A method for quickly adjusting astigmatism and laser beam expander thereof

Abstract

A method for quickly adjusting astigmatism and a laser beam expander thereof, the method for quickly adjusting astigmatism comprising the following steps: S01, based on a Gaussian optical transmission matrix, establishing a functional relationship between a prism incident angle and an astigmatism compensation value when a light beam passes through, and determining the prism incident angle based on the astigmatism value to be compensated; S02, setting the initial positions of a prism, a first reflector, and a second reflector, and ensuring that the input and output of the light beam are coaxial after the light beam passes through the prism, the first reflector, and the second reflector in sequence, the present invention makes the input and output of the light beam coaxial during the astigmatism adjustment process through the cooperation of the prism, the first reflector, and the second reflector. That is, the initial positions of the prism, the first reflector, and the second reflector are set, and then the deflection angles of the three are synchronously adjusted on the basis of the initial positions to compensate for astigmatism, so as to ensure that the input and output of the adjusted light beam are coaxial.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to a method for quickly adjusting astigmatism and a laser beam expander thereof. Background Art

[0002] With the development of laser technology, laser processing has begun to penetrate into many process steps in traditional manufacturing technology. Laser processing (including drilling, marking, cutting, welding and surface treatment, etc.) has greatly promoted the development of advanced manufacturing technology. The beam quality of the laser mainly includes M2 factor, divergence angle, spot size, roundness, astigmatism and energy distribution. Among them, M2 factor, ellipticity, astigmatism and energy distribution are mainly determined by the laser resonant cavity, while divergence angle and spot size can be adjusted by an external beam expander. Under normal circumstances, when the designed laser has sufficient mode selection ability, the M2 factor of the laser can achieve a fundamental mode output close to 1.0, and the ellipticity can also be close to 100%. However, due to the complexity of laser design, it is usually designed as a folded laser. The tilted reflector inevitably introduces astigmatism. Although part of the astigmatism can be compensated by symmetrical folding, most resonant cavities are not symmetrical structures, so astigmatism is inevitable.

[0003] In order to compensate for astigmatism, compensation is usually done as much as possible during the laser design stage. A representative example is the patent document with publication number CN112025088A, which discloses a laser beam astigmatism compensation method and a laser processing system. The method adds an astigmatism compensation device to the external light path of the laser processing system, observes and records the spot shape and ellipticity of the focused light spot at the focal position and the defocused position through a beam quality analyzer, adjusts the rotation angle of the optical element in the astigmatism compensation device, makes the astigmatism generated by the astigmatism compensation device equal in magnitude and opposite in direction to the astigmatism of the original laser processing system, and reversely compensates for the astigmatism of the entire laser processing system, thereby reducing the astigmatism of the laser beam that finally reaches the processing table, making the focused and defocused light spots both a circular spot, and improving the consistency of the line width and depth in any direction when performing laser processing in a defocused state. Eliminating the astigmatism problem of the laser beam can significantly improve the laser processing quality.

[0004] Although the technical solution disclosed in the above patent document can solve the astigmatism problem of the laser beam to a certain extent, there are still limitations in the specific operation, because the technical solution disclosed in the above patent document records two compensation methods by tilting the prism. Although choosing a suitable angle can compensate for a certain astigmatism value, the tilted prism will cause the light path to be deflected. During use, it is often necessary to correct the light path again (when it is necessary to compensate for astigmatism, the compensation is often made by tilting the prism. At this time, although the astigmatism is successfully compensated, the light path is offset again, that is, there is no way to achieve the operations of astigmatism compensation and light path correction at the same time).

[0005] Therefore, how to solve the above-mentioned deficiencies in the prior art has become a subject to be studied and solved by the present invention. Summary of the invention

[0006] The present invention provides a method for quickly adjusting astigmatism and a laser beam expander thereof, aiming to solve the technical problems raised in the above background technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for quickly adjusting astigmatism, comprising the following steps:

[0008] S01. Based on the Gaussian optical transmission matrix, a functional relationship between the prism incident angle and the astigmatism compensation value when the light beam passes through is established, and based on the astigmatism value to be compensated, the prism incident angle is determined;

[0009] S02, setting the initial positions of the prism, the first reflector, and the second reflector, and ensuring that the input and output of the light beam are coaxial after the light beam passes through the prism, the first reflector, and the second reflector in sequence;

[0010] The prism, the first reflector and the second reflector are all arranged to rotate about their respective rotation axes, and the rotation axis of the prism is A, the rotation axis of the first reflector is B, and the rotation axis of the second reflector is C;

[0011] The rotation axis A, the rotation axis B and the rotation axis C are arranged in parallel;

[0012] S03, synchronously adjusting the deflection angles of the prism, the first reflector, and the second reflector to compensate for astigmatism, while ensuring that the input and output of the light beam after the angle adjustment are coaxial.

