Beam shaping device and optical system
By optimizing the cross-section and energy distribution of the laser beam into a rectangular and flat-top shape using a beam shaping device, the problem of low efficiency and energy utilization of existing laser beams in thin film processing is solved, achieving a more efficient thin film processing effect.
Patent Information
- Application Number
- CN202410811035.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-21
- Publication Date
- 2025-12-23
AI Technical Summary
The existing laser beams have a circular cross-section and a Gaussian energy distribution, resulting in low efficiency and low energy utilization in thin film processing, which cannot meet the optimal requirements of thin film processing.
A beam shaping device is used, including a beam splitting unit, a delay unit, and an imaging unit. By splitting the beam into multiple beams in a plane and adjusting their propagation length and polarization direction, the beam forms a rectangular cross-section and a flat-top energy distribution after imaging.
This technology enabled the laser beam cross-section to be changed from circular to rectangular, and the energy distribution to be changed from Gaussian to flat-top, thereby improving the efficiency and energy utilization of thin film processing.
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Figure CN121187003A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of laser, in particular to a light beam shaping device and an optical system. BACKGROUND
[0002] Laser is more and more important in material processing; in most cases, the laser beam emitted by the laser has a circular cross section and a Gaussian energy distribution. However, the above laser beam is not advantageous for film processing, for example, the efficiency is low when the laser beam with a circular cross section is used for film processing, and in addition, the Gaussian energy distribution has a very low energy utilization rate for film processing.
[0003] In fact, for film processing, the optimal cross section of the laser beam is rectangular or square, and the optimal energy distribution is flat-top distribution; therefore, how to obtain the optimal laser beam suitable for film processing is an urgent technical problem to be solved by those skilled in the art. SUMMARY
[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a light beam shaping device and an optical system for solving the problem that the existing laser beam is not suitable for film processing.
[0005] To achieve the above-mentioned purpose and other related purposes, the present application provides a light beam shaping device, which comprises:
[0006] A first optical module, the first optical module comprising a light splitting unit, a delay unit and an imaging unit;
[0007] The light splitting unit is used for splitting the first light beam into N first split light beams in a first plane and emitting them in parallel, N being a natural number greater than or equal to 2;
[0008] The delay unit is arranged on the light emitting side of the light splitting unit and is used for making each of the first split light beams emit after passing through different propagation lengths, wherein the minimum delay value between each of the first split light beams is greater than or equal to the coherence length of the first light beam;
[0009] The imaging unit is arranged on the light emitting side of the delay unit and is used for imaging each of the first split light beams after passing through different propagation lengths, wherein the difference between the longitudinal positions of the real images of each of the first split light beams is less than 1 Rayleigh length, and the transverse positions of the real images of each of the first split light beams overlap.
[0010] Optionally, the light splitting unit comprises N positive lenses arranged in one-dimensional array or two-dimensional array.
[0011] Optionally, the number of the positive lenses is two or four.
[0012] Optionally, the delay unit comprises a transmissive optical element, the transmissive optical element comprises N transmissive regions, and the N transmissive regions have different thicknesses and / or refractive indexes, and the N first sub-beams have different propagation lengths after passing through the N transmissive regions respectively.
[0013] Optionally, the delay unit comprises a reflective optical element, the reflective optical element comprises N reflective regions, and the N reflective regions are arranged in a stepped manner, and the N first sub-beams change the directions of emission and have different propagation lengths after passing through the N reflective regions respectively; wherein, each of the first sub-beams has an included angle between the direction of emission and the direction of incidence, and the included angle is greater than 0° and less than 180°.
[0014] Optionally, the reflective optical element comprises N plane mirrors or curved mirrors, wherein the N plane mirrors or curved mirrors are arranged in a stepped manner to form the N reflective regions; and / or the included angle is 90°.
[0015] Optionally, the delay unit comprises a reflective optical element, a polarizer and a λ / 4 wave plate, the reflective optical element is arranged on the light-emitting side of the beam-splitting unit, the polarizer and the λ / 4 wave plate are arranged between the beam-splitting unit and the reflective optical element in sequence, the reflective optical element comprises N reflective regions, and the N reflective regions are arranged in a stepped manner, the reflective optical element, the polarizer and the λ / 4 wave plate cooperate to change the polarization directions and the directions of emission of the N first sub-beams and make them have different propagation lengths; wherein, each of the first sub-beams has an included angle between the direction of emission and the direction of incidence, and the included angle is greater than 0° and less than 180°.
