Multilayer optical system and optical path control method thereof

Abstract

The invention relates to the technical field of multi-layer optical systems, in particular to a multi-layer optical system and an optical path control method thereof, and the multi-layer optical system specifically comprises a first external optical path module, a light beam hierarchical control module and a second external optical path module, the first external light path module is used for adjusting the polarization direction of the laser beam; the light beam layering control module is used for splitting and combining the laser beams; and the second external light path module is used for carrying out focusing and scanning control on the combined laser beams, and the problems that in the prior art, double-layer cutting cannot be carried out on a to-be-cut target object at the same time, so that the cutting time is long, and the cutting rate is uncontrollable are solved.

Description

Technical Field

[0001] The invention relates to the technical field of multi-layer optical systems, and relates to a multi-layer optical system and an optical path control method thereof. Background Art

[0002] All-femtosecond surgery is an advanced laser refractive surgery used to correct vision problems such as myopia, hyperopia and astigmatism. It mainly uses femtosecond laser to create a lens-shaped incision inside the cornea, and then removes the lens through a small incision, thereby changing the curvature of the cornea to achieve the purpose of correcting vision. In the existing laser cutting optical system, a laser beam on a single optical path is usually used to first create a lens-shaped incision in the upper layer of the cornea through a predetermined path, then create another lens-shaped incision in the lower layer of the cornea, and finally remove the lens through a small incision, thereby completing the cutting task step by step; but the step-by-step cutting process of the laser beam on a single optical path will prolong the cutting time and increase the patient's discomfort. At the same time, when performing cutting tasks with higher cutting thickness, the existing laser cutting optical system cannot achieve precise control and adjustment of the cutting surface pattern, which will increase the cutting rate of the target object to be cut and cause greater damage. Summary of the invention

[0003] The technical problem to be solved by the present invention is that in the prior art, double-layer cutting of the target object to be cut cannot be performed simultaneously, resulting in long cutting time and uncontrollable cutting rate. A multi-layer optical system and its optical path control method are proposed.

[0004] In order to achieve the above object, the present invention discloses a multilayer optical system, comprising: a first external optical path module, a beam layering control module, and a second external optical path module; The first external optical path module is used to adjust the polarization direction of the laser beam; The beam layering control module performs beam splitting and beam combining processing on the laser beam; The second external optical path module is used to focus and scan the combined laser beams.

[0005] Specifically, the first external optical path module includes: a beam expander, a main optical path shutter, a half-wave plate and a first 45° reflector arranged in sequence along the optical path; Wherein, the main optical path shutter is used to control the on-off of the optical path of the multi-layer optical system; Specifically, the strategy for adjusting the polarization direction of the laser beam specifically includes: the linearly polarized laser is injected into the multilayer optical system through a beam expander, and reaches the half-wave plate after passing through a main optical path optical gate; The polarization direction of the linearly polarized laser is changed by a half-wave plate to obtain a redirected polarized laser, wherein the angle between the polarization direction of the redirected polarized laser and the normal direction of the paper surface is 45°, the plane where the direction vector of the polarization direction of the redirected polarized laser is located is perpendicular to the laser propagation direction; and the components of the redirected polarized laser in the horizontal and vertical directions are equal.

[0006] Furthermore, the half-wave plate does not change the polarization state of the linearly polarized laser.

[0007] Specifically, the light beam layering control module includes: a first polarization beam splitter prism, a main light path control unit, a branch light path control unit, a second polarization beam splitter prism and a convex lens; Wherein, the main light path control unit comprises: a second 45° reflector, a first concave lens and a glass plate arranged in sequence along the light path; The branch light path control unit comprises: a branch light path shutter, a second concave lens and a third 45° reflecting mirror arranged in sequence along the light path; The glass plate is used to increase the optical path of the main light path; The branch light path shutter is used to control the on and off of the branch light path; Specifically, the polarized laser beam is divided into a first sub-polarized light and a second sub-polarized light having equal intensities and mutually perpendicular polarization directions after passing through a first polarization beam splitter prism; Wherein, the optical path where the first sub-polarized light is located is a main optical path, and the polarization direction of the first sub-polarized light on the main optical path is parallel to the paper surface; The first sub-polarized light propagates downward, passes through the second 45° reflector, the first concave lens and the glass plate in sequence, and then reaches the second polarization beam splitter prism; The optical path where the second sub-polarized light is located is a branch optical path, and the polarization direction of the second sub-polarized light on the branch optical path is perpendicular to the paper surface; The second sub-polarized light propagates forward, passes through the branch light path shutter, the second concave lens and the third 45° reflector in sequence, and then reaches the second polarization beam splitter prism.