[0013] Furthermore, the specific steps of establishing the functional relationship between the prism incident angle and the astigmatism compensation value in step S01 are:

[0014] S101, obtaining a prism processed into a wedge shape, and guiding a light beam to pass through the wedge-shaped prism;

[0015] S102, obtaining a meridional plane transmission matrix and a sagittal plane transmission matrix in the light transmission matrix of the wedge-shaped prism, wherein the meridional plane transmission matrix is:

[0016] TT= ; The sagittal plane transfer matrix is:

[0017] TS= ;

[0018] S103, according to the Gaussian optical transmission matrix, obtain the transmission matrix of the wedge prism to the Gaussian laser:

[0019] The meridional plane transfer matrix is:

[0020] MT= ;

[0021] The sagittal plane transfer matrix is:

[0022] MS= ; S104, obtaining the functional relationship between the prism incident angle and the astigmatism compensation value: astigmatism DS=S2t-S2s;

[0023] Wherein, θ is the incident angle, θ' is the exit angle, β is the wedge angle of the wedge prism, d is the optical path in the prism, and L is the distance from the incident point to the vertex of the wedge prism; sinθ=nsinα, sinθ'=nsinα', β=α+α', d=Lsinα+Lcosαtanα';

[0024] S1 is the distance from the incident beam waist to the incident surface of the wedge prism, S2t is the distance from the meridian beam waist to the incident surface of the prism after transmission through the prism, and S2s is the distance from the sagittal beam waist to the incident surface of the prism after transmission through the prism.

[0025] Furthermore, the specific operation of setting the prism, the first reflector and the second reflector in S02 is:

[0026] Firstly, the prism, the first reflector and the second reflector are fixed on the base by using an interface that uses spur teeth and gear linkage, and the functional relationship between the incident angle and the moving distance of the spur teeth is obtained according to the functional relationship between the incident angle of the prism and the astigmatism compensation value, where the moving distance = θ × R;

[0027] Secondly, based on the functional relationship between the incident angle and the moving distance of the spur gear, the scale and the rotating guide groove are designed on the base;

[0028] Secondly, the incident angle θ of the prism is set to 0, the deflection angle of the light beam after passing through is θ', the first reflector is placed parallel to the light path, and the initial angle of the second reflector to the light path is the inherent deflection angle θ' / 2;

[0029] Finally, based on the preset angle, the horizontal position of the first reflector and the initial position of the second reflector are designed.

[0030] Furthermore, after the light beam passes through the prism, the outgoing light beam is offset toward the opposite side of the acute angle of the prism compared with the incident light beam, and the deflection angle is θ+θ'-β.

[0031] Furthermore, the first reflector and the second reflector adjust their angles synchronously, and the angles are adjusted in opposite directions.

[0032] Further, when the wedge-shaped prism is deflected, the incident angle of the light beam on the first reflector changes from θ1 to θ1'', and the deflection angle of the first reflector is (θ1-θ1'') / 2;

[0033] The deflection angle of the second reflector is (θ1-θ1'') / 2+7.5π / 180-(7.5π / 180) / 20.

[0034] The present invention also provides a laser beam expander with a method for quickly adjusting astigmatism, the laser beam expander comprising an adjusting mirror portion and lens portions arranged at both ends of the adjusting mirror portion, the adjusting mirror portion comprising: an inner sleeve, a prism, a first reflecting mirror, a second reflecting mirror and an adjusting sleeve;

[0035] The inner sleeve is a base;

[0036] A cavity for guiding light to pass through is formed inside the inner sleeve, and a plurality of limiting parts are arranged on the inner side wall of the inner sleeve;

[0037] The prism, the first reflector and the second reflector are rotatably arranged on the inner wall of the cavity in sequence through a transmission mechanism along the irradiation direction of the light beam. The transmission mechanisms on the three are arranged in one-to-one correspondence with three of the plurality of limiting parts, and the rotation axes of the transmission mechanisms of the three are arranged in parallel.

[0038] The adjusting sleeve is sleeved on the outer side wall of the inner sleeve, and the adjusting sleeve can guide the prism, the first reflector and the second reflector to adjust their angles synchronously in the cavity by driving the transmission mechanism;

[0039] When the angles of the prism, the first reflector and the second reflector are not adjusted, the light beam passes through the prism, the first reflector and the second reflector in sequence, and the input and output of the light beam are coaxial after passing through;

[0040] When the prism, the first reflector and the second reflector complete the angle adjustment, the input and output of the light beam are still coaxial.

[0041] Furthermore, a rotation guide groove is provided on the surface of the adjusting sleeve;

[0042] The transmission mechanism comprises a spur gear block and an adjustment bracket rotatably connected in the cavity, the adjustment bracket can be positioned and connected to the prism, the first reflector or the second reflector, a deflection gear block is arranged on the adjustment bracket, and a rotating column rotatably connected to the inner side wall of the inner sleeve is arranged on the side wall of the adjustment bracket;

[0043] The spur gear block is slidably connected in the limiting portion and meshed with the deflection gear block. A boss is installed on the surface of the spur gear block. The boss is located in the rotation guide groove and is slidably arranged relative to the adjustment sleeve. When the adjustment sleeve rotates around the axis of the inner sleeve, the boss moves in the rotation guide groove to pull the spur gear block to slide along the limiting portion.

