CN116088188B - Laser intensity homogenizing device - Google Patents

Abstract

The invention proposes a laser intensity homogenization device. The outgoing light of the light source extends along the first direction and passes through the collimating beam expander lens, the chirped array lens assembly and the focusing lens in sequence; the side of the light-transmitting medium facing the focusing lens has a second An installation surface, the light-transmitting medium has a second installation surface on the side facing the collimating beam expander lens; a plurality of first sub-lenses are sequentially arranged on the first installation surface along the second direction; a plurality of second sub-lenses are arranged along the second The directions are sequentially arranged on the second installation surface; the second direction is perpendicular to the first direction, and the width of the light-transmitting medium in the first direction is tapered toward the second direction. The technical scheme of the invention adopts the non-periodic structure of the chirped array lens assembly, suppresses the multi-beam interference effect, improves the uniformity of the light intensity of the top-hat beam, and is more suitable for light sources with strong coherence and strong universality.

Description

Laser Intensity Homogenizer

technical field

The invention relates to the technical field of laser equipment, in particular to a laser intensity homogenizing device.

Background technique

The radiation intensity of a laser light source generally conforms to a Gaussian distribution, with high energy in the central area, strong light intensity, and relatively low edge intensity. In the field of laser precision machining, especially when high-energy laser light sources are used, problems such as damage to materials and uneven ablation will occur during the interaction between the laser and the material. A common solution is to shape the Gaussian beam into a flat-hat beam, so that the energy density distribution of the spot tends to be uniform.

In the current prior art, a more common method is to use a microlens array to split the incident beam, and combine with a focusing lens to superimpose multiple sub-beams on the focal plane to achieve beam homogenization. However, due to the influence of the coherence of the light source, there is interference between different sub-beams, and the interference fringes reduce the uniformity of the focused spot.

Contents of the invention

The main purpose of the present invention is to provide a laser intensity homogenization device, which aims to solve the technical problems in the prior art that multi-beam interference is caused by the coherence of the light source, and the uniformity of the focused spot is affected by the light intensity peak modulation.

In order to achieve the above object, the present invention proposes a laser intensity homogenization device, which includes a light source, a collimator beam expander lens, a chirped array lens assembly, and a focusing lens arranged at intervals along the first direction. The outgoing light of the light source is emitted along the first direction and sequentially passes through the collimating beam expander lens, the chirped array lens assembly and the focusing lens;

The chirped array lens assembly includes:

A light-transmitting medium, the light-transmitting medium has a first installation surface on the side facing the focusing lens, and the light-transmitting medium has a second installation surface on the side facing the collimating beam expander lens;

A plurality of first sub-lenses, the plurality of first sub-lenses are sequentially arranged on the first installation surface along the second direction;

A plurality of second sub-lenses, the plurality of second sub-lenses are sequentially arranged on the second installation surface along the second direction;

Wherein, the second direction is perpendicular to the first direction, the width of the light-transmitting medium in the first direction is tapered toward the second direction, and the number of the first sub-lenses is the same as the number of the first sub-lenses. The number of the second sub-lenses is consistent and set in one-to-one correspondence.

Optionally, the first installation surface is parallel to the second direction;

There is an included angle between the second installation surface and the second direction, and the included angle is larger than the critical angle of the light-transmitting medium; or,

The second installation surface is parallel to the second direction, and the second installation surface is arranged in a step shape, and each step side wall of the second installation surface is respectively provided with a second sub-lens , the geometric center points of the plurality of second sub-lenses are all located on the same straight line, and there is an included angle between the line connecting the geometric center points of the plurality of second sub-lenses and the second direction, the The included angle is greater than the critical angle of the light-transmitting medium.

Optionally, the multiple first sub-lenses have the same numerical aperture, denote the numerical aperture as NA, the refractive index of the light-transmitting medium n _index , the critical angle α _c , and the numerical aperture as NA and the refractive index n _index of the light-transmitting medium satisfy the following relationship;

。

.

Optionally, the first sub-lens is a cylindrical lens, the side wall of the first sub-lens connected with the light-transmitting medium is a rectangular side wall, and the side wall of the rectangular side wall is connected with the second direction The length of a parallel edge is 2a _n ; the focal length of the first sub-lens is f _n ; the length of the edge is 2a _n , the focal length of the first sub-lens is f _n and the numerical aperture is NA Satisfy the following relationship;

NA=a _n /f _n .

