Broadband spectrum light source-based light beam shaping system construction method, shaping system and shaping method

Abstract

The invention discloses a light beam shaping system construction method based on a broadband spectrum light source, a shaping system and a shaping method.The light beam shaping system based on the broadband spectrum light source comprises a light source, a focusing lens set, a first cylindrical lens set, a second cylindrical lens set and a microscope objective which are sequentially arranged along an optical axis, and the light source is the broadband spectrum light source; the first cylindrical lens group performs light spot size shaping on the light beam in the Y direction, and the second cylindrical lens group performs light spot size shaping on the light beam in the X direction. According to the light beam shaping system construction method based on the broadband spectrum light source, the shaping system for the broadband spectrum light source can be simply and accurately constructed, the shaping system can realize shaping of a circular light spot in the X direction and the Y direction, and the aspect ratio of the light spot is changed; a circular light spot can be shaped into an elliptical light spot with uniform energy distribution, the utilization rate of light energy can be improved in practice, and energy loss is reduced.

Description

Technical Field

[0001] This invention belongs to the field of optical system technology, and in particular relates to a method for constructing a beam shaping system based on a broadband light source, a shaping system, and a shaping method. Background Technology

[0002] In advanced manufacturing and precision optical inspection, the spatial distribution characteristics of light beams have a decisive impact on processing quality and inspection accuracy. Common single-lens beam expanders can only produce circular spots and cannot control the aspect ratio; spatial light modulators are expensive and cannot meet the need for low-cost beam shaping; while beam shaping using microlens optical diffraction elements is highly sensitive to wavelength, with efficiency dropping by more than 30% in the ultraviolet / infrared bands, limiting its effectiveness for broadband light sources. Furthermore, in semiconductor quantity detection, the repetitive scanning area of ​​circular spots reaches 32%, significantly impacting inspection speed. Using linear spots can increase the coverage area of ​​a single scan, significantly improving efficiency compared to point scanning. Therefore, it is necessary to design an optical system capable of shaping the beam spot, transforming a circular spot into a linear one.

[0003] In the prior art, the laser spot shaping device and laser lamp with the laser spot shaping device disclosed in Chinese patent application publication number CN107479204A use curved lenses to compress the spot in a first direction and a second direction to shape the spot. The curved lenses include plano-convex cylindrical lenses and / or plano-concave cylindrical lenses. This solution shapes the laser spot. Since the laser has good monochromaticity, this solution can indeed guarantee the size and brightness of the spot. However, if the above solution is used for broadband light sources, the shaped spot will have aberrations, and the size and brightness of the shaped spot cannot be guaranteed. The spot will be unclear, thus affecting the detection accuracy.

[0004] Therefore, it is necessary to provide a method for constructing a beam shaping system based on a broadband light source, a shaping system, and a shaping method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for constructing a beam shaping system based on a broadband light source, which can simply and accurately construct a beam shaping system for a broadband light source.

[0006] This invention achieves the above objective through the following technical solution: a method for constructing a beam shaping system based on a broadband light source, comprising the following steps: S1. Set initial parameters, including object aperture and broadband light source wavelength; S2. Set an initial structure according to the initial parameters. The initial structure includes several optical elements, including a focusing lens group, several cylindrical lenses, and a microscope objective. S3. Set the optical parameters of the optical element to obtain an initial shaping system, wherein the optical parameters are one or more of the following: radius of curvature, center thickness, glass material type, orientation of the optical element, and distance between optical elements; S4. Set a multi-objective evaluation function to determine whether the imaging of the initial shaping system meets the requirements. The multi-objective evaluation function includes a spot size control sub-function and a parallelism control sub-function. The spot size control sub-function is used to control the spot size of light of different wavelengths on the image plane. The parallelism control sub-function is used to control the angle at which light of different wavelengths is incident on the image plane. S5. The optical parameters of the initial shaping system are optimized using the damped least squares method to obtain the final shaping system.

[0007] Another objective of this invention is to provide a beam shaping system based on a broadband light source, which can shape a circular light spot in the X and Y directions and change the aspect ratio of the light spot.

[0008] The present invention achieves the above-mentioned objective through the following technical solution: a beam shaping system based on a broadband light source, which is constructed based on the above-mentioned method for constructing a beam shaping system based on a broadband light source, and includes a light source, a focusing lens group, a first cylindrical lens group, a second cylindrical lens group, and a microscope objective arranged sequentially along the optical axis. The light source is a broadband light source. The first cylindrical lens group includes a plano-concave cylindrical lens and a plano-convex cylindrical lens. The second cylindrical lens group includes a plano-convex cylindrical lens and a plano-concave cylindrical lens. The light source emits a broadband beam, which is converged by the focusing lens group, then the beam is shaped in the Y direction by the first cylindrical lens group, then the beam is shaped in the X direction by the second cylindrical lens group, and finally a parallel elliptical beam is output by the microscope objective.

[0009] Furthermore, the focusing lens group is a cemented lens group, and the cemented lens group is provided in two sets.

[0010] Furthermore, the plano-concave cylindrical lens, the plano-convex cylindrical lens, the plano-convex cylindrical lens, and the plano-concave cylindrical lens are arranged orthogonally in pairs.

[0011] Furthermore, the focal length F1 of the plano-concave cylindrical lens ranges from -30mm to -50mm.

[0012] Furthermore, the focal length F2 of the plano-convex cylindrical lens ranges from 20mm to 40mm.

[0013] Furthermore, the focal length F3 of the plano-convex cylindrical lens ranges from 15mm to 30mm.

[0014] Furthermore, the focal length F4 of the plano-concave cylindrical lens ranges from -10mm to -4mm.

[0015] Furthermore, the light source, the focusing lens group, the plano-concave cylindrical lens, the plano-convex cylindrical lens, the plano-convex cylindrical lens, the plano-concave cylindrical lens, and the microscope objective can all be detachably mounted on the mounting frame.

[0016] Another objective of this invention is to provide a beam shaping method based on a broadband light source, which can shape a circular light spot into an elliptical light spot with uniform energy distribution, thereby improving the utilization rate of light energy and reducing energy loss in practice.

[0017] The present invention achieves the above-mentioned objective through the following technical solution: a beam shaping method based on a broadband light source, which is based on the aforementioned beam shaping system based on a broadband light source, and includes the following steps: S100, The light source outputs a broadband first beam, and the spot of the first beam is a circular spot; S200, the focusing lens group converges the output first beam to form a second beam; S300, The first cylindrical lens group shapes the spot size of the second beam in the Y direction to form a third beam; S400, The second cylindrical lens group reshapes the spot size of the third beam in the X direction to form a fourth beam; S500, the microscope objective converts the fourth beam into a fifth beam, the fifth beam being parallel light, and the spot of the parallel light being elliptical.

[0018] Compared with existing technologies, the advantages of the present invention regarding the construction method, shaping system, and shaping method of a beam shaping system based on a broadband light source are as follows: (1) The method of constructing a beam shaping system based on a broadband light source can simply and accurately construct a shaping system for a broadband light source. The constructed shaping system can shape a circular light spot in the X and Y directions, change the aspect ratio of the light spot, and shape the circular light spot into an elliptical light spot with uniform energy distribution. In practice, it can improve the utilization rate of light energy and reduce energy loss. Moreover, by adjusting the position and / or focal length of several cylindrical lenses, it can achieve the output of light spots with different aspect ratios. The shape of the light spot can be flexibly changed according to the needs, and it has good versatility. (2) The shaping system is equipped with a focusing lens group, which is a cemented lens group. It can converge the diverging broadband beam and reduce the overall beam divergence angle. When the light source is a broadband light source, the use of a cemented lens group can reduce aberrations and make the imaging of light with different functional wavelengths as close as possible, thereby ensuring that the size, brightness and clarity of the light spot after shaping are as consistent as possible. (3) The light source, focusing lens group, plano-concave cylindrical lens, plano-convex cylindrical lens, plano-convex cylindrical lens, plano-concave cylindrical lens and microscope objective can all be detachably mounted on the mounting frame without any other structural components. The beam shaping system has a simple structure and a simple debugging and assembly process. The cylindrical lens used is easy to process and has a low cost, making it suitable for a variety of application scenarios, such as defect detection, laser micro-nano processing, etc. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the beam shaping system based on a broadband light source according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the elliptical light spots after imaging at a wavelength of 300nm according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the elliptical light spots after imaging at a wavelength of 588nm according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the elliptical light spots after imaging at a wavelength of 700nm according to an embodiment of the present invention; The numbers in the image represent: 100 - Beam shaping system based on broadband light source; 101-Light source, 102-Focusing lens group, 103-Planar-concave cylindrical lens, 104-Planar-convex cylindrical lens, 105-Planar-convex cylindrical lens, 106-Planar-concave cylindrical lens, 107-Microscopic objective lens. Detailed Implementation

[0020] This embodiment provides a method for constructing a beam shaping system based on a broadband light source, which includes the following steps: S1. Set initial parameters, including the object-side aperture and the wavelength of the broadband light source. In this embodiment, the object-side aperture NA = 0.22, and the wavelengths are 300 nm, 588 nm, and 700 nm. In other embodiments, the size of the object-side aperture and other different wavelengths can be set according to the actual situation.

[0021] S2. Set the initial structure according to the initial parameters. The initial structure includes several optical elements. In this embodiment, the optical elements include a focusing lens group, several cylindrical lenses, and a microscope objective. In other embodiments, other optical elements may also be included, which are not limited here.

[0022] S3. Set the optical parameters of the optical elements to obtain the initial shaping system. The optical parameters are one or more of the following: radius of curvature, center thickness, glass material type, orientation of the optical elements, and distance between the optical elements. Other parameters may also be included, which are not limited here.

[0023] Specifically, the surface shape of the focusing lens group is set to a standard sphere. The radius of curvature, center thickness, and type of glass material used for the focusing lens group are set. The glass material needs to be selected to be suitable for a wide spectrum, such as common materials like CaF2, fused silica, and N-BK7, in order to reduce lens costs. The radius of curvature and center thickness of the focusing lens group are set according to the actual situation and are not restricted here.

[0024] Specifically, the surface shape of each cylindrical lens is set as a toroidal surface, and the radius of curvature, center thickness, glass material type, direction, and spacing between each cylindrical lens are set. In this embodiment, four cylindrical lenses are required. The first two cylindrical lenses are set in the Y direction to shape the beam in the Y direction, and the last two cylindrical lenses are set in the X direction to shape the beam in the X direction. In this embodiment, the distance between the cylindrical lenses ranges from 0.5mm to 100mm, and the center thickness ranges from 1mm to 6mm. In other embodiments, the radius of curvature, center thickness, glass material type, direction, and spacing between the cylindrical lenses are set according to actual conditions and are not limited here.

[0025] Specifically, the microscope objective is a lens group and is configured with a paraxial surface, which can simultaneously reduce chromatic aberration and spherical aberration. In other embodiments, the microscope objective can be set according to actual conditions, and there are no restrictions here.

[0026] S4. Set up a multi-objective evaluation function to determine whether the imaging of the initial shaping system meets the requirements. The multi-objective evaluation function includes a spot size control sub-function and a parallelism control sub-function. The spot size control sub-function is used to control the spot size of light of different wavelengths on the image plane, and the parallelism control sub-function is used to control the angle at which light of different wavelengths is incident on the image plane.

[0027] Spot size control sub-function: In ZEMAX optical design software, the operands REAY and REAX are used to shape the spot size in the Y and X directions, respectively, to obtain the desired spot size. In this embodiment, the final desired spot size is 0.2mm × 0.05mm. In other embodiments, the spot size can be set according to the actual situation. In ZEMAX optical design software, the operands REAY and REAX are the core operands used for ray tracing and image plane control. They correspond to the Y-direction (meridian plane) and X-direction (sagittal plane) coordinates of the light rays on the image plane, respectively, and are key tools for analyzing image quality and optimizing image plane size.

[0028] Parallelism control subfunction: In ZEMAX optical design software, the operand RAID is used to constrain the exit angle of each wavelength of light to ensure it conforms to the target incident angle deviation. In this embodiment, the target incident angle deviation is ≤0.05°; in other embodiments, it can be set according to actual conditions. In ZEMAX optical design software, the operand RAID is a key operand used for light angle analysis and control, mainly used to calculate and optimize the incident angle of the beam in the optical system, playing an important role in scenarios such as telecentric system design and parallel light exit control.

[0029] S5. The initial structure and / or optical parameters of the initial shaping system are optimized using the damped least squares method (DLS) to obtain the final shaping system.

[0030] Damped least squares (DLS) is used to optimize optical parameters, and it includes the following steps: S51. Establish the Jacobian matrix and calculate the deviation between the currently obtained imaging parameters and the target value; S52. Introduce a damping factor λ to control the iteration step size. The initial value is set to 1.0, and it decreases with the number of iterations according to λ_(n+1)=0.8λ_n, where n is the number of iterations. S53. Set convergence conditions: Terminate optimization when the change in the multi-objective evaluation function is less than 0.1% after three consecutive iterations; S54. Output the final optical parameters to ensure that the system outputs a parallel elliptical light spot of 0.2mm × 0.05mm.

[0031] If optimizing the optical parameters alone is insufficient to achieve the optimal shaping system, return to step S2 and continue following steps S2 to S5 in sequence. Redesign the initial structure and set the optical parameters, then evaluate and optimize again to obtain the optimal shaping system.

[0032] Please refer to Figures 1-4This embodiment also provides a beam shaping system 100 based on a broadband light source, which is constructed based on the above-described method for constructing a beam shaping system based on a broadband light source. It includes a light source 101, a focusing lens group 102, a first cylindrical lens group, a second cylindrical lens group, and a microscope objective 107 connected in sequence. The first cylindrical lens group includes a plano-concave cylindrical lens 103 and a plano-convex cylindrical lens 104, and the second cylindrical lens group includes a plano-convex cylindrical lens 105 and a plano-concave cylindrical lens 106. The plano-concave cylindrical lens 103, plano-convex cylindrical lens 104, plano-convex cylindrical lens 105, and plano-concave cylindrical lens 106 are arranged sequentially. Figure 1 As shown. Among them, the light source 101, focusing lens group 102, plano-concave cylindrical lens 103, plano-convex cylindrical lens 104, plano-convex cylindrical lens 105, plano-concave cylindrical lens 106, and microscope objective 107 are all positioned according to actual conditions and are not limited here.

[0033] The light source 101 is a broadband light source, which can be selected from one or more of halogen lamps, xenon lamps, deuterium lamps, and deuterium-tungsten lamps, or other types of lamps. No restrictions are placed on this, as long as a broadband light source can be provided. The light source 101, after being coupled with an optical fiber coupler, outputs a divergent point light source with a circular light spot. The structure and principle of the optical fiber coupler are existing technologies and will not be described in detail here.

[0034] The focusing lens group 102 is a cemented lens group, which is used to converge divergent broadband beams and reduce the overall beam divergence angle. The cemented lens group is formed by bonding two or more lenses or plane mirrors together using optical adhesive or photoresist. The bonding surfaces form mutually conforming optical surfaces, which need to be bonded according to certain technical requirements. This bonding technology is existing technology and will not be described in detail here.

[0035] When light source 101 is a broadband light source, using a cemented lens group can reduce aberrations and make the imaging of light with different functional wavelengths as close as possible, thereby ensuring that the size, brightness, and sharpness of the shaped light spot are as consistent as possible. Figures 2-4As shown, the elliptical light spots formed by light with wavelengths of 300nm, 588nm, and 700nm are nearly identical. Specifically, reducing aberrations includes reducing chromatic aberration and spherical aberration. The following explains how chromatic aberration and spherical aberration are reduced. When light of different wavelengths passes through a single lens, chromatic aberration causes different divergence angles, preventing them from converging at a single point. However, a cemented lens assembly consists of several lenses and / or plane mirrors made of different materials with different refractive indices. As light of different wavelengths passes through these lenses sequentially, chromatic aberration is eliminated, and the divergence angles become the same. Therefore, light of different wavelengths can converge at a single point after passing through a cemented lens assembly, thus reducing chromatic aberration. Since a cemented lens assembly is formed by bonding two or more lenses or plane mirrors together using optical or photoresist, a refractive surface is formed at the bonding surface. Increasing the number of refractive surfaces reduces spherical aberration, allowing paraxial and paraxial light to focus as much as possible at the same point. The more refractive surfaces added, the better the reduction of spherical aberration.

[0036] In this embodiment, the cemented lens group is a cemented doublet lens, which includes a convex lens and a plane mirror. The use of two cemented doublet lens groups can better reduce the aberrations of light of different wavelengths, that is, reduce the chromatic aberration and spherical aberration of light of different wavelengths.

[0037] In other embodiments, the cemented lens group may be one, three or other quantities, and the cemented lens group may include three or more lenses and / or plane mirrors. There are no limitations on this, and it can be set according to the actual situation.

[0038] The first cylindrical lens group is used to shape the beam spot size in the Y direction, but does not converge or diverge the beam in the X direction. Specifically, the plano-concave cylindrical lens 103 and the plano-convex cylindrical lens 104 have curvature changes in the Y direction, and are used to shape the beam spot size in the Y direction.

[0039] In this embodiment, the focal length F1 of the plano-concave cylindrical lens 103 ranges from -30mm to -50mm, and preferably, in actual use, the focal length F1 is -40mm; the focal length F2 of the plano-convex cylindrical lens 104 ranges from 20mm to 40mm, and preferably, in actual use, the focal length F2 is 30mm. In other embodiments, the values ​​of focal length F1 and focal length F2 can be adjusted according to actual conditions.

[0040] The second cylindrical lens group is used to shape the beam spot size in the X direction, but does not converge or diverge the beam in the Y direction. Specifically, the plano-convex cylindrical lens 105 and the plano-concave cylindrical lens 106 both have curvature changes in the X direction, and are used to shape the beam spot size in the X direction.

[0041] In this embodiment, the focal length F3 of the plano-convex cylindrical lens 105 ranges from 15mm to 30mm, and preferably, in actual settings, the focal length F3 is 22mm; the focal length F4 of the plano-concave cylindrical lens 106 ranges from -10mm to -4mm, and preferably, in actual settings, the focal length F1 is -4mm. In other embodiments, the values ​​of focal length F3 and focal length F4 can be adjusted according to actual conditions.

[0042] The four cylindrical lenses (plano-concave cylindrical lens 103, plano-convex cylindrical lens 104, plano-convex cylindrical lens 105, and plano-concave cylindrical lens 106) are arranged in pairs orthogonal. This beam shaping system can greatly improve the degree of freedom of control, and can achieve independent control in the X and Y directions, thus improving the flexibility of operation.

[0043] This scheme includes a first cylindrical lens group and a second cylindrical lens group. The plano-concave cylindrical lens 103 and plano-convex cylindrical lens 104 of the first cylindrical lens group can shape the spot size of the beam in the Y direction, while the plano-convex cylindrical lens 105 and plano-concave cylindrical lens 106 of the second cylindrical lens group can shape the spot size of the beam in the X direction. This dual-degree-of-freedom approach allows for the shaping of a circular spot in both the X and Y directions. By changing the aspect ratio of the spot, a circular spot can be shaped into an elliptical spot with uniform energy distribution, improving the utilization rate of light energy and reducing energy loss in practice. Furthermore, by adjusting the position and / or focal length of several cylindrical lenses, different aspect ratios of the output spot can be achieved. The shape of the spot can be flexibly changed according to requirements, offering good versatility.

[0044] The microscope objective 107 is used to convert the converging beam output from the second cylindrical lens into a parallel beam output, that is, to convert the focal image output from the plano-concave cylindrical lens 106 into a magnified and uniformly intense elliptical light spot, which is convenient for subsequent processing and inspection.

[0045] In this solution, the light source 101, focusing lens group 102, plano-concave cylindrical lens 103, plano-convex cylindrical lens 104, plano-convex cylindrical lens 105, plano-concave cylindrical lens 106, and microscope objective 107 can all be detachably mounted on the mounting frame. There are no other structural components. The beam shaping system has a simple structure and a simple debugging and assembly process. Moreover, the cylindrical lenses used are easy to process and have low cost, making it suitable for various application scenarios, such as defect detection, laser micro-nano processing, etc.

