CN213876189U - Optical system for generating quasi-flat-top circular light spots - Google Patents
Optical system for generating quasi-flat-top circular light spots Download PDFInfo
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- CN213876189U CN213876189U CN202023349320.8U CN202023349320U CN213876189U CN 213876189 U CN213876189 U CN 213876189U CN 202023349320 U CN202023349320 U CN 202023349320U CN 213876189 U CN213876189 U CN 213876189U
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Abstract
The utility model discloses a generate optical system of class flat top circle facula belongs to laser optics application, include: the device comprises a first polarization beam splitter prism, a spiral phase plate, a first total reflection lens, a second total reflection lens and a second polarization beam splitter prism; the first polarization beam splitter prism separates incident laser beams with Gaussian distribution into P beams with horizontal polarization and S beams with vertical polarization; the spiral phase plate and the first total reflection lens are sequentially arranged on a light path of the S light beam, the spiral phase plate converts the S light beam into a vortex light beam, and the first total reflection lens reflects the vortex light beam to the second polarization splitting prism; the second total reflection lens is positioned on the light path of the P light beam and used for reflecting the P light beam to the second polarization beam splitter prism; the second polarization beam splitter prism is used for superposing the P light beam and the vortex light beam so as to generate and output the flat-top-round-like light spot. The system is simple in structure and easy to build, can obtain quasi-flat-top round light spots with uniform energy distribution and good anti-maladjustment characteristics, and is suitable for various laser processing fields.
Description
Technical Field
The utility model belongs to laser optics application, more specifically relates to an optical system who generates class flat top circle light spot.
Background
The energy distribution of the ordinary Gaussian beam decreases from the center to the edge, and most of the energy is concentrated in the central area. When laser processing is carried out by using laser with Gaussian energy distribution, if the power is too high, the central energy is too high, and phenomena such as ablation, air holes and the like are easy to occur; if the power is low, the edge energy is insufficient, and the situation of incomplete processing occurs, and the defect is particularly obvious in the processing fields of high-power laser welding, cladding, surface modification and the like. Therefore, the light spot with uniformly distributed energy has more advantages in the application field of laser optics.
The prior art generally selects a diffractive optical element to obtain a flat-top circular light spot, which has high uniformity relative to the energy distribution of a gaussian beam. However, the flat-topped circular light spot designed based on the traditional diffractive optical element is very sensitive, the energy distribution of the flat-topped circular light spot is very easily influenced by factors such as the size of an incident light spot, the center deviation of an incident light beam, the fluctuation of a working distance and the like, the uniformity is continuously reduced in the subsequent propagation process, and the requirement is difficult to meet in the actual processing process. Therefore, it is very important for those skilled in the art how to form a light spot with uniform energy distribution and strong stability.
SUMMERY OF THE UTILITY MODEL
To prior art's defect and improvement demand, the utility model provides a generate optical system of class flat apical circle facula, its aim at provides a simple structure's optical system, through the mating reaction between each subassembly in the optical system, obtains the even class flat apical circle facula that just anti maladjustment characteristic is good of energy distribution.
In order to achieve the above object, the present invention provides an optical system for generating quasi flat top round light spot, including: the device comprises a first polarization beam splitter prism, a spiral phase plate, a first total reflection lens, a second total reflection lens and a second polarization beam splitter prism; the first polarization beam splitter prism is used for splitting incident laser beams with Gaussian distribution into P beams with horizontal polarization and S beams with vertical polarization; the spiral phase plate and the first full-reflection lens are sequentially arranged on a light path of the S light beam, the spiral phase plate is used for converting the S light beam into a vortex light beam, and the first full-reflection lens is used for reflecting the vortex light beam to the second polarization splitting prism; the second total reflection lens is positioned on the light path of the P light beam and used for reflecting the P light beam to the second polarization beam splitter prism; and the second polarization beam splitter prism is used for superposing the P light beam and the vortex light beam so as to generate and output the flat-top-round-like light spot.
Furthermore, the P beam and the S beam reach the second polarization splitting prism after being transmitted at equal distances.
Still further, still include: the half wave plate, the third polarization beam splitter prism and the second total reflection lens are sequentially arranged on the light path of the P light beam; and adjusting the energy ratio of the P beam and the vortex beam by rotating the half wave plate.
Still further, still include: and the laser is used for generating laser beams with Gaussian distribution, collimating the laser beams and outputting the collimated laser beams to the first polarization splitting prism.
Furthermore, the wavelength and the power of the laser beam generated by the laser are matched with the first polarization beam splitter prism, the spiral phase plate and the second polarization beam splitter prism.
Further, the diameter and power of the flat-top-like circular spot are controlled by changing the topological number of the spiral phase plate.
