Light beam homogenizing and shaping method based on aspheric cylindrical lens group

Abstract

The invention discloses a light beam homogenizing and shaping method based on an aspheric cylindrical lens group, and relates to the technical field of light beam shaping, and the method comprises the steps: constructing an optical system for laser beam homogenizing and shaping, the optical system comprises a front shaping aspheric plane-concave cylindrical lens and a rear shaping aspheric plane-concave cylindrical lens, the invention provides a light beam homogenizing and shaping method based on an aspheric cylindrical lens group, which can be used for independently shaping laser in a single direction without influencing the original intensity distribution of light spots in a direction vertical to the laser. Two aspheric cylindrical lens groups which are orthogonally arranged are combined, circular Gaussian light spots are shaped into rectangular light spots with uniformly distributed light intensity in the X direction and the Y direction respectively, the method has the advantages of ideal shaping effect, low energy loss, simple use structure and the like, target aspheric cylindrical lens parameters obtained by the method are even-order aspheric surface type data, and the method is suitable for large-scale popularization and application. The method can be directly applied to actual lens processing.

Description

Technical Field

[0001] The invention relates to the technical field of beam shaping, and in particular to a beam homogenization and shaping method based on an aspherical cylindrical lens group. Background Art

[0002] The laser beams emitted by traditional helium-neon lasers and fiber lasers are generally circular spots with Gaussian intensity distribution, and most of the energy is concentrated in the central area. Due to the presence of laser diodes, semiconductor lasers have different divergence angles on the fast and slow axes. The spot shape of the laser beam directly emitted by them is elliptical, and the intensity distribution in two vertical directions presents a quasi-Gaussian distribution. Since the intensity distribution of the Gaussian beam directly output by the laser is uneven, with high intensity in the middle and low intensity around, it often causes problems such as uneven irradiation, low energy utilization, and the introduction of additional measurement errors, which limits its further development in some application fields. Therefore, it is of great significance to study and design optical systems that realize homogenization and shaping of laser beams in practical applications. At present, the common beam shaping methods mainly include microlens array shaping method, diffraction element shaping method, liquid crystal spatial light modulator method, aspheric lens group method, and aperture stop method. Among them, the aspheric lens group has the advantages of simple structure, high damage threshold, and high transmittance, and is widely used in the field of laser shaping.

[0003] But there are some drawbacks: (1) It is difficult to meet the requirements of converting Gaussian beams into flat-top beams in the X and Y directions; (2) The traditional method of achieving a uniform light spot of small size cannot achieve a uniform light spot of any size.

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a beam homogenization and shaping method based on an aspheric cylindrical lens group, which can independently shape the laser in a single direction without affecting the original intensity distribution of the light spot in the perpendicular direction, so as to achieve the effect of shaping the circular Gaussian beam generated by a general laser into a linear light spot with uniform light intensity distribution; if two groups of orthogonally placed aspheric cylindrical lens groups are used in combination, the circular Gaussian light spot can be shaped into a rectangular light spot with uniform light intensity distribution; it has the advantages of ideal shaping effect, low energy loss, simple structure, etc., and can be expanded to shape a light spot of any given light intensity distribution into a light spot of any light intensity distribution. Summary of the invention

[0005] The purpose of the present invention is to provide a light beam homogenization and shaping method based on an aspherical cylindrical lens group in order to solve the above problems, thereby solving the problems mentioned in the background technology.

[0006] In order to solve the above problems, the present invention provides a technical solution: A beam homogenization and shaping method based on an aspherical cylindrical lens group comprises the following specific steps: S1. Construct an optical system for homogenizing and shaping a laser beam, wherein the optical system comprises a front-shaping aspheric plano-concave cylindrical lens and a rear-shaping aspheric plano-concave cylindrical lens, and can shape a circular Gaussian spot into a rectangular spot with uniform light intensity distribution in the X and Y directions respectively; S2, using an aspherical cylindrical lens group for shaping, and giving multiple sets of constraints; S3. According to the law of conservation of energy, the energy of the incident light and the outgoing light is normalized; S4. Solve the surface shape according to the theory of geometric optics; S5. Use nonlinear fitting of the aspheric cylindrical lens surface shape, take the even-order aspheric surface as the target surface shape, homogenize the circular Gaussian beam in the X-axis and Y-axis directions, and import the solution into the ray tracing software for simulation.

[0007] As a preferred technical solution, the multiple sets of constraints in step S2 include but are not limited to the waist radius of the incident Gaussian beam, the width of the output flat-top beam in the X-axis direction, the width in the Y-axis direction perpendicular to the X-axis direction, and the distance between the front shaping cylindrical lens and the rear shaping cylindrical lens.

[0008] As a preferred technical solution, the beam waist radius and the spot width in step S2 are reduced to 1 / e of the maximum light intensity according to the light intensity. 2 Perform calculations.

[0009] As a preferred technical solution, the following formula is required to perform normalization in step S3, namely: ; in, is the coordinate value of any light ray on the incident surface, is the coordinate value of the corresponding exit surface, is the incident light intensity, is the outgoing light intensity, is the waist of the Gaussian beam, is the radius of the flat-top beam.

[0010] As a preferred technical solution, after the normalization process is completed in step S3, the incident light beam needs to obey the Gaussian distribution, and its light intensity distribution can be expressed as ; The homogenized Lorentz function is selected as the output beam, and its intensity distribution can be expressed as ; Here, q represents the order. The larger the value of the order q, the closer it is to the flat-top distribution. Its value is generally 50~100.

[0011] Furthermore, from the above three equations, we can get the mapping relationship between the incident light and the outgoing light: ; As a preferred technical solution, the surface shape of the aspherical cylindrical lens is obtained when solving the surface shape in step S4. , The incident angle of the incident light The relationship is: ; in They are the surface functions of the front shaping lens and the back shaping lens respectively. , The derivation of According to Snell's law: ; Where d is the distance between the center points of the curved surfaces of the front shaping lens and the back shaping lens; The surface formula of the aspheric shaping lens group is: ; ; Where r is the half width of the front and back shaping lenses, and n is the refractive index of the lens.

[0012] As a preferred technical solution, the surface shape formula of the aspherical cylindrical lens in step S5 is: .

[0013] As a preferred technical solution, Z in step S5 is a curve coordinate equation, to are coefficients of each order, r is the vertical distance from a point on the curve to the central axis of the curve, c is the inverse of the radius of curvature, and k is the quadratic surface coefficient.

[0014] As a preferred technical solution, the waist radius of the circular Gaussian spot in step S5 is The light spot is 8mm, and at a distance of 600mm from the rear shaping cylindrical lens, the light spot is shaped into a rectangular light spot with a half width of 16mm in the X-axis direction and a half width of 90mm in the Y-axis direction.

[0015] As a preferred technical solution, when the solution result is imported into the ray tracing software for simulation in step S5, Figure 4 , Figure 5 , Figure 6 As shown, it can be seen that in the shaping target direction of the light beam, the optical system shapes the Gaussian light beam in this direction into an approximately flat-top light beam. Overall, the Gaussian distribution spot is shaped into a rectangular spot with uniform light intensity distribution.

[0016] The beneficial effects of the present invention are as follows: the present invention provides a beam homogenization shaping method based on an aspheric cylindrical lens group, which can independently shape a single direction of the laser without affecting the original intensity distribution of the light spot in the perpendicular direction. The present invention uses two groups of orthogonally placed aspheric cylindrical lens groups to shape the circular Gaussian light spot into a rectangular light spot with uniform light intensity distribution in the X and Y directions, respectively. The method has the advantages of ideal shaping effect, low energy loss, and simple structure. The target aspheric cylindrical lens parameters obtained by the present invention are even-order aspheric surface data, which can be directly applied to the actual processing of lenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For ease of explanation, the present invention is described in detail with reference to the following specific implementations and the accompanying drawings.

[0018] Figure 1 is a schematic diagram of an aspherical cylindrical lens group in an implementation example; Figure 2 Schematic diagram of incident light beam spot in an implementation example; Figure 3 A schematic diagram of a cross-sectional curve of the light intensity distribution of an incident light beam in an implementation example; Figure 4 Schematic diagram of the outgoing light beam spot in the implementation example; Figure 5 It is a schematic diagram of the cross-sectional curve of the light intensity distribution of the outgoing light beam in the x-axis direction in the implementation example; Figure 6 Schematic diagram of the cross-sectional curve of the light intensity distribution of the outgoing light beam in the Y-axis direction in the implementation example. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0020] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0021] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0022] It should be understood that, although the terms first, second, third, etc. may be used to describe in the embodiments of the present application, these descriptions should not be limited to these terms. These terms are only used to distinguish the descriptions. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0023] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0024] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0025] It should be particularly noted that any symbols and / or numbers in the specification that are not marked in the accompanying drawings are not drawing marks.

[0026] The optional embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0027] like Figure 1-Figure 6 As shown, this specific implementation adopts the following technical solutions: A beam homogenization and shaping method based on an aspherical cylindrical lens group comprises the following specific steps: S1. Construct an optical system for homogenizing and shaping a laser beam, wherein the optical system comprises a front-shaping aspheric plano-concave cylindrical lens and a rear-shaping aspheric plano-concave cylindrical lens, and can shape a circular Gaussian spot into a rectangular spot with uniform light intensity distribution in the X and Y directions respectively; S201, using an aspherical cylindrical lens group to perform shaping, and providing multiple groups of constraint conditions; S202, multiple groups of constraint conditions include but are not limited to the waist radius of the incident Gaussian beam, the width of the output flat-top beam in the X-axis direction, the width in the Y-axis direction perpendicular to the X-axis direction, and the distance between the front shaping cylindrical lens and the rear shaping cylindrical lens; S203, beam waist radius and spot width are reduced to 1 / e of the maximum light intensity according to the light intensity 2 Perform calculations; S301, normalizing the energy of incident light and outgoing light according to the law of conservation of energy; S302: When performing normalization processing, the following formula is required for operation, namely: ; in, is the coordinate value of any light ray on the incident surface, is the coordinate value of the corresponding exit surface, is the incident light intensity, is the outgoing light intensity, is the waist of the Gaussian beam, is the radius of the flat-top beam.

[0028] S303. After the normalization process is completed, the incident light beam needs to obey the Gaussian distribution, and its light intensity distribution can be expressed as ; The homogenized Lorentz function is selected as the output beam, and its intensity distribution can be expressed as ; Here, q represents the order. The larger the value of the order q, the closer it is to the flat-top distribution. Its value is generally 50~100.

[0029] Furthermore, from the above three equations, we can get the mapping relationship between the incident light and the outgoing light: ; S401. Solve the surface shape according to the theory of geometric optics; S402, when solving the surface shape, the surface shape of the aspherical cylindrical lens is obtained , The incident angle of the incident light The relationship is: ; in They are the surface functions of the front shaping lens and the back shaping lens respectively. , The derivation of According to Snell's law: ; Where d is the distance between the center points of the curved surfaces of the front shaping lens and the back shaping lens; The surface formula of the aspheric shaping lens group is: ; ; Where r is the half width of the front and back shaping lenses, and n is the refractive index of the lens; S501, using nonlinear fitting of the aspheric cylindrical lens surface, taking the even-order aspheric surface as the target surface, homogenizing the circular Gaussian beam in the X-axis and Y-axis directions, and importing the solution into the ray tracing software for simulation.

[0030] S502, the surface formula of aspherical cylindrical lens is: ; Z is the curve coordinate equation, to are coefficients of each order, r is the vertical distance from a point on the curve to the central axis of the curve, c is the inverse of the radius of curvature, and k is the coefficient of the quadratic surface; S503, homogenize the circular Gaussian beam in the X-axis and Y-axis directions: the waist radius of the circular Gaussian spot is 8 mm, and the spot is shaped into a rectangular spot with a half width of 16 mm in the X-axis direction and a half width of 90 mm in the Y-axis direction at a distance of 600 mm from the rear shaping cylindrical lens. According to the mapping relationship between the incident light and the output light and the nonlinear fitting of the aspherical cylindrical lens surface, the following lens group parameters are obtained: Parameter table of even-order aspheric surface of shaping cylindrical lens group: ; S504, when the solution result is imported into the ray tracing software for simulation, Figure 4 , Figure 5 , Figure 6 As shown, it can be seen that in the shaping target direction of the light beam, the optical system shapes the Gaussian light beam in this direction into an approximately flat-top light beam. Overall, the Gaussian distribution spot is shaped into a rectangular spot with uniform light intensity distribution.

[0031] Specifically: The purpose of the present invention is to provide a beam homogenization and shaping method based on an aspheric cylindrical lens group, which can independently shape the laser in a single direction without affecting the original intensity distribution of the light spot in the perpendicular direction, so as to achieve the effect of shaping the circular Gaussian beam generated by a general laser into a linear light spot with uniform light intensity distribution; if two groups of orthogonally placed aspheric cylindrical lens groups are used in combination, the circular Gaussian light spot can be shaped into a rectangular light spot with uniform light intensity distribution; it has the advantages of ideal shaping effect, low energy loss, simple structure, etc., and can be expanded to shape a light spot with any given light intensity distribution into a light spot with any light intensity distribution.

[0032] Those of ordinary skill in the art will appreciate that the modules and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0033] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices, equipment and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0034] In the several embodiments provided in the present application, it should be understood that the disclosed devices, systems and methods can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or units can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or equipment, which can be electrical, mechanical or other forms.

[0035] In addition, it should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0036] It should be noted that the above examples are only specific embodiments of the present invention, and the present invention is obviously not limited to the above examples, and there are many similar variations. All variations directly derived or associated from the contents disclosed by the technicians in this field should fall within the protection scope of the present invention.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A beam homogenization and shaping method based on an aspherical cylindrical lens group, characterized in that: The specific steps include: S1. Constructing an optical system for homogenizing and shaping a laser beam, wherein the optical system comprises a front-shaping aspheric plano-concave cylindrical lens and a rear-shaping aspheric plano-concave cylindrical lens; S2, using an aspherical cylindrical lens group for shaping, and giving multiple sets of constraints; S3. According to the law of conservation of energy, the energy of the incident light and the outgoing light is normalized; S4. Solve the surface shape according to the theory of geometric optics; S5. Use nonlinear fitting of the aspheric cylindrical lens surface shape, take the even-order aspheric surface as the target surface shape, homogenize the circular Gaussian beam in the X-axis and Y-axis directions, and import the solution into the ray tracing software for simulation.

2. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens group according to claim 1, characterized in that: The multiple groups of constraints in step S2 include: the waist radius of the incident Gaussian beam, the width of the output flat-top beam in the X-axis direction, the width in the Y-axis direction perpendicular to the X-axis direction, and the distance between the front shaping cylindrical lens and the rear shaping cylindrical lens.

3. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens group according to claim 2, characterized in that: The beam waist radius and spot width in step S2 are reduced to 1 / e of the maximum light intensity according to the light intensity. 2 Perform calculations.

4. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens group according to claim 2, characterized in that: In step S3, the following formula is required for normalization: ， in, is the coordinate value of any light ray on the incident surface, is the coordinate value of the corresponding exit surface, is the incident light intensity, is the outgoing light intensity, is the waist of the Gaussian beam, is the radius of the flat-top beam.

5. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens group according to claim 4, characterized in that: After the normalization process is completed in step S3, the incident light beam needs to obey the Gaussian distribution, and its light intensity distribution is expressed as: ； The homogenized Lorentz function is selected as the output beam, and its intensity distribution is expressed as: ； Where q represents the order. The larger the value of the order q is, the closer it is to the flat-top distribution. Its value is 50~100. From the above three formulas, we can get the mapping relationship between incident light and outgoing light: 。 6. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens assembly according to claim 5, characterized in that: The surface shape of the aspherical cylindrical lens is obtained by solving the surface shape in step S4. , The incident angle of the incident light The relationship is: ； in They are the surface functions of the front shaping lens and the back shaping lens respectively. , The derivation of According to Snell's law: ; Where d is the distance between the center points of the curved surfaces of the front shaping lens and the back shaping lens; The surface formula of the aspheric shaping lens group is: ； ； Where r is the half width of the front and back shaping lenses, and n is the refractive index of the lens.

7. The method for light beam homogenization and shaping based on an aspherical cylindrical lens group according to claim 2, characterized in that: The surface shape formula of the aspherical cylindrical lens in step S5 is: 。 8. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens assembly according to claim 7, characterized in that: The Z in step S5 is the curve coordinate equation, to are coefficients of each order, r is the vertical distance from a point on the curve to the central axis of the curve, c is the inverse of the radius of curvature, and k is the quadratic surface coefficient.

9. The method for homogenizing and shaping a beam based on an aspherical cylindrical lens assembly according to claim 1, characterized in that: The waist radius of the circular Gaussian spot in step S5 The light spot is 8mm, and at a distance of 600mm from the rear shaping cylindrical lens, the light spot is shaped into a rectangular light spot with a half width of 16mm in the X-axis direction and a half width of 90mm in the Y-axis direction.

10. The method for light beam homogenization and shaping based on an aspherical cylindrical lens group according to claim 9, characterized in that: When the solution result is imported into the ray tracing software for simulation in step S5, the optical system shapes the Gaussian beam in the direction into an approximate flat-top beam.

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