Flat-top intensity distribution laser generating device

Abstract

The invention discloses a flat-topped intensity distribution laser generating device, relates to the technical field of laser beams, and is used for solving the problems that a traditional laser is single in output mode and uneven in flat-topped beam distribution. The device comprises a point defect total reflection mirror, a first aperture diaphragm, a polarization splitting prism, a quarter-wave plate, a side pump laser module, a focusing lens, a first plane reflection mirror, a second aperture diaphragm and a second plane reflection mirror. A light beam generated by the side pump laser module is split by the polarization splitting prism to obtain a first polarized light beam and a second polarized light beam; the first polarized light beam passes through a point defect total reflection mirror and a first aperture diaphragm to obtain a hollow-intensity annular light beam, and the second polarized light beam passes through a second plane reflection mirror and a second aperture diaphragm to obtain a fundamental mode Gaussian light beam; and the fundamental mode Gaussian beam and the annular beam are coaxially combined to obtain a circular flat-topped beam. The device is simple in structure, convenient to adjust and suitable for laser processing, laser medical treatment and the like with the requirement for light spot uniformity.

Description

Technical Field

[0001] The invention relates to the technical field of laser beams, and in particular to a flat-top intensity distribution laser generating device. Background Art

[0002] The circular flat-top beam has a uniform intensity profile in a certain beam shape, which is different from the Gaussian beam profile of most laser beams, where the intensity decreases smoothly from the maximum value along the beam axis to 0. This uniform intensity distribution makes the flat-top beam very useful in scenarios that require uniform light distribution, such as laser processing, medical diagnosis, communications, and optical imaging. In the process of high-power nonlinear frequency conversion, the efficiency will be higher if a flat-top beam is used. This is because the intensity distribution of the flat-top beam is uniform, which is conducive to improving the conversion efficiency. At the same time, the circular flat-top beam can achieve more accurate and efficient cutting and welding during laser processing, which is of great significance for improving production efficiency and product quality. Due to its uniform intensity distribution, high-efficiency nonlinear frequency conversion, and improved processing accuracy and efficiency, the circular flat-top beam has important research significance and application value in many fields.

[0003] At present, the conventional methods for obtaining circular flat-top beams mainly include the following: multi-transverse mode superposition method, partially coherent beam mode decomposition method, method of generating circular flat-top beams based on beam shaping technology, method of generating circular flat-top beams based on aspheric mirror system design, and method of generating circular flat-top beams based on strong focusing of circularly polarized vortex beams, etc. However, these methods all have problems such as unadjustable focusing spot size and energy, low stability, and poor spot uniformity due to light interference. Summary of the invention

[0004] In view of the above problems, the present invention proposes a flat-top intensity distribution laser generating device to try to solve or alleviate one or more of the above problems.

[0005] A flat-top intensity distribution laser generating device comprises: a point defect total reflector 1, a first aperture diaphragm 2, a polarization beam splitter prism 3, a side pump laser module 5, a focusing lens 6, a first plane reflector 7, a second aperture diaphragm 8, and a second plane reflector 9; wherein the point defect total reflector 1, the first aperture diaphragm 2, the polarization beam splitter prism 3, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 are sequentially arranged at intervals, and the arrangement direction is parallel to the direction of the light beam generated by the side pump laser module 5; the second aperture diaphragm 8 and the second plane reflector 9 are sequentially arranged at intervals, and the arrangement direction is perpendicular to the direction of the light beam generated by the side pump laser module 5;

[0006] The process of generating a flat-top intensity distribution laser using the above device includes:

[0007] The side pump laser module 5 generates pump light in the fundamental mode Gaussian light mode, and the pump light enters the polarization beam splitter prism 3 for beam splitting to obtain a first polarized light beam and a second polarized light beam perpendicular to each other; wherein the first polarized light beam is parallel polarized light, and the second polarized light beam is vertically polarized light;