[0044] Furthermore, the adjusting sleeve is fixedly sleeved with an outer sleeve;

[0045] The side wall of the inner sleeve is provided with a limiting slide groove, and a plurality of steel balls are provided in the limiting slide groove. A plurality of top screws 2 are fixedly installed on the outer sleeve, and each top screw 2 is respectively provided corresponding to each steel ball, and an elastic member is fixedly connected between each top screw 2 and each steel ball.

[0046] Furthermore, the surface of the inner sleeve is provided with scales;

[0047] The stroke of the boss in the rotating guide groove is divided into two parts according to the scale, one of which is used to display the deflection angle of the prism, the first reflector or the second reflector, and the other is used to limit the rotation of the adjustment sleeve.

[0048] The terms “first”, “second”, etc. used in this document do not specifically refer to an order or sequence, nor are they used to limit the present case. They are only used to distinguish components or operations described with the same technical terms.

[0049] As used herein, “connected” or “positioned” may refer to two or more components or devices being in direct physical contact with each other, or being in indirect physical contact with each other, or may refer to two or more components or devices operating or moving with each other.

[0050] The terms “include,” “including,” “have,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0051] The terms used in this document generally have the ordinary meaning of each term used in this field, in the context of the case and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the present invention.

[0052] The terms "front", "back", "up", "down", "left", "right", etc. used in this article are all directional terms. In this case, they are only used to illustrate the positional relationship between the various structures, and are not used to limit the protection plan of this case and the specific direction during actual implementation.

[0053] The working principle and advantages of the present invention are as follows:

[0054] The present invention can ensure that the input and output of a light beam are coaxial during the process of adjusting astigmatism by cooperating with a prism, a first reflector and a second reflector. Specifically, the prism incident angle is controlled by adjusting the rotation angle of the prism so that the astigmatism value to be compensated is confirmed, and the initial positions of the prism, the first reflector and the second reflector are set at the same time. Then, the deflection angles of the prism, the first reflector and the second reflector are synchronously adjusted based on the initial positions to compensate for the astigmatism and ensure that the input and output of the light beam after the angle adjustment are coaxial. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of the outer sleeve in the present invention;

[0056] Figure 2 It is a schematic diagram of the scale in the present invention;

[0057] Figure 3 It is a schematic diagram of the longitudinal cross-section structure of the laser beam expander in the present invention;

[0058] Figure 4 It is a schematic diagram of the rotary guide groove in the present invention;

[0059] Figure 5 Schematic diagram of the restriction part in the present invention;

[0060] Figure 6 It is a schematic diagram of the deflection gear block in the present invention;

[0061] Figure 7 is a schematic diagram of light passing through a prism in the present invention;

[0062] Figure 8 Schematic diagram of the relationship between the incident angle and the astigmatism value when the wedge angle of the wedge prism in the present invention is equal to 5;

[0063] Fig. 9 Schematic diagram of the relationship between the incident angle and the astigmatism value when the wedge angle of the wedge prism in the present invention is equal to 10;

[0064] Fig.10 Schematic diagram of the relationship between the incident angle and the astigmatism value when the wedge angle of the wedge prism is equal to 15 in the present invention;

[0065] Fig.11Schematic diagram of the relationship between the incident angle and the exit angle when the wedge angle of the wedge prism in the present invention is equal to 5;

[0066] Fig.12 Schematic diagram of the relationship between the incident angle and the exit angle when the wedge angle of the wedge prism in the present invention is equal to 10;

[0067] Fig.13 Schematic diagram of the relationship between the incident angle and the exit angle when the wedge angle of the wedge prism in the present invention is equal to 15;

[0068] Fig.14 A principle diagram of an optical path provided for the method for quickly adjusting astigmatism in the present invention;

[0069] Fig.15 A detailed schematic diagram of the light path reflection performed by the first reflector in the present invention;

[0070] Fig.16 is a schematic diagram of the relationship between the incident angle of the first reflector and the deflection angle of the first reflector when the wedge angle of the wedge-shaped prism in the present invention is equal to 10;

[0071] Fig.17 is a schematic diagram of the relationship between the incident angle of the second reflector and the deflection angle of the second reflector when the wedge angle of the wedge prism in the present invention is equal to 10;

[0072] Fig.18 It is a schematic diagram of the formula for deriving that the outgoing light beam is offset toward the opposite side of the acute angle of the prism compared with the incident light beam after the light beam passes through the prism in the present invention.

[0073] In the above drawings: 1. inner sleeve; 2. limiting part; 3. prism; 4. first reflector; 5. second reflector; 6. spur gear block; 7. adjusting sleeve; 8. rotating guide groove; 9. adjusting bracket; 10. deflection gear block; 11. boss; 12. outer sleeve; 13. limiting slide groove; 14. steel ball; 15. top screw 2; 16. elastic member; 17. scale; 18. rotating column. DETAILED DESCRIPTION

[0074] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0075] Embodiment: The present invention will be clearly described below with diagrams and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0076] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0077] See also Figure 7-Figure 18 As shown, a method for quickly adjusting astigmatism includes the following steps:

[0078] S01, based on the Gaussian optical transmission matrix, establish a functional relationship between the incident angle of the prism 3 when the light beam passes through and the astigmatism compensation value, and determine the incident angle of the prism 3 based on the astigmatism value to be compensated;