[0016] Optionally, the reflective optical element comprises N plane mirrors or curved mirrors, wherein the N plane mirrors or curved mirrors are arranged in a stepped manner to form the N reflective regions; and / or the included angle is 90°.
[0017] Optionally, the imaging unit comprises a first lens group and a common lens, which are arranged on the light-emitting side of the delay unit in sequence, the first lens group comprises N first lenses, and the N first lenses form N first telescopes with the common lens respectively, so that the N first sub-beams are imaged after passing through the N first telescopes respectively; or, a second lens group is used to replace the common lens, the second lens group comprises N second lenses, at this time, the N first lenses and the N second lenses correspond to each other and form the N first telescopes; wherein, at least (N-1) of the N first telescopes are off-axis telescopes.
[0018] Optionally, the first optical module further comprises a position adjustment unit arranged between the light splitting unit and the delay unit, for adjusting the longitudinal position of the real image of each first split beam.
[0019] Optionally, the position adjustment unit comprises a third lens group and a fourth lens group, which are sequentially arranged between the light splitting unit and the delay unit, the third lens group comprises N third lenses, the fourth lens group comprises N fourth lenses, the N third lenses and the N fourth lenses correspond to each other and form N second telescopes, wherein the magnification of each second telescope is not equal to 1; the longitudinal positions of the real images of the first split beams are adjusted to be the same by adjusting the distance between each second telescope and the delay unit, so that the longitudinal positions of the real images of the first split beams overlap.
[0020] Optionally, when the imaging unit comprises the second lens group, the longitudinal positions of the real images of the first split beams are adjusted to be the same by adjusting the distance between each first telescope and the delay unit, so that the longitudinal positions of the real images of the first split beams overlap.
[0021] Optionally, the beam shaping device further comprises a second optical module and an intermediate imaging module, the second optical module comprises a polarization changing unit and a beam superposition unit; wherein the intermediate imaging module, the polarization changing unit and the beam superposition unit are sequentially arranged on the light output side of the first optical module, or the polarization changing unit, the beam superposition unit and the intermediate imaging module are sequentially arranged on the light input side of the first optical module.
[0022] The polarization changing unit is used for splitting the second beam into two second split beams with different polarization directions in a second plane, and the beam superposition unit is used for spatially superimposing the two second split beams and emitting in the same direction.
[0023] When the intermediate imaging module is arranged on the light output side of the first optical module, the intermediate imaging module is used for secondary imaging of the imaging beam of the first optical module to obtain the second beam.
[0024] When the intermediate imaging module is arranged on the light output side of the second optical module, the intermediate imaging module is used for imaging the superimposed beam of the second optical module to obtain the first beam.
[0025] Optionally, the polarization changing unit comprises a λ / 2 wave plate, and / or the beam superposition unit comprises a beam displacer.
[0026] Optionally, the intermediate imaging module comprises a fifth lens and a sixth lens, and the fifth lens and the sixth lens correspond to each other and form a third telescope.
[0027] Optionally, the third telescope comprises a cylindrical telescope or a spherical telescope.
[0028] The present application also provides an optical system comprising a beam shaping device as described above and a beam generating device for providing a light beam to the beam shaping device.
[0029] Optionally, the beam generating device comprises an ultra-short pulse laser.
[0030] As described above, the beam shaping device and the optical system of the present application can modify the cross section of the light beam in the first plane to be flat-topped, such as modifying the circular cross section of the light beam to be rectangular cross section, by the design of the first optical module; and can modify the cross section of the light beam in the second plane to be flat-topped, such as modifying the Gaussian energy distribution of the light beam to be flat-topped energy distribution, by the design of the second optical module; thus, an optimal laser beam with rectangular cross section and flat-topped energy distribution can be obtained, which is suitable for thin film processing. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 A first structure schematic diagram of the first optical module of the present application is shown.
[0032] Figure 2 A structure schematic diagram of the light splitting unit of the present application is shown.
[0033] Figure 3 Another structure schematic diagram of the light splitting unit of the present application is shown.
[0034] Figure 4 A structure schematic diagram of the transmissive optical element of the present application is shown.
[0035] Figure 5 Another structure schematic diagram of the transmissive optical element of the present application is shown.
[0036] Figure 6 A second structure schematic diagram of the first optical module of the present application is shown.
[0037] Figure 7 A third structure schematic diagram of the first optical module of the present application is shown.
[0038] Figure 8 A structure schematic diagram of the first lens group of the present application is shown.
[0039] Figure 9 Another structure schematic diagram of the first lens group of the present application is shown.