Optionally, the number of the first sub-lens is N, n=N-1; wherein, the included angle is α, and the light-transmitting medium is tapered from the first end to the second end, The focal length of one of the first sub-lenses near the second end is f ₀ , the edge length of one of the first sub-lenses near the second end is a ₀ , and the edges of the other first sub-lenses are The side length a _i satisfies the following relationship:

；

;

The focal length _fi of the other first sub-lenses satisfies the following relationship:

；

;

Where n is any integer greater than 1, i is any integer from 1 to n, and i represents the order of the first sub-lens in the direction from the second end to the first end of the current first sub-lens. .

Optionally, the first sub-lens and the corresponding second sub-lens have the same numerical aperture, focal length and edge length.

Optionally, when there is an included angle between the second installation surface and the second direction, the geometric center point of the first sub-lens and the corresponding geometric center point of the second sub-lens The connecting line is parallel to the first direction.

Optionally, when the second installation surface is parallel to the second direction and the second installation surface is arranged in a stepped shape, the optical axis of the second sub-lens and its corresponding first sub-lens overlapping.

Optionally, the first sub-lens, the second sub-lens and the light-transmitting medium are integrally formed.

Optionally, the first sub-lens is located on the back focal plane of the corresponding second sub-lens.

The technical scheme of the present invention adopts the non-periodic structure of the chirped array lens assembly to suppress the multi-beam interference effect, and the final focused spot is modulated by non-equally spaced light intensity peaks to improve the uniformity of the flat-top beam intensity, and the energy The utilization rate is high, and it is more suitable for light sources with strong coherence, and it does not need to consider the initial intensity distribution of the incident light source, so it has strong universality.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative effort.

Fig. 1 is the front view of laser intensity homogenization device of the present invention;

Fig. 2 is the top view of laser intensity homogenization device of the present invention;

Fig. 3 is a structural schematic diagram of the first embodiment of the chirped array lens assembly in the laser intensity homogenization device of the present invention;

Fig. 4 is a schematic structural diagram of the second embodiment of the chirped array lens assembly in the laser intensity homogenization device of the present invention;

5 is a simulation effect diagram of the third embodiment of the laser intensity homogenization device of the present invention;

FIG. 6 is a simulation effect diagram of the fourth embodiment of the laser intensity homogenization device of the present invention.

Explanation of reference numbers:

The realization of the purpose of the present invention, functional characteristics and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relationship between the components in a certain posture (as shown in the figure). Relative positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly.

In addition, in the present invention, descriptions such as "first", "second" and so on are used for description purposes only, and should not be understood as indicating or implying their relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise specified and limited, the terms "connection" and "fixation" should be understood in a broad sense, for example, "fixation" can be a fixed connection, a detachable connection, or an integral body; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be an internal communication between two elements or an interaction relationship between two elements, unless otherwise clearly defined. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In addition, the technical solutions of the various embodiments of the present invention can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered as a combination of technical solutions. Does not exist, nor is it within the scope of protection required by the present invention.

The present invention proposes a laser intensity homogenization device, please refer to Fig. 1 and Fig. 2, the laser intensity homogenization device includes a light source 40, a collimating beam expander lens 10, and a chirped array lens assembly arranged at intervals in sequence along the first direction 20 and a focusing lens 30 , the outgoing light of the light source 40 extends along a first direction and passes through the collimating beam expander lens 10 , the chirped array lens assembly 20 and the focusing lens 30 in sequence.

The chirped array lens assembly 20 includes a light-transmitting medium 23, a plurality of first sub-lenses 21 and a plurality of second sub-lenses 22, and the light-transmitting medium 23 has a first mounting surface on the side facing the focusing lens 30 231, the light-transmitting medium 23 has a second installation surface 232 on the side facing the collimator beam expander lens 10; a plurality of the first sub-lenses 21 are sequentially arranged on the first installation surface 231 along the second direction above; a plurality of second sub-lenses 22 are sequentially arranged on the second installation surface 232 along the second direction; wherein, the second direction is perpendicular to the first direction, and the light-transmitting medium 23 The width of the first sub-lens 21 is tapered along the second direction, and the number of the first sub-lenses 21 is consistent with the number of the second sub-lenses 22 and arranged in one-to-one correspondence.

The collimating beam expander lens 10 , the chirped array lens assembly 20 and the focusing lens 30 are all located on the optical path of the light source 40 . The light beam emitted by the light source 40 along the first direction A, that is, the emitted light of the light source 40 extends along the first direction A. Referring to FIG.

The collimator and beam expander lens 10 is used for collimating and expanding the beam emitted by the light source 40 . In this embodiment, a three-dimensional coordinate system is established with the first direction A as the Z axis, and the collimator beam expander lens 10 is capable of controlling the outgoing light of the light source 40 in the direction of the Y axis and/or the X axis. Collimating and expanding the beam, so that the outgoing light can achieve beam expansion of a certain magnification in the Y-axis and/or X-axis direction.

Wherein, the beam expansion magnifications in the Y-axis and X-axis directions can be the same or different, and can be adjusted specifically by adjusting the lens structure of the collimator beam expander lens 10 .

The collimating beam expander lens 10 includes at least one adjusting sub-lens 11, and the adjusting sub-lens 11 is a cylindrical lens with a semi-cylindrical structure. When the quantity of the adjusting sub-lens 11 is one, the top surface and the bottom surface of the adjusting sub-lens 11 are arranged perpendicular to the X-axis, so that the beam expansion magnification emitted on the Y-axis can be changed, that is, the size of the outgoing light; similarly, The top surface and the bottom surface of the adjustment sub-lens 11 are arranged perpendicular to the Y axis, so that the beam expansion ratio emitted on the X axis can be changed.

When two adjusting sub-lenses 11 are provided, the two adjusting sub-lenses 11 are arranged at intervals along the first direction A. By adjusting the distance between the two adjusting sub-lenses 11 and the orientation of the top surface and the bottom surface, it is possible to simultaneously change the beam expansion ratio of the outgoing light on the X-axis and/or Y-axis, that is, the beam expansion ratio of the outgoing light. Size.

After exiting the collimating beam expander lens 10 , the outgoing light enters the chirped array lens assembly 20 , and the chirped array lens assembly 20 has optical functions both in the Y-axis and X-axis directions.

The arrangement position of the chirped array lens assembly 20 is adjusted so that the outgoing light is vertically incident on the chirped array lens assembly 20 .

After the incident light passes through the chirped array lens assembly 20, the chirped array lens assembly 20 divides the outgoing light, and the non-periodic structure can reduce the influence of multi-beam interference and improve the uniformity of the focused light spot.

During normal installation, both the first installation surface 231 and the second installation surface 232 are perpendicular to the first direction A, so as to ensure that the incident light enters vertically.

The top surface and the bottom surface of the light-transmitting medium 23 are flat planes, and both are parallel to the plane formed by the Z-axis and the X-axis in the coordinate system, and the second direction B is parallel to the Y-axis in the above-mentioned three-dimensional coordinate system.

The one-to-one corresponding arrangement of the first sub-lens 21 and the second sub-lens 22 means that the height of the bottom surface of the light-transmitting medium 23 is 0, and the height gradually increases toward the top surface along the second direction B , the height of the first sub-lens 21 and the corresponding second sub-lens 22 are the same.

Moreover, the arrangement directions and arrangement positions of the plurality of first sub-lenses 21 on the first installation surface 231 and the plurality of second sub-lenses 22 on the second installation surface 232 are correspondingly the same. .

The width of the light-transmitting medium 23 is tapered or gradually expanded toward the second direction. When tapered, the top of the light-transmitting medium 23 is narrow and the bottom is wide; The second direction is gradually expanding.

The optical parameters of the plurality of first sub-lenses 21 are different by adopting a tapered or tapered mode, and at the same time, in order to ensure that the first sub-lens 21 can be located on the back focal plane of the second sub-lens 22, Therefore, the size of the light-transmitting medium 23 is adjusted so that the corresponding positions of the first sub-lens 21 and the second sub-lens 22 correspond, thereby forming a non-periodic structure. Therefore, the influence of multi-beam interference can be reduced, and the uniformity of the focused light spot can be improved.

The outgoing light enters the focusing lens 30 after exiting the chirped array lens assembly 20 .