[0079] S02, setting the initial positions of the prism 3, the first reflector 4 and the second reflector 5, and ensuring that the input and output of the light beam are coaxial after the light beam passes through the prism 3, the first reflector 4 and the second reflector 5 in sequence;

[0080] The prism 3, the first reflector 4 and the second reflector 5 are all arranged to rotate about their respective rotation axes, and the rotation axis of the prism 3 is A, the rotation axis of the first reflector 4 is B, and the rotation axis of the second reflector 5 is C;

[0081] The rotation axis A, the rotation axis B and the rotation axis C are arranged in parallel;

[0082] S03, synchronously adjusting the deflection angles of the prism 3, the first reflector 4 and the second reflector 5 to compensate for astigmatism, while ensuring that the input and output of the light beam after the angle adjustment are coaxial.

[0083] The present invention can ensure that the input and output of the light beam are coaxial during the process of adjusting the astigmatism through the cooperation of the prism 3, the first reflector 4 and the second reflector 5. Specifically, the prism incident angle is controlled by adjusting the rotation angle of the prism 3 so that the astigmatism value to be compensated is confirmed, and the initial positions of the prism, the first reflector and the second reflector 5 are set at the same time. Then, the deflection angles of the prism 3, the first reflector 4 and the second reflector 5 are synchronously adjusted on the basis of the initial positions to compensate for the astigmatism and ensure that the input and output of the light beam after the angle adjustment are coaxial.

[0084] For details, please refer to Figure 7 , which shows a schematic diagram of light passing through prism 3.

[0085] In some specific implementations, the specific steps of establishing the functional relationship between the incident angle of the prism 3 and the astigmatism compensation value in step S01 are:

[0086] S101, obtaining a prism 3 processed into a wedge shape, and guiding a light beam to pass through the wedge-shaped prism;

[0087] S102, obtaining a meridional plane transmission matrix and a sagittal plane transmission matrix in the light transmission matrix of the wedge-shaped prism, wherein the meridional plane transmission matrix is:

[0088] TT= ;

[0089] The sagittal plane transfer matrix is:

[0090] TS= ; S103, according to the Gaussian optical transmission matrix, obtain the transmission matrix of the wedge prism to the Gaussian laser:

[0091] The meridional plane transfer matrix is:

[0092] MT= ;

[0093] The sagittal plane transfer matrix is:

[0094] MS= ; S104, obtaining the functional relationship between the incident angle of prism 3 and the astigmatism compensation value: astigmatism DS=S2t-S2s;

[0095] Wherein, θ is the incident angle, θ' is the exit angle, β is the wedge angle of the wedge prism, d is the optical path in prism 3, and L is the distance from the incident point to the vertex of the wedge prism; sinθ=nsinα, sinθ'=nsinα', β=α+α', d=Lsinα+Lcosαtanα'; Figure 7 The letter l is lowercase. In order to distinguish it from the number "1", the uppercase letter L is used in the document to represent it.

[0096] S1 is the distance from the incident beam waist position to the incident surface of the wedge prism, S2t is the distance from the meridian beam waist to the incident surface of prism 3 after transmission through prism 3, and S2s is the distance from the sagittal beam waist to the incident surface of prism 3 after transmission through prism 3.

[0097] The relationship between astigmatism and prism 3 can be determined by the above method. Figure 8 , 9 10, which shows a wedge mirror with a fixed wedge angle, DS can be converted into a schematic diagram of a function of the incident angle θ.

[0098] That is, by analyzing the meridian plane transfer matrix and the sagittal plane transfer matrix, calculating the focal lengths of the meridian plane and the sagittal plane, and then obtaining their difference to represent the astigmatism. (This is the prior art, so it will not be elaborated on in detail).

[0099] Specifically, the meridian plane is the plane formed by the principal ray of the off-axis object point and the principal axis of the optical system, and the sagittal plane is the plane passing through the principal ray of the off-axis object point and perpendicular to the meridian plane, which is called the sagittal plane of the optical system imaging.

[0100] In some specific implementations, the specific operation of setting the prism 3, the first reflector 4 and the second reflector 5 in S02 is:

[0101] First, the prism 3, the first reflector 4 and the second reflector 5 are fixed on the base by using an interface that uses spur teeth and gear linkage, and the functional relationship between the incident angle and the moving distance of the spur teeth is obtained according to the functional relationship between the incident angle of the prism 3 and the astigmatism compensation value, and the moving distance = θ × Rθ is in radians;

[0102] Secondly, based on the functional relationship between the incident angle and the moving distance of the spur gear, a scale 17 and a rotating guide groove 8 are designed on the base;

[0103] Next, the incident angle θ of the prism 3 is set to 0 (i.e., the initial position is determined), the deflection angle of the light beam after passing through is θ', the first reflector 4 is placed parallel to the light path, and the second reflector 5 has an inherent deflection angle θ' / 2 with respect to the initial angle of the light path;

[0104] Finally, based on the preset angle, the horizontal position of the first reflector 4 and the initial position of the second reflector 5 are designed.