[0008] Specifically, the second polarization beam splitter prism is used to combine a first sub-polarized light beam that arrives after the first sub-polarized light passes through the main light path and a second sub-polarized light beam that arrives after the second sub-polarized light passes through the branch light path to obtain a combined polarized light; The combined polarized light beam continues to propagate forward, passes through the convex lens, and is incident on the second external optical path module.

[0009] Specifically, the second external optical path module includes: a 2D scanning galvanometer and a field mirror arranged in sequence along the optical path; The incident light beam of the second external optical path module passes through the 2D scanning galvanometer and the field lens in sequence, and the incident light beam interacts with the target object to be cut through the field lens.

[0010] Specifically, the first concave lens, the second concave lens and the convex lens constitute a Galilean beam expansion optical module.

[0011] Furthermore, the Galilean beam expansion optical module can effectively expand the diameter of the incident beam and collimate the divergent beam to keep it at a small divergence angle. This beam expansion effect helps to evenly distribute the laser energy and reduce the divergence of the beam, thereby improving the quality and focusing ability of the beam and effectively reducing energy loss and thermal damage.

[0012] At the same time, in the Galileo beam expansion optical module, by moving the first concave lens and the second concave lens back and forth, optical path control and focus adjustment are achieved, ensuring that the first sub-polarized beam on the main light path and the second sub-polarized beam on the branch light path can simultaneously cut the upper and lower corneas.

[0013] In addition, the technical solution of a light path control method of a multi-layer optical system of the present invention includes the following specific steps: S1: Preset a corresponding cutting pattern according to the cutting task of the target object to be cut, and debug and initialize the multi-layer optical system; S2: Adjust the polarization direction of the laser beam to obtain a polarized laser with variable direction; S3: dividing the polarized laser beam into a first sub-polarized light and a second sub-polarized light, and executing an electric control strategy on the first concave lens and the second concave lens; S4: Start the 2D scanning galvanometer, and make the laser beam interact with the target object to be cut according to the cutting pattern, so as to complete the scanning and cutting of the target object to be cut.

[0014] Specifically, in S1, the cutting task includes single-layer cutting and double-layer cutting; and the cutting pattern is a sawtooth Fresnel ring.

[0015] Specifically, the Fresnel lens is a thin lens with a surface shape of Fresnel rings. Its surface is composed of multiple concentric Fresnel rings, and the curvature of each Fresnel ring is much smaller than that of a traditional flat lens. Under the same curvature parameters, the Fresnel lens itself is thinner, and its multiple concentric rings design enables the light beam to be efficiently focused. Preferably, the design of cutting the surface of the target object to be cut into jagged Fresnel rings reduces the required cutting thickness of the target object itself; in order to make the target object to be cut achieve the same curvature after cutting, setting the cutting pattern of the cutting surface to a jagged Fresnel ring can reduce the cutting amount compared to setting the cutting pattern of the cutting surface to a smooth horizontal plane.

[0016] Wherein, the double-layer cutting includes: a first sub-polarized light beam on the main light path and a second sub-polarized light beam on the branch light path simultaneously cut the target object to be cut.

[0017] When the cutting task is single-layer cutting, the branch light path shutter is controlled to close the branch light path, and the single-layer cutting task is completed through the first sub-polarized light beam on the main light path; When the cutting task is double-layer cutting, the branch light path shutter is controlled to open the branch light path, and at the same time, the optical path of the main light path is increased by controlling the thickness of the glass plate, so that the first sub-polarized light beam on the main light path reaches the upper layer of the target object to be cut later than the second sub-polarized light beam on the branch light path; Wherein, the double-layer cutting further comprises: the first sub-polarized light beam on the main light path cuts the upper layer of the target object to be cut, and the second sub-polarized light beam on the branch light path cuts the lower layer of the target object to be cut.

[0018] Specifically, the electric control strategy specifically includes: controlling the first concave lens and the second concave lens to move forward and backward on the main light path and the branch light path respectively, changing the laser divergence angle of the first sub-polarized light beam on the main light path and the second sub-polarized light beam on the branch light path; Wherein, the distance of the forward and backward movement does not exceed a preset movement range threshold; During the forward and backward movement, it is ensured that the laser focal points of the first sub-polarized light beam on the main light path and the second sub-polarized light beam on the branch light path move on the optical axis, and the optical axis coincides with the optical axis of the field lens.

[0019] Compared with the prior art, the technical effects of the present invention are as follows: The multilayer optical system of the present invention can realize double-layer cutting of the target object to be cut by properly arranging the Galilean beam expansion optical module. Specifically, the multilayer optical system of the present invention can cut the upper and lower layers of the target object at the same time, and ensure the synchronization and accuracy of the two-layer cutting by adjusting the optical path and focus position of the light beam.

[0020] The multi-layer optical system of the present invention, by using Fresnel rings as a technical solution for cutting patterns, can achieve a cutting effect comparable to that of a traditional flat lens while reducing the amount of cutting. Specifically, the multi-focal design of the Fresnel lens enables the laser energy to be evenly distributed in a smaller area, thereby reducing the energy concentration at a single focus, reducing the risk of thermal damage and over-cutting. Despite the reduction in cutting volume, the Fresnel-shaped cutting pattern can still provide high-quality cutting accuracy and a smooth cutting surface, which can greatly reduce the cutting rate of the target object to be cut and reduce damage to the target object to be cut. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 A schematic diagram of an optical path of a multi-layer optical system of the present invention; Figure 2 A schematic flow chart of a method for controlling an optical path of a multi-layer optical system according to the present invention; Figure 3 Schematic diagram of the optical path for completing the double-layer cutting task simultaneously through the multi-layer optical system in an embodiment of the present invention; Figure 4 A schematic diagram showing a comparison between a cutting effect curve obtained by completing a double-layer cutting task through a multi-layer optical system in an embodiment of the present invention and an existing cutting effect curve; Figure 5 A schematic structural diagram of the physical arrangement of optical elements of a multi-layer optical system of the present invention; Figure 6 This is an example diagram of the actual viewing angle of the convex lens in the embodiment of the present invention; Figure 7 This is a diagram showing the cutting effect after the double-layer corneal cutting task is completed by the multi-layer optical system in an embodiment of the present invention.

[0022] Figure numerals: 1. beam expander; 2. main light path light gate; 3. half-wave plate; 4. first 45° reflector; 5. first polarization beam splitter prism; 6. second 45° reflector; 7. first concave lens; 8. glass plate; 9. second polarization beam splitter prism; 10. branch light path light gate; 11. second concave lens; 12. third 45° reflector; 13. convex lens; 14. 2D scanning galvanometer; 15. field lens; 16. target object to be cut; 17. second sub-polarized beam on the branch light path; 18. first sub-polarized beam on the main light path; 19. upper target cutting point of the cornea; 20. lower target cutting point of the cornea; 21. existing cutting effect curve; 22. optimized first cutting effect sub-curve; 23. optimized second cutting effect sub-curve; 24. optimized third cutting effect sub-curve. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0026] Example 1

[0027] like Figure 1 As shown, a multilayer optical system according to an embodiment of the present invention comprises: a first external optical path module, a beam layering control module, and a second external optical path module; The first external optical path module is used to adjust the polarization direction of the laser beam; The first external optical path module comprises: a beam expander 1, a main optical path shutter 2, a half-wave plate 3 and a first 45° reflector 4 arranged in sequence along the optical path; Wherein, the main optical path shutter 2 is used to control the on-off of the optical path of the multi-layer optical system; For example, in this embodiment, those skilled in the art can realize the start time and stop time of corneal cutting in the all-femtosecond surgery by opening or closing the main light path shutter 2 according to actual technical needs.

[0028] The strategy for adjusting the polarization direction of the laser beam specifically includes: the linearly polarized laser is injected into the multilayer optical system through a beam expander 1, and reaches a half-wave plate 3 after passing through a main optical path optical gate 2; The polarization direction of the linearly polarized laser is changed by a half-wave plate 3 to obtain a redirected polarized laser, wherein the angle between the polarization direction of the redirected polarized laser and the normal direction of the paper surface is 45°, and the plane where the direction vector of the polarization direction of the redirected polarized laser is located is perpendicular to the laser propagation direction; the components of the redirected polarized laser in the horizontal and vertical directions are equal.

[0029] The half-wave plate 3 is a half-wave plate, and the half-wave plate 3 does not change the polarization state of the linearly polarized laser.

[0030] The beam layering control module performs beam splitting and beam combining processing on the laser beam; The light beam layering control module comprises: a first polarization beam splitter prism 5, a main light path control unit, a branch light path control unit, a second polarization beam splitter prism 9 and a convex lens 13; Wherein, the main light path control unit comprises: a second 45° reflector 6, a first concave lens 7 and a glass plate 8 arranged in sequence along the light path; The branch light path control unit comprises: a branch light path shutter 10, a second concave lens 11 and a third 45° reflecting mirror 12 arranged in sequence along the light path; The glass plate 8 is used to increase the optical path of the main light path; The branch light path shutter 10 is used to control the on and off of the branch light path; Illustratively, in this embodiment, the branch light path shutter 10 is used to cut off the branch light path laser, and those skilled in the art can perform single-layer cutting of the target object 16 to be cut according to actual technical needs.

[0031] The polarized laser beam is divided into a first sub-polarized light and a second sub-polarized light having equal intensities and mutually perpendicular polarization directions after passing through the first polarization beam splitting prism 5; Wherein, the optical path where the first sub-polarized light is located is a main optical path, and the polarization direction of the first sub-polarized light on the main optical path is parallel to the paper surface; The first sub-polarized light propagates downward, passes through the second 45° reflector 6, the first concave lens 7 and the glass plate 8 in sequence, and then reaches the second polarization beam splitter prism 9; The optical path where the second sub-polarized light is located is a branch optical path, and the polarization direction of the second sub-polarized light on the branch optical path is perpendicular to the paper surface; The second sub-polarized light propagates forward, passes through the branch light path shutter 10, the second concave lens 11 and the third 45° reflecting mirror 12 in sequence, and then reaches the second polarization beam splitting prism 9.

[0032] The second polarization beam splitter prism 9 is used to combine the first sub-polarized light beam that arrives after the first sub-polarized light passes through the main light path and the second sub-polarized light beam that arrives after the second sub-polarized light passes through the branch light path to obtain a combined polarized light; The combined polarized light beam continues to propagate forward, passes through the convex lens 13 and is incident on the second external optical path module.

[0033] The second external optical path module is used to focus and scan the combined laser beams.

[0034] The second external optical path module includes: a 2D scanning galvanometer 14 and a field lens 15 arranged in sequence along the optical path; The incident light beam of the second external optical path module passes through the 2D scanning galvanometer 14 and the field lens 15 in sequence, and the incident light beam interacts with the target object 16 to be cut through the field lens 15 .

[0035] The first concave lens 7, the second concave lens 11 and the convex lens 13 form a Galilean beam expansion optical module.

[0036] Example 2 Exemplarily, in this embodiment, in the refractive correction surgery, the target object 16 to be cut is the cornea.

[0037] like Figure 2 As shown, a light path control method of a multi-layer optical system according to an embodiment of the present invention comprises the following steps: S1: Presetting a corresponding cutting pattern according to the corneal cutting task, and debugging and initializing the multi-layer optical system; The cutting task needs to be set by technicians in this field according to the patient's own eye data and refractive data; In S1, the cutting task includes single-layer cutting and double-layer cutting; the cutting task also includes: the corneal cutting amount set by the technicians in this field according to the patient's own eye data and refractive data.

[0038] Exemplarily, in this embodiment, the cutting task is double-layer cutting.

[0039] In this embodiment, the cutting patterns of the upper layer and the lower layer of the cornea are both jagged Fresnel rings.

[0040] Among them, the double-layer cutting also includes: the first sub-polarized beam on the main light path and the second sub-polarized beam on the branch light path simultaneously cut the target object 16 to be cut, the first sub-polarized beam on the main light path is used to cut the upper target cutting area of ​​the cornea, and the second sub-polarized beam on the branch light path is used to cut the lower target cutting area of ​​the cornea.

[0041] When the cutting task is single-layer cutting, the branch light path shutter 10 is controlled to close the branch light path, and the single-layer cutting task is completed through the first sub-polarized light beam on the main light path; When the cutting task is double-layer cutting, the branch light path shutter 10 is controlled to open the branch light path, and at the same time, the optical path of the main light path is increased by controlling the thickness of the glass plate 8, so that the first sub-polarized light beam on the main light path arrives at the upper target cutting position of the cornea later than the second sub-polarized light beam on the branch light path; For example, in this embodiment, which is a double-layer cutting task, the branch light path shutter 10 needs to be controlled to open the branch light path, and at the same time, the optical path of the main light path is increased by controlling the thickness of the glass plate 8 .

[0042] S2: Adjust the polarization direction of the laser beam to obtain a polarized laser with variable direction; S3: dividing the polarized laser beam into a first sub-polarized light and a second sub-polarized light, and at the same time performing an electric control strategy on the first concave lens 7 and the second concave lens 11 through piezoelectric ceramics, wherein the control accuracy of the piezoelectric ceramics is 1 micron; For example, Figure 2As shown by the double-headed arrows at the first concave lens 7 and the second concave lens 11 in the embodiment, the double-headed arrows indicate the dynamic movement process of the concave mirror. In this embodiment, the electric control strategy specifically includes: controlling the first concave lens 7 and the second concave lens 11 to move forward and backward on the main light path and the branch light path respectively through piezoelectric ceramics, changing the laser divergence angles of the first sub-polarized light beam on the main light path and the second sub-polarized light beam on the branch light path, and obtaining two laser beams with different laser divergence angles; Wherein, the distance of the forward and backward movement does not exceed a preset movement range threshold; In this embodiment, the moving range threshold is set by those skilled in the art according to specific requirements.

[0043] During the forward and backward movement, it is ensured that the laser focal points of the first sub-polarized light beam on the main light path and the second sub-polarized light beam on the branch light path move on the optical axis, and the optical axis coincides with the optical axis of the field lens 15 .

[0044] Example 3 For example, Figure 3 As shown, two laser beams with different laser divergence angles are used to simultaneously complete scanning and cutting of the upper cornea and the lower cornea.

[0045] A light path control method for a multi-layer optical system, further comprising: S4: starting the 2D scanning galvanometer 14, and making the laser beam and the cornea interact with each other according to the cutting pattern, and completing the scanning and cutting of the upper cornea and the lower cornea at the same time by using two laser beams with different laser divergence angles; like Figure 3 As shown, S4 also includes: cutting the lower target cutting position 20 of the cornea through the second sub-polarized light beam 17 on the branch light path; and cutting the upper target cutting position 19 of the cornea through the first sub-polarized light beam 18 on the main light path.

[0046] Example 4 For example, Figure 4 As shown, in the all-femtosecond surgery with a corneal refractive power of 10D, a double-layer cutting task is completed through a multi-layer optical system to obtain a cutting effect curve and compare it with the existing cutting effect curve; Exemplarily, the cutting effect curve for completing the double-layer cutting task by the multi-layer optical system includes: an optimized first cutting effect sub-curve 22, an optimized second cutting effect sub-curve 23, and an optimized third cutting effect sub-curve 24; in this embodiment, the division of the cutting effect sub-curve is only one implementation method, and there may be other division methods in actual implementation, wherein the total number of the cutting effect sub-curves is three or four segments; In this embodiment, the optimized first cutting effect sub-curve 22 has a curvature of 5D and a diameter of 4.5 mm; the optimized second cutting effect sub-curve 23 has a curvature of 3D and a diameter of 6 mm; the optimized third cutting effect sub-curve 24 has a curvature of 2D and a diameter of 7.5 mm; Compared with the existing cutting effect curve 21 formed by cutting the cornea by the cutting means in the existing all-femtosecond surgery, the cutting effect curve of the double-layer cutting task completed by the multi-layer optical system presents a stepped sawtooth Fresnel ring of 5:3:2; According to the above embodiments, compared with the prior art, the technical effects of the present invention also include: Compared with the existing cutting effect curve formed after the cornea is cut by the cutting means in the existing all-femtosecond surgery, the cutting effect curve formed after the double-layer cutting task is completed by the multi-layer optical system of the present invention can save the cut corneal tissue and reduce the damage to the patient's cornea; The present invention completes the double-layer cutting task through the multi-layer optical system, which can expand the applicable diopter of the existing all-femtosecond surgery from 0-8D to about 0-12D.