[0008] The first polarized light beam passes through the first aperture diaphragm 2 and enters the point defect total reflector 1, and the point defect total reflector 1 generates an annular light beam, and the annular light beam enters the first aperture diaphragm 2 and the polarization beam splitter prism 3 in sequence; the second polarized light beam passes through the second aperture diaphragm 8 and enters the second plane reflector 9, and the fundamental mode Gaussian light beam reflected back by the second plane reflector 9 enters the second aperture diaphragm 8 and the polarization beam splitter prism 3 in sequence; the polarization direction of the annular light beam is orthogonal to that of the fundamental mode Gaussian light beam;

[0009] The annular light beam passes through the polarization beam splitter prism 3 and is coaxially combined with the fundamental mode Gaussian light beam reflected by the polarization beam splitter prism 3, and then passes through the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 to obtain a flat-top intensity distribution laser.

[0010] In a possible implementation, the surface of the point defect total reflection mirror 1 is coated with a high-reflection medium film corresponding to the laser wavelength emitted by the side pump laser module 5, and point defects of different sizes are etched on the surface.

[0011] In a possible implementation, the spot radius of the annular light beam generated by the point defect total reflector 1 satisfies the following formula:

[0012]

[0013] Where m is the angular index of the Laguerre-Gaussian beam, m∈[1,+∞); ω0 is the beam radius of the pump light generated by the side pump laser module 5 .

[0014] In a possible implementation, the point defect total reflection mirror 1 is placed on a three-dimensional displacement platform, and the three-dimensional displacement platform is used to adjust the point defect total reflection mirror 1 to move along the optical axis within a set distance from the splitting surface of the polarization splitting prism 3.

[0015] In a possible implementation, the first aperture stop 2 and the second aperture stop 8 are circular holes with adjustable sizes, which are used to control the size and energy of the light beam.

[0016] In a possible implementation, the reflective surface of the polarization beam splitter prism 3 is at an angle of 45° to the optical axis, and each light-transmitting surface of the polarization beam splitter prism 3 is coated with a high-reflective dielectric film corresponding to the laser wavelength emitted by the side pump laser module 5 and is perpendicular to the optical axis.

[0017] In a possible implementation, the focusing lens 6 is a plano-convex focusing lens, the incident surface of the focusing lens 6 is coated with a high-transmittance medium film corresponding to the laser wavelength emitted by the side pump laser module 5 and is perpendicular to the optical axis, and the distance between the focusing lens 6 and the side pump laser module 5 is adjustable.

[0018] In a possible implementation, the first plane reflector 7 is a plane reflector, the surface of which is coated with a dielectric film that partially transmits the laser wavelength emitted by the side pump laser module 5, and is placed at an angle perpendicular to the optical axis; the second plane reflector 9 is a plane reflector, the reflective surface of which is coated with a high-reflective film that corresponds to the laser wavelength emitted by the side pump laser module 5 and is perpendicular to the optical axis.

[0019] In a possible implementation, the ratio of the point defect radius D used by the point defect total reflector 1 to the beam radius ω0 of the pump light generated by the side pump laser module 5 is ε, and ε satisfies the following formula:

[0020]

[0021] Wherein, l is the radial index of the annular light beam generated by the point defect total reflection mirror 1; T represents the transmittance of the first plane reflection mirror 7.

[0022] In a possible implementation, the device further includes: a quarter wave plate 4 is arranged between the polarization beam splitter prism 3 and the side pump laser module 5, the arrangement direction of the quarter wave plate 4 is parallel to the direction of the light beam generated by the side pump laser module 5; the surface of the quarter wave plate 4 is perpendicular to the first polarized light beam, the fast axis of the quarter wave plate 4 is at an angle of 45° to the polarization direction of the polarization beam splitter prism 3 and is coated with an anti-reflection medium film corresponding to the laser wavelength emitted by the side pump laser module 5; the quarter wave plate 4 is combined with the polarization beam splitter prism 3 to control the intensity ratio of the Gaussian light beam and the hollow intensity distribution light beam.

