An optical device and laser system for achieving laser spot homogenization

Abstract

This invention relates to the field of optical technology and discloses an optical device and laser system for achieving laser homogenization of the laser spot. The optical device for achieving laser homogenization of the laser spot includes: multiple optical fibers arranged in a projection array within a first plane formed by a first direction and a second direction, both of which are perpendicular to a third direction, which is the optical axis direction of the target optical fiber located at the center of the multiple optical fibers; multiple collimating lenses, each corresponding to one of the multiple optical fibers, disposed on the light-emitting side of the corresponding optical fiber, and coaxial with the corresponding optical fiber; the multiple optical fibers and multiple collimating lenses are arranged in a preset position so that the laser spots formed after collimation by the collimating lenses from each optical fiber overlap, forming the target spot on the working surface of the receiving screen. This invention, through the mutual cooperation of multiple optical fibers and multiple collimating lenses corresponding to each of the multiple optical fibers, can generate a high-power, large-divergence-angle, and uniformly homogenized laser spot.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more specifically to an optical device and laser system for achieving laser spot homogenization. Background Technology

[0002] In fields such as laser display, lighting, and materials processing, the application of high-power (e.g., above 10kW) and large divergence angle (e.g., divergence half angle greater than 7°) homogenized light spots is becoming increasingly widespread. When the divergence angle of the homogenized light spot is large, the light diverges relatively during propagation. When received at the same distance, the light spot size is larger and the coverage is wider. At the same time, the laser power is higher, which can achieve higher energy density.

[0003] Currently, high-power, large-divergence-angle light spots are mostly formed using aspherical shaping structures or spot splicing methods. However, aspherical shaping structures are relatively complex, and the power they can withstand is limited by lens materials and coatings. Spot splicing, on the other hand, suffers from unevenness at the splicing points. Therefore, there is an urgent need for a homogenizing light spot device that can generate high-power, large-divergence-angle, and uniform light spots. Summary of the Invention

[0004] This invention provides an optical device and laser system for achieving laser homogenization of light spots, in order to solve the problem of difficulty in generating high-power, large-divergence-angle, and uniform laser homogenization light spots.

[0005] In a first aspect, the present invention provides an optical device for realizing laser homogenization of light spots, comprising: a plurality of optical fibers arranged in a projection array in a first plane formed by a first direction and a second direction, wherein the first direction and the second direction are both perpendicular to a third direction, and the third direction is the optical axis direction of the target optical fiber located at the center of the plurality of optical fibers; a plurality of collimating lenses corresponding one-to-one with the plurality of optical fibers, wherein the collimating lenses are disposed on the light-emitting side of the corresponding optical fibers and are coaxial with the corresponding optical fibers; the plurality of optical fibers and the plurality of collimating lenses are arranged in a preset position so that the light spots formed by the laser emitted from each optical fiber after being collimated by the collimating lenses overlap and form a target light spot on the working surface of the receiving screen.

[0006] The optical device for achieving laser beam homogenization provided by this invention comprises multiple optical fibers and multiple collimating lens arrays. The fiber arrays emit light simultaneously, and the output power of the entire optical device is increased by superimposing the beam spots. The power borne by a single optical fiber and a single collimating lens remains unchanged. The output power of the optical device can be flexibly adjusted by adjusting the number of optical fibers. The collimating lens array can achieve large-angle beam divergence. At the same time, the multiple optical fibers and multiple collimating lenses are arranged in preset positions to ensure that the beam spots after collimation by the collimating lenses on the working surface of the receiving screen overlap, avoiding the problem of uneven beam spots at the splicing points in related technologies.