[0105] In some specific embodiments, in order to make the optical path of the light beam after passing through the prism 3 correspond to the initial position of the first reflector 4, the outgoing light beam after passing through the prism 3 is offset toward the opposite side of the acute angle of the prism 3 compared with the incident light beam, and the deflection angle is θ+θ'-β.

[0106] Specifically, when there is a fixed wedge angle β and a distance L from the incident point to the vertex of the wedge prism, the functional relationship between the output offset value (i.e., the output angle) and the incident angle can be referred to: Fig.11 , Fig.12 , Fig.13 and Fig.18 .

[0107] Reference Fig.18 , create a new auxiliary line N, which is parallel to the original side M; angle B is equal to angle C if both sides of angle C are parallel, B=90-θ=C; angle A=β; D=90-A=90-β; E=CD=β-θ;

[0108] So the output deflection angle is equal to θ'-β+θ.

[0109] In some specific embodiments, when the initial position and angle adjustment of the prism 3 are known, the first reflector 4 and the second reflector 5 are adjusted in angle synchronously, and the angle adjustment directions are opposite.

[0110] Among them, you can refer to Fig.15 , a detailed schematic diagram of the light path reflection performed by the first reflector 4.

[0111] In some specific embodiments, when the wedge-shaped prism is deflected, the incident angle of the light beam on the first reflector 4 changes from θ1 to θ1'', and the deflection angle of the first reflector 4 is (θ1-θ1'') / 2;

[0112] The deflection angle of the second reflecting mirror 5 is (θ1-θ1'') / 2+7.5π / 180-(7.5π / 180) / 20.

[0113] Please refer to Fig.14 , a schematic diagram of the optical path is provided for this method of quickly adjusting astigmatism.

[0114] The following example is taken as β=10°. When the incident angle θ is 0, the light beam is approximately deflected at the same point, and the deflection angle is θ'. From the geometric relationship, it can be seen that the first reflector 4 is placed parallel to the light path, and θ1=θ'. The incident angle of the second reflector 5 is θ2=θ' / 2, and the initial angle between the second reflector 5 and the light path is the inherent deflection angle θ' / 2. The horizontal position of the first reflector 4 and the initial position of the second reflector 5 are designed. When the wedge prism is deflected, the incident angle changes, and the rotation position can be approximately considered to be the same point, and the output angle becomes θ'. After the rotation, the incident angle of the first reflector 4 is θ1'', and the deflection angle of the first reflector 4 is (θ1-θ1'') / 2.

[0115] Refer to Fig.15 , since the lenses are all parallel in the initial position, the exit angle of the first reflector 4 is θ1'=θ1=θ, and the incident angle of the second reflector 5 is π / 2-θ;

[0116] refer to Fig.13 According to the deflection angle formula of the first reflector 4 (θ1-θ1'') / 2, it can be known that the overall deflection angle of the laser does not exceed 11°, that is, the incident angle of the second reflector 5 after deflection can be obtained according to the small angle approximation method, that is, according to the incident angle of the second reflector 5 at the initial position, it can be deduced that the incident angle of the second reflector 5 after deflection is equal to π / 2-θ''.

[0117] Then the overall deflection angle of the second reflector 5 is approximately (θ'-θ'') / 2.

[0118] In addition, since the incident angle obtained after the second reflector 5 is deflected is an approximate value, the approximate value needs to be compensated. The maximum value of the deflection of 7.5° when β=10° is taken to obtain the compensation empirical value, which is 7.5π / 180-(7.5π / 180) / 20.

[0119] Finally, by adding the compensation empirical value to the overall deflection angle of the second reflector 5 , the deflection angle of the second reflector 5 can be obtained as (θ1-θ1'') / 2+7.5π / 180-(7.5π / 180) / 20.

[0120] Refer to Fig.16 , which is a schematic diagram showing the relationship between the incident angle of the first reflector 4 and the deflection angle of the first reflector 4.

[0121] Since the first reflector 4 and the prism 3 need to rotate the same amount, that is, the gears and spur gear structures of the first reflector 4 and the prism 3 are the same, the product of the deflection angle of the first prism 4 and the gear radius R is the spur gear moving distance. Three rotating guide grooves 8 can be set, corresponding to the prism 3, the first reflector 4 and the second reflector 5 respectively. The three rotating guide grooves 8 are divided into 50 equal parts in the same way, and each of the 45 parts represents one degree of rotation of the first reflector 4. After the light beam passes through the prism 3 and the first reflector 4, the light path can be irradiated to the specified position of the second reflector 5 (because after the prism 3 is adjusted, the astigmatism compensation operation is completed, and then it is necessary to ensure that the light path output is coaxial with the input).

[0122] Therefore, refer to Fig.17 , which shows a schematic diagram of the incident angle on the second reflector 5 and the deflection angle of the second reflector 5. Since the deflection angle of the second reflector 5 can be approximately expressed as (θ1-θ1'') / 2+7.5π / 180-(7.5π / 180) / 20, when the incident angle on the second reflector 5 is 45 degrees, the deflection angle of the second reflector 5 is 324 degrees. Only in this way can the light path reflected by the second reflector 5 be coaxial with the initial incident light of the light beam.