[0023] The beneficial technical effects of the present invention are:

[0024] The present invention uses a point defect total reflector to convert a Gaussian beam into an annular beam. The annular beam is different from an ordinary first-order Gaussian annular beam. The light intensity on the outer side of the ring is stronger than that on the inner side, and it is coaxially combined with the fundamental mode Gaussian beam to obtain a circular flat-top beam. In the present invention, the polarization directions of the annular beam and the circular flat-top beam are orthogonal, and no interference will occur after superposition, eliminating the unevenness caused by interference. The intensity of the annular beam and the Gaussian beam of the present invention can be adjusted by the main axis direction of the quarter-wave plate, and the spot size and energy of the Gaussian beam and the annular beam can be adjusted by the size of the aperture diaphragm and the distance from the focusing lens to the side pump laser module, thereby realizing the adjustment of the flat-top beam spot size and the control of the flat-top beam energy, and the conversion efficiency and stability are high. The present invention can directly obtain a laser output with a flat-top intensity distribution through a laser resonant cavity, and can realize the conversion output of Gaussian and annular beams and flat-top beams at the same time, overcoming the problem of a single output mode of a traditional laser and uneven distribution of a flat-top beam. The present invention has a simple structure and is easy to adjust, and is suitable for laser processing, laser medical treatment, etc. that require spot uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which:

[0026] Figure 1 A schematic structural diagram of a flat-top intensity distribution laser generating device provided in an embodiment of the present invention.

[0027] Figure 2 This is an example diagram of an annular beam spot provided by an embodiment of the present invention.

[0028] Figure 3 This is an example diagram of a Gaussian beam spot provided in an embodiment of the present invention.

[0029] Figure 4 This is an example diagram of a circular flat-top beam spot generated by an embodiment of the present invention.

[0030] In the accompanying drawings, the list of components represented by each number is as follows: 1-point defect total reflection mirror, 2-first aperture diaphragm, 3-polarization splitter prism, 4-quarter wave plate, 5-side pump laser module, 6-focusing lens, 7-first plane reflector, 8-second aperture diaphragm, 9-second plane reflector. DETAILED DESCRIPTION

[0031] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0032] The present invention provides a flat-top intensity distribution laser generating device, which uses a point defect total reflector to convert a Gaussian beam into an annular beam, and coaxially combines it with a fundamental mode Gaussian beam to obtain a circular flat-top beam. The polarization directions of the annular beam and the circular flat-top beam are orthogonal, and no interference will occur after superposition, thereby eliminating the unevenness caused by interference. The intensity of the annular beam and the Gaussian beam of the present invention can be adjusted by the main axis direction of a quarter-wave plate, and the spot size and energy of the Gaussian beam and the annular beam can be adjusted by the size of the aperture diaphragm and the distance from the focusing lens to the side pump laser module, thereby realizing a laser with a flat-top intensity distribution with controllable energy, strong stability, and strong uniformity.

[0033] Because the hollow intensity distribution of Laguerre-Gaussian (LG) beam is one of the eigenmodes of the cylindrical symmetric cavity, the LG mode can be directly generated in the cavity by mode selection without any optical phase modulation element. Compared with the method relying on phase modulation of light outside the cavity, the laser generated directly from the cavity has higher power and excellent beam quality and transmission stability. The direct radiation of the resonant cavity mainly depends on controlling the TEM in the resonant cavity. 00 and LG modes to achieve an oscillating output with a hollow intensity distribution.

[0034] Point defect total reflector is an effective method to directly generate annular beams from laser resonant cavities. Point defect reflectors cause the loss of low-order transverse modes in the cavity, resulting in a lower threshold of high-order transverse modes than low-order transverse modes. Therefore, it suppresses low-order transverse modes and directly obtains high-order transverse modes, thereby obtaining the desired annular beam. By controlling the relative size of the eigenmode and the point defect on the surface of the point defect cavity mirror, LG modes with different topological charges can be output. Therefore, point defect mirrors can be used to realize the selective oscillation of LG beams, and the intracavity synthesis of Gaussian beams can realize the direct generation of flat-top beams.