The focusing lens 30 is used for converging the outgoing light of the light source 40 . The back focal plane of the focusing lens 30 is located on a side of the focusing lens 30 away from the chirped array lens assembly 20 . After the outgoing light passes through the focusing lens 30 , a uniform light spot 50 is formed on the back focal plane of the focusing lens 30 .

The first sub-lens 21 is located on the back focal plane of the corresponding second sub-lens 22 to ensure the imaging effect of the final light spot.

After passing through the optical structure of the laser intensity homogenizing device, the intensity of the outgoing light is more uniform, that is, even if the energy density distribution of the spot 50 tends to be uniform, it is no longer modulated by equal-spaced light intensity peaks, and can be applied to similar Gaussian and irregular laser beams. Single-wavelength laser light source with equal intensity distribution.

Therefore, in this embodiment, the light source 40 may be a laser light source with a single wavelength and a spectral range much smaller than the central wavelength. Its light intensity distribution includes Gaussian, anti-Gaussian, random and other distributions. Wherein, the light source 40 is preferably a laser light source with a wavelength of 355 nm.

The technical solution of the present invention adopts the non-periodic structure of the chirped array lens assembly 20 to suppress the multi-beam interference effect, and the final focused spot is modulated by non-equally spaced light intensity peaks to improve the uniformity of the flat-hat beam intensity, and The energy utilization rate is high, and it is more suitable for the light source 40 with strong coherence, and there is no need to consider the initial intensity distribution of the incident light source, so the universality is strong.

The first sub-lens 21 and the second sub-lens 22 can be etched on the first installation surface 231 and the second installation surface 232, that is, the first sub-lens 21, The second sub-lens 22 and the transparent medium 23 are integrally formed.

Further, as an embodiment, the first installation surface 231 is parallel to the second direction, and there is an included angle between the second installation surface 232 and the second direction, and the included angle is larger than the The critical angle of the light-transmitting medium 23 .

In this embodiment, the second installation surface 232 is a flat plane, and the second installation surface 232 is inclined to form the angle α with the second direction.

The second sub-lenses 22 are continuously disposed on the flat and inclined second installation surface 232 .

In order to ensure that the chirped array lens assembly 20 divides and rearranges the outgoing light, the included angle α should be set to be greater than the critical angle α _c of the light-transmitting medium 23, so as to improve the homogenization effect of the outgoing light .

The critical angle α _c of the transparent medium 23 can be calculated from the refractive index of the transparent medium 23 and the optical parameters of the first sub-lens 21 .

Specifically, the optical parameters of the first sub-lens 21 include a numerical aperture, the numerical apertures of a plurality of the first sub-lenses 21 are the same, and the numerical aperture is denoted as NA, and the refractive index of the light-transmitting medium 23 is n _index , calculate the critical angle α _c according to the following formula;

。Formula 1:

.

Further, the first sub-lens 21 is a cylindrical lens, and the side wall of the first sub-lens 21 connected to the light-transmitting medium 23 is a rectangular side wall.

The optical parameters of the first sub-lens 21 also include edge length and focal length, note that the edge length on the rectangular side wall parallel to the second direction is 2a _n ; the first sub-lens 21 The focal length is f _n ; the numerical aperture of the first sub-lens 21 is calculated according to the following formula;

Formula 2: NA=a _n /f _n .

Further, in the FIG. 3 , the first end is the bottom of the light-transmitting medium 23, the second end is the top of the light-transmitting medium 23, and the first end to the second The end direction is the second direction B.

The total number of the first sub-lenses 21 is N, where n=N-1, the included angle is denoted as α, and the focal length of one of the first sub-lenses 21 near the second end is f ₀ , also That is, the focal length of the first first sub-lens 21 at the top is denoted as f ₀ ; the edge lengths a _i of the remaining first sub-lenses 21 satisfy the following relationship:

；Formula 3:

;

The focal length _fi of the remaining first sub-lens 21 satisfies the following relationship:

。Formula 4:

.

It can be understood that, wherein n is any integer greater than 1, i is any integer from 1 to n, and i represents that the first sub-lens 21 currently moves from the second end to the first end. The order of the sub-lenses 21.