[0123] The above-mentioned method of adjusting the astigmatism is realized by rotating the prism 3, the first reflector 4 and the second reflector 5. Figure 1-Figure 6 , the following provides a laser beam expander based on a method for quickly adjusting astigmatism for this method, the laser beam expander includes an adjustment mirror portion and lens portions arranged at both ends of the adjustment mirror portion, the adjustment mirror portion includes: an inner sleeve 1, a prism 3, a first reflector 4, a second reflector 5 and an adjustment sleeve 7;

[0124] The inner sleeve 1 is a base;

[0125] A cavity for guiding light to pass through is formed inside the inner sleeve 1, and a plurality of limiting portions 2 are provided on the inner side wall of the inner sleeve 1;

[0126] The prism 3, the first reflector 4 and the second reflector 5 are respectively rotatably arranged on the inner wall of the cavity through a transmission mechanism along the irradiation direction of the light beam. The transmission mechanisms on the three are arranged one-to-one correspondingly to three of the plurality of limiting parts 2, and the rotation axes of the transmission mechanisms of the three are arranged in parallel.

[0127] The adjusting sleeve 7 is sleeved on the outer wall of the inner sleeve 1, and the adjusting sleeve 7 can guide the prism 3, the first reflector 4 and the second reflector 5 to adjust their angles synchronously in the cavity by driving the transmission mechanism;

[0128] When the angles of the prism 3, the first reflector 4 and the second reflector 5 are not adjusted, the light beam passes through the prism 3, the first reflector 4 and the second reflector 5 in sequence, and the input and output of the light beam are coaxial after passing through;

[0129] When the prism 3, the first reflector 4 and the second reflector 5 complete the angle adjustment, the input and output of the light beam are still coaxial.

[0130] It should be noted that the transmission mechanism can also choose a screw and gear combination mode, that is, a hole for accommodating the screw is set on the adjusting sleeve 7, a plurality of vacancies are set on the inner side of the hole, and threads of different rotation directions are set on the side wall of the screw. By rotating the screw, the purpose of driving the prism 3, the first reflector 4 and the second reflector 5 to rotate simultaneously in different rotation directions can be achieved.

[0131] Specifically, the laser beam expander utilizes the cooperation of the prism 3, the first reflector 4 and the second reflector 5 so that the laser beam can quickly adjust the astigmatism. At the same time, since the optical path is coaxial for input and output, the laser directivity remains unchanged.

[0132] The limiting portion 2 may be a hole to limit the rotation axis A, the rotation axis B and the rotation axis C, or may be a groove, or a sleeve installed in a cavity.

[0133] In some specific embodiments, a rotation guide groove 8 is provided on the surface of the adjustment sleeve 7;

[0134] The transmission mechanism includes a spur gear block 6 and an adjustment bracket 9 rotatably connected in the cavity. The adjustment bracket 9 can be positioned and connected to the prism 3, the first reflector 4 or the second reflector 5. The adjustment bracket 9 is provided with a deflection gear block 10. The side wall of the adjustment bracket 9 is provided with a rotating column 18 rotatably connected to the inner side wall of the inner sleeve 1.

[0135] The spur gear block 6 is slidably connected in the limiting portion 2 and meshingly connected with the deflection gear block 10. A boss 11 is installed on the surface of the spur gear block 6. The boss 11 is located in the rotating guide groove 8 and is slidably arranged relative to the adjusting sleeve 7. When the adjusting sleeve 7 rotates around the axis of the inner sleeve 1, the boss 11 moves in the rotating guide groove 8 to pull the spur gear block 6 to slide along the limiting portion 2.

[0136] It should be noted that: there are multiple adjustment brackets 9, and the multiple adjustment brackets 9 can be set to the same structure or different structures. In this application, they are different structures. It is not a mandatory requirement, as long as the adjustment bracket 9 can be used to position and connect the prism 3, the first reflector 4 or the second reflector 5 in the cavity.

[0137] In some specific embodiments, the adjusting sleeve 7 is fixedly sleeved with an outer sleeve 12;

[0138] A limiting groove 13 is provided on the side wall of the inner sleeve 1, and a plurality of steel balls 14 are provided in the limiting groove 13. A plurality of top screws 15 are fixedly installed on the outer sleeve 12, and each top screw 15 is respectively provided corresponding to each steel ball 14, and an elastic member 16 is fixedly connected between each top screw 15 and each steel ball 14.

[0139] Specifically, the lens portion includes a negative lens sleeve arranged at one end of the inner sleeve 1. The connection method between the negative lens sleeve and the inner sleeve 1 can be the same as the connection method between the outer sleeve 12 and the inner sleeve 1. A negative lens is arranged inside the end of the negative lens sleeve away from the inner sleeve 1, and a thread is arranged on the outer side wall of the end of the negative lens sleeve away from the inner sleeve 1 for threaded connection with the laser (threaded connection and pin connection are both detachable fixed connection methods, and can also be used between other structures).