[0035] A flat-top intensity distribution laser generating device provided by the present invention is described below in conjunction with the accompanying drawings.

[0036] The embodiment of the present invention provides a flat-top intensity distribution laser generating device, such as Figure 1As shown, the device includes a point defect total reflector 1, a first aperture diaphragm 2, a polarization beam splitter prism 3, a side pump laser module 5, a focusing lens 6, a first plane reflector 7, a second aperture diaphragm 8, and a second plane reflector 9. The point defect total reflector 1, the first aperture diaphragm 2, the polarization beam splitter prism 3, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 are sequentially arranged at intervals, and the arrangement direction is parallel to the direction of the light beam generated by the side pump laser module 5; the second aperture diaphragm 8 and the second plane reflector 9 are sequentially arranged at intervals, and the arrangement direction is perpendicular to the direction of the light beam generated by the side pump laser module 5.

[0037] In this embodiment, preferably, the point defect total reflector 1 is arranged coaxially with the incident light beam, and a high reflective dielectric film for the laser wavelength λ is coated on the surface of the point defect total reflector 1, and point defects of different sizes are etched on the surface. The radius of the point defect used is D, and the range of D can be selected from 30μm to 200μm. The point defect total reflector 1 can be moved and adjusted along the optical axis near the set distance from the splitting surface of the polarization splitting prism 3. The point defect total reflector 1 can generate a spot radius of ω s , an annular beam with radial index l, satisfies Where m is the angular index of the LG beam, g(m) can be approximately regarded as 1.

[0038] In this embodiment, preferably, the first aperture stop 2 and the second aperture stop 8 are circular small holes, the size of which is adjustable, and the size and energy of the light beam can be controlled.

[0039] Exemplarily, the larger the circular hole corresponding to the first aperture stop 2, the larger the size and energy of the first polarized light beam and the generated annular light beam passing through the first aperture stop 2; otherwise, the smaller the size and energy of the first polarized light beam and the generated annular light beam of the first aperture stop 2. The larger the circular hole corresponding to the second aperture stop 8, the larger the size and energy of the second polarized light beam and the generated annular light fundamental transverse mode Gaussian light beam passing through the second aperture stop 8; otherwise, the smaller the size and energy of the second polarized light beam and the generated fundamental transverse mode Gaussian light beam of the second aperture stop 8.

[0040] It should be noted that, in this embodiment, the sizes of the first aperture stop 2 and the second aperture stop 7 are not specifically limited, and they can be adjusted according to actual needs. The first aperture stop 2 and the second aperture stop 8 can be adjusted separately, and the sizes of the first aperture stop 2 and the second aperture stop 8 can be the same or different.

[0041] In this embodiment, preferably, the reflective surface of the polarization beam splitter prism 3 forms an angle of 45° with the optical axis, and each light-transmitting surface of the polarization beam splitter prism 3 is coated with a high-reflective dielectric film for the laser wavelength λ and is perpendicular to the optical axis.

[0042] In this embodiment, preferably, the side pump laser module 5 generates pump light with a wavelength of λ, a beam radius of ω0, and a fundamental mode Gaussian light mode in the resonant cavity.

[0043] In this embodiment, preferably, the focusing lens 6 is a plano-convex focusing lens, and the incident surface of the focusing lens 6 is coated with a high-transmittance dielectric film for the laser wavelength λ and is perpendicular to the optical axis. The distance between the focusing lens 6 and the side pump laser module 5 can be adjusted to control the intracavity mode size and increase the stability of the resonant cavity.

[0044] In this embodiment, preferably, the first plane reflector 7 is a plane reflector, the surface of which is coated with a dielectric film partially transmitting the laser wavelength λ, and the placement angle is perpendicular to the optical axis, and the transmittance is T. The second plane reflector 9 is a plane reflector, and the reflective surface of the second plane reflector 9 is coated with a high reflective film for the laser wavelength λ and is perpendicular to the optical axis.