[0007] In one alternative implementation, within the second plane formed by the second direction and the third direction, the position of the vertex of the rear surface of the collimating lens satisfies the following formula:

[0008]

[0009] In the formula, Indicates the diameter of the target light spot. Indicates the first j The coordinates of the vertex position of the rear surface of the collimating lens in the second direction. j It is an integer. This indicates the focal length of the collimating lens. Indicates the first j The angle between the emission direction of the optical fiber corresponding to each collimating lens and the third plane, where the third plane is the plane composed of the first direction and the third direction. This represents the distance from the vertex of the collimating lens's rear surface, located at the origin of the coordinate system, to the working surface of the receiving screen. Indicates the first j The position of the vertex of the back surface of a collimating lens in the third direction. This indicates the divergence angle of the laser emitted from the optical fiber after passing through the collimating lens. The rear surface of the collimating lens is the surface of the collimating lens that faces away from the end face of the optical fiber.

[0010] In one alternative implementation, the first is determined by the following formula: j The angle between the emission direction of the optical fiber corresponding to each collimating lens and the third plane:

[0011] .

[0012] In one alternative implementation, the diameter of the target light spot is determined by the following formula:

[0013]

[0014] In the formula, In radians .

[0015] In one optional embodiment, the collimating lens is an aspherical lens, wherein both the front and rear surfaces of the collimating lens are aspherical and satisfy the following formula:

[0016]

[0017] In the formula, This represents the sag of the collimating lens along the optical axis of the fiber. Represents the curvature of an aspherical surface. Represents radial coordinates, Represents the conic coefficient. Represents even-order aspherical coefficients, corresponding to The order of the polynomial is Q, which represents the highest order of the aspherical polynomial expansion. The front surface of the collimating lens is the surface of the collimating lens closest to the fiber end face.

[0018] In this embodiment, the curved profile of the aspherical lens is an even-order aspherical surface, which can accurately compensate for the optical path difference of light rays with different incident angles. This allows the light rays emitted from the optical fiber to be nearly collimated after passing through the aspherical surface. Moreover, collimation using an aspherical lens with diffraction-limited imaging quality can maintain the uniformity of light intensity distribution within the light spot cross-section consistent with the core diameter.

[0019] In one optional embodiment, the collimating lens has a focal length of 0.5 mm, a curvature of 1 / 0.295 on its front surface, a conic coefficient of -1 on both the front and rear surfaces, a highest order of 6 in the polynomial expansion of the front surface, and even-order aspherical coefficients of the front surface including... The curvature of the back surface is -1 / 3.7, the highest order of the back surface polynomial expansion is 3, and the even-order aspherical coefficients of the back surface include... The thickness of the collimating lens .

[0020] In this embodiment, by optimizing the aspherical profile, optical system aberrations can be corrected, avoiding problems such as light spot distortion, deviation from the preset shape, decreased light spot uniformity, or unclear or unsharp light spot edges.

[0021] In one optional embodiment, the focal length of the collimating lens is not 0.5mm, the conicity of the collimating lens is -1, and the curvature of the collimating lens is... Even-order aspherical coefficient of a collimating lens The thickness of the collimating lens ,in, This represents the ratio of the focal length of the collimating lens to the focal length of the reference lens, where the reference lens is a collimating lens with a focal length of 0.5 mm. Indicates the curvature of the reference lens. This represents the even-order aspherical coefficient of the reference lens.

[0022] In one alternative implementation, the distance from the vertex of the collimating lens's rear surface at the origin to the working surface of the receiving screen is greater than 10 times the Rayleigh interval.

[0023] In one optional embodiment, the optical device for achieving laser homogenization of the light spot further includes multiple focusing lenses; the multiple focusing lenses correspond one-to-one with multiple collimating lenses, the focusing lenses are disposed on the light-emitting side of the corresponding collimating lenses, and the focusing lenses and the corresponding collimating lenses are on the same optical axis.