[0040] Figure 10 An imaging principle schematic diagram of the second telescope is shown.
[0041] Figure 11 An imaging principle schematic diagram of an off-axis telescope is shown.
[0042] Figure 12 A fourth structural schematic diagram of the first optical module of the present application is shown.
[0043] Figure 13 A fifth structural schematic diagram of the first optical module of the present application is shown.
[0044] Figure 14 A structural schematic diagram of the second optical module of the present application is shown.
[0045] Figure 15 A polarization direction schematic diagram of the second light beam of the present application is shown.
[0046] Figure 16 A polarization direction schematic diagram of the two second light beams after passing through the polarization changing unit of the present application is shown.
[0047] Figure 17 A structural schematic diagram of the light beam shaping device of the present application is shown.
[0048] Element number explanation
[0049] 10 Light beam shaping device
[0050] 100 First optical module
[0051] 110 Light splitting unit
[0052] 111 Positive lens
[0053] 111a Cylindrical positive lens
[0054] 111b Spherical positive lens
[0055] 120 Delay unit
[0056] 121 Transmissive optical element
[0057] 121a Transmissive area
[0058] 122 Reflective optical element
[0059] 122a Reflective area
[0060] 123 Polarization mirror
[0061] 124 λ / 4 wave plate
[0062] 130 Imaging unit
[0063] 131 First lens group
[0064] 131a first lens
[0065] 132 common lens
[0066] 133 second lens group
[0067] 133a second lens
[0068] 134 superimposed imaging
[0069] 140 position adjustment unit
[0070] 141 third lens group
[0071] 141a third lens
[0072] 142 fourth lens group
[0073] 142a fourth lens
[0074] 200 second optical module
[0075] 210 polarization change unit
[0076] 220 beam superposition unit
[0077] 300 intermediate imaging module DETAILED DESCRIPTION
[0078] The present application is herein described, by way of example only, with reference to embodiments thereof. It is to be understood that variations and modifications will be apparent to those skilled in the art and that the scope of the application encompasses all such variations and modifications as fall within the spirit and scope of the application. Various embodiments of the application are described herein with reference to the following drawings.
[0079] Reference will now be made to the drawings, wherein: Figures 1 to 17 It is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments will be apparent to those of skill in the art upon reading the above description. The scope of the application should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with their full scope of equivalents. The description of embodiments is intended to cover any and all modifications and variations of the various embodiments thereof that may become apparent to those of skill in the art once inspired by the above description.
[0080] As shown in Figure 1 , Figure 6 , Figure 7 , Figure 12 , Figure 13 , Figure 14 and Figure 17 , the present embodiment provides a light beam shaping device 10, which comprises a first optical module 100, further comprising a second optical module 200 and an intermediate imaging module 300.
[0081] The first optical module 100 is configured to modify the cross section of the first light beam B1 in the first plane into a flat-top type or a near flat-top type; wherein the first optical module 100 comprises a splitting unit 110, a delaying unit 120 and an imaging unit 130.
[0082] The splitting unit 110 is configured to split the first light beam B1 into N first split light beams (e.g., B11 to B1N) in the first plane and parallelly emit, wherein N is a natural number greater than or equal to 2.
[0083] As an example, the splitting unit 110 comprises N positive lenses 111 arranged in a one-dimensional array or a two-dimensional array, and the N positive lenses 111 split the incident first light beam B1 into N first split light beams. In one embodiment, N equals to 2, i.e., the splitting unit 110 comprises two positive lenses 111, and the two positive lenses 111 split the first light beam B1 (e.g., a one-dimensional light beam) into two first split light beams B11 and B12; specifically, the two positive lenses 111 are arranged in a one-dimensional array and both of the two positive lenses 111 are cylindrical positive lenses 111a, as shown in FIG. 1B. Figure 2 As another example, N equals to 4, i.e., the splitting unit 110 comprises four positive lenses 111, and the four positive lenses 111 split the first light beam B1 (e.g., a two-dimensional light beam) into four first split light beams B11, B12, B13 and B14; specifically, the four positive lenses 111 are arranged in a two-dimensional array and all of the four positive lenses 111 are spherical positive lenses 111b, as shown in FIG. 1C. Figure 3 Of course, in other embodiments, N can also be other values, the splitting unit 110 comprises other number of positive lenses 111 and splits the first light beam B1 into corresponding number of first split light beams by corresponding number of positive lenses 111, which has no substantial influence on the present embodiment.
[0084] In fact, the first light beam B1 can also be split by the delaying unit 120, but when the first light beam B1 is split by the delaying unit 120, the light path difference between different regions of the delaying unit 120 will cause inaccurate splitting and edge effect; while the splitting unit 110 is additionally arranged at the light-in side of the delaying unit 120 and splits the first light beam B1 by the splitting unit 110, accurate splitting can be achieved and edge effect can be avoided.
[0085] The delaying unit 120 is arranged at the light-out side of the splitting unit 110 and configured to make each first split light beam emit after passing through different propagation lengths, wherein the minimum delay value between each first split light beam is greater than or equal to the coherence length of the first light beam B1.
[0086] By making each first sub-beam exit through a different propagation length, and making the minimum delay value between each first sub-beam exiting greater than or equal to the coherence length of the first beam B1, interference between each first sub-beam can be avoided, each first sub-beam can be imaged without interference in the rear imaging unit 130, the intensity distribution of the superimposed beam can be equal to the sum of the intensity distribution of each first sub-beam, and thus a flat-top or approximately flat-top intensity distribution in the first plane can be obtained.
[0087] It should be noted that the minimum delay value between each first sub-beam exiting refers to that there is a delay value between two adjacent first sub-beams exiting, and the minimum value is selected from each delay value as the minimum delay value; for the case where the number of first sub-beams is two, the minimum delay value is the time difference when the two first sub-beams exit; for the case where the number of first sub-beams is four, the first sub-beam exiting first and the second sub-beam exiting have a first delay value, the second sub-beam exiting and the third sub-beam exiting have a second delay value, and the third sub-beam exiting and the fourth sub-beam exiting have a third delay value, and the minimum value is selected from the first, second, and third delay values as the minimum delay value; of course, the same applies to other values of the number of first sub-beams, which will not be listed one by one here.
[0088] As an example, the delay unit 120 includes a transmissive optical element 121, as shown in Figure 1 wherein the transmissive optical element 121 includes N transmissive regions 121a. In an embodiment, the N transmissive regions 121a have different thicknesses, and at this time, the N first sub-beams have different propagation lengths after passing through the N transmissive regions 121a, Figure 4 showing the arrangement and thickness design of each transmissive region 121a when N is equal to 2, Figure 5The arrangement and thickness design of each transmission region 121a when N equals 4 are shown. The arrangement of each transmission region 121 is the same as the arrangement of the positive lens 111 in the light splitting unit 110. By designing the thickness of the N transmission regions 121a, the minimum delay value between the N first light beams can be greater than or equal to the coherence length of the first light beam B1. In another embodiment, the N transmission regions 121a have different refractive indices. In this case, the N first light beams have different propagation lengths after passing through the N transmission regions 121a. By designing the refractive indices of the N transmission regions 121a, the minimum delay value between the N first light beams can be greater than or equal to the coherence length of the first light beam B1. Of course, in other embodiments, the thickness and the refractive index of the N transmission regions 121a can be adjusted. Specifically, among the N transmission regions 121a, at least two transmission regions 121a have different thicknesses, and at least two transmission regions 121a have different refractive indices. Of course, the refractive indices of the two transmission regions 121a with different thicknesses can be the same or different. Similarly, the thicknesses of the two transmission regions 121a with different refractive indices can be the same or different.
[0089] As another example, the delay unit 120 includes a reflective optical element 122, as shown in FIG. 2B. The reflective optical element 122 includes N reflection regions 122a arranged in a stepped manner. In this case, the N first light beams change the directions of emission and have different propagation lengths after passing through the N reflection regions 122a. Figure 6 As another example, the delay unit 120 includes a reflective optical element 122, as shown in FIG. 2B. The reflective optical element 122 includes N reflection regions 122a arranged in a stepped manner. In this case, the N first light beams change the directions of emission and have different propagation lengths after passing through the N reflection regions 122a.
[0090] As another example, the delay unit 120 includes a reflective optical element 122, a polarizer 123, and a λ / 4 wave plate 124, as shown in FIG. 2C. The reflective optical element 122 is arranged on the light-emitting side of the light splitting unit 110. The polarizer 123 and the λ / 4 wave plate 124 are arranged between the light splitting unit 110 and the reflective optical element 122 in sequence. Figure 7The reflective optical element 122 includes N reflective regions 122a arranged in a step shape. The reflective optical element 122, the polarizer 123, and the λ / 4 wave plate 124 cooperate to change the polarization direction and the exit direction of the N first light beams and make the N first light beams have different propagation lengths. In the example, the exit direction of each first light beam is different from the incident direction, and the angle between the exit direction and the incident direction is greater than 0° and less than 180°. As an optional solution, the reflective optical element 122 is arranged in parallel to the light exit side of the light reflection unit 110, and the polarizer 123 is arranged at an angle of 45° between the light splitting unit 110 and the reflective optical element 122. In this case, the exit direction of each first light beam is perpendicular to the incident direction, that is, the angle is 90°. The step height difference of the N reflective regions 122a, that is, the position of the reflective surface, is designed to make the minimum delay value between the N first light beams greater than or equal to the coherence length of the first light beam B1. The λ / 4 wave plate 124 is arranged in parallel to the light incident side of the reflective optical element 122 and between the polarizer 123 and the reflective optical element 122. Each first light beam incident on the polarizer 123 first passes through the λ / 4 wave plate 124 to the reflective optical element 122, and each first light beam reflected by the reflective optical element 122 passes through the λ / 4 wave plate 124 to the polarizer 123 and then exits. After passing through the λ / 4 wave plate 124 twice, the horizontal polarization light in each first light beam is adjusted to vertical polarization light, the polarization direction is adjusted, and the interference between the first light beams is eliminated by using the polarization effect. In the example, the reflective optical element 122 includes N plane mirrors or N curved mirrors arranged in a step shape to form the N reflective regions 122a.
[0091] The imaging unit 130 is arranged on the light exit side of the delay unit 120 and is used to image the N first light beams having different propagation lengths. The longitudinal positions of the real images of the N first light beams are different by less than one Rayleigh length, and the transverse positions of the real images of the N first light beams overlap. In this way, the intensity distribution of the overlapped light beams is equal to the sum of the intensity distributions of the N first light beams, and a flat-top or approximately flat-top intensity distribution is obtained in the first plane.
[0092] As an example, the imaging unit 130 includes a first lens group 131 and a common lens 132 arranged in sequence on the light exit side of the delay unit 120, as shown in FIG. 1C. Figure 1 、 Figure 6 、 Figure 7 、 Figure 12 and Figure 17As shown, of course, the first lens group 131 can also be replaced by a lens array; wherein the first lens group 131 includes N first lenses 131a, and the N first lenses 131a respectively form N first telescopes with the common lens 132, so that the N first light beams can be respectively imaged in a telecentric manner after passing through the N first telescopes, Figure 8 As shown, when N equals 2, the arrangement of the first lenses 131a is shown, Figure 9 As shown, when N equals 4, the arrangement of the first lenses 131a is shown, and the arrangement of the first lenses 131a is the same as the arrangement of the zones of the delay unit 120. In addition, the first lenses 131a can be cylindrical positive lenses or spherical positive lenses. In order to make the difference between the longitudinal positions of the real images of the N first light beams less than 1 Rayleigh length, at least (N-1) of the N first telescopes are off-axis telescopes, such as Figure 11 As shown; as an optional solution, the N first telescopes are all off-axis telescopes, so that the N first light beams can be respectively imaged in a telecentric manner after passing through the N off-axis telescopes; in practical applications, the off-axis telescopes can be formed by designing the size and arrangement of the corresponding lenses.
[0093] In the above example, due to the difference in optical path of the delay unit 120, although the off-axis telescopes are used in the imaging unit 130 to overlap the longitudinal positions, for the case of large optical path difference, the longitudinal positions of the real images of the N first light beams are different, and complete overlap cannot be achieved. In order to achieve complete overlap, the first optical module 100 further includes a position adjustment unit 140 arranged between the light splitting unit 110 and the delay unit 120, for adjusting the longitudinal positions of the real images of the N first light beams, as shown. Figure 12 In an embodiment, the position adjustment unit 140 includes a third lens group 141 and a fourth lens group 142, which are sequentially arranged between the light splitting unit 110 and the delay unit 120; wherein the third lens group 141 includes N third lenses 141a, and the fourth lens group 142 includes N fourth lenses 142a, the N third lenses 141a and the N fourth lenses 142a correspond to each other and form N second telescopes, and the magnifications M of the N second telescopes are not equal to 1, as shown. Figure 10 By adjusting the distance between the second telescopes and the delay unit 120, the longitudinal positions of the real images of the N first light beams after passing through the delay unit 120 are adjusted, so that the longitudinal positions of the real images of the N first light beams are adjusted to be the same, and the longitudinal positions of the real images of the N first light beams are overlapped.
[0094] As another example, the second lens group 133 is used to replace the common lens 132, and the second lens group 133 includes N second lenses 133a, at this time, the N first lenses 131a and the N second lenses 133a correspond to each other and form N first telescopes, as shown. Figure 13The second lens group 133 is shown in the form of a lens array. Of course, it is also possible for the second lens group 133 to be replaced by a lens array. That is, the imaging unit 130 includes the first lens group 131 and the second lens group 133, which are arranged in sequence on the light exit side of the delay unit 120; the first lens group 131 includes N first lenses 131a, and the second lens group 133 includes N second lenses 133a, the N first lenses 131a and the N second lenses 133a correspond to each other and form N first telescopes, so that the N first light beams can be imaged in sequence through the N first telescopes; in the actual application, the first lens 131a and the second lens 133a in each first telescope in the above example are confocal. In order to make the longitudinal position difference of the real images of the N first light beams less than 1 Rayleigh length, at least (N-1) of the N first telescopes are off-axis telescopes; as an optional solution, the N first telescopes are all off-axis telescopes, so that the N first light beams can be imaged in sequence through the N off-axis telescopes in a telecentric manner.
[0095] In the above example, in order to realize that the longitudinal positions of the real images of the N first light beams are completely overlapped, in addition to the position adjustment unit 140 being additionally arranged between the light splitting unit 110 and the delay unit 120 as described above, the longitudinal positions of the real images of the N first light beams on the imaging plane can also be adjusted by adjusting the distance between each first telescope and the delay unit 120, so that the longitudinal positions of the real images of the N first light beams are the same, the longitudinal positions of the real images of the N first light beams are adjusted to be the same, and the longitudinal positions of the real images of the N first light beams are overlapped.
[0096] The second optical module 200 is used to modify the cross section of the second light beam B2 in the second plane into a flat top or an approximately flat top; the second optical module 200 includes a polarization changing unit 210 and a light beam superposition unit 220, as shown in Figure 14 .
[0097] The polarization changing unit 210 is used to split the second light beam B2 in the second plane into two second light beams with different polarization directions. As an example, the polarization changing unit 210 includes a λ / 2 wave plate, which can be made of quartz, YVO4 (yttrium vanadate), alpha-BBO (barium metaborate), etc.; the λ / 2 wave plate is placed in the light beam path, for example, arranged to cover half of the cross section of the second light beam B2 in the second plane, so that the second light beam B2 is split into two second light beams B21 and B22 with different polarization directions after passing through the λ / 2 wave plate, the polarization of the second light beam B21 passing through the λ / 2 wave plate is rotated by 90°, from vertical polarization to horizontal polarization, while the polarization of the second light beam B22 not passing through the λ / 2 wave plate remains unchanged, still vertical polarization, as shown in Figure 15 and Figure 16The polarization changing unit 210 is used to change the polarization state of the second light beam B2. As shown in the figure, the polarization changing unit 210 is implemented by a half-wave plate. Of course, in other examples, the polarization changing unit 210 can also be implemented by a quartz rotator, a TGG (terbium gallium garnet) Faraday rotator, a YIG (yttrium iron garnet) Faraday rotator, or a reflecting surface rotator; the propagation speeds of different polarized light beams are different, and after the light beams pass through the above-mentioned rotator, the phases of different polarizations will experience different delays, thereby changing the relative relationship and polarization state between different polarization components.
[0098] The beam superposition unit 220 is used to superpose two second light beams in space and based on the same direction. As an example, the beam superposition unit 220 includes a beam displacer; the beam displacer is a birefringent medium, and light beams of different polarizations are refracted differently when entering and leaving the medium, by using a beam displacer with parallel entrance and exit faces, so that two second light beams of different polarizations are based on the same direction after passing through the beam displacer, in addition, the length of the beam displacer along the propagation direction is designed to realize the superposition of two second light beams in space; wherein the birefringent medium includes YVO4 (yttrium vanadate), alpha-BBO (barium borate), quartz, LiNbO3 (lithium tantalate). Since the polarization directions of the two second light beams are perpendicular, the intensity distribution of the light beam emitted after passing through the beam displacer is equal to the sum of the intensity distributions of the two second light beams, therefore, the interference and the related intensity modulation are eliminated.