[0045] In this embodiment, preferably, the ratio of the point defect radius D used by the point defect total reflector 1 to the laser radius ω0 of the side pump laser module 5 is ε, which satisfies the following formula:

[0046]

[0047] Wherein, l is the radial index of the annular light beam generated by the point defect total reflection mirror 1; T represents the transmittance of the first plane reflection mirror 7.

[0048] The process of generating a flat-top intensity distribution laser by the above-mentioned device is as follows: the side pump laser module 5 generates a pump light with a laser wavelength of λ and a beam radius of ω0, and the pump light enters the polarization beam splitter prism 3 for beam splitting to obtain a first polarized light beam and a second polarized light beam perpendicular to each other; wherein the first polarized light beam is a parallel polarized light beam (p polarized light), and the second polarized light beam is a vertical polarized light beam (s polarized light); the first polarized light beam passes through the first aperture diaphragm 2 and the point defect total reflector 1 in sequence, and then is reflected by the point defect total reflector 1 through the first aperture diaphragm 2 to enter the polarization beam splitter prism 3, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 to obtain a p-polarized annular light beam; the second polarized light beam passes through the second aperture diaphragm 8 and the second plane reflector 9 in sequence, and then is reflected by the second plane reflector 9 through the second aperture diaphragm 8 to enter the polarization beam splitter prism 3, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 to obtain a fundamental mode Gaussian light beam.

[0049] The polarization direction of the annular light beam is orthogonal to that of the fundamental mode Gaussian light beam; after the annular light beam passes through the polarization beam splitter prism 3, it is coaxially combined with the fundamental mode Gaussian light beam obtained after reflection by the polarization beam splitter prism 3, and then passes through the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 to obtain a laser with a flat-top intensity distribution.

[0050] In this embodiment, preferably, the optical paths of the first polarized light beam and the second polarized light beam obtained by the polarization beam splitting prism 3 are equal.

[0051] In this embodiment, preferably, the device further comprises: a quarter wave plate 4 is arranged between the polarization beam splitter prism 3 and the side pump laser module 5, and its arrangement direction is still parallel to the direction of the light beam generated by the side pump laser module 5; the surface of the quarter wave plate 4 is perpendicular to the first polarized light beam, the fast axis of the quarter wave plate 4 is at an angle of 45° to the polarization direction of the polarization beam splitter prism 3 and is coated with an anti-reflection medium film for the laser wavelength λ, and the quarter wave plate 4 is combined with the polarization beam splitter prism 3 to control the intensity ratio of the Gaussian light beam and the hollow intensity distribution light beam.

[0052] The process of generating a flat-top intensity distribution laser by the device after adding the quarter-wave plate 4 is as follows: the laser wavelength λ and the beam radius ω0 generated by the side pump laser module 5 enter the polarization beam splitter prism 3 for beam splitting to obtain a first polarized beam and a second polarized beam perpendicular to each other, wherein the first polarized beam is p-polarized light and the second polarized beam is s-polarized light; the first polarized beam passes through the point defect total reflector 1, the first aperture diaphragm 2, the polarization beam splitter prism 3, the quarter-wave plate 4, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 in sequence to obtain a p-polarized beam. The annular beam, the second polarized beam sequentially passes through the second aperture diaphragm 8, the second plane reflector 9, the polarization beam splitter prism 3, the quarter wave plate 4, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 to obtain a fundamental mode Gaussian beam, and the polarization direction of the annular beam is orthogonal to that of the fundamental mode Gaussian beam; the annular beam passes through the polarization beam splitter prism 3 and is coaxially combined with the fundamental mode Gaussian beam obtained after being reflected by the polarization beam splitter prism 3, and then passes through the quarter wave plate 4, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 to obtain a laser with a flat-top intensity distribution.