[0024] In a second aspect, the present invention provides a laser system, which includes an optical device for achieving laser homogenization of the laser spot according to the first aspect or any corresponding embodiment described above. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a first-view schematic diagram of an optical device for achieving laser homogenization of a light spot according to an embodiment of the present invention;

[0027] Figure 2 This is a second-view schematic diagram of an optical device for achieving laser homogenization of a laser spot according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of another optical device for achieving laser homogenization of a laser spot according to an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram showing the overlapping of light spots formed by the lasers emitted from each optical fiber after being collimated by a collimating lens according to an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the arrangement of collimating lenses on the second plane according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of a collimating lens according to an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of another optical device for achieving laser homogenization of the laser spot according to an embodiment of the present invention;

[0033] Figure 8 This is a schematic diagram of a target light spot according to an embodiment of the present invention;

[0034] Figure 9 This is a schematic diagram of another target light spot according to an embodiment of the present invention;

[0035] Figure 10 This is a schematic diagram of another target light spot according to an embodiment of the present invention.

[0036] Reference numerals: 110, optical fiber; 120, collimating lens; 121, front surface; 122, rear surface; 130, focusing lens; 200, receiving screen. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention, not the entire structure.

[0038] In the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the invention. Various structural schematic diagrams according to embodiments of the invention are shown in the accompanying drawings. These drawings are not to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from actual designs due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0039] This invention provides an optical device and laser system for achieving laser homogenization of the laser spot. Through the cooperation of multiple optical fibers and multiple collimating lenses corresponding one-to-one with the fibers, a high-power, large-divergence-angle, and uniformly homogenized laser spot can be generated. The homogenized spot generated by the optical device (optical system) provided by this invention can be applied in fields including, but not limited to, laser coating, laser welding, and laser lighting.

[0040] The optical device for achieving laser homogenization of light spots provided by the present invention will now be described in detail with reference to the accompanying drawings.

[0041] like Figure 1 and Figure 2 As shown, the optical device for achieving laser homogenization of the spot provided by the present invention includes multiple optical fibers 110 and multiple collimating lenses 120.

[0042] Multiple optical fibers 110 are projected into a first plane formed by the first direction X and the second direction Y. Both the first direction X and the second direction Y are perpendicular to the third direction Z. The third direction Z is the optical axis direction of the target optical fiber located at the center of the multiple optical fibers. The first direction X can be horizontal and the second direction Y can be vertical. That is, when the multiple optical fibers 110 are projected into the first plane in three-dimensional space, it is a two-dimensional optical fiber array structure with M rows × N columns, where M and N are both positive integers. Figure 1 and Figure 2 Taking M and N as both being 5 as an example, but not limited to this, for example, M and N can be 3, 7, or 9, etc. Among them, if M=5 and N=5, then the target optical fiber is the optical fiber in the 3rd row and 3rd column.

[0043] When M×N optical fibers emit light simultaneously, their power can be superimposed, thereby increasing the overall output power of the optical device. For example, if the output power of a single optical fiber is 250W, a 9×9 fiber array can achieve an output power of over 20kW; if the output power of a single optical fiber is 400W, a 9×9 fiber array can achieve an output power of over 32kW.

[0044] Multiple collimating lenses 120 correspond one-to-one with multiple optical fibers 110. The collimating lenses 120 are disposed on the light-emitting side of the corresponding optical fibers. Each optical fiber and its corresponding collimating lens are coaxial, and the third direction Z is also the thickness direction of the collimating lens corresponding to the target optical fiber. When the number of optical fibers is M×N, the number of collimating lenses is also M×N.

[0045] The light emitted from each fiber is collimated by a corresponding collimating lens, which can increase the divergence angle of the light spot. For example, when the core diameter of a square fiber is 600 μm and the numerical aperture (NA) of the fiber is 0.22, the divergence angle of the beam without collimation lens is about 12.71°. When the light emitted from the fiber is collimated by a lens with a focal length of 0.5 mm, the divergence angle is 34.38°, which is about 2.7 times higher. At the same time, the beam without collimation lens has a Gaussian or super-Gaussian distribution behind the fiber end face, which is a non-uniform light spot. However, after collimation by the collimating lens, when the working distance is greater than ten times Rayleigh distance, the light spot becomes a near-field image of the fiber end face. At this time, a large-size uniform light spot with a uniformity of more than 90% can be generated.

[0046] The optical fiber core diameter (NA) is a key parameter characterizing the light-guiding properties of optical fibers. It is determined by the refractive index of the fiber core and the optical cladding, and describes the fiber's ability to receive incident / outgoing light or its divergence angle range. A higher NA value indicates a wider angle of light reception (stronger light-receiving ability) and a larger divergence angle of the outgoing light. The core diameter can refer to the side length (or diameter) of the fiber core. It also describes the divergence angle of the beam after collimation by a collimating lens. Focal length of the collimating lens f The relationship is shown in formula (1):

[0047]

[0048] In equation (1), The beam waist represents the area from the optical fiber to the collimating lens. , This indicates the core diameter of the optical fiber, meaning the waist size is equal to the radius of the optical fiber.

[0049] like Figure 3As shown, the working distance is L1, the distance from the collimating lens to the working surface of the receiving screen 200. The Rayleigh interval (Rayleigh range) is a core parameter describing the propagation characteristics of a Gaussian beam, used to define the effective interval for approximately collimation and parallelism of the laser beam. The Rayleigh interval can be determined by formula (2):

[0050]

[0051] In equation (2), Indicates the Rayleigh interval. Indicates the beam quality factor. Indicates the laser wavelength.

[0052] In this invention, multiple optical fibers 110 and multiple collimating lenses 120 are arranged in a preset position so that the light spots formed after the lasers emitted from each optical fiber are collimated by the collimating lenses overlap (see...). Figure 4 The target light spot is formed on the working surface of the receiving screen 200. Specifically, after determining the working distance, the size (such as the diameter) of the target light spot, and the focal length of the collimating lens according to the processing requirements, in order to ensure that the light spots after the optical fiber output on the working surface of the receiving screen are collimated by the collimating lens and that the target light spot with a light spot uniformity greater than a preset value (such as 90%) is formed on the working surface of the receiving screen 200, the placement positions of the multiple collimating lenses and multiple optical fibers are preset positions, which can be determined by calculation or simulation.

[0053] The uniformity of the light spot (target light spot) presented on the working surface of the receiving screen 200 can be characterized by the following formula (3):

[0054]

[0055] In formula (3), Indicates the uniformity of the light spot. This represents the maximum light intensity of all pixels within the selected light spot area. This represents the average light intensity of all pixels within the selected light spot area.

[0056] The optical device for achieving laser beam homogenization provided by this invention comprises multiple optical fibers and multiple collimating lens arrays. The fiber arrays emit light simultaneously, and the output power of the entire optical device is increased by superimposing the beam spots. The power borne by a single optical fiber and a single collimating lens remains unchanged. The output power of the optical device can be flexibly adjusted by adjusting the number of optical fibers. The collimating lens array can achieve large-angle beam divergence. At the same time, the multiple optical fibers and multiple collimating lenses are arranged in preset positions to ensure that the beam spots after collimation by the collimating lenses on the working surface of the receiving screen overlap, avoiding the problem of uneven beam spots at the splicing points in related technologies.

[0057] Furthermore, such as Figure 1 and Figure 2 As shown, to facilitate the calculation of the preset position, multiple optical fibers and corresponding collimating lenses are symmetrically arranged along the second plane and the third plane, and their distribution is the same in the second plane (YZ plane) and the third plane (XZ plane). The second plane is the plane formed by the second direction Y and the third direction Z, and the third plane is the plane formed by the first direction X and the third direction Z.

[0058] At this point, the position coordinates of the vertex of the collimating lens's rear surface can be... Both i and j are integers. Let represent the coordinates of the vertex of the collimating lens's back surface in the first direction at row i and column j. Let represent the coordinates of the vertex of the collimating lens's back surface in the i-th row and j-th column in the second direction. This represents the coordinates of the vertex of the back surface of the collimating lens in the i-th row and j-th column in the third direction. The origin O is the position of the vertex of the back surface of the collimating lens located at the center of the first direction X and the center of the second direction Y among M×N collimating lenses. The coordinates of the collimating lens at the origin are... When the collimating lens is in the first quadrant, both i and j are positive. The rear surface of the collimating lens is the surface of the collimating lens that faces away from the fiber end face, and the front surface of the collimating lens is the surface of the collimating lens that faces near the fiber end face.

