A method and optical system for producing a spherical focused spot

Abstract

The application provides a method and an optical system for generating a spherical focusing light spot, and belongs to the technical field of optical imaging. The method comprises the following steps: 1) a refractive mask plate is used for dividing an incident laser beam into different regions, and the light in different regions is deflected based on the principle of refraction; and 2) a focusing mirror is used for imaging the deflected light to different positions on a focal plane to form a spherical focusing light spot. The application realizes the regulation of focal point intensity based on the principle of refraction of the refractive mask plate and the imaging principle of the focusing mirror, and a spherical symmetric single-beam focal spot, i.e. a spherical focusing light spot, is formed on the focal plane. The whole method is simple to operate, and has universality and generality. The application has important popularization significance in the fields of laser three-dimensional manufacturing technology, microscopic imaging technology and laser measurement technology.

Description

Technical Field

[0001] This invention belongs to the field of optical imaging technology, specifically laser imaging technology, and is a method and optical system for generating a spherical focused light spot. Background Technology

[0002] Focusing laser beams is the most fundamental and common operation in laser manufacturing, microscopic imaging, and laser coherence measurement. Focusing a TEM00 (fundamental transverse mode) laser beam with a spherical lens produces a three-dimensional spot with an intensity distribution resembling an oval; focusing a TEM00 mode laser beam with a cylindrical lens produces a three-dimensional distribution resembling a thin sheet with an elliptical cross-section; focusing a sheet-like beam with a spherical lens also produces a three-dimensional distribution resembling a thin sheet with an elliptical cross-section. Both the oval-shaped and sheet-like three-dimensional spot intensity distributions are deformed spots and lead to asymmetry in the intensity distribution of the focused area.

[0003] To generate a three-dimensional symmetrical spherical laser spot, the medium in the laser focal region must be highly transparent within the laser wavelength range, such as water, air, quartz glass, sapphire, silicon carbide, zinc sulfide, spinel, calcite, UV-sensitive adhesive SU8, and PMMA polymers in the visible light range. One proposal suggests focusing two orthogonal TEM00 mode laser beams at the same spatial position; when the two orthogonal beams perfectly overlap, the intersection approximates a sphere. Through nonlinear effects such as femtosecond laser two-photon aggregation, a spherical focused spot can be generated. However, this approach is not only structurally complex but also difficult to align accurately in space, especially since the spherical aberration and aberrations of the two beams must be nearly identical, greatly limiting the widespread application of this technology. Therefore, current technologies cannot generate focused spherical spots with simple optical path structures and operation methods, which significantly restricts the further development of laser three-dimensional manufacturing technology, microscopic imaging technology, and laser measurement technology. Summary of the Invention

[0004] To address the problem described above, the existing technology cannot generate a focused spherical light spot with a simple optical path structure and operation method, which greatly restricts the further development of laser three-dimensional manufacturing technology, microscopic imaging technology and laser measurement technology, this invention proposes a method and optical system for generating a spherical focused light spot.

[0005] The mask proposed in this invention is not a phase mask, but a refractive mask. Traditional phase masks operate based on Fresnel or Fraunhofer diffraction theories, using Fourier transform to generate spatial intensity changes through phase shifts. In contrast, the refractive mask of this invention achieves focal intensity control based on the refraction of optical materials and the imaging principle of lenses, exhibiting a spherically symmetrical single-beam focal spot. Its optical path structure is simple, and its operation is straightforward, possessing versatility and universality. It has significant application and promotion value in laser 3D manufacturing technology, microscopic imaging technology, and laser measurement technology. The specific technical solution is as follows:

[0006] A method for generating a spherical focused light spot includes the following steps:

[0007] 1) A refractive mask divides the incident laser beam into different regions and deflects the light from each region based on the principle of refraction;

[0008] 2) The focusing lens images the deflected light onto different positions on the focal plane, forming a spherical focused light spot.