[0053] In this embodiment, optionally, the side-pump laser module 5 adopts a LD side-pumped Nd:YAG module, the length of the Nd:YAG crystal rod is 80 mm, the generated laser wavelength is 1064 nm, and the radius is about 580 μm; the point defect radius size is 40-200 μm, the step size is 20 μm, and the point defect total reflection mirror 1 is located on a three-dimensional displacement platform, so that the point defect total reflection mirror 1 can be moved and adjusted along the optical axis direction near the set distance from the splitting surface of the polarization splitting prism 3. The first aperture diaphragm 2 and the second aperture diaphragm 8 are both circular holes with adjustable sizes, which are used to control the sizes of the Gaussian and LG modes oscillating in the cavity; the focusing lens 6 is a plano-convex lens with f=1000mm, the first plane reflector 7 is coated with a dielectric film with a laser wavelength of 1064nm and a transmittance of T=15%, the second plane reflector 9 is coated with a dielectric film with a laser wavelength of 1064nm and a reflectivity of 100%, the reflecting surface of the polarization beam splitter prism 3 is at an angle of 45° to the optical axis, and each light-transmitting surface of the polarization beam splitter prism 3 is coated with a high-reflection dielectric film for the laser wavelength of 1064nm and is perpendicular to the optical axis.

[0054] Because the Laguerre-Gaussian (LG) beam is one of the eigenmodes of the resonant cavity, the point defect has no reflection near the optical axis, which suppresses the oscillation of the low-order transverse mode beam and can be used to generate a ring-shaped LG beam with a hollow intensity distribution. At the same time, with the increase of the radial index, the ring width of the LG beam remains unchanged, and the hollow size becomes larger. Therefore, by designing the size of the point defect and the size of the fundamental transverse mode Gaussian beam, the radius of the ring beam can be controlled.

[0055] The first polarized light beam passes through the point defect total reflector 1 to generate a ring-shaped light beam with a radial index of 1 (LG 01 ), the laser radius generated by the side pump laser module 5 is about 580 μm, and the ratio of the point defect radius D to the laser radius ω0 is ε. After calculation by the formula, ε=0.103, so the radius of the point defect used in the experiment is D=60 μm.

[0056] In the experiment, the distance from the point defect total reflector 1 to the polarization beam splitter prism 3 is 75 mm, the point defect radius size is D = 60 μm, the distance from the second plane reflector 9 to the polarization beam splitter prism 3 is 75 mm, the first aperture diaphragm 2 is located between the point defect total reflector 1 and the polarization beam splitter prism 3, the second aperture diaphragm 8 is located between the second plane reflector 9 and the polarization beam splitter prism 3, the distance from the polarization beam splitter prism 3 to the left side of the Nd: YAG crystal rod in the side pump laser module 5 is 75 mm, and the quarter wave plate 4 is located between the polarization beam splitter prism 3 and the side pump laser module 5, the quarter wave plate 4 and the polarization beam splitter prism 3 are combined to control the intensity ratio of the Gaussian beam and the hollow intensity distribution beam; the 1064nm laser generated by the side pump laser module 5 is incident perpendicular to the quarter wave plate 4, the focusing lens 6 is 10mm away from the right side of the Nd:YAG crystal rod in the side pump laser module 5, and the focusing lens 6 is equipped with a displacement platform that can move parallel to the optical axis direction to adjust the distance between the focusing lens 6 and the side pump laser module 5; the distance between the Nd:YAG crystal rod in the side pump laser module 5 and the first plane reflector 7 is 500mm.

[0057] The side pump laser module 5 generates a 1064nm laser, and the light beam passes through the polarization beam splitter prism 3 to obtain a first polarized light beam and a second polarized light beam. The direction of the first polarized light beam is parallel to the direction of the optical axis, and is vertically incident on the first aperture diaphragm 2, the point defect total reflector 1 and the quarter wave plate 4. The first polarized light beam passes through the point defect total reflector 1, the first aperture diaphragm 2, the polarization beam splitter prism 3, the quarter wave plate 4, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 in sequence to obtain an annular light beam, which is transmitted through the first plane reflector 7 to obtain an annular light beam. The obtained annular light beam is as shown in FIG. Figure 2 shown.