[0140] A positive lens is arranged inside the other end of the inner sleeve 1. The light beam emitted by the laser first passes through the negative lens and then passes through the prism 3, the first reflector 4 and the second reflector 5 in sequence, and finally passes through the positive lens.

[0141] Specifically, the specific structure of the rotating guide groove 8 can refer to Figure 4 Three circular rings are provided, which correspond to the prism 3, the first reflector 4 and the second reflector 5 respectively, and are all unconnected at the ends.

[0142] During operation, the outer sleeve 12 is directly rotated, and then the outer sleeve 12 will rotate around the axis of the inner sleeve 1 together with the adjusting sleeve 7. When the adjusting sleeve 7 rotates around the axis of the inner sleeve 1, since the prism 3, the first reflector 4 and the second reflector 5 are all rotatably connected in the cavity through the transmission mechanism, it means that the prism 3, the first reflector 4 and the second reflector 5 will correspond to a boss 11 respectively. When the adjusting sleeve 7 rotates, the three bosses 11 will slide along the corresponding rotating guide grooves 8 respectively.

[0143] The sliding movement of the boss 11 and the rotating guide groove 8 can be referred to the cylindrical cam mechanism, so when the boss 11 slides along the rotating guide groove 8, each boss 11 will slide along the limiting portion 2 with the corresponding spur gear block 6.

[0144] When the spur gear block 6 slides, the deflection gear block 10 meshing therewith will deflect by a certain angle, that is, at this time, the prism 3, the first reflector 4 and the second reflector 5 will deflect, so that the astigmatism compensation is completed, and the optical path of the light beam is coaxial in the input and output directions.

[0145] In some specific embodiments, the adjusting sleeve 7 is fixedly sleeved with an outer sleeve 12;

[0146] A limiting groove 13 is provided on the side wall of the inner sleeve 1, and a plurality of steel balls 14 are provided in the limiting groove 13. A plurality of top screws 15 are fixedly installed on the outer sleeve 12, and each top screw 15 is respectively provided corresponding to each steel ball 14, and an elastic member 16 is fixedly connected between each top screw 15 and each steel ball 14.

[0147] In order to prevent the rotation between the adjusting sleeve 7, the outer sleeve 12 and the inner sleeve 1 from sliding along the axial direction of the light beam, the outer sleeve 12 and the inner sleeve 1 are connected in the following manner:

[0148] The elastic member 16 (a spring can be selected) is squeezed by the second top screw 15 so that the elastic member 16 pushes the steel ball 14 to always be pressed in the limiting slide groove 13, thereby completing the axial limitation of the outer sleeve 12 and the inner sleeve 1, and the outer sleeve 12 and the adjusting sleeve 7 can be detachably connected by means of components such as pins.

[0149] In some specific embodiments, the surface of the inner sleeve 1 is provided with scales 17;

[0150] The stroke of the boss 11 in the rotating guide groove 8 is equally divided according to the scale 17, and is divided into two parts after being equally divided, one of which is used to display the deflection angle of the prism 3, the first reflector 4 or the second reflector 5, and the other is used to limit the rotation of the adjustment sleeve 7. (A blocking structure can be set in this part, or the rotating guide groove 8 can be blocked by the inner wall of the groove in this part, that is, the entire rotating guide groove 8 is, and the rotation limit can be achieved in these two cases).

[0151] The scale 17 is set on the surface of the inner sleeve 1, and the scale 17 includes the 0-level and the division level. In actual use, according to the need for astigmatism compensation, you can choose to place the 0-level of the inner sleeve 1 on the horizontal top and bottom, vertical left and right sides. This way, it has a direction and can universally compensate for positive and negative astigmatism in the horizontal and vertical directions. The horizontal here is based on the end face of the inner sleeve 1.

[0152] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for quickly adjusting astigmatism, characterized in that: The steps include: S01, based on the Gaussian optical transmission matrix, establishing a functional relationship between the incident angle of the prism (3) when the light beam passes through and the astigmatism compensation value, and determining the incident angle of the prism (3) based on the astigmatism value to be compensated; S02, setting the initial positions of the prism (3), the first reflector (4), and the second reflector (5), and ensuring that the input and output of the light beam are coaxial after the light beam passes through the prism (3), the first reflector (4), and the second reflector (5) in sequence; The prism (3), the first reflector (4) and the second reflector (5) are all arranged to rotate about their respective rotation axes, and the rotation axis of the prism (3) is A, the rotation axis of the first reflector (4) is B, and the rotation axis of the second reflector (5) is C; The rotation axis A, the rotation axis B and the rotation axis C are arranged in parallel; S03, synchronously adjusting the deflection angles of the prism (3), the first reflector (4) and the second reflector (5) to compensate for astigmatism, while ensuring that the input and output of the light beam after the angle adjustment are coaxial.