[0046] This embodiment also provides a beam shaping method based on a broadband light source, which is based on one of the above-mentioned beam shaping systems based on a broadband light source, and includes the following steps: S100 and light source 101 output a broadband first beam, and the spot of the first beam is a circular spot. S200 and focusing lens group 102 converge the output first beam to form a second beam; S300, The first cylindrical lens group shapes the spot size of the second beam in the Y direction to form the third beam; S400, the second cylindrical lens group shapes the spot size of the third beam in the X direction to form the fourth beam; S500 and microscope objective 107 convert the fourth beam into a fifth beam, which is a parallel beam with an elliptical spot.

[0047] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for constructing a beam shaping system based on a broadband light source, characterized in that: It includes the following steps: S1. Set initial parameters, including object aperture and broadband light source wavelength; S2. Set an initial structure according to the initial parameters. The initial structure includes several optical elements, including a focusing lens group, several cylindrical lenses, and a microscope objective. S3. Set the optical parameters of the optical element to obtain an initial shaping system, wherein the optical parameters are one or more of the following: radius of curvature, center thickness, glass material type, orientation of the optical element, and distance between optical elements; S4. Set a multi-objective evaluation function to determine whether the imaging of the initial shaping system meets the requirements. The multi-objective evaluation function includes a spot size control sub-function and a parallelism control sub-function. The spot size control sub-function is used to control the spot size of light of different wavelengths on the image plane. S5. The optical parameters of the initial shaping system are optimized using the damped least squares method to obtain the final shaping system.

2. A beam shaping system based on a broadband light source, characterized in that: It is constructed based on the beam shaping system construction method based on a broadband light source as described in claim 1, and includes a light source, a focusing lens group, a first cylindrical lens group, a second cylindrical lens group, and a microscope objective arranged sequentially along the optical axis. The light source is a broadband light source. The first cylindrical lens group includes a plano-concave cylindrical lens and a plano-convex cylindrical lens. The second cylindrical lens group includes a plano-convex cylindrical lens and a plano-concave cylindrical lens. The light source emits a broadband beam, which is converged by the focusing lens group, then the beam is shaped in the Y direction by the first cylindrical lens group, then the beam is shaped in the X direction by the second cylindrical lens group, and finally a parallel beam is output by the microscope objective. The beam spot of this beam is elliptical.

3. The beam shaping system based on a broadband light source as described in claim 2, characterized in that: The focusing lens group is a cemented lens group, and there are two cemented lens groups.

4. The beam shaping system based on a broadband light source as described in claim 2, characterized in that: The plano-concave cylindrical lens, the plano-convex cylindrical lens, the plano-convex cylindrical lens, and the plano-concave cylindrical lens are arranged in pairs orthogonally.

5. A beam shaping system based on a broadband light source as described in claim 2, characterized in that: The focal length F1 of the plano-concave cylindrical lens ranges from -30mm to -50mm.

6. The beam shaping system based on a broadband light source as described in claim 2, characterized in that: The focal length F2 of the plano-convex cylindrical lens ranges from 20mm to 40mm.

7. A beam shaping system based on a broadband light source as described in claim 2, characterized in that: The focal length (F3) of the plano-convex cylindrical lens ranges from 15mm to 30mm.

8. The beam shaping system based on a broadband light source as described in claim 2, characterized in that: The focal length (F4) of the plano-concave cylindrical lens ranges from -10mm to -4mm.

9. A beam shaping system based on a broadband light source as described in claim 2, characterized in that: The light source, the focusing lens group, the plano-concave cylindrical lens, the plano-convex cylindrical lens, the plano-convex cylindrical lens, the plano-concave cylindrical lens, and the microscope objective are all detachably mounted on the mounting frame.

10. A beam shaping method based on a broadband light source, characterized in that, It is accomplished based on a beam shaping system based on a broadband light source as described in any one of claims 2 to 9, and includes the following steps: S100, The light source outputs a broadband first beam, and the spot of the first beam is a circular spot; S200, the focusing lens group converges the output first beam to form a second beam; S300, The first cylindrical lens group shapes the spot size of the second beam in the Y direction to form a third beam; S400, The second cylindrical lens group reshapes the spot size of the third beam in the X direction to form a fourth beam; S500, the microscope objective converts the fourth beam into a fifth beam, the fifth beam being parallel light, and the spot of the parallel light being elliptical.

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