[0059] The distribution of optical fibers and collimating lenses in the YZ plane is the same as their distribution in the XZ plane. Taking the YZ plane as an example, the preset positions are explained below. These preset positions include the position coordinates of the vertex of the back surface of each collimating lens, the placement angle of each optical fiber, and the distance between the optical fiber and the collimating lens. The distance between the optical fiber and the collimating lens is... l The focal length of the collimating lens 。

[0060] Specifically, the collimating lenses are arranged in the second plane (YZ plane) as follows: Figure 5 As shown, at this time, The angle between the fiber's emission direction and the second plane The vertex position of the rear surface 122 of the collimating lens and Satisfy the following formula (4):

[0061]

[0062] In formula (4), This indicates the diameter (side length) of the target light spot. Indicates the first j The coordinates of the vertex position of the rear surface of the collimating lens in the second direction. Indicates the first j The angle between the emission direction of the optical fiber corresponding to each collimating lens and the third plane. This represents the distance from the vertex of the collimating lens's rear surface, located at the origin of the coordinate system, to the working surface of the receiving screen. L It is also the working distance. Indicates the first j The position of the vertex of the rear surface of a collimating lens in the third direction.

[0063] It should be noted that, in order to ensure that the light spots from the optical fiber on the working surface of the final receiving screen are aligned after being collimated by the collimating lens, the positions of the vertices of the rear surfaces of the multiple collimating lenses in the second direction are not necessarily on a straight line in the third direction. In other words, the positions of the vertices of the rear surfaces of the multiple collimating lenses are curved surfaces rather than planes in a three-dimensional view.

[0064] No. j The angle between the emission direction of the optical fiber corresponding to each collimating lens and the third plane. It can be determined by the following formula (5):

[0065]

[0066] To simplify calculations, the collimating lenses are arranged at equal intervals along the second direction, with the distance between two adjacent collimating lenses along the second direction being... At this time, j ≥1, , Indicates the first j- The coordinates of the vertex position of the rear surface of a collimating lens in the second direction. ,spacing It can be determined based on the outer diameter of the collimating lens and the lens spacing (the minimum distance between two collimating lenses). It is known that the coordinates of the vertex position of the back surface of each collimating lens can be determined using the above formulas (4) and (5). The angle between the exit direction of the optical fiber corresponding to the collimating lens and the third plane. .

[0067] It should be understood that and The method for determining is similar to that described above. When i≠0 and j≠0, we can... As a new Substituting into formula (4) and combining with formula (5), we obtain That is and the obtained That is , for The projection angle on the third plane, for The projection angle on the second plane will not be elaborated here.

[0068] For example, the diameter of the target light spot can be determined by the following formula (6). D :

[0069]

[0070] In formula (6), In radians , .

[0071] For example, the focal length of a collimating lens The fiber diameter is 0.5mm, the fiber is square, the NA is 0.22, and the fiber core diameter is... With a focal length of 600 μm, the laser emitted from the fiber, after being collimated by a collimating lens, can obtain a large divergence angle spot with a divergence angle of 34.38°. According to formula (6), the working distance can be determined. The diameter of the light spot at 1500mm The magnification of the laser spot emitted by the optical fiber is approximately 1800mm. Furthermore, as the working distance increases, the spot size continuously increases, and the magnification also increases. It can be seen that the present invention can obtain a large-sized uniform spot.

[0072] It should be understood that the present invention can change the shape and size of the fiber core (core layer) according to different spot shapes and divergence angle requirements, so as to ensure that the target spot can present a preset shape (such as rectangle, circle, etc.) and preset size.