2. The method for quickly adjusting astigmatism according to claim 1, characterized in that: The specific steps of establishing the functional relationship between the incident angle of the prism (3) and the astigmatism compensation value in step S01 are: S101, obtaining a prism (3) processed into a wedge shape, and guiding a light beam to pass through the prism (3) processed into a wedge shape; S102, obtaining a meridional plane transmission matrix and a sagittal plane transmission matrix in the light transmission matrix of the wedge-shaped prism, wherein the meridional plane transmission matrix is: TT= , The sagittal plane transfer matrix is: TS= ; S103, according to the Gaussian optical transmission matrix, obtain the transmission matrix of the wedge prism to the Gaussian laser: The meridional plane transfer matrix is: MT= , the sagittal plane transfer matrix is: MS= ; S104, obtaining the functional relationship between the incident angle of the prism (3) and the astigmatism compensation value: astigmatism DS=S2t-S2s; Wherein, θ is the incident angle, θ' is the exit angle, β is the wedge angle of the wedge prism, d is the optical path in the prism (3), L is the distance from the incident point to the vertex of the wedge prism; sinθ=nsinα, sinθ'=nsinα', β=α+α', d=Lsinα+Lcosαtanα'; n is the relative refractive index of a light beam of known wavelength passing through the wedge-shaped prism (3); S1 is the distance from the incident beam waist position to the incident surface of the wedge prism, S2t is the distance from the meridian beam waist after transmission through the prism (3) to the incident surface of the prism (3), and S2s is the distance from the sagittal beam waist after transmission through the prism (3) to the incident surface of the prism (3).

3. The method for quickly adjusting astigmatism according to claim 2, characterized in that: The specific operation of setting the prism (3), the first reflector (4) and the second reflector (5) in S02 is: Firstly, a prism (3), a first reflector (4) and a second reflector (5) are fixed on a base using an interface in which spur teeth and gears are linked, and a functional relationship between the incident angle and the spur tooth moving distance is obtained based on a functional relationship between the incident angle of the prism (3) and the astigmatism compensation value, where the moving distance = θ × R (θ is measured in radians); Secondly, based on the functional relationship between the incident angle and the moving distance of the spur gear, a scale (17) and a rotating guide groove (8) are designed on the base; Next, the incident angle θ of the prism (3) is set to 0, the deflection angle of the light beam after passing through is θ', the first reflector (4) is placed parallel to the light path, and the second reflector (5) has an inherent deflection angle θ' / 2 with respect to the initial angle of the light path; Finally, based on the preset angle, the horizontal position of the first reflector (4) and the initial position of the second reflector (5) are designed.

4. The method for quickly adjusting astigmatism according to claim 1 or 3, characterized in that: After the light beam passes through the prism (3), the outgoing light beam deviates toward the opposite side of the acute angle of the prism (3) compared with the incident light beam, and the deflection angle is θ+θ'-β; Among them, θ is the incident angle, θ' is the exit angle, and β is the wedge angle of the wedge prism.

5. The method for quickly adjusting astigmatism according to claim 4, characterized in that: The first reflector (4) and the second reflector (5) adjust their angles synchronously, and the angle adjustment directions are opposite.

6. The method for quickly adjusting astigmatism according to claim 5, characterized in that: When the wedge-shaped prism is deflected, the incident angle of the light beam on the first reflector (4) changes from θ1 to θ1'', and the deflection angle of the first reflector (4) is (θ1-θ1'') / 2; The deflection angle of the second reflector (5) is (θ1-θ1'') / 2+7.5π / 180-(7.5π / 180) / 20.

7. A laser beam expander based on the method for quickly adjusting astigmatism according to any one of claims 1 to 6, the laser beam expander comprising an adjustment mirror portion and lens portions arranged at both ends of the adjustment mirror portion, characterized in that: The adjustable mirror portion comprises: an inner sleeve (1), a prism (3), a first reflector (4), a second reflector (5), and an adjustable sleeve (7); The inner sleeve (1) is a base; A cavity for guiding light to pass through is formed inside the inner sleeve (1), and a plurality of limiting portions (2) are provided on the inner side wall of the inner sleeve (1); The prism (3), the first reflector (4) and the second reflector (5) are arranged on the inner wall of the cavity in sequence and rotationally along the irradiation direction of the light beam through a transmission mechanism, the transmission mechanisms on the three are arranged in one-to-one correspondence with three of the plurality of limiting parts (2), and the rotation axes of the three transmission mechanisms are arranged in parallel; The adjusting sleeve (7) is sleeved on the outer wall of the inner sleeve (1), and the adjusting sleeve (7) can guide the prism (3), the first reflector (4) and the second reflector (5) to adjust their angles synchronously in the cavity by driving the transmission mechanism; When the angles of the prism (3), the first reflector (4) and the second reflector (5) are not adjusted, the light beam passes through the prism (3), the first reflector (4) and the second reflector (5) in sequence, and the input and output of the light beam are coaxial after passing through; When the prism (3), the first reflector (4) and the second reflector (5) have completed angle adjustment, the input and output of the light beam are still coaxial.

8. The laser beam expander according to the method for quickly adjusting astigmatism according to claim 7, characterized in that: The surface of the adjusting sleeve (7) is provided with a rotation guide groove (8); The transmission mechanism comprises a spur gear block (6) and an adjustment bracket (9) rotatably connected in the cavity, the adjustment bracket (9) being capable of being positioned and connected to the prism (3), the first reflector (4) or the second reflector (5), the adjustment bracket (9) