waist. This distribution characteristic cannot meet a wide range of needs in some fields, especially applications that need to cover a large area or achieve uniform processing. In these cases, a laser homogenization and beam expansion device is needed to ensure the consistency and processing range of laser processing.

[0003] There are some shortcomings in the laser beam expansion and homogenization devices of the related technology. General homogenization and expansion devices cannot achieve a large beam expansion, and when the Powell prism is used to increase the beam expansion ratio, it will be limited by the beam shape. Although high-power laser beam expansion and homogenization devices can significantly increase the beam expansion ratio, they are bulky and expensive. At the same time, these devices have certain defects in the uniformity of the intensity distribution after the beam is homogenized, the beam expansion ratio is greatly affected by the size of the incident beam, and the overall homogenization of the beam cannot be effectively achieved at a long distance. Therefore, there are certain challenges in the application requirements of long-distance and wide-area laser processing. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a wide-area high-gain laser homogenization and expansion method and device, which can improve the uniformity of the Gaussian beam in light intensity distribution and increase the expansion distance and expansion multiple of the original beam.

[0005] The first technical solution adopted by the present invention is: a wide-area high-gain laser homogenization and beam expansion method, comprising the following steps:

[0006] Obtain a Gaussian laser beam and perform a first concentrated processing through a convex lens to obtain a first concentrated Gaussian laser beam;

[0007] The first concentrated Gaussian laser beam is converged by a convex lens to obtain a second concentrated Gaussian laser beam;

[0008] The second concentrated Gaussian laser beam is expanded and homogenized to output a flat-top laser beam after expansion.

[0009] The second technical solution adopted by the present invention is: a wide-area high-gain laser homogenization and beam expansion device, comprising a first lens, a second lens and a third lens, wherein the first lens and the second lens constitute a beam shaping structure, the first lens, the second lens and the third lens are arranged in sequence along the central axis of the laser beam, the incident surface of the first lens is a spherical surface, the exit surface of the first lens is an even-order aspherical surface, the incident surface of the second lens is an even-order aspherical surface, the exit surface of the second lens is a spherical surface, the incident surface of the third lens is a cylindrical spherical surface, and the exit surface of the third lens is an even-order aspherical surface, wherein:

[0010] The first lens is used to obtain the Gaussian laser beam and perform a first concentrated processing to obtain a first concentrated Gaussian laser beam;

[0011] The second lens is used to converge the first concentrated Gaussian laser beam to obtain a second concentrated Gaussian laser beam;

[0012] The third lens is used to perform beam expansion and homogenization processing on the second concentrated Gaussian laser beam, and output a flat-top laser beam after beam expansion.

[0013] Furthermore, the first lens and the second lens are both convex lenses, the third lens is in a meniscus shape, and the curvature direction of the third lens is consistent with the direction of the incident light.

[0014] Furthermore, the thickness of the first lens and the thickness of the second lens are both 12 to 15 mm, the thickness of the third lens is 8 to 10 mm, the distance between the first lens and the second lens is 48 to 50 mm, the distance between the second lens and the third lens is 8 to 10 mm, and the total length of the laser homogenization and beam expansion device formed by the first lens, the second lens and the third lens is less than 100 mm.

[0015] Further, the even-order aspheric surface of the first lens, the even-order aspheric surface of the second lens, and the even-order aspheric surface of the third lens all satisfy a first preset polynomial, and the expression of the first preset polynomial is specifically as follows:

[0016]

[0017] In the above formula, c represents the central curvature, k represents the quadratic surface coefficient, a1, a2, a3, a4, a5, a6 represent the aspheric surface coefficients, z represents the distance from the point on the aspheric surface to the vertex of the aspheric surface in the direction of the optical axis, and r represents the distance from the point on the aspheric surface to the optical axis.

[0018] Furthermore, the spherical surface of the first lens, the spherical surface of the second lens, and the cylindrical spherical surface of the third lens all satisfy a second preset polynomial, and the expression of the second preset polynomial is specifically as follows:

[0019]

[0020] In the above formula, c represents the central curvature, k represents the quadratic surface coefficient, r represents the distance from the point on the aspherical surface to the optical axis, and Z represents the distance from the point on the aspherical surface to the vertex of the aspherical surface in the direction of the optical axis.

[0021] The beneficial effects of the method and system of the present invention are as follows: the present invention realizes high-multiple beam expansion and high-precision homogenization of laser light by combining a cylindrical mirror and an even-order aspheric mirror into a meniscus lens, and cooperates with the even-order aspheric mirror, and can reduce the requirements for incident light, improve the uniformity of the Gaussian beam in the light intensity distribution, and increase the beam expansion distance and expansion multiple of the original beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of steps of a wide-area high-gain laser homogenization and beam expansion method of the present invention;

[0023] Figure 2 It is a structural block diagram of a wide-area high-gain laser homogenization and beam expansion device of the present invention;

[0024] Figure 3 It is a schematic diagram of lens positions of a laser homogenizing and beam expanding device provided in a specific embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of energy distribution of an incident Gaussian beam provided by a specific embodiment of the present invention;

[0026] Figure 5 is a schematic diagram of the energy distribution of the outgoing light beam provided by a specific embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of the energy distribution of the cross section of the outgoing light beam provided by a specific embodiment of the present invention.

[0028] Reference numerals: 1, first lens; 2, second lens; 3, third lens; 4, receiving surface. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0030] Reference Figure 1 The present invention provides a wide-area high-gain laser homogenization and beam expansion method, the method comprising the following steps:

[0031] S100, obtaining a Gaussian laser beam and performing a first concentrated processing through a convex lens to obtain a first concentrated Gaussian laser beam;

[0032] S200, converging the first concentrated Gaussian laser beam through a convex lens to obtain a second concentrated Gaussian laser beam;

[0033] S300, performing beam expansion and homogenization processing on the second concentrated Gaussian laser beam, and outputting a flat-top laser beam after beam expansion.

[0034] In this embodiment, the Gaussian beam enters the system through the incident surface of the first lens, and the intensity distribution diagram of the Gaussian beam is as follows: Figure 4 As shown in the figure, after the light beam passes through the incident surface of the first lens, it enters the beam shaping system to form a more concentrated light beam. The shaping system consists of the first lens and the second lens. The light beam passes through the shaping mechanism and is captured by the incident surface of the third lens. After the third lens expands and homogenizes the light beam, a flat-top beam with a high beam expansion multiple and excellent homogenization quality is formed on the receiving surface. For the final light intensity distribution, please refer to Figure 5 . This laser beam expansion system uses a cylindrical mirror combined with an even-order aspheric mirror to form a meniscus lens, and cooperates with the even-order aspheric mirror to achieve beam expansion and homogenization of the outgoing light beam. This device overcomes the limitations of the Powell prism in the beam shaping shape and further optimizes the uniformity of the homogenized beam. Compared with ordinary beam shaping systems, this device has greater advantages in beam expansion distance and beam expansion multiple, and the requirements for incident light are also more relaxed. Compared with high-power beam shaping systems, this device has a more compact size and excellent homogenization effect, and presents higher practical value in practical applications.

[0035] Reference Figure 2 A wide-area high-gain laser homogenization and beam expansion device comprises a first lens 1, a second lens 2 and a third lens 3, wherein the first lens and the second lens constitute a beam shaping structure, the first lens, the second lens and the third lens are arranged in sequence along the central axis of the laser beam, the incident surface of the first lens is a spherical surface, the exit surface of the first lens is an even-order aspherical surface, the incident surface of the second lens is an even-order aspherical surface, the exit surface of the second lens is a spherical surface, the incident surface of the third lens is a cylindrical spherical surface, and the exit surface of the third lens is an even-order aspherical surface, wherein:

[0036] The first lens is used to obtain the Gaussian laser beam and perform a first concentrated processing to obtain a first concentrated Gaussian laser beam;

[0037] The second lens is used to converge the first concentrated Gaussian laser beam to obtain a second concentrated Gaussian laser beam;

[0038] The third lens is used to perform beam expansion and homogenization processing on the second concentrated Gaussian laser beam, and output a flat-top laser beam after beam expansion.

[0039] Specifically, the first lens and the second lens are both convex lenses, the third lens is in a meniscus shape, and the curvature direction of the third lens is consistent with the direction of the incident light.

[0040] It should be noted that in order to make the wide-area high-gain laser homogenization and beam expansion system produce more excellent effects, the beam exit surface of the first lens, the beam incident surface of the second lens and the beam exit surface of the third lens 3 adopt even-order aspherical surfaces, and the corresponding beam incident surface of the first lens and the beam exit surface of the second lens are spherical surfaces, and the beam incident surface of the third lens is a cylindrical spherical surface.

[0041] like Figure 3 As shown, both sides of the first lens and the second lens are convex lenses, and the third lens is a positive curvature meniscus lens, which is bent in the direction of the incident light beam. In this shaping mechanism, the cylindrical spherical surface is combined with the even-order aspherical surface, and the spherical surface is coupled with the even-order aspherical surface to ensure the homogenization and expansion effect of the Gaussian beam. Too many aspherical lenses will increase the cost, complicate the structure, and cause the volume of the optical system to expand. On the contrary, using too few aspherical lenses will reduce the homogenization and expansion performance of the system.

[0042] The first lens and the second lens together form a beam shaping mechanism, which is used to shape the incident Gaussian beam into a focused beam. Subsequently, the beam is coupled to the third lens, and after passing through the third lens, the beam is homogenized and expanded, ultimately achieving a high-multiple and high-quality expansion and homogenization effect at a long distance.

[0043] More specifically, the thickness of the first lens and the thickness of the second lens are both 12 to 15 mm, the thickness of the third lens is 8 to 10 mm, the distance between the first lens and the second lens is 48 to 50 mm, the distance between the second lens and the third lens is 8 to 10 mm, and the total length of the laser homogenization and beam expansion device formed by the first lens, the second lens and the third lens is less than 100 mm.

[0044] It should be noted that the even-order aspheric surfaces of the beam exit surface of the first lens, the beam incident surface of the second lens, and the beam exit surface of the third lens should satisfy the following polynomials:

[0045]

[0046] In the above formula, c represents the central curvature, k represents the quadratic surface coefficient, a1, a2, a3, a4, a5, a6 represent the aspheric surface coefficients, z represents the distance from the point on the aspheric surface to the vertex of the aspheric surface in the direction of the optical axis, and r represents the distance from the point on the aspheric surface to the optical axis.

[0047] Furthermore, the spherical surfaces of the first lens beam incident surface, the second lens beam exit surface, and the third lens beam incident surface should satisfy the following formula:

[0048]

[0049] In the above formula, c represents the central curvature, k represents the quadratic surface coefficient, r represents the distance from the point on the aspherical surface to the optical axis, and Z represents the distance from the point on the aspherical surface to the vertex of the aspherical surface in the direction of the optical axis.

[0050] In this embodiment, the laser homogenization and beam expansion device includes a first lens, a second lens, and a third lens, which are arranged in sequence on the optical path and propagate along the central axis of the main optical path. The first lens and the second lens are both convex lenses, composed of spherical and aspherical surfaces, forming a laser beam shaping mechanism, which is specially designed to shape the incident Gaussian beam so as to effectively couple it into the third lens. The third lens is composed of a cylindrical spherical mirror and an even-order aspherical mirror, and its task is to achieve beam expansion and homogenization of the laser beam, thereby expanding the beam and making it evenly distributed. The optical axes of the three lenses are all located on the main optical path to ensure the coordinated work of the optical system. Finally, on the long-distance receiving surface 4, a flat-top beam with a high beam expansion multiple and excellent homogenization quality is achieved.

[0051] Finally, the first aspheric lens, the second aspheric lens and the third aspheric lens are optical glass, which can transmit Gaussian light beams of corresponding wavelengths, and can be made of materials such as germanium, chalcogenide glass, and borosilicate crown glass.

[0052] Furthermore, Figure 6 After the Gaussian beam shown in the figure passes through this system, the beam expansion multiple reaches more than 30 times, the beam expansion distance exceeds 1500mm, and the homogenization degree reaches more than 90%, achieving higher quality homogenization of the Gaussian beam and high-multiple beam expansion over a long distance. The homogenization degree detection formula is as follows:

[0053]

[0054] In the above formula, E i It represents the light intensity value at any sampling point. It represents the average light intensity of all sampling points, N is the number of selected sampling points, the number of sampling points of this device is 1000, and the energy uniformity of the shaped line light spot obtained by sampling calculation is 92.8%, which meets the requirements of actual application conditions.

[0055] In summary, the laser beam expansion system of the embodiment of the present invention includes a first lens, a second lens and a third lens, which are arranged in sequence on the optical path and propagate along the central axis of the main optical path. The first lens and the second lens are both convex lenses, which are composed of spherical and aspherical surfaces, forming a laser beam shaping mechanism, which is specially designed to shape the incident Gaussian beam so as to effectively couple it into the third lens. The third lens is composed of a cylindrical spherical mirror and an even-order aspherical mirror, and its task is to achieve beam expansion and homogenization of the laser beam, thereby expanding the beam and making it evenly distributed. The optical axes of the three lenses are all located on the main optical path to ensure the coordinated operation of the optical system. Finally, on the long-distance receiving surface, a flat-top beam with a high beam expansion multiple and excellent homogenization quality is achieved. By combining the cylindrical spherical surface with the even-order aspherical surface and coupling the spherical surface with the even-order aspherical surface, high-multiple beam expansion and high-precision homogenization of the laser are achieved, which makes up for the limitations of the Powell prism in the beam shaping shape and further optimizes the uniformity of the homogenized beam. Compared with ordinary beam shaping systems, this system has greater advantages in beam expansion distance and beam expansion multiple, and the requirements for incident light are also more relaxed. Compared with high-power beam shaping systems, this system has a more compact size and excellent homogenization effect, showing higher practical value in actual applications.

[0056] The contents of the above method embodiments are all applicable to the present device embodiments. The functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0057] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A wide-area high-gain laser homogenization and beam expansion method, characterized in that: The following steps are involved: Obtain a Gaussian laser beam and perform a first concentrated processing through a convex lens to obtain a first concentrated Gaussian laser beam; The first concentrated Gaussian laser beam is converged by a convex lens to obtain a second concentrated Gaussian laser beam; The second concentrated Gaussian laser beam is expanded and homogenized to output a flat-top laser beam after expansion.

2. A wide-area high-gain laser homogenization and beam expansion device, characterized in that: The invention comprises a first lens, a second lens and a third lens, wherein the first lens and the second lens constitute a beam shaping structure, the first lens, the second lens and the third lens are sequentially arranged along the central axis of the laser beam, the incident surface of the first lens is a spherical surface, the exit surface of the first lens is an even-order aspherical surface, the incident surface of the second lens is an even-order aspherical surface, the exit surface of the second lens is a spherical surface, the incident surface of the third lens is a cylindrical spherical surface, and the exit surface of the third lens is an even-order aspherical surface, wherein: The first lens is used to obtain the Gaussian laser beam and perform a first concentrated processing to obtain a first concentrated Gaussian laser beam; The second lens is used to converge the first concentrated Gaussian laser beam to obtain a second concentrated Gaussian laser beam; The third lens is used to perform beam expansion and homogenization processing on the second concentrated Gaussian laser beam, and output a flat-top laser beam after beam expansion.

3. The wide-area high-gain laser homogenization and beam expansion device according to claim 2, characterized in that: The first lens and the second lens are both convex lenses, the third lens is in a meniscus shape, and the curvature direction of the third lens is consistent with the direction of the incident light.

4. The wide-area high-gain laser homogenization and beam expansion device according to claim 3, characterized in that: The thickness of the first lens and the thickness of the second lens are both 12 to 15 mm, the thickness of the third lens is 8 to 10 mm, the distance between the first lens and the second lens is 48 to 50 mm, the distance between the second lens and the third lens is 8 to 10 mm, and the total length of the laser homogenization and beam expansion device formed by the first lens, the second lens and the third lens is less than 100 mm.

5. The wide-area high-gain laser homogenization and beam expansion device according to claim 4, characterized in that: The even-order aspheric surface of the first lens, the even-order aspheric surface of the second lens, and the even-order aspheric surface of the third lens all satisfy a first preset polynomial, and the expression of the first preset polynomial is specifically as follows: In the above formula, c represents the central curvature, k represents the quadratic surface coefficient, a1, a2, a3, a4, a5, a6 represent the aspheric surface coefficients, z represents the distance from the point on the aspheric surface to the vertex of the aspheric surface in the direction of the optical axis, and r represents the distance from the point on the aspheric surface to the optical axis.

6. The wide-area high-gain laser homogenization and beam expansion device according to claim 5, characterized in that: The spherical surface of the first lens, the spherical surface of the second lens, and the cylindrical spherical surface of the third lens all satisfy a second preset polynomial, and the expression of the second preset polynomial is specifically as follows: In the above formula, c represents the central curvature, k represents the quadratic surface coefficient, r represents the distance from the point on the aspherical surface to the optical axis, and Z represents the distance from the point on the aspherical surface to the vertex of the aspherical surface in the direction of the optical axis.

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