Method for weakening light spot distortion, lens and optical system

Abstract

The invention is suitable for the technical field of optics, and provides a method for weakening light spot distortion, a lens and an optical system.The method comprises the steps that the propagation direction of a square light spot formed after laser passes through a light spot shaping element is obtained; a special lens is arranged at the outer end of the light spot shaping element along the propagation direction of the square light spot; the special lens consists of a middle part, a waist part and an edge position; the curvatures of the middle part, the waist part and the edge positions are different; calculating the optical path difference change of the square light spot passing through different positions of the special lens; and controlling the position of the square light spot passing through the special lens, dynamically adjusting the curvature of the middle part, the waist part and the edge position based on the optical path difference change of different positions, and compensating the optical path difference of different positions so as to weaken the light spot distortion. According to the invention, large-angle laser output can be realized while light spot homogenization is ensured.

Description

Technical Field

[0001] The present application belongs to the field of optical technology, and in particular relates to a method for reducing light spot distortion, a lens and an optical system. Background Art

[0002] In the prior art, the application of surface light spots has become more and more widespread. However, the laser surface light spots on the market are generally small-angle, which leads to certain limitations in their use. In order to meet the lighting needs of a larger angle, the light spot shaping technology can be used.

[0003] Traditionally, there are three main ways to achieve a surface light spot: the diffractive optical element (DOE) method, the Powell superposition method, and the cylindrical array method. The DOE diffractive optical element achieves the surface light spot effect by diffraction, while the Powell superposition method uses two Powell prisms to shape the light into a square light spot, and the cylindrical array method uses two cylindrical arrays to superimpose to achieve the shaping effect. However, these methods all have large distortion problems when shooting lasers at large angles, which will have an adverse effect on the homogenization of the entire light spot and will result in a lot of energy waste.

[0004] Due to the distortion and energy waste of the traditional surface spot realization method at large angles, it is unable to meet the lighting needs at large angles, and the spot shaping technology faces great challenges. How to achieve large-angle laser output while ensuring the uniformity of the spot has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to overcome the problems existing in the related art, the embodiments of the present application provide a method, a lens and an optical system for reducing light spot distortion, which can achieve large-angle laser output while ensuring light spot homogenization.

[0006] This application is implemented through the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a method for reducing spot distortion, comprising:

[0008] Obtain the propagation direction of the square spot formed after the laser passes through the spot shaping element;

[0009] At the outer end of the light spot shaping element, a special lens is arranged along the propagation direction of the square light spot; the special lens is composed of a middle part, a waist part and an edge part; the curvatures of the middle part, the waist part and the edge part are different;

[0010] Calculate the change in optical path difference of a square light spot passing through different positions of a special lens;

[0011] The position of the square light spot passing through the special lens is controlled, and based on the changes in the optical path difference at different positions, the curvature of the middle, waist and edge positions is dynamically adjusted to compensate for the optical path difference at different positions to reduce the light spot distortion.

[0012] In a possible implementation manner of the first aspect, the curvature of the middle portion is greater than the curvature of the waist portion, and the curvature of the edge portion is greater than the curvature of the waist portion.

[0013] In a possible implementation manner of the first aspect, controlling the position of the square light spot passing through the special lens includes:

[0014] Based on the change of optical path difference at different positions, the four corners of the square light spot are controlled to pass through the edge positions of the special lens, the middle areas of the edges of the square light spot are controlled to pass through the middle of the special lens, and the middle area of ​​the square light spot is controlled to pass through the middle of the special lens.

[0015] In a possible implementation manner of the first aspect, based on the change of the optical path difference at different positions, the curvatures of the middle, waist and edge positions are dynamically adjusted to compensate for the optical path difference at different positions, including:

[0016] Determine the degree of distortion based on the degree of change in the optical path difference at different positions;

[0017] Based on the degree of distortion, the curvature of the middle, waist and edge positions is adjusted to compensate for the optical path difference at different positions.

[0018] In a possible implementation manner of the first aspect, adjusting the curvatures of the middle, waist, and edge positions based on the degree of distortion includes:

[0019] The greater the degree of distortion, the greater the change in curvature from the edge position to the waist.

[0020] In a possible implementation manner of the first aspect, obtaining a propagation direction of a square light spot formed after the laser passes through a light spot shaping element includes:

[0021] Define the surface equation of the spot shaping element;

[0022] Based on the surface equation of the spot shaping element, the propagation direction model of the square spot formed after the laser passes through the spot shaping element is determined.

[0023] In a possible implementation manner of the first aspect, the mathematical model z(x, y) of the surface shape of the tailor-made lens is expressed as:

[0024] z(x,y)=Cx 2 +Dy 2

[0025] Wherein, (x, y) is the coordinate of any position of the special lens; C is the curvature constant of the special lens in the x direction, and D is the curvature constant of the special lens in the y direction.

[0026] In a possible implementation of the first aspect, at the outer end of the spot shaping element, if the angle at which the spot shaping element generates the square spot is larger, when a special lens is set along the propagation direction of the square spot, the distance between the special lens and the front end spot shaping element is closer.

[0027] On the second aspect, an embodiment of the present application provides a lens for reducing spot distortion, wherein the lens is a special lens and is arranged at the outer end of a spot shaping element along the propagation direction of a square spot; the special lens consists of a middle part, a waist part and an edge part; the curvatures of the middle part, the waist part and the edge part are different; wherein, by controlling the position of the square spot passing through the special lens and based on the change of the optical path difference of the square spot passing through different positions of the special lens, the curvatures of the middle part, the waist part and the edge part are dynamically adjusted to compensate for the optical path difference at different positions so as to reduce the spot distortion.

[0028] In a third aspect, an embodiment of the present application provides an optical system for reducing spot distortion, comprising a spot shaping element and a special lens as in the second aspect.

[0029] It can be understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0030] Compared with the related art, the embodiments of the present application have the following beneficial effects:

[0031] In the embodiment of the present application, by calculating the change in the optical path difference of a square light spot passing through different positions of a special lens, the source of the light spot distortion can be accurately identified, so that the light spot can be more evenly distributed when passing through the lens, thereby significantly improving the homogenization effect of the light spot. Subsequently, by dynamically adjusting the curvature of the middle, waist and edge positions of the special lens, the optical path difference at these positions can be compensated in a targeted manner, thereby ensuring that the laser can maintain a larger angle range when output. By dynamically adjusting the curvature of the special lens, dynamic adjustments can be made according to different light spot distortion conditions, and it can be applied to a variety of optical systems, whether it is a simple lens system or a complex multi-lens system, better imaging effects can be obtained through this method, and ultimately the image quality can be significantly improved by reducing the light spot distortion, which is of particular significance for fields that require high-precision imaging, such as optical measurement, optical detection, medical imaging, etc.

[0032] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 is a schematic diagram of the structure of a fly-eye lens provided in one embodiment of the present application;

[0035] Figure 2 is a structural schematic diagram of a cylindrical array provided in an embodiment of the present application;

[0036] Figure 3 This is a schematic diagram of square spot distortion provided by an embodiment of the present application;

[0037] Figure 4 is a flow chart of a method for reducing light spot distortion provided by an embodiment of the present application;

[0038] Figure 5 This is a schematic diagram of the correspondence between the special lens provided in one embodiment of the present application and the position of the distorted light spot before correction;

[0039] Figure 6 Schematic diagram of a square light spot after distortion correction provided by an embodiment of the present application. DETAILED DESCRIPTION

[0040] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0041] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0042] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0043] As used in the present specification and the appended claims, the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0044] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0045] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0046] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0047] It is important to understand that a small-angle surface spot usually refers to a small divergence angle of the spot, that is, the light is relatively concentrated during the propagation process, and the illumination range formed is narrow. This type of surface spot is more common in applications such as laser scanning, laser cutting, and laser welding. Due to the small divergence angle, the light can be more accurately focused on the target area, thereby achieving high-precision processing or measurement.

[0048] A large-angle surface light spot refers to a light spot with a large divergence angle, that is, the light is relatively dispersed during the propagation process, forming a wider illumination range. This type of surface light spot is widely used in lighting, display, environmental monitoring and other fields. Due to the large divergence angle, the light can cover a wider area and provide uniform lighting or detection effects.

[0049] Currently, there are solutions on the market that use DOE diffraction plates to shape the light spot into a square, but the cost is very high, and the cost is even higher when the uniformity requirement is high. If the angle is large, the energy at the edge of the light spot will be low. In addition, there are compound eye lenses, such as Figure 1As shown, the light spot is shaped into a square. This method has high light spot uniformity, but the light spot angle size is too small and cannot be used in large-angle applications.

[0050] There are also two cylindrical arrays placed vertically, such as Figure 2 As shown in the figure, the light spot is shaped into a line, and then the line spot is widened to obtain a surface spot. However, the large-angle light spot obtained in this way will have a large distortion, such as Figure 3 shown.

[0051] Therefore, in combination with the above-mentioned background technology, it can be understood that it is currently difficult to achieve large-angle laser output while ensuring the homogenization of the light spot.

[0052] Figure 4 FIG. 1 is a flow chart of a method for reducing light spot distortion provided by an embodiment of the present application. Figure 4 , the method for reducing the spot distortion is described in detail as follows:

[0053] Step 101, obtaining the propagation direction of the square light spot formed after the laser passes through the light spot shaping element.

[0054] For example, the laser light may be parallel light, focused light or diffuse light, and after passing through the spot shaping element, the spot will be shaped into a linear spot. The spot shaping element may be a DOE diffractive optical element, a Powell lens, a cylindrical array or a compound eye lens, or a combination thereof, which has the function of shaping a linear spot.

[0055] The incident laser will be converted into a linear spot under the influence of the spot shaping element. After the light passes through the spot shaping element, the propagation direction of the light changes. Therefore, it is necessary to use the characteristics of the spot shaping element to redefine the propagation direction of the formed square spot.

[0056] Step 102: a special lens is arranged at the outer end of the light spot shaping element along the propagation direction of the square light spot.

[0057] The special lens is composed of a middle part, a waist part and an edge part, and the curvatures of the middle part, the waist part and the edge part are different. The distorted square light spot can be corrected in a targeted manner by utilizing the different curvatures of the middle part, the waist part and the edge part.

[0058] Step 103, calculating the change in optical path difference of the square light spot passing through different positions of the special lens.

[0059] At different positions of the special lens, the curvature changes differently, which will result in different changes in the optical path of the light path. This change is particularly obvious at the edge position. Therefore, the changes in the optical path difference at different positions of the special lens can be grasped, which in turn can prepare for customizing the curvature of the special lens for the corresponding distortion.

[0060] Step 104, controlling the position of the square light spot passing through the special lens, and dynamically adjusting the curvature of the middle, waist and edge positions based on the change of the optical path difference at different positions, compensating for the optical path difference at different positions, so as to reduce the light spot distortion.

[0061] This embodiment can accurately identify the source of light spot distortion by calculating the change in optical path difference when the square light spot passes through different positions of the special lens, so that the light spot can be more evenly distributed when passing through the lens, thereby significantly improving the homogenization effect of the light spot. Subsequently, by dynamically adjusting the curvature of the middle, waist and edge positions of the special lens, the optical path difference at these positions can be compensated in a targeted manner, thereby ensuring that the laser can maintain a larger angle range when output. By dynamically adjusting the curvature of the special lens, it can be dynamically adjusted according to different light spot distortion conditions, which can reduce the light spot distortion and obtain better imaging effects.

[0062] In one embodiment, a process of determining the propagation direction of a square light spot formed after the laser passes through a light spot shaping element is introduced. Step 101 includes:

[0063] First, define the surface equation of the spot shaping element.

[0064] The surface equation of the spot shaping element can be defined according to the characteristics of each element having the function of shaping a linear spot, such as a DOE diffractive optical element, a Powell lens, a cylindrical array or a compound eye lens.

[0065] For example, taking a cylindrical array as an example, the surface equation of the cylindrical array is defined as z=f(x,y), where f(x,y) is a function describing the curvature of the cylindrical array, and the incident parallel light will be converted into a linear light spot under the influence of the cylindrical array.

[0066] Then, based on the surface equation of the spot shaping element, the propagation direction model of the square spot formed after the laser passes through the spot shaping element is determined.

[0067] After the light passes through the cylindrical array, the propagation direction R of the light changes, and the corresponding propagation direction model of the square light spot can be expressed as:

[0068]

[0069] The cylindrical array makes the incident light converge in the horizontal axis direction to form a linear light spot. After passing through two intersecting cylindrical arrays, a surface light spot will be formed, but there will be distortion.

[0070] This embodiment lays a foundation for the subsequent determination of distortion through the propagation direction model of the square light spot.

[0071] In one embodiment, it is described how to tailor the curvature of the lens at the center, waist and edge.

[0072] Exemplarily, the curvature of the middle portion is greater than that of the waist portion, and the curvature of the edge portion is greater than that of the waist portion.

[0073] At the outer end of the cylindrical array, a special lens, such as Figure 5 As shown in the figure, the square light spot passes through the middle of the lens, and the curvature of the middle of the lens is approximately a plane, which has almost no effect on changing the optical path, and the optical path changes slightly; there is a gentle curvature change at the waist, which will cause the optical path of the light path to change, and the optical path difference is relatively small; there is an obvious curvature change at the edge, the optical path change is particularly obvious, and the optical path difference is large.

[0074] The mathematical model z(x,y) of the surface shape of the special lens is expressed as:

[0075] z(x,y)=Cx 2 +Dy 2

[0076] Wherein, (x, y) is the coordinate of any position of the special lens; C is the curvature constant of the special lens in the x direction, and D is the curvature constant of the special lens in the y direction.

[0077] For example, the curvature of the edge position may range from 10 to 25 (the unit of curvature is not indicated, but is m). -1 ), the curvature of the waist can range from 25 to 50, and the curvature of the center can range from 50 to infinity (plane).

[0078] The curvature at the edge is set to 10-25. In this area, the light propagation path will bend greatly, resulting in a significant change in the optical path difference. The curvature at the waist is set to 25-50. The curvature change in this area is relatively gentle, and the optical path difference change is relatively small, but it still has an impact. The curvature in the middle is 50 to nearly infinity (i.e., a plane). In this area, the optical path difference is close to zero, and the light propagation path hardly changes.

[0079] The curvature piecewise function of the custom lens can be expressed as:

[0080]

[0081] Among them, C1 is the curvature constant of the edge of the special lens in the x direction, and D1 is the curvature constant of the edge of the special lens in the y direction; C2 is the curvature constant of the edge of the special lens in the x direction, and D2 is the curvature constant of the edge of the special lens in the y direction; C3 is the curvature constant of the edge of the special lens in the x direction, and D3 is the curvature constant of the edge of the special lens in the y direction; as x and y increase, the curvature gradually increases.

[0082] Next, in step 103, we can use the optical path formula to calculate the optical path difference when the light passes through different positions of the lens. Assume that the light passes through the lens surface from the incident point (x0, y0, z0) and refracts along the direction R = (R x ,R y ,R z ) propagation, the change in the curvature of the lens will cause the optical path difference of the light propagation path.

[0083] The optical path difference can be calculated by the following formula:

[0084] ΔL=∫ 光线轨迹 n(x,y)dl

[0085] Where n(x,y) is the refractive index at (x,y), dl is the small change in the light path, and the integral range is the light trajectory from the incident point to the exit point, where the exit point is determined by the incident point and the propagation direction R. The optical path difference is different for different areas of the lens, depending on the curvature of the lens and the incident angle of the light. Due to the change in curvature, the light will have different refraction angles when passing through different areas of the lens, which will affect the size of the optical path difference. Especially when the spot distortion is large, the curvature change from the edge to the waist needs to be increased to compensate for the imaging distortion caused by the irregular optical path difference.

[0086] Since the light spot is a square spot, the light spots at the four corners of the light spot act differently on the middle, waist and edge of the lens, which will form different optical path differences, thereby achieving the effect of correcting distortion.

[0087] Exemplarily, in step 104, controlling the position of the square light spot passing through the special lens includes:

[0088] Based on the change of optical path difference at different positions, the four corners of the square light spot are controlled to pass through the edge positions of the special lens, the middle areas of the edges of the square light spot are controlled to pass through the middle of the special lens, and the middle area of ​​the square light spot is controlled to pass through the middle of the special lens.

[0089] like Figure 5 As shown, the maximum distortion of the four sides of the square light spot pincushion distortion is tangent to the dividing line between the middle and the waist, so that the circle enclosed by the maximum distortion is in the middle. This part of the light spot is mostly uniform and almost does not need to be corrected. The part outside the circle enclosed by the maximum distortion corresponds to the waist and edge positions according to the direction of the four corners. The four corners of the square light spot act on the edge positions of the special lens respectively, and the concave part of the pincushion distortion gradually transitions from the edge position to the waist to form a correspondence, so that the curvature changes at different positions according to different distortion degrees, compensate for the corresponding optical path difference, and reduce the light spot distortion. The square light spot after reducing the light spot distortion is as follows: Figure 6 shown.

[0090] Here, the pincushion distortion is the main distortion form of the square surface spot during the application process, and barrel distortion generally does not occur. Therefore, this application only describes the relevant solutions for the pincushion distortion.

[0091] Therefore, in step 104, based on the change of the optical path difference at different positions, the curvatures of the middle, waist and edge positions are dynamically adjusted to compensate for the optical path difference at different positions, including:

[0092] The degree of distortion is determined based on the degree of change in the optical path difference at different positions. Based on the degree of distortion, the curvature of the middle, waist and edge positions is adjusted to compensate for the optical path difference at different positions.

[0093] Exemplarily, based on the degree of distortion, adjusting the curvatures of the middle, waist, and edge positions includes:

[0094] The greater the degree of distortion, the greater the change in curvature from the edge position to the waist.

[0095] It should be noted that, in addition to cylindrical arrays, Powell prisms and cylindrical lenses will have similar effects on the shaping and distortion of the light spot. They can bend the light at a certain angle and change the shape of the light spot. The optical path difference of Powell prisms and cylindrical lenses is similar to the change in the curvature of the lens, and the distortion can be compensated by adjusting the refraction path of the light.

[0096] This embodiment can effectively control the propagation path and optical path difference of light by designing the curvature of different positions of the special lens, such as the curvature difference at the middle, waist and edge positions. For the square light spot, the distortion can be corrected in a targeted manner according to its different effects in different areas of the lens (middle, waist, edge). When processing the pincushion distortion of the light spot, the curvature changes at different positions can be corresponding to different degrees of distortion, thereby compensating for the corresponding optical path difference and achieving a better light spot shaping effect. And this principle of using the curvature of a special lens to adjust the optical path difference to compensate for distortion is similar to the Powell prism and cylindrical lens, and has a certain reference value for studying the shaping and distortion control of the light spot, and can be widely used in scenes in optical systems that require precise control of the light spot shape and correction of distortion, thereby improving the imaging quality of the optical system.

[0097] In addition, with the continuous development of science and technology, the requirements for spot shaping and distortion correction are getting higher and higher. In the future, more advanced optical components or combinations may appear, which can handle the distortion problems of various shapes of spots more efficiently and accurately. For example, the distortion of the spot can be monitored in real time through an intelligent control system, and the relevant parameters of special lenses, Powell prisms or cylindrical lenses can be automatically adjusted according to the monitoring results to achieve adaptive spot shaping and distortion correction. This will have broad application prospects in many fields such as laser processing and optical imaging.

[0098] In one embodiment, the placement position of the special lens is related to the angle of generating the square light spot. At the outer end of the light spot shaping element, if the angle of the light spot shaping element generating the square light spot is larger, when a special lens is set along the propagation direction of the square light spot, the distance between the special lens and the front end light spot shaping element is closer.

[0099] For example, if the angle of the spot shaping element (cylindrical array, Powell, cylindrical lens or combination thereof) that generates a square spot is larger, the distance between the special lens and the lens of the front combination is closer. For example, in the case of a 53° full angle, the distance between the special lens and the spot shaping element of the front group is 20 mm to 35 mm.

[0100] The angle θ produced by the spot shaping element that produces a square spot is expressed as:

[0101] θ=α+Δθ

[0102] Among them, α is the incident angle of the light to the special lens, and Δθ is the angle change caused by the distance d between the special lens and the spot shaping element of the front group.

[0103] The method for reducing light spot distortion provided in the embodiment of the present application can accurately identify the source of light spot distortion by calculating the change in optical path difference of a square light spot passing through different positions of a special lens, so that the light spot can be more evenly distributed when passing through the lens, thereby significantly improving the homogenization effect of the light spot. Subsequently, by dynamically adjusting the curvature of the middle, waist and edge positions of the special lens, the optical path difference at these positions can be compensated in a targeted manner, thereby ensuring that the laser can maintain a larger angle range when output. By dynamically adjusting the curvature of the special lens, dynamic adjustment can be made according to different light spot distortion conditions, and it can be applied to a variety of optical systems, whether it is a simple lens system or a complex multi-lens system, better imaging effects can be obtained through this method, and finally by reducing the light spot distortion, the image quality can be significantly improved, which is of particular significance for fields that require high-precision imaging, such as optical measurement, optical detection, medical imaging, etc.

[0104] An embodiment of the present application provides a lens for reducing spot distortion, wherein the lens is a special lens and is arranged at the outer end of a spot shaping element along the propagation direction of a square spot; the special lens consists of a middle part, a waist part and an edge part; the curvatures of the middle part, the waist part and the edge part are different; wherein, by controlling the position where the square spot passes through the special lens and based on the change in the optical path difference of the square spot passing through different positions of the special lens, the curvatures of the middle part, the waist part and the edge part are dynamically adjusted to compensate for the optical path difference at different positions so as to reduce the spot distortion.

[0105] An embodiment of the present application provides an optical system for reducing light spot distortion, including a light spot shaping element and a special lens as in the above embodiment.

[0106] It can be understood that the beneficial effects of the above-mentioned lens for reducing spot distortion and the optical system for reducing spot distortion can be found in the relevant description of the above-mentioned method for reducing spot distortion, which will not be repeated here.

[0107] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0108] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for reducing spot distortion, characterized in that: include: Obtain the propagation direction of the square spot formed after the laser passes through the spot shaping element; A special lens is arranged at the outer end of the light spot shaping element along the propagation direction of the square light spot; the special lens consists of a middle part, a waist part and an edge part; the curvatures of the middle part, the waist part and the edge part are different; Calculate the change of optical path difference of the square light spot passing through different positions of the special lens; The position where the square light spot passes through the special lens is controlled, and based on the change of the optical path difference at different positions, the curvatures of the middle, waist and edge positions are dynamically adjusted to compensate for the optical path difference at different positions to reduce the light spot distortion.

2. The method for reducing spot distortion according to claim 1, characterized in that: The curvature of the middle portion is greater than that of the waist portion, and the curvature of the edge portion is greater than that of the waist portion.

3. The method for reducing spot distortion according to claim 2, characterized in that: The step of controlling the position of the square light spot passing through the special lens comprises: Based on the change of the optical path difference at different positions, the four corners of the square light spot are controlled to pass through the edge positions of the special lens, the middle areas of the edges of the square light spot are controlled to pass through the middle of the special lens, and the middle area of ​​the square light spot is controlled to pass through the middle of the special lens.

4. The method for reducing spot distortion according to claim 1, characterized in that: The method of dynamically adjusting the curvatures of the middle portion, the waist, and the edge positions based on the change of the optical path difference at the different positions to compensate for the optical path difference at the different positions includes: Determining the degree of distortion based on the degree of change of the optical path difference at different positions; Based on the degree of distortion, the curvatures of the middle portion, the waist portion and the edge portion are adjusted to compensate for the optical path differences at different positions.

5. The method for reducing spot distortion according to claim 4, characterized in that: The adjusting the curvatures of the middle portion, the waist portion, and the edge portion based on the degree of distortion includes: The greater the degree of distortion, the greater the degree of change in curvature of the waist when adjusting the edge position.

6. The method for reducing spot distortion according to claim 1, characterized in that: The step of obtaining the propagation direction of the square light spot formed after the laser passes through the light spot shaping element comprises: Defining a surface equation of the light spot shaping element; Based on the surface equation of the light spot shaping element, a propagation direction model of a square light spot formed after the laser passes through the light spot shaping element is determined.

7. The method for reducing spot distortion according to claim 1, characterized in that: The mathematical model z(x,y) of the surface shape of the special lens is expressed as: z(x,y)=Cx 2 +Dy 2 Wherein, (x, y) is the coordinate of any position of the special lens; C is the curvature constant of the special lens in the x direction, and D is the curvature constant of the special lens in the y direction.

8. The method for reducing spot distortion according to any one of claims 1 to 7, characterized in that: At the outer end of the light spot shaping element, if the angle at which the light spot shaping element generates the square light spot is larger, when a special lens is set along the propagation direction of the square light spot, the distance between the special lens and the front end of the light spot shaping element is closer.

9. A lens for reducing light spot distortion, characterized in that: The lens is a special lens, which is arranged at the outer end of the light spot shaping element along the propagation direction of the square light spot; the special lens consists of a middle part, a waist part and an edge part; the curvatures of the middle part, the waist part and the edge part are different; wherein, by controlling the position where the square light spot passes through the special lens, and based on the change of the optical path difference of the square light spot passing through different positions of the special lens, the curvatures of the middle part, the waist part and the edge part are dynamically adjusted to compensate for the optical path difference of the different positions, so as to reduce the light spot distortion.

10. An optical system for reducing light spot distortion, characterized in that: It comprises a light spot shaping element and the special lens as claimed in claim 9.

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