[0099] In actual application, the second optical module 200 can be arranged on the light exit side of the first optical module 100, or arranged on the light entrance side of the first optical module 100, and the intermediate imaging module 300 is arranged between the first optical module 100 and the second optical module 200; when the second optical module 200 is arranged on the light exit side of the first optical module 100, the intermediate imaging module 300, the polarization changing unit 210 and the beam superposition unit 220 are sequentially arranged on the light exit side of the first optical module 100, as shown in the figure; when the second optical module 200 is arranged on the light entrance side of the first optical module 100, the polarization changing unit 210, the beam superposition unit 220 and the intermediate imaging module 300 are sequentially arranged on the light entrance side of the first optical module 100. Figure 17
[0100] In addition, when the intermediate imaging module 300 is arranged on the light exit side of the first optical module 100, the intermediate imaging module 300 is used to perform secondary imaging on the imaging light beam of the first optical module 100 to obtain the second light beam B2, at this time, the first light beam B1 is the input light beam of the beam shaping device 10; when the intermediate imaging module 300 is arranged on the light exit side of the second optical module 200, the intermediate imaging module 300 is used to image the superposed light beam of the second optical module 200 to obtain the first light beam B1, at this time, the second light beam B2 is the input light beam of the optical module 10.
[0101] As an example, the intermediate imaging module 300 includes a fifth lens (not shown in the figure) and a sixth lens (not shown in the figure), and the fifth lens and the sixth lens form a third telescope; the imaging of the imaging light beam of the first optical module 100 or the superposition light beam of the second optical module 200 through the third telescope corresponds to obtain the second light beam B2 or the first light beam B1. Specifically, in the above example, the third telescope includes a cylindrical telescope or a spherical telescope.
[0102] As shown in Figure 17 As an example, the intermediate imaging module 300 includes a fifth lens (not shown in the figure) and a sixth lens (not shown in the figure), and the fifth lens and the sixth lens form a third telescope; the imaging of the imaging light beam of the first optical module 100 or the superposition light beam of the second optical module 200 through the third telescope corresponds to obtain the second light beam B2 or the first light beam B1. Specifically, in the above example, the third telescope includes a cylindrical telescope or a spherical telescope.
[0103] Correspondingly, the embodiment also provides an optical system, which comprises the beam shaping device 10 and a beam generating device (not shown in the figure), the beam shaping device 10 is arranged on the light emitting side of the beam generating device, and the beam generating device is used for providing the beam shaping device 10 with a light beam (the light beam is the input light beam of the beam shaping device 10). As an optional solution, the beam generating device is an ultra-short pulse laser; of course, the beam generating device is also other types of lasers, which has no substantial influence on the embodiment.
[0104] In summary, the beam shaping device and the optical system of the embodiment can modify the cross section of the light beam in the first plane to be flat-topped, such as modifying the circular cross section of the light beam to be rectangular; and can modify the cross section of the light beam in the second plane to be flat-topped, such as modifying the Gaussian energy distribution of the light beam to be flat-topped energy distribution; thus, an optimal laser beam with a rectangular cross section and a flat-topped energy distribution can be obtained, which is suitable for film processing. Therefore, the embodiment effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.
[0105] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.
Claims
1. A beam shaping device, characterized in that, The beam shaping device includes: The first optical module includes a beam-splitting unit, a delay unit, and an imaging unit. The beam splitting unit is used to split the first beam into N first beams in the first plane and emit them in parallel, where N is a natural number greater than or equal to 2. The delay unit is disposed on the light-emitting side of the beam splitting unit and is used to make each of the first beam splits emit after different propagation lengths, wherein the minimum delay value between each of the emitted first beam splits is greater than or equal to the coherence length of the first beam. The imaging unit is disposed on the light-emitting side of the delay unit and is used to image each of the first beams emitted after different propagation lengths, wherein the difference in the longitudinal position of the real image of each first beam is less than 1 Rayleigh length, and the lateral positions of the real images of each first beam overlap.
2. The beam shaping device according to claim 1, characterized in that, The beam splitting unit includes N positive lenses arranged in a one-dimensional or two-dimensional array.
3. The beam shaping device according to claim 2, characterized in that, The number of positive lenses is two or four.
4. The beam shaping device according to claim 1, characterized in that, The delay unit includes a transmissive optical element, which includes N transmissive regions with different thicknesses and / or refractive indices. The N first beams have different propagation lengths after passing through the N transmissive regions.
5. The beam shaping device according to claim 1, characterized in that, The delay unit includes a reflective optical element, which includes N reflective regions arranged in a stepped manner. The N first beams change their exit direction and have different propagation lengths after passing through the N reflective regions. The exit direction of each first beam has an angle with the incident direction, which is greater than 0° and less than 180°.