Furthermore, the topological number of the spiral phase plate is 1, and the power ratio of the P beam to the vortex beam is 0.66: 1.
Further, the number of the topologies of the spiral phase plate is 2, and the power ratio of the P beam to the vortex beam is 0.37: 1.
Furthermore, the topological number of the spiral phase plate is 3, and the power ratio of the P beam to the vortex beam is 0.31: 1.
Generally, through the utility model discloses above technical scheme who conceives can gain following beneficial effect:
(1) compared with the flat-top circular light spot, the flat-top circular light spot can effectively solve the problems of uneven energy distribution and light beam sensitivity, improve the energy distribution uniformity and light spot stability of the light spot, maintain uniform energy distribution in a certain focal depth range, improve various processing defects caused by uneven temperature in the laser processing process and improve the processing quality and precision; the optical system for generating the flat-top-like circular light spot is provided, the flat-top-like circular light spot with uniform energy distribution and good anti-maladjustment property is obtained through the matching among the components, the anti-maladjustment property of the light spot is good, the uniformity of the light spot energy can be maintained in a certain focal depth range, the optical system is not easily influenced by the conditions of incident light size, incident light divergence angle, offset distance and the like, and is more suitable for the actual laser processing process;
(2) the polarization state and the phase of the light beam are regulated and controlled through the polarization beam splitter prism and the spiral phase plate, and undesirable optical phenomena such as diffraction, interference and the like are avoided;
(3) the energy proportion of the P light beam and the vortex light beam can be adjusted through the half wave plate and the third polarization beam splitter prism, and the angle direction of the half wave plate can continuously rotate, so that any light intensity proportion is realized;
(4) the quasi-flat-top circular light spots with different sizes are obtained by selecting spiral phase plates with different topological numbers, so that the quasi-flat-top circular light spots are suitable for different application scenes; the optical system is simple in structure and easy to build, and unnecessary input and modulation devices are reduced on the premise of acquiring required light spots.
Drawings
Fig. 1 is a schematic structural diagram of an optical system for generating a quasi-flat-top circular light spot according to an embodiment of the present invention;
fig. 2 is a schematic view of a working principle of a polarization splitting prism in an optical system for generating quasi-flat-top circular light spots provided by the embodiment of the present invention;
fig. 3 is a schematic structural diagram of a spiral phase plate in an optical system for generating quasi-flat-top circular light spots according to an embodiment of the present invention;
FIG. 4 is a cross-sectional light field profile of a Gaussian distributed incident laser beam;
FIG. 5 is a cross-sectional light field profile of a Gaussian distributed P-beam;
FIG. 6 is a cross-sectional light field profile of a vortex beam;
FIG. 7 is a cross-sectional light field distribution diagram of a plano-topped circular spot.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
the device comprises a first polarization beam splitter prism 1, a spiral phase plate 2, a first total reflection lens 3, a second total reflection lens 4, a second polarization beam splitter prism 5, a half wave plate 6, a third polarization beam splitter prism 7 and a laser 8.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below 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 are not intended to limit the invention. Furthermore, the technical features mentioned in the embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
In the present application, the terms "first," "second," and the like (if any) in the present application and the drawings are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
Fig. 1 is a schematic structural diagram of an optical system for generating a quasi-flat-top circular light spot according to an embodiment of the present invention. Referring to fig. 1, the optical system for generating the flat-top-like circular spot in the present embodiment is described in detail with reference to fig. 2 to 7.
The embodiment of the utility model provides a circular facula of kind flat top. Compared with flat-top circular light spots, the flat-top circular light spots can effectively solve the problems of uneven energy distribution and light beam sensitivity, improve the energy distribution uniformity and light spot stability of the light spots, maintain uniform energy distribution in a certain focal depth range, improve various processing defects caused by uneven temperature in the laser processing process and improve the processing quality and precision.
The optical system for generating the quasi-flat-top circular light spot comprises a first polarization beam splitter prism 1, a spiral phase plate 2, a first total reflection lens 3, a second total reflection lens 4 and a second polarization beam splitter prism 5. The first polarization splitting prism 1 serves to split the incident laser beam of the gaussian distribution into a P beam of horizontal polarization and an S beam of vertical polarization, as shown in fig. 2. The spiral phase plate 2 and the first full-reflection lens 3 are sequentially arranged on a light path of the S light beam, the spiral phase plate 2 is used for converting the S light beam into a vortex light beam, and the energy of the reflected S light beam is changed into annular distribution from Gaussian distribution after passing through the spiral phase plate 2; the first total reflection lens 3 is used for reflecting the vortex light beam to the second polarization splitting prism 5. The second total reflection lens 4 is located on the light path of the P light beam and used for reflecting the P light beam to the second polarization splitting prism 5, and the transmitted P light beam keeps the gaussian distribution unchanged. The second polarization beam splitter prism 5 is used for superposing the P light beam and the vortex light beam to generate and output a flat-top-circle-like light spot.