[0047] Example 5 For example, Figure 5 As shown, in this embodiment, a schematic diagram of the structure of the physical placement of optical elements of a multi-layer optical system is provided. When completing the double-layer cutting task, Figure 6 As shown, in this embodiment, an example diagram of the actual viewing angle at the convex lens 13 is provided; Figure 6 It includes: an image formed by combining two infrared laser beams with different divergence angles, among which the middle area with high brightness is the sum of the two beams of light, and the edge area with weak brightness is the image of the infrared laser with a large emission angle.

[0048] Example 6 For example, Figure 7 As shown, in this embodiment, a cutting effect display diagram is provided after the double-layer cutting task of the cornea is completed by a multi-layer optical system.

[0049] According to the above embodiments, compared with the prior art, the technical effects of the present invention also include: The multi-layer optical system described in the present invention enables all-femtosecond surgery to achieve personalized corneal cutting like half-femtosecond surgery, thereby increasing the design space for technicians in this field in the personalized design of cutting curves and also expanding the range of applicable patients.

[0050] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.

[0051] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only one, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0052] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0053] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0055] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

[0056] In summary, compared with the prior art, the technical effects of the present invention include: 1. The multilayer optical system of the present invention can realize double-layer cutting of the target object to be cut by properly arranging the Galilean beam expansion optical module. Specifically, the multilayer optical system of the present invention can cut the upper and lower layers of the target object at the same time, and ensure the synchronization and accuracy of the two-layer cutting by adjusting the optical path and focus position of the light beam.

[0057] 2. The multi-layer optical system of the present invention, by using Fresnel lens as a technical solution for cutting pattern, can achieve a cutting effect equivalent to that of a traditional flat lens while reducing the amount of cutting. Specifically, the multi-focal design of the Fresnel lens enables the laser energy to be evenly distributed in a smaller area, thereby reducing the energy concentration at a single focus, reducing the risk of thermal damage and over-cutting. Despite the reduction in cutting volume, the Fresnel-shaped cutting pattern can still provide high-quality cutting accuracy and a smooth cutting surface, which can greatly reduce the cutting rate of the target object to be cut and reduce damage to the target object to be cut.

[0058] 3. The cutting effect curve formed after the multi-layer optical system completes the double-layer cutting task can save corneal tissue and reduce damage to the patient's cornea, compared with the existing cutting effect curve formed after the cornea is cut by the cutting means in the existing all-femtosecond surgery.

[0059] 4. The present invention completes the double-layer cutting task through the multi-layer optical system, which can expand the applicable refractive power of the existing all-femtosecond surgery from 0~8D to about 0~12D.

[0060] 5. The multi-layer optical system described in the present invention enables all-femtosecond surgery to achieve personalized corneal cutting like half-femtosecond surgery, which increases the design space for technicians in this field in the personalized design of cutting curves and also expands the range of applicable patients.

Claims

1. A multi-layer optical system, characterized in that: The multilayer optical system comprises: a first external optical path module, a beam layering control module, and a second external optical path module; The first external optical path module is used to adjust the polarization direction of the laser beam; The beam layering control module performs beam splitting and beam combining processing on the laser beam; The second external optical path module is used to focus and scan the combined laser beams.

2. A multilayer optical system according to claim 1, characterized in that: The first external optical path module comprises: a beam expander (1), a main optical path shutter (2), a half-wave plate (3) and a first 45° reflector (4) arranged in sequence along the optical path; The main optical path shutter (2) is used to control the on and off of the optical path of the multi-layer optical system.

3. A multilayer optical system according to claim 2, characterized in that: The strategy for adjusting the polarization direction of the laser beam specifically includes: the linearly polarized laser is injected into the multilayer optical system through a beam expander (1), passes through a main optical path optical gate (2), and reaches a half-wave plate (3); The polarization direction of the linearly polarized laser is changed by a half-wave plate (3) to obtain a redirected polarized laser, wherein the angle between the polarization direction of the redirected polarized laser and the normal direction of the paper surface is 45°, the plane where the direction vector of the polarization direction of the redirected polarized laser lies is perpendicular to the laser propagation direction; and the components of the redirected polarized laser in the horizontal and vertical directions are equal.

4. A multilayer optical system according to claim 3, characterized in that: The light beam layering control module comprises: a first polarization beam splitting prism (5), a main light path control unit, a branch light path control unit, a second polarization beam splitting prism (9) and a convex lens (13); The main light path control unit comprises: a second 45° reflector (6), a first concave lens (7) and a glass plate (8) arranged in sequence along the light path; The branch light path control unit comprises: a branch light path shutter (10), a second concave lens (11) and a third 45° reflecting mirror (12) arranged in sequence along the light path; The glass plate (8) is used to increase the optical path of the main light path; The branch light path optical shutter (10) is used to control the on and off of the branch light path.

5. A multilayer optical system according to claim 4, characterized in that: The direction-changing polarized laser light is divided into a first sub-polarized light and a second sub-polarized light having equal intensities and mutually perpendicular polarization directions after passing through a first polarization beam splitting prism (5); Wherein, the optical path where the first sub-polarized light is located is a main optical path, and the polarization direction of the first sub-polarized light on the main optical path is parallel to the paper surface; The first sub-polarized light propagates downwards, passes through the second 45° reflector (6), the first concave lens (7) and the glass plate (8) in sequence, and then reaches the second polarization beam splitting prism (9); The optical path where the second sub-polarized light is located is a branch optical path, and the polarization direction of the second sub-polarized light on the branch optical path is perpendicular to the paper surface; The second sub-polarized light propagates forward, passes through the branch light path shutter (10), the second concave lens (11) and the third 45° reflector (12) in sequence, and then reaches the second polarization beam splitting prism (9).

6. A multilayer optical system according to claim 5, characterized in that: The second polarization beam splitter (9) is used to combine a first sub-polarized light beam arriving after the first sub-polarized light passes through the main light path and a second sub-polarized light beam arriving after the second sub-polarized light passes through the branch light path to obtain a combined polarized light; The combined polarized light beam continues to propagate forward, passes through the convex lens (13), and is incident on the second external optical path module.

7. A multilayer optical system according to claim 6, characterized in that: The second external optical path module comprises: a 2D scanning galvanometer (14) and a field lens (15) arranged in sequence along the optical path; The incident light beam of the second external light path module passes through the 2D scanning galvanometer (14) and the field lens (15) in sequence, and the incident light beam interacts with the target object (16) to be cut through the field lens (15).

8. A multilayer optical system according to claim 7, characterized in that: The first concave lens (7), the second concave lens (11) and the convex lens (13) form a Galilean beam expansion optical module.

9. A light path control method for a multi-layer optical system, applied to a multi-layer optical system as claimed in any one of claims 1 to 8, characterized in that: The method comprises the following specific steps: S1: Presetting a corresponding cutting pattern according to a cutting task of a target object (16) to be cut, and debugging and initializing a multi-layer optical system; S2: Adjust the polarization direction of the laser beam to obtain a polarized laser with variable direction; S3: dividing the polarized laser beam into a first sub-polarized light and a second sub-polarized light, and simultaneously executing an electric control strategy on the first concave lens (7) and the second concave lens (11); S4: starting the 2D scanning galvanometer (14) to make the laser beam and the target object (16) to be cut interact with each other according to the cutting pattern, thereby completing the scanning and cutting of the target object (16) to be cut.

10. The optical path control method of a multi-layer optical system according to claim 9, characterized in that: In S1, the cutting task includes single-layer cutting and double-layer cutting; the cutting pattern is a sawtooth Fresnel ring; Wherein, the double-layer cutting comprises: a first sub-polarized light beam on a main light path and a second sub-polarized light beam on a branch light path simultaneously cut the target object (16) to be cut.

11. The optical path control method of a multi-layer optical system according to claim 9, characterized in that: The electric control strategy specifically includes: controlling the first concave lens (7) and the second concave lens (11) to move forward and backward on the main light path and the branch light path respectively, so as to change the laser divergence angles of the first sub-polarized light beam on the main light path and the second sub-polarized light beam on the branch light path; Wherein, the distance of the forward and backward movement does not exceed a preset movement range threshold; During the forward and backward movement, it is ensured that the laser focal points of the first sub-polarized light beam on the main light path and the second sub-polarized light beam on the branch light path move on the optical axis, and the optical axis coincides with the optical axis of the field lens (15).

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