6. The beam shaping device according to claim 5, characterized in that, The reflective optical element includes N plane mirrors or curved mirrors, wherein the N plane mirrors or curved mirrors are arranged in a stepped manner to form N reflection areas; and / or, the included angle is 90°.
7. The beam shaping device according to claim 1, characterized in that, The delay unit includes a reflective optical element, a polarizer, and a λ / 4 waveplate. The reflective optical element is disposed on the light-emitting side of the beam splitting unit. The polarizer and the λ / 4 waveplate are sequentially disposed between the beam splitting unit and the reflective optical element. The reflective optical element includes N reflection zones arranged in a stepped manner. The reflective optical element, the polarizer, and the λ / 4 waveplate cooperate to change the polarization direction and emission direction of the N first beam splitters and make them have different propagation lengths. The emission direction of each first beam splitter has an angle with the incident direction, which is greater than 0° and less than 180°.
8. The beam shaping apparatus according to claim 7, characterized in that, The reflective optical element includes N plane mirrors or curved mirrors, wherein the N plane mirrors or curved mirrors are arranged in a stepped manner to form N reflection areas; and / or, the included angle is 90°.
9. The beam shaping device according to claim 1, characterized in that, The imaging unit includes a first lens group and a common lens, which are sequentially arranged on the light-emitting side of the delay unit. The first lens group includes N first lenses, and the N first lenses and the common lens respectively form N first telescopes, so that the N first beams are imaged after passing through the N first telescopes. Alternatively, the common lens can be replaced by a second lens group, which includes N second lenses. In this case, the N first lenses correspond one-to-one with the N second lenses to form N first telescopes; wherein at least (N-1) of the N first telescopes are off-axis telescopes.
10. The beam shaping apparatus according to claim 9, characterized in that, The first optical module further includes a position adjustment unit disposed between the beam splitting unit and the delay unit, for adjusting the longitudinal position of the real image of each of the first beam splitters.
11. The beam shaping apparatus according to claim 10, characterized in that, The position adjustment unit includes a third lens group and a fourth lens group, which are sequentially disposed between the beam splitting unit and the delay unit. The third lens group includes N third lenses, and the fourth lens group includes N fourth lenses. The N third lenses and the N fourth lenses correspond one-to-one to form N second telescopes, wherein the magnification of each second telescope is not equal to 1. By adjusting the distance between each second telescope and the delay unit, the longitudinal position of the real image of each first beam splitting is adjusted to be the same, so that the longitudinal positions of the real images of each first beam splitting overlap.
12. The beam shaping apparatus according to claim 9, characterized in that, When the imaging unit includes the second lens group, the longitudinal positions of the real images of each of the first telescopes and the delay unit are adjusted to be the same, so that the longitudinal positions of the real images of each of the first beams overlap.
13. The beam shaping apparatus according to any one of claims 1 to 12, characterized in that, The beam shaping device further includes a second optical module and an intermediate imaging module. The second optical module includes a polarization changing unit and a beam superposition unit. The intermediate imaging module, the polarization changing unit, and the beam superposition unit are sequentially disposed on the light-emitting side of the first optical module, or the polarization changing unit, the beam superposition unit, and the intermediate imaging module are sequentially disposed on the light-incoming side of the first optical module. The polarization changing unit is used to split the second beam into two second beams with different polarization directions in the second plane, and the beam superposition unit is used to superimpose the two second beams in space and emit them based on the same direction. When the intermediate imaging module is disposed on the light-emitting side of the first optical module, the intermediate imaging module is used to perform secondary imaging on the imaging beam of the first optical module to obtain the second beam. When the intermediate imaging module is disposed on the light-emitting side of the second optical module, the intermediate imaging module is used to image the superimposed light beam of the second optical module to obtain the first light beam.
14. The beam shaping apparatus according to claim 13, characterized in that, The polarization changing unit includes a λ / 2 waveplate, and / or the beam superposition unit includes a beam shifter.
15. The beam shaping apparatus according to claim 13, characterized in that, The intermediate imaging module includes a fifth lens and a sixth lens, the fifth lens and the sixth lens corresponding to each other to form a third telescope.
16. The beam shaping apparatus according to claim 15, characterized in that, The third telescope includes a cylindrical telescope or a spherical telescope.
17. An optical system, characterized in that, The optical system includes a beam generating device and a beam shaping device as described in any one of claims 1 to 16, wherein the beam generating device is used to provide a beam to the beam shaping device.
18. The optical system according to claim 17, characterized in that, The beam generating device includes an ultrashort pulse laser.