[0009] Further specifying, the step in step 1) where the refracting mask divides the incident laser beam into different regions is as follows:

[0010] 1.1) Select the partition width of the refractive mask;

[0011] 1.2) Divide the refractive mask into n regions based on the partition width of the refractive mask and the spot diameter of the incident laser beam. The calculation formula is as follows:

[0012] n = d / w;

[0013] In the formula, n is the number of partitions on one side of the refracting mask along the center; d is the spot diameter of the incident laser beam in mm; and w is the partition width of the refracting mask in mm.

[0014] Further specifying, the step of deflecting light from different regions in step 1) is as follows:

[0015] 1.3) Determine the diameter of the largest circular spot based on the incident laser beam's spot diameter and the focusing lens's focal length. The calculation formula is as follows:

[0016] ω0 = 1.22 * λ * M² / NA;

[0017] NA = 0.5d / f;

[0018] In the formula, ω0 is the diameter of the largest circular sheet-like light spot, mm; λ is the wavelength of the incident laser beam, mm; M2 is the beam quality factor of the incident laser beam, dimensionless; NA is the numerical aperture, dimensionless; d is the spot diameter of the incident laser beam, mm; and f is the focal length of the focusing lens, mm.

[0019] 1.4) Calculate the maximum deflection angle α of the refracting mask based on the diameter of the largest circular spot and the focal length of the focusing lens. The calculation formula is:

[0020] α = ω0 / f;

[0021] In the formula, α is the maximum deflection angle of the refracting mask in radians; ω0 is the diameter of the largest circular spot in mm; and f is the focal length of the focusing lens in mm.

[0022] 1.5) Calculate the maximum angle δ of the refracting mask based on the maximum deflection angle α and the refractive index r of the refracting mask material. The calculation formula is:

[0023] δ=α×(r-r0);

[0024] In the formula, δ is the maximum angle between the edges of the refractive mask, in radians; α is the maximum deflection angle of the refractive mask, in radians; r is the refractive index of the material of the refractive mask, dimensionless; and r0 is the refractive index of air, dimensionless.

[0025] 1.6) Calculate the included angle θ between adjacent regions based on the maximum included angle of the refracting mask. The calculation formula is:

[0026] θ = δ / n;

[0027] In the formula, θ is the included angle between adjacent regions in radians; δ is the maximum included angle between the edges of the refractive mask in radians; and n is the number of partitions along the center side of the refractive mask.

[0028] 1.7) The refractive mask deflects light from different regions based on the angle θ between the edges of adjacent regions.

[0029] Further defining step 2), the focusing lens images the deflected light onto different positions on the focal plane, forming a circular sheet-like light spot with the largest radius at the center of the focal plane, and extending outwards along the opposite sides of the center of the focal plane to form symmetrical circular sheet-like light spots with proportionally decreasing radii, and then aggregating the circular sheet-like light spots at different positions on the focal plane to form a spherical focused light spot.

[0030] Further specifying, in step 2), the focusing lens refracts the deflected light to different positions on the focal plane according to the angle θ between the edges of adjacent regions.

[0031] Furthermore, the partition width of the refractive mask ranges from 200μm to 600μm.

[0032] The optical system for generating a spherical focused spot formed by the above-described method includes a refractive mask and a focusing lens, wherein the refractive mask and the focusing lens are arranged sequentially from front to back along the incident direction of the incident laser beam.

[0033] The refractive mask is used to divide the incident laser beam into different regions and deflect the light in different regions based on the principle of refraction.

[0034] The focusing lens images the deflected light onto different positions on the focal plane, forming a spherical focused light spot.

[0035] Further defined, the refractive mask includes mask parameters, which include the number of partitions n along one side of the center of the refractive mask and the included angle θ between the edges of adjacent regions.

[0036] Further specifying, the formula for calculating the number of partitions n along one side of the center of the refractive mask is:

[0037] n = d / w;

[0038] In the formula, n is the number of partitions on one side of the refractive mask along the center; d is the spot diameter of the incident laser beam, mm; w is the partition width of the refractive mask, mm;

[0039] The process for determining the included angle θ between the adjacent regions is as follows:

[0040] The diameter of the largest circular patch of light is determined by the following formula:

[0041] ω0 = 1.22 * λ * M² / NA;

[0042] NA = 0.5d / f;

[0043] In the formula, ω0 is the diameter of the largest circular sheet-like light spot, mm; λ is the wavelength of the incident laser beam, mm; M2 is the beam quality factor of the incident laser beam, dimensionless; NA is the numerical aperture, dimensionless; d is the spot diameter of the incident laser beam, mm; and f is the focal length of the focusing lens, mm.

[0044] The maximum deflection angle α of the refracting mask is determined by the following formula:

[0045] α = ω0 / f;

[0046] In the formula, α is the maximum deflection angle of the refracting mask in radians; ω0 is the diameter of the largest circular spot in mm; and f is the focal length of the focusing lens in mm.

[0047] The maximum included angle δ of the refracting mask is determined by the following formula:

[0048] δ=α×(r-r0);

[0049] In the formula, δ is the maximum angle between the edges of the refractive mask, in radians; α is the maximum deflection angle of the refractive mask, in radians; r is the refractive index of the material of the refractive mask, dimensionless; and r0 is the refractive index of air, dimensionless.

[0050] The formula for determining the included angle θ between adjacent regions is as follows:

[0051] θ = δ / n;

[0052] In the formula, θ is the angle between adjacent regions in radians; δ is the maximum angle between the edges of the refractive mask in radians; and n is the number of partitions along the center side of the refractive mask.

[0053] Further defined, the focusing lens images the deflected light onto different positions of the focal plane, forming a circular sheet-like light spot with the largest radius at the center of the focal plane, and extending outwards from both sides of the center of the focal plane to form symmetrical circular sheet-like light spots with proportionally decreasing radii, and the circular sheet-like light spots at different positions of the focal plane are aggregated to form a spherical focused light spot.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] 1. This invention discloses a method for generating a spherical focused light spot. The method employs a refractive mask to divide an incident laser beam into different regions, deflects the light from each region, and then refracts the deflected light to different positions on the focal plane using a focusing lens, thus forming a focused light spot. The mask used in this invention is a refractive mask. Based on the refraction principle of the refractive mask and the imaging principle of the focusing lens, the focal intensity is controlled, resulting in a spherically symmetrical single-beam focus spot at the focal plane, i.e., a spherical focused light spot. The entire method is simple to operate, has versatility and universality, and has significant application and promotion value in laser 3D manufacturing technology, microscopic imaging technology, and laser measurement technology.

[0056] 2. This invention uses a focusing lens to image the deflected light onto different positions on the focal plane. At the center of the focal plane, a circular sheet-like light spot with the largest radius is formed. Circular sheet-like light spots with proportionally decreasing radii are formed outwards from the opposite sides of the center of the focal plane. The circular sheet-like light spots at different positions on the focal plane are then aggregated to form a spherical focused light spot. The spherical focused light spot formed by this invention is a complete spherical shape without any spherical aberration or distortion.

[0057] 3. The optical system for generating a spherical focused light spot according to the present invention includes a refractive mask and a focusing lens. The refractive mask and the focusing lens are arranged sequentially from front to back along the incident direction of the incident laser beam. The entire optical system has a simple structure and is versatile and universal. Attached Figure Description

[0058] Figure 1This is a schematic diagram of the optical system for generating a spherical focused light spot according to the present invention;

[0059] Figure 2 This is a schematic diagram illustrating the partitioning of a laser beam using the principle of refraction, as described in this invention.

[0060] Figure 3 This is a schematic diagram of the structure of a refractive mask;

[0061] Figure 4 These are micrographs of damage points generated inside quartz glass using a spherical focused laser spot produced by a refractive mask and a 20x objective lens. In the image, a is a micrograph of the damage point in the XZ plane, and b is a micrograph of the damage point in the YZ plane. The parameters are: w = 400 μm, incident laser beam spot diameter = 6 mm, focusing lens NA = 0.42, focusing lens focal length f = 20 mm, refractive index of quartz glass = 1.5, incident laser beam wavelength λ = 800 nm, and incident laser beam beam quality factor M² = 1.3.

[0062] Among them, 1-incident laser beam, 2-refractive mask, 3-focusing lens, 4-circular sheet-like light spot. Detailed Implementation

[0063] The technical solution of the present invention will be further explained and described below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the embodiments described below.

[0064] Example 1

[0065] This embodiment describes a method for generating a spherical focused light spot, comprising the following steps:

[0066] 1) The refractive mask 2 divides the incident laser beam 1 into different regions and deflects the light from different regions based on the principle of refraction;

[0067] 2) The focusing lens 3 images the deflected light onto different positions of the focal plane, forming a spherical focused light spot.

[0068] This embodiment forms a focused spot at the focal plane of the focusing lens 3 based on the refraction principle of the refractive mask 2 and the imaging principle of the focusing lens 3.

[0069] In step 1), the refractive mask 2 divides the incident laser beam 1 into different regions as follows:

[0070] 1.1) Select the partition width of the refractive mask 2;

[0071] 1.2) Divide the refractive mask 2 into n regions based on the partition width of the refractive mask 2 and the spot diameter of the incident laser beam 1. The calculation formula is as follows:

[0072] n = d / w;

[0073] In the formula, n is the number of partitions on one side of the center of the refractive mask 2, d is the diameter of the incident laser beam 1, mm; w is the width of the partition of the refractive mask 2, mm.

[0074] Step 1) involves deflecting light from different regions as follows:

[0075] 1.3) Based on the spot diameter of the incident laser beam 1 and the focal length of the focusing lens 3, determine the diameter of the largest circular sheet-like spot 4. The calculation formula is as follows:

[0076] ω0 = 1.22 * λ * M² / NA;

[0077] NA = 0.5d / f;

[0078] In the formula, ω0 is the diameter of the largest circular sheet-like light spot 4, mm; λ is the wavelength of the incident laser beam 1, mm; M2 is the beam quality factor of the incident laser beam 1, dimensionless; NA is the numerical aperture, dimensionless; d is the spot diameter of the incident laser beam 1, mm; and f is the focal length of the focusing lens 3, mm.

[0079] 1.4) Calculate the maximum deflection angle α of the refracting mask 2 based on the diameter of the largest circular spot 4 and the focal length of the focusing lens 3. The calculation formula is as follows:

[0080] α = ω0 / f;

[0081] In the formula, α is the maximum deflection angle of the refractive mask 2 in radians; ω0 is the diameter of the maximum circular spot 4 in mm; and f is the focal length of the focusing lens 3 in mm.

[0082] 1.5) Calculate the maximum angle δ of the refracting mask 2 based on the maximum deflection angle α and the refractive index r of the material of the refracting mask 2. The calculation formula is:

[0083] δ=α×(r-r0);

[0084] In the formula, δ is the maximum angle of the refracting mask 2 in radians; α is the maximum deflection angle of the refracting mask 2 in radians; r is the refractive index of the material of the refracting mask 2, dimensionless; and r0 is the refractive index of air, dimensionless.

[0085] 1.6) Calculate the included angle θ of adjacent regions based on the maximum included angle of the refracting mask 2. The calculation formula is as follows:

[0086] θ = δ / n;

[0087] In the formula, θ is the included angle between adjacent regions in radians; δ is the maximum included angle between the edges of the refractive mask 2 in radians; and n is the number of partitions of the refractive mask 2 along one side of the center.

[0088] 1.7) The refractive mask 2 deflects light from different regions based on the angle θ between the edges of adjacent regions.

[0089] For details, see Figure 2 and Figure 3 The refractive mask 2 is divided into two sections along the center position to opposite sides, with each side divided into n sections. One side is deflected upward along the rotation axis of baseline 1 (positive direction), and the other side is deflected downward along the rotation axis of baseline 2 (negative direction). Finally, the positive, negative, and center positions are combined to form a spherical focused spot. The refraction angle of the center position region of the refractive mask 2 is 0. From region 1 to n, the refraction angle increases by δ in an arithmetic sequence. In the opposite direction, from region -1 to -n, the refraction angle decreases by -δ in an arithmetic sequence.

[0090] Step 2) Specifically, the focusing lens 3 images the deflected light onto different positions on the focal plane, forming a circular sheet-like light spot 4 with the largest radius at the center of the focal plane. Circular sheet-like light spots 4 are formed outwards from the opposite sides of the center of the focal plane, with the radius decreasing proportionally and symmetrically. The circular sheet-like light spots 4 at different positions on the focal plane are then converged to form a spherical focused light spot; that is, the circular sheet-like light spots 4 on both sides of the center of the focal plane are symmetrical about the center of the focal plane.

[0091] In step 2), the focusing lens 3 refracts the deflected light to different positions on the focal plane according to the angle θ between the edges of adjacent areas.

[0092] The partition width of the refractive mask 2 ranges from 200μm to 600μm. Specifically, the partition width of the refractive mask 2 can be 200μm, 300μm, 400μm, 500μm or 600μm.

[0093] It should be noted that the shorter the focal length of the focusing lens 3, the narrower the partition width of the refractive mask 2; the longer the focusing lens 3, the wider the partition width of the refractive mask 2.

[0094] Example 2

[0095] See Figure 1 The optical system for generating a spherical focused spot in this embodiment is formed using the method for generating a spherical focused spot in this embodiment. It includes a refractive mask 2 and a focusing lens 3, which are arranged sequentially from front to back along the incident direction of the incident laser beam 1.

[0096] The refractive mask 2 is used to divide the incident laser beam 1 into different regions and deflect the light in different regions based on the principle of refraction.

[0097] The focusing lens 3 images the deflected light onto different positions on the focal plane, forming a spherical focused light spot.

[0098] This embodiment forms a focused spot at the focal plane of the focusing lens 3 based on the refraction principle of the refractive mask 2 and the imaging principle of the focusing lens 3.

[0099] The refractive mask 2 includes mask parameters, which include the number of partitions n along one side of the center of the refractive mask 2 and the angle θ between the edges of adjacent regions.

[0100] The formula for calculating the number of partitions n along one side of the center of the refractive mask 2 is:

[0101] n = d / w;

[0102] In the formula, n is the number of partitions on one side of the center of the refractive mask 2, d is the diameter of the incident laser beam 1, mm; w is the partition width of the refractive mask 2, mm;

[0103] The process of determining the included angle θ between adjacent regions is as follows:

[0104] The diameter of the largest circular patch 4 is determined using the following formula:

[0105] ω0 = 1.22 * λ * M² / NA;

[0106] NA = 0.5d / f;

[0107] In the formula, ω0 is the diameter of the largest circular sheet-like light spot 4, mm; λ is the wavelength of the incident laser beam 1, mm; M2 is the beam quality factor of the incident laser beam 1, dimensionless; NA is the numerical aperture, dimensionless; d is the spot diameter of the incident laser beam 1, mm; and f is the focal length of the focusing lens 3, mm.

[0108] The maximum deflection angle α of the refractive mask 2 is determined by the following formula:

[0109] α = ω0 / f;

[0110] In the formula, α is the maximum deflection angle of the refractive mask 2 in radians; ω0 is the diameter of the maximum circular spot 4 in mm; and f is the focal length of the focusing lens 3 in mm.

[0111] The maximum included angle δ of the refracting mask 2 is determined by the following formula:

[0112] δ=α×(r-r0);

[0113] In the formula, δ is the maximum angle of the refracting mask 2 in radians; α is the maximum deflection angle of the refracting mask 2 in radians; r is the refractive index of the material of the refracting mask 2, dimensionless; and r0 is the refractive index of air, dimensionless.

[0114] The formula for determining the included angle θ between adjacent regions is as follows:

[0115] θ = δ / n;

[0116] In the formula, θ is the angle between adjacent regions in radians; δ is the maximum angle between the edges of the refractive mask 2 in radians; and n is the number of partitions along the center side of the refractive mask 2.

[0117] The focusing lens 3 images the deflected light onto different positions on the focal plane, forming a circular sheet-like light spot 4 with the largest radius at the center of the focal plane. Circular sheet-like light spots 4 are formed by extending outwards from both sides of the center of the focal plane, with the radius decreasing proportionally and symmetrically. The circular sheet-like light spots 4 at different positions on the focal plane are then aggregated to form a spherical focused light spot.

[0118] For details, see Figure 2 and Figure 3 The refractive mask 2 is divided into two sections along the center position to opposite sides, with each side divided into n sections. One side is deflected upward along the rotation axis of baseline 1 (positive direction), and the other side is deflected downward along the rotation axis of baseline 2 (negative direction). Finally, the positive, negative, and center positions are combined to form a spherical focused spot. The refraction angle of the center position region of the refractive mask 2 is 0. From region 1 to n, the refraction angle increases by δ in an arithmetic sequence. In the opposite direction, from region -1 to -n, the refraction angle decreases by -δ in an arithmetic sequence.

[0119] See Figure 4 a and Figure 4 b. At different positions of the liquid crystal light modulator (refractive mask 2), the prism phase is applied to cause the incident laser beam 1 to be refracted. After refraction, the beam is deflected. The deflected light is imaged by the focusing lens 3 to the focal plane of the focusing lens 3, forming a spherical focused spot. Damage points are generated inside the quartz glass through the spherical focused spot.

Claims

1. A method for generating a spherical focused light spot, characterized in that, Includes the following steps: 1) The refractive mask (2) divides the incident laser beam (1) into different regions and deflects the light in different regions based on the principle of refraction; 2) The focusing lens (3) images the deflected light onto different positions of the focal plane, forming a spherical focused light spot; Step 2) specifically involves: the focusing lens (3) images the deflected light onto different positions of the focal plane, forming a circular sheet-like light spot (4) with the largest radius at the center of the focal plane, extending outward along the opposite sides of the center of the focal plane to form circular sheet-like light spots (4) with proportionally decreasing radii and symmetrical, and then aggregating the circular sheet-like light spots (4) at different positions of the focal plane to form a spherical focusing light spot.

2. The method for generating a spherical focused light spot as described in claim 1, characterized in that, The step in step 1) where the refracting mask (2) divides the incident laser beam (1) into different regions is as follows: 1.1) Select the partition width of the refractive mask (2); 1.2) Divide the refractive mask (2) into n regions according to the partition width of the refractive mask (2) and the spot diameter of the incident laser beam (1). The calculation formula is as follows: n = d / w; In the formula, n is the number of partitions on one side of the center of the refractive mask (2), d is the spot diameter of the incident laser beam (1), mm; w is the partition width of the refractive mask (2), mm.

3. The method for generating a spherical focused light spot as described in claim 2, characterized in that, The step of deflecting light from different regions in step 1) is as follows: 1.3) Based on the spot diameter of the incident laser beam (1) and the focal length of the focusing lens (3), determine the diameter of the largest circular sheet-like spot (4). The calculation formula is as follows: ω0 = 1.22 * λ * M² / NA; NA = 0.5d / f; In the formula, ω0 is the diameter of the largest circular sheet-like light spot (4), mm; λ is the wavelength of the incident laser beam (1), mm; M2 is the beam quality factor of the incident laser beam (1), dimensionless; NA is the numerical aperture, dimensionless; d is the spot diameter of the incident laser beam (1), mm; f is the focal length of the focusing lens (3), mm; 1.4) Calculate the maximum deflection angle α of the refractive mask (2) based on the diameter of the largest circular spot (4) and the focal length of the focusing lens (3). The calculation formula is as follows: α = ω0 / f; In the formula, α is the maximum deflection angle of the refractive mask (2) in radians; ω0 is the diameter of the largest circular spot (4) in mm; and f is the focal length of the focusing lens (3) in mm. 1.5) Calculate the maximum angle δ of the refracting mask (2) based on the maximum deflection angle α and the refractive index r of the material of the refracting mask (2). The calculation formula is as follows: δ=α×(r-r0); In the formula, δ is the maximum angle of the refracting mask (2) in radians; α is the maximum deflection angle of the refracting mask (2) in radians; r is the refractive index of the material of the refracting mask (2) in dimensionless; r0 is the refractive index of air in dimensionless. 1.6) Calculate the included angle θ of adjacent regions based on the maximum included angle of the refracting mask (2). The calculation formula is as follows: θ = δ / n; In the formula, θ is the angle between adjacent regions in radians; δ is the maximum angle between the edges of the refractive mask (2) in radians; n is the number of partitions along the center side of the refractive mask (2); 1.7) Refraction mask (2) Deflects light from different regions according to the angle θ between the edges of adjacent regions.

4. The method for generating a spherical focused light spot as described in claim 1, 2, or 3, characterized in that, In step 2), the focusing lens (3) refracts the deflected light to different positions on the focal plane according to the angle θ between the edges of adjacent regions.

5. The method for generating a spherical focused light spot as described in claim 4, characterized in that, The partition width of the refractive mask (2) ranges from 200μm to 600μm.

6. An optical system for generating a spherical focused light spot, formed using the method for generating a spherical focused light spot according to any one of claims 1-3, characterized in that, It includes a refractive mask (2) and a focusing lens (3), which are arranged sequentially from front to back along the incident direction of the incident laser beam (1); The refractive mask (2) is used to divide the incident laser beam (1) into different regions and deflect the light in different regions based on the principle of refraction. The focusing lens (3) images the deflected light onto different positions of the focal plane to form a spherical focused light spot. Specifically, the focusing lens (3) images the deflected light onto different positions of the focal plane, forming a circular sheet-like light spot (4) with the largest radius at the center of the focal plane. Circular sheet-like light spots (4) with proportionally decreasing radii are formed outwards along the opposite sides of the center of the focal plane. The circular sheet-like light spots (4) at different positions of the focal plane are then aggregated to form a spherical focused light spot.

7. The optical system for generating a spherical focused light spot as described in claim 6, characterized in that, The refractive mask (2) includes mask parameters, which include the number of partitions n along one side of the center of the refractive mask (2) and the angle θ between the edges of adjacent regions.

8. The optical system for generating a spherical focused light spot as described in claim 7, characterized in that, The formula for calculating the number of partitions n on one side of the center of the refractive mask (2) is: n = d / w; In the formula, n is the number of partitions on one side of the center of the refractive mask (2); d is the spot diameter of the incident laser beam (1) in mm; w is the partition width of the refractive mask (2) in mm; The process for determining the included angle θ between the adjacent regions is as follows: The diameter of the largest circular patch (4) is determined by the following formula: ω0 = 1.22 * λ * M² / NA; NA = 0.5d / f; In the formula, ω0 is the diameter of the largest circular sheet-like light spot (4), mm; λ is the wavelength of the incident laser beam (1), mm; M2 is the beam quality factor of the incident laser beam (1), dimensionless; NA is the numerical aperture, dimensionless; d is the spot diameter of the incident laser beam (1), mm; f is the focal length of the focusing lens (3), mm; The maximum deflection angle α of the refractive mask (2) is determined by the following formula: α = ω0 / f; In the formula, α is the maximum deflection angle of the refractive mask (2) in radians; ω0 is the diameter of the largest circular spot (4) in mm; and f is the focal length of the focusing lens (3) in mm. The maximum included angle δ of the refracting mask (2) is determined by the following formula: δ=α×(r-r0); In the formula, δ is the maximum angle of the refracting mask (2) in radians; α is the maximum deflection angle of the refracting mask (2) in radians; r is the refractive index of the material of the refracting mask (2) in dimensionless; r0 is the refractive index of air in dimensionless. The formula for determining the included angle θ between adjacent regions is as follows: θ = δ / n; In the formula, θ is the angle between adjacent regions in radians; δ is the maximum angle between the edges of the refractive mask (2) in radians; and n is the number of partitions of the refractive mask (2) along the center side.

9. The optical system for generating a spherical focused light spot as described in claim 8, characterized in that, The focusing lens (3) images the deflected light onto different positions of the focal plane, forming a circular sheet-like light spot (4) with the largest radius at the center of the focal plane, and extending outwards along both sides of the center of the focal plane to form circular sheet-like light spots (4) with proportionally decreasing radii and symmetrical, and then aggregating the circular sheet-like light spots (4) at different positions of the focal plane to form a spherical focusing light spot.

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