[0073] For example, the distance from the vertex of the collimating lens's rear surface located at the origin to the working surface of the receiving screen (working distance) When the Rayleigh interval is greater than 10 times, a near-field image is formed at the fiber end face at the working distance, and the target spot is a homogenized spot.

[0074] In some embodiments, the collimating lens 120 is an aspherical lens, such as... Figure 6 As shown, the front surface 121 and the rear surface 122 of the collimating lens are both aspherical surfaces, and the aspherical surfaces satisfy the following formula (7):

[0075]

[0076] In formula (7), This represents the sag of the collimating lens along the optical axis of the fiber. Represents the curvature of an aspherical surface. Represents radial coordinates, Represents the conic coefficient. Represents even-order aspherical coefficients, corresponding to The order of the polynomial is given by Q, where Q represents the highest order of the aspherical polynomial expansion.

[0077] In this embodiment, the aspherical lens has an even-order aspherical profile, which can accurately compensate for the optical path difference of light rays with different incident angles. This allows the light rays emitted from the optical fiber to be nearly collimated after passing through the aspherical surface. Furthermore, using an aspherical lens with diffraction-limited imaging quality for collimation ensures that the distribution of light intensity within the light spot cross-section remains uniform, consistent with the core diameter. An even-order aspherical surface is an optical element whose surface shape deviates from a standard sphere, and its surface shape is symmetrical about the optical axis.

[0078] In one example, the collimating lens has a focal length of 0.5 mm, the curvature of its front surface 121 is 1 / 0.295, the conic coefficients of both the front and rear surfaces are -1, the highest order of the polynomial expansion of the front surface is 6, and the even-order aspherical coefficients of the front surface include... The curvature of the back surface is -1 / 3.7, the highest order of the back surface polynomial expansion is 3, and the even-order aspherical coefficients of the back surface include... The thickness of the collimating lens The material for aspherical lenses can be moldable glass material D-ZK3.

[0079] In this embodiment, optical system aberrations can be corrected by optimizing the aspherical profile. It should be understood that when there are significant aberrations in the optical system, the target light spot may be distorted, deviating from a predetermined shape (e.g., square), or the spot uniformity may decrease (brightness is uneven between the center and edges of the spot), or the spot edges may be unclear or blunt. This embodiment, by optimizing the aspherical profile to correct aberrations, can avoid problems such as target light spot distortion, deviating from a predetermined shape, decreased spot uniformity, or unclear or blunt spot edges.

[0080] In other examples, the focal length of the collimating lens is not 0.5mm. In this case, by scaling the parameters of the reference lens according to the focal length of the collimating lens, aspherical lenses with various focal lengths can be obtained. These lenses are then paired with optical fibers of different core diameters to obtain homogenized light spots with different divergence angles. The reference lens is a collimating lens with a focal length of 0.5mm.

[0081] Specifically, the conicity of the collimating lens is -1, and the curvature of the collimating lens is... Even-order aspherical coefficient of a collimating lens The thickness of the collimating lens ,in, Indicates the focal length of the collimating lens focal length relative to the reference lens The ratio, , Indicates the curvature of the reference lens. This represents the even-order aspherical coefficient of the reference lens.

[0082] In some embodiments, such as Figure 7 As shown, the optical device for achieving laser homogenization of the spot also includes multiple focusing lenses 130.

[0083] Specifically, multiple focusing lenses 130 correspond one-to-one with multiple collimating lenses 120. The focusing lens 130 is disposed on the light-emitting side of the corresponding collimating lens, and the focusing lens 130 and the corresponding collimating lens are coaxial. In this embodiment, an additional focusing lens 130 is added. By changing the distance between the collimating lens 120 and the focusing lens 130, the size of the target light spot can be adjusted.

[0084] The effects achievable by the optical device for achieving laser homogenization of light spots provided by the present invention will be explained below with specific examples.

[0085] Example 1

[0086] The optical device for achieving laser homogenization of the spot provided in this embodiment includes 3×3 optical fibers and 3×3 collimating lenses. The optical fibers are square optical fibers with an NA of 0.22 and a core diameter of 600 μm. The collimating lenses are aspherical lenses with a focal length of 0.5 mm. The spacing between the optical fibers along the first direction and along the second direction is 3 mm. The coordinates of the vertex of the back surface of the collimating lens at each position and the incident angle of the optical fiber are calculated using the above formula as follows:

[0087] , , ;

[0088] , , ;

[0089] , , ;

[0090] , , ;

[0091] , , ;

[0092] , , ;

[0093] , , ;

[0094] , , ;

[0095] , , .

[0096] At a working distance of 1500mm, the target spot is as follows Figure 8 As shown, by formula (3), it can be concluded that the uniformity of the rectangular spot of the optical device for achieving laser homogenization provided by the present invention is greater than 90% at the working surface of the receiving screen.

[0097] Example 2

[0098] Compared to Example 1, this implementation adds a focusing lens to the light-emitting side of each collimating lens. The fiber core diameter is 400μm, and the focal length of the focusing lens is 4mm. When the distance between the focusing lens and the collimating lens is 0.05mm, the target light spot at a working distance of 1500mm is as follows: Figure 9 As shown, when the distance between the focusing lens and the collimating lens is 1.15mm, the target spot at a working distance of 1500mm is as follows. Figure 10 As shown, when the distance between the focusing lens and the collimating lens is adjusted from 0.05mm to 1.15mm, the spot size at a working distance of 1500mm changes from 1080mm to 770mm, achieving continuous adjustment of the spot size, and the spot uniformity within the change area is >90%.

[0099] in, Figure 8 , Figure 9 and Figure 10 This is a total irradiance map, representing a measurement of the irradiance distribution of the laser energy incident on the working surface of the detector screen. The horizontal axis represents the position coordinates of the light spot in the horizontal direction, in millimeters, and the vertical axis represents the position coordinates of the light spot in the vertical direction, also in millimeters. The irradiance color mapping scale is in watts per square meter (W / m²). 2 Different colors correspond to different positions on the light spot, representing the light power density.

[0100] This invention utilizes a fiber optic array scheme, employing spot superposition and power superposition methods to improve the output power of the entire optical device while ensuring that the power borne by a single fiber and a single lens group remains unchanged. The fiber optic array and collimating lens array are arranged in specific positions to ensure that each spot overlaps at the working distance, resulting in a uniformity of >90%. The collimating lens is used to achieve large divergence angle light output, increasing the spot size at the same working distance.

[0101] Collimating lenses include aspherical lenses with a focal length of 0.5mm, whose surface shape conforms to the aspherical equation. By scaling the focal length using its surface shape parameters, aspherical lenses with various focal lengths can be obtained. These lenses can be paired with optical fibers of different core diameters to obtain homogenized light spots with different divergence angles. High-power, large-size light spots can be used in, but are not limited to, laser coating, laser welding, and laser illumination. The collimating system array can change the focal length by adding a lens array after the original aspherical array, and the light spot can be adjusted by changing the spacing between the two lenses.

[0102] The present invention also provides a laser system, which includes the optical device for achieving laser spot homogenization provided in any of the above embodiments. The laser system also includes a laser disposed at the end of each optical fiber away from the collimating lens. The laser system can be a laser display system, a laser illumination system, or a laser coating system, etc.

[0103] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction.

[0104] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0105] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention.

[0106] Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention.

Claims

1. An optical device for achieving laser spot homogenization, characterized in that, include: Multiple optical fibers are arranged in a projection array within a first plane formed by a first direction and a second direction. Both the first direction and the second direction are perpendicular to a third direction, which is the optical axis direction of the target optical fiber located at the center of the multiple optical fibers. Multiple collimating lenses are provided, each corresponding to one of the multiple optical fibers. The collimating lenses are disposed on the light-emitting side of the corresponding optical fibers, and the collimating lenses are coaxial with the corresponding optical fibers. The plurality of optical fibers and the plurality of collimating lenses are arranged in a preset position so that the light spots formed by the lasers emitted from each optical fiber after being collimated by the collimating lenses overlap and form a target light spot on the working surface of the receiving screen. Within the second plane formed by the second direction and the third direction, the position of the vertex of the rear surface of the collimating lens satisfies the following formula: In the formula, Indicates the diameter of the target light spot. Indicates the first j The coordinates of the vertex position of the rear surface of the collimating lens in the second direction. j It is an integer. This indicates the focal length of the collimating lens. Indicates the first j The angle between the emission direction of the optical fiber corresponding to each collimating lens and the third plane, wherein the third plane is the plane formed by the first direction and the third direction. This represents the distance from the vertex of the collimating lens's rear surface corresponding to the target optical fiber to the working surface of the receiving screen. Indicates the first j The position of the vertex of the rear surface of the collimating lens is in the third direction. This indicates the divergence angle of the laser emitted from the optical fiber after passing through the collimating lens, where the rear surface of the collimating lens is the surface of the collimating lens that faces away from the end face of the optical fiber. The number is determined by the following formula. j The angle between the emission direction of the optical fiber corresponding to each collimating lens and the third plane: 。 2. The optical device for achieving laser homogenization of the laser spot according to claim 1, characterized in that, The diameter of the target light spot is determined by the following formula: In the formula, In radians .

3. The optical device for achieving laser homogenization of the laser spot according to claim 1 or 2, characterized in that, The collimating lens is an aspherical lens, and both its front and rear surfaces are aspherical, satisfying the following formula: In the formula, This represents the sagittal height of the collimating lens along the optical axis of the optical fiber. Represents the curvature of an aspherical surface. Represents radial coordinates, Represents the conic coefficient. Represents even-order aspherical coefficients, corresponding to The order of the polynomial is Q, which represents the highest order of the aspherical polynomial expansion. The front surface of the collimating lens is the surface of the collimating lens near the end face of the optical fiber.

4. The optical device for achieving laser homogenization of the laser spot according to claim 3, characterized in that, The collimating lens has a focal length of 0.5 mm, the curvature of the front surface is 1 / 0.295, the conic coefficients of both the front and rear surfaces are -1, the highest order of the polynomial expansion of the front surface is 6, and the even-order aspherical coefficients of the front surface include... The curvature of the back surface is -1 / 3.7, the highest order of the polynomial expansion of the back surface is 3, and the even-order aspheric coefficients of the back surface include... The thickness of the collimating lens .

5. The optical device for achieving laser homogenization of the spot according to claim 3, characterized in that, The collimating lens has a focal length other than 0.5mm, a conic coefficient of -1, and a curvature of [missing information]. The even-order aspherical coefficient of the collimating lens The thickness of the collimating lens ,in, This represents the ratio of the focal length of the collimating lens to the focal length of the reference lens, where the reference lens is a collimating lens with a focal length of 0.5 mm. The curvature of the reference lens is indicated. This represents the even-order aspherical coefficient of the reference lens.

6. The optical device for achieving laser homogenization of the spot according to claim 3, characterized in that, The distance from the vertex of the collimating lens's rear surface located at the origin to the working surface of the receiving screen is greater than 10 times the Rayleigh interval.

7. The optical device for achieving laser homogenization of the laser spot according to claim 1 or 2, characterized in that, The optical device for achieving laser homogenization of the spot also includes multiple focusing lenses; The plurality of focusing lenses correspond one-to-one with the plurality of collimating lenses. The focusing lens is disposed on the light-emitting side of the corresponding collimating lens, and the focusing lens and the corresponding collimating lens are on the same optical axis.

8. A laser system, characterized in that, The laser system includes the optical device for achieving laser homogenization of the laser spot as described in any one of claims 1 to 7.

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