[0058] The second polarized light beam is perpendicular to the optical axis and vertically enters the second aperture stop 8 and the second plane reflector 9. The second polarized light beam passes through the second aperture stop 8, the second plane reflector 9, the polarization beam splitter prism 3, the quarter wave plate 4, the side pump laser module 5, the focusing lens 6, and the first plane reflector 7 in sequence to obtain a fundamental mode Gaussian light beam as shown in FIG. Figure 3 As shown, the polarization directions of the annular beam and the fundamental mode Gaussian beam are orthogonal. After the annular beam passes through the polarization beam splitter prism 3, it is coaxially combined with the fundamental mode Gaussian beam obtained after being reflected by the polarization beam splitter prism 3 to obtain the following: Figure 4 The flat-top intensity distribution of the laser is shown.

[0059] The position of the second plane reflector is adjusted along the optical axis direction of the second polarized light beam so that the optical paths of the first polarized light and the second polarized light are approximately equal after passing through the first polarization beam splitter prism, and the optical path error is generally within 1 mm.

[0060] The present invention proposes a flat-top intensity distribution laser generating device, which is used to split the polarization beam splitting prism 3 to obtain two polarized light beams, the first polarized light beam generates an annular light beam through a point defect total reflector, and the second polarized light beam generates a fundamental mode Gaussian light beam, and the first polarized light beam and the second polarized light beam are combined to obtain a circular flat-top light beam. The intensity of the annular light beam and the Gaussian light beam of the present invention can be adjusted by the main axis direction of the quarter wave plate 4, and the spot size and energy of the Gaussian light beam and the annular light beam can be adjusted by the size of the first aperture diaphragm 2 and the second aperture diaphragm 8, and the distance from the focusing lens 6 to the side pump laser module 5, thereby realizing the adjustment of the flat-top light beam spot size and the control of the flat-top light beam energy, and the conversion efficiency and stability are high. The present invention has a simple structure and is easy to adjust, and is suitable for laser processing and laser medical treatment that require spot uniformity.

[0061] Although the spirit and principle of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined to benefit, and such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the attached claims.

Claims

1. A flat-top intensity distribution laser generating device, characterized in that: include: A point defect total reflection mirror (1), a first aperture diaphragm (2), a polarization beam splitter prism (3), a side pump laser module (5), a focusing lens (6), a first plane reflection mirror (7), a second aperture diaphragm (8), and a second plane reflection mirror (9); wherein the point defect total reflection mirror (1), the first aperture diaphragm (2), the polarization beam splitter prism (3), the side pump laser module (5), the focusing lens (6), and the first plane reflection mirror (7) are sequentially arranged at intervals, and the arrangement direction is parallel to the direction of the light beam generated by the side pump laser module (5); and the second aperture diaphragm (8) and the second plane reflection mirror (9) are sequentially arranged at intervals, and the arrangement direction is perpendicular to the direction of the light beam generated by the side pump laser module (5); The process of generating a flat-top intensity distribution laser using the above device includes: The side pump laser module (5) generates pump light in the fundamental mode Gaussian light mode, and the pump light enters the polarization beam splitter prism (3) for beam splitting to obtain a first polarized light beam and a second polarized light beam that are perpendicular to each other; wherein the first polarized light beam is parallel polarized light, and the second polarized light beam is vertical polarized light; The first polarized light beam passes through a first aperture diaphragm (2) and enters a point defect total reflector (1), the point defect total reflector (1) generates an annular light beam, and the annular light beam enters the first aperture diaphragm (2) and a polarization beam splitter prism (3) in sequence; the second polarized light beam passes through a second aperture diaphragm (8) and enters a second plane reflector (9), and a fundamental mode Gaussian light beam reflected back by the second plane reflector (9) enters the second aperture diaphragm (8) and a polarization beam splitter prism (3) in sequence; the polarization directions of the annular light beam and the fundamental mode Gaussian light beam are orthogonal; The annular light beam passes through the polarization beam splitter prism (3) and is coaxially combined with the fundamental mode Gaussian light beam reflected by the polarization beam splitter prism (3), and then passes through a side pump laser module (5), a focusing lens (6) and a first plane reflector (7) to obtain a flat-top intensity distribution laser.