The embodiment of the utility model provides an in, second polarization beam splitter is reachd after equal distance' S transmission to P light beam and S light beam. Namely, after the first polarization beam splitter 1 splits the incident laser beam into a P beam and an S beam, the two beams are transmitted at equal intervals and then reach the second polarization beam splitter 5, and then are combined by the second polarization beam splitter 5, so that the energy ratio of the gaussian beam and the vortex beam is fixed.
The topological number of the spiral phase plate 2 can be set independently, and the diameter and the power of the flat-top-round-like light spot can be controlled by changing the topological number of the spiral phase plate 2. Referring to fig. 3, the spiral phase plate 2 is a transparent plate with a fixed refractive index, one surface of the transparent plate is a planar structure, the opposite surface of the planar structure is a step structure with a spiral shape whose height varies with azimuth angle, and the thickness of the spiral phase plate 2 varies with azimuth angle. The thickness increased by the steps of the spiral phase plate 2 can be directly calculated according to the phase distribution and the material refractive index of the diffraction optical element; the thickness of the diffractive optical element is typically in the order of microns and is negligible, so the spiral phase plate 2 has a negligible effect on the light intensity. After the S light beam in this embodiment passes through the spiral phase plate 2, the phase of the outgoing light beam is also changed due to the different optical paths traveled at different azimuth angles, and the outgoing light beam is added with a spiral phase factor exp (il θ), so as to be changed into a vortex light beam. Where l is the topological number of the spiral phase plate 2, l can vary with the angular difference between the two diffractive optical elements, and i represents the complex sign. The size of the vortex light beam is influenced by the topological number, and the larger the topological number is, the larger the area of the central energy depression of the obtained vortex light beam is, and the larger the light spot diameter is.
When the spiral phase plates 2 with different topological numbers are selected, the power ratio of the Gaussian-distributed beam splitting power to the vortex beam splitting power is not fixed, and the adjustment and optimization can be performed according to the actual light intensity distribution condition of the focal plane. When the number of the topologies of the spiral phase plate 2 is 1, the ratio of the Gaussian-distributed P-beam power to the vortex-beam power is 0.66: 1. When the number of the topology of the spiral phase plate 2 is 2, the ratio of the Gaussian-distributed P-beam power to the vortex-beam power is 0.37: 1. When the topological number of the spiral phase plate 2 is 1, the ratio of the Gaussian-distributed P-beam power to the vortex-beam power is 0.31: 1.
The optical system for generating the flat-top-like circular light spot further comprises a half wave plate 6 and a third polarization beam splitter prism 7. And the half wave plate 6, the third polarization splitting prism 7 and the second total reflection lens 4 are sequentially arranged on the light path of the P light beam. The P light beam enters the half wave plate 6, the polarization direction of the emergent light is changed, the emergent light is separated into two light beams with mutually vertical polarization directions through the third polarization splitting prism 7, the energy of the splitting path is changed by rotating the half wave plate 6, so that the energy ratio of the P light beam and the vortex light beam is adjusted, and the flat-top-like circular light beam with better uniformity is obtained. When the spiral phase plates 2 with different topological numbers are selected, the sizes of the obtained flat-topped circular light spots are different, and the energy proportion of the Gaussian distribution beam splitting is required to be adjusted to obtain the high-uniformity flat-topped circular light spots.
The first polarization beam splitter prism 1, the second polarization beam splitter prism 5 and the third polarization beam splitter prism 7 are all cubic crystals formed by plating a multilayer film structure on the inclined plane of a right-angle prism and gluing. By utilizing the property that the P polarization light transmittance is 1 and the S polarization light transmittance is less than 1 when the light ray is incident at the Brewster angle, after the light ray passes through the multilayer film structure for multiple times at the Brewster angle, the P polarization component is completely transmitted, and at least more than 90% of the S polarization component is reflected.
The optical system generating the flat-topped circular spot further comprises a laser 8. The laser 8 is used for generating a laser beam with gaussian distribution, collimating the laser beam and outputting the collimated laser beam to the first polarization splitting prism 1. The wavelength and power of the laser beam generated by the laser 8 are matched with the first polarization splitting prism 1, the spiral phase plate 2 and the second polarization splitting prism 5. Further, the wavelength and power of the laser beam generated by the laser 8 should also be matched with the third polarization splitting prism 7.