Please refer to FIG. 3 for details. For example, along the two sections to the first end, the order of the first sub-lenses 21 from top to bottom is sequentially coded as 0, 1, 2, 3...n. The order of the first first sub-lens 21 at the top is 0, and the order of the first, second, third...n ones downwards. Then i indicates that the current first sub-lens 21 is the i-th downward first sub-lens 21 .

The value of N is preferably 23, the refractive index of the transparent medium 23 is 1.5, the numerical aperture NA of the sub-lens is 0.05, and the focal length of the first sub-lens 21 located near the second end of the transparent medium 23 is set to 1 mm and a diameter of 0.1 mm, the focal length of the focusing lens 30 is 30 mm. The simulation results show that the multi-beam interference effect is obvious, and the focused spot is modulated by the light intensity peak.

It should be noted that, the focal length of the i-th first sub-lens 21 is defined as f _i , the edge length is defined as a _i , and the numerical aperture is defined as NA. When the values of i are different, f _i and a _i are different, and NA is always the same. That is, the numerical apertures of the plurality of first sub-lenses 21 are the same. Between the corresponding first sub-lens 21 and the second sub-lens 22, the numerical aperture, focal length and edge length between them are the same, that is, the first sub-lens 21 and its corresponding The numerical aperture, focal length and edge length of the second sub-lens 22 are all the same.

Specifically, in order to ensure the presentation effect, the first sub-lens 21 and the corresponding second sub-lens 22 should be kept at the same height, that is, the geometric center point of the first sub-lens 21 and the corresponding first sub-lens 21 should maintain the same height. The line connecting the geometric center points of the two sub-lenses 22 is parallel to the first direction.

The geometric center point of the sub-lens refers to: the geometric center of the rectangular side wall of the sub-lens, that is, the position of the intersection of two diagonal lines of the rectangular side wall.

In the above process, if the plurality of second sub-lenses 22 are arranged continuously and obliquely, due to the refraction principle of light, the optical axis of the outgoing light is no longer kept parallel to the first direction A, but obliquely downward , after passing through the focusing lens 30, the light spot 50 is below the field of view.

Therefore, the present invention proposes another embodiment, the second installation surface 232 is parallel to the second direction, and the second installation surface 232 is arranged in a stepped shape, and each step of the second installation surface 232 One of the second sub-lenses 22 is correspondingly arranged on the side wall 233, the geometric center points of the plurality of second sub-lenses 22 are all located on the same straight line, and the geometric centers of the plurality of second sub-lenses 22 There is an included angle between the line connecting the points and the second direction, and the included angle is larger than the critical angle of the light-transmitting medium 23 .

In this embodiment, an included angle between the geometric center points of the plurality of second sub-lenses 22 and the second direction is equal to the included angle α.

The stepped side wall 233 is a side wall facing one side of the collimating beam expander lens 10 or the focusing lens 30 .

Each stepped side wall 233 on the second installation surface 232 is respectively provided with a second sub-lens 22 ,

To ensure that the first sub-lens 21 and the corresponding second sub-lens 22 are at the same height, the optical axes of the second sub-lens 22 and the corresponding first sub-lens 21 overlap.

In this embodiment, the size of the rectangular sidewall of the second sub-lens 22 is adapted to the size of the corresponding stepped sidewall 233, that is, the second sub-lens 22 covers the entire stepped sidewall 233 , so as to ensure the final effect of spot 50.

Similarly, the geometric center point of the sub-lens refers to the geometric center of the rectangular side wall of the sub-lens, that is, the position of the intersection of two diagonal lines of the rectangular side wall.

It should be noted that, in the above-mentioned solution, no matter adopting the way of inclined setting or stepped setting, the positions of the first installation surface 231 and the second installation surface 232 can be replaced with each other, that is, the first The mounting surface 231 can be set towards the side of the collimating beam expander lens 10 , or can be set towards the side of the focusing lens 30 .

The included angle α may be set at 7°-14°. When the included angle α is set to 7°, the normalized light intensity simulation result of the centerline of the spot 50 is as shown in Figure 5; when the included angle α is set to 14°, the normalized light intensity of the centerline of the spot 50 The light intensity simulation result is shown in FIG. 6 ; the light spot 50 is no longer modulated by equally spaced light intensity peaks, and the uniformity is improved.

The above is only a preferred embodiment of the present invention, and does not therefore limit the patent scope of the present invention. Under the inventive concept of the present invention, the equivalent structural transformation made by using the description of the present invention and the contents of the accompanying drawings, or direct/indirect use All other relevant technical fields are included in the patent protection scope of the present invention.

Claims (8)

1. A laser intensity homogenization device, characterized in that, the laser intensity homogenization device comprises a light source, a collimating beam expander lens, a chirped array lens assembly and a focusing lens arranged at intervals along the first direction, the light source The outgoing light is emitted along a first direction and sequentially passes through the collimating beam expander lens, the chirped array lens assembly and the focusing lens; The chirped array lens assembly includes: A light-transmitting medium, the light-transmitting medium has a first installation surface on the side facing the focusing lens, and the light-transmitting medium has a second installation surface on the side facing the collimating beam expander lens; A plurality of first sub-lenses, the plurality of first sub-lenses are sequentially arranged on the first installation surface along the second direction; A plurality of second sub-lenses, the plurality of second sub-lenses are sequentially arranged on the second installation surface along the second direction; Wherein, the second direction is perpendicular to the first direction, the width of the light-transmitting medium in the first direction is tapered toward the second direction, and the number of the first sub-lenses is the same as the number of the first sub-lenses. The number of the second sub-lenses is consistent and set in one-to-one correspondence; The first mounting surface is parallel to the second direction; There is a first angle between the second installation surface and the second direction, and the first angle is greater than the critical angle of the light-transmitting medium; or, The second installation surface is parallel to the second direction, and the second installation surface is arranged in a step shape, and each step side wall of the second installation surface is respectively provided with a second sub-lens , the geometric center points of the plurality of second sub-lenses are all located on the same straight line, and the line connecting the geometric center points of the plurality of second sub-lenses has a second included angle with the second direction, The second included angle is greater than the critical angle of the light-transmitting medium; Multiple first sub-lenses have the same numerical aperture, denote the numerical aperture as NA, the refractive index of the light-transmitting medium is n _index , the number of the first sub-lenses is N, n=N-1 ; Wherein, record the first angle or the second angle as α, the light-transmitting medium is tapered from the first end to the second end, and one of the first sub-angles close to the second end The focal length of the lens is f ₀ , the edge length of one of the first sub-lenses close to the second end is a ₀ , and the edge lengths a _i of the other first sub-lenses satisfy the following relationship:

; The focal length _fi of the other first sub-lenses satisfies the following relationship:

; Where n is any integer greater than 1, i is any integer from 1 to n, and i represents the order of the first sub-lens in the direction from the second end to the first end of the current first sub-lens. . 2. laser intensity homogenization device according to claim 1, is characterized in that, described critical angle α _c , described numerical aperture are NA and the refractive index n _index of described light-transmitting medium satisfy following relation;

. 3. The laser intensity homogenizing device according to claim 2, wherein the first sub-lens is a cylindrical lens, and the side wall of the first sub-lens connected with the light-transmitting medium is rectangular The side wall, the length of an edge parallel to the second direction on the rectangular side wall is 2a _n ; the focal length of the first sub-lens is f _n ; the length of the edge is 2a _n , the second The focal length of a sub-lens is f _n and the numerical aperture is NA and satisfies the following relationship; NA=a _n /f _n . 4 . The laser intensity homogenizing device according to claim 3 , wherein the first sub-lens and the corresponding second sub-lens have the same numerical aperture, focal length and edge length. 5. The laser intensity homogenizing device according to any one of claims 2 to 4, wherein when there is the first included angle between the second mounting surface and the second direction, the A connecting line between the geometric center point of the first sub-lens and the corresponding geometric center point of the second sub-lens is parallel to the first direction. 6. The laser intensity homogenizing device according to any one of claims 2 to 4, wherein when the second installation surface is parallel to the second direction and the second installation surface is stepped When set, the optical axis of the second sub-lens and its corresponding first sub-lens overlap. 7 . The laser intensity homogenizing device according to claim 1 , wherein the first sub-lens, the second sub-lens, and the light-transmitting medium are integrally formed. 8 . The laser intensity homogenization device according to claim 1 , wherein the first sub-lens is located on the back focal plane of the corresponding second sub-lens.

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