2. A flat-top intensity distribution laser generating device according to claim 1, characterized in that: The surface of the point defect total reflection mirror (1) is plated with a high-reflection medium film corresponding to the laser wavelength emitted by the side pump laser module (5), and point defects of different sizes are etched on the surface.

3. A flat-top intensity distribution laser generating device according to claim 2, characterized in that: The spot radius of the annular light beam generated by the point defect total reflector (1) satisfies the following formula: Where m is the angular index of the Laguerre-Gaussian beam, m∈[1,+∞); ω0 is the beam radius of the pump light generated by the side pump laser module (5).

4. The flat-top intensity distribution laser generating device according to claim 3, characterized in that: The point defect total reflection mirror (1) is placed on a three-dimensional displacement platform, and the three-dimensional displacement platform is used to adjust the point defect total reflection mirror (1) to move along the optical axis within a set distance from the splitting surface of the polarization splitting prism (3).

5. The flat-top intensity distribution laser generating device according to claim 1, characterized in that: The first aperture stop (2) and the second aperture stop (8) are circular small holes with adjustable sizes, which are used to control the size and energy of the light beam.

6. The flat-top intensity distribution laser generating device according to claim 1, characterized in that: The reflection surface of the polarization beam splitter prism (3) is at an angle of 45° to the optical axis, and each light-transmitting surface of the polarization beam splitter prism (3) is plated with a high-reflection dielectric film corresponding to the laser wavelength emitted by the side pump laser module (5) and is perpendicular to the optical axis.

7. The flat-top intensity distribution laser generating device according to claim 1, characterized in that: The focusing lens (6) is a plano-convex focusing lens, the incident surface of the focusing lens (6) is coated with a high-transmittance medium film corresponding to the laser wavelength emitted by the side pump laser module (5) and is perpendicular to the optical axis, and the distance between the focusing lens (6) and the side pump laser module (5) is adjustable.

8. The flat-top intensity distribution laser generating device according to claim 1, characterized in that: The first plane reflector (7) is a plane reflector, the surface of which is coated with a dielectric film that partially transmits the wavelength of the laser emitted by the side pump laser module (5), and is placed at an angle perpendicular to the optical axis; the second plane reflector (9) is a plane reflector, the reflection surface of which is coated with a high reflection film that corresponds to the wavelength of the laser emitted by the side pump laser module (5) and is perpendicular to the optical axis.

9. The flat-top intensity distribution laser generating device according to claim 4, characterized in that: The ratio of the point defect radius D used by the point defect total reflector (1) to the beam radius ω0 of the pump light generated by the side pump laser module (5) is ε, and ε satisfies the following formula: In the formula, l is the radial index of the annular light beam generated by the point defect total reflection mirror (1); T represents the transmittance of the first plane reflection mirror (7).

10. The flat-top intensity distribution laser generating device according to claim 1, characterized in that: The device further comprises: a quarter wave plate (4) is arranged between the polarization beam splitter prism (3) and the side pump laser module (5); the arrangement direction of the quarter wave plate (4) is parallel to the direction of the light beam generated by the side pump laser module (5); the surface of the quarter wave plate (4) is perpendicular to the first polarized light beam, the fast axis of the quarter wave plate (4) forms an angle of 45° with the polarization direction of the polarization beam splitter prism (3) and is coated with an anti-reflection medium film corresponding to the laser wavelength emitted by the side pump laser module (5); the quarter wave plate (4) is combined with the polarization beam splitter prism (3) to control the intensity ratio of the Gaussian light beam and the hollow intensity distribution light beam.

Images