In this embodiment, the unpolarized gaussian distributed incident beam is separated into two linearly polarized light beams perpendicular to each other by the first polarization splitting prism 1, the laser beam incident on the first polarization splitting prism 1 is shown in fig. 4, and fig. 4 exemplifies the unpolarized gaussian distributed incident beam with a wavelength of 1064 nm. One of the light beams passes through the spiral phase plates 2 with different topological numbers and is converted into a vortex light beam, the generated vortex light beam is shown in fig. 6, and fig. 6 takes the topological number of the spiral phase plates 2 as 1 as an example. The other light beam enters the half-wave plate 6, the polarization direction is changed, the third polarization beam splitter prism 7 separates the P light with the required energy proportion, the energy proportion is determined by the rotation angle of the half-wave plate 6, the energy of the gaussian beam is adjusted in real time by observing the flat-top-like circular light spot output from the system, the light beam with gaussian distribution is shown in fig. 5, and fig. 5 takes the energy proportion of the half-wave plate 6 and the third polarization beam splitter prism 7 after adjustment as an example of 0.66. The two light beams are transmitted at equal intervals and then combined by the second polarization beam splitter prism 5 to obtain flat-top-like circular light spots with uniform energy, and the generated flat-top-like circular light spots are shown in fig. 7.
The flat-top round light spot can effectively solve the processing defect caused by uneven energy in the actual laser processing process, can effectively improve the quality of processed products, and is suitable for various fields such as laser cladding, welding, surface modification and the like. The flat top circular light spot with good maladjustment resistance has great significance to the application field of laser optics, in the practical application process, the conditions of the size of incident light, the emitting angle of the incident light, the offset distance and the like are difficult to be in an ideal state, and the flat top circular light spot with good maladjustment resistance can ensure high-quality processing to the maximum extent.
It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. An optical system for generating a flat-topped circular spot, comprising: the device comprises a first polarization splitting prism (1), a spiral phase plate (2), a first total reflection lens (3), a second total reflection lens (4) and a second polarization splitting prism (5);
the first polarization beam splitter prism (1) is used for splitting incident laser beams with Gaussian distribution into P beams with horizontal polarization and S beams with vertical polarization;
the spiral phase plate (2) and the first fully-reflecting lens (3) are sequentially arranged on a light path of the S light beam, the spiral phase plate (2) is used for converting the S light beam into a vortex light beam, and the first fully-reflecting lens (3) is used for reflecting the vortex light beam to the second polarization beam splitter prism (5);
the second total reflection lens (4) is positioned on the light path of the P light beam and used for reflecting the P light beam to the second polarization beam splitter prism (5);
and the second polarization beam splitter prism (5) is used for superposing the P light beam and the vortex light beam to generate and output a flat-top-round-like light spot.
2. The optical system for generating a flat-top circular spot according to claim 1, wherein the P-beam and the S-beam reach the second polarization splitting prism (5) after being transmitted at equal distances.
3. The optical system for generating a flat-top circular spot according to claim 1, further comprising: the half wave plate (6), the third polarization beam splitter prism (7) and the second total reflection lens (4) are sequentially arranged on the light path of the P light beam; the energy ratio of the P beam and the vortex beam is adjusted by rotating the half wave plate (6).
4. The optical system for generating a flat-top circular spot according to claim 1, further comprising: and the laser (8) is used for generating a laser beam with Gaussian distribution, collimating the laser beam and outputting the collimated laser beam to the first polarization splitting prism (1).
5. The optical system for generating a flat-top circular spot according to claim 4, wherein the laser (8) generates a laser beam with a wavelength and power matched to the first polarizing beam splitter prism (1), the spiral phase plate (2) and the second polarizing beam splitter prism (5).
6. The optical system for generating a plano-topped circular spot according to any one of claims 1-5, wherein the diameter and power of the plano-topped circular spot are controlled by modifying the number of topologies of the helical phase plate (2).
7. The optical system for generating a flat-topped circular spot according to claim 6, wherein the number of topologies of the spiral phase plate (2) is 1, and the power ratio of the P beam to the vortex beam is 0.66: 1.
8. The optical system for generating a flat-top circular spot according to claim 6, wherein the number of topologies of the spiral phase plate (2) is 2, and the power ratio of the P beam to the vortex beam is 0.37: 1.
9. The optical system for generating a flat-topped circular spot according to claim 6, wherein the number of topologies of the spiral phase plate (2) is 3, and the power ratio of the P beam to the vortex beam is 0.31: 1.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114094444A (en) * | 2021-10-26 | 2022-02-25 | 中国电子科技集团公司第十一研究所 | Laser diode area array system for realizing uniform flat top distribution |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114094444A (en) * | 2021-10-26 | 2022-02-25 | 中国电子科技集团公司第十一研究所 | Laser diode area array system for realizing uniform flat top distribution |
| CN114094444B (en) * | 2021-10-26 | 2024-04-19 | 中国电子科技集团公司第十一研究所 | Laser diode area array system for realizing uniform flat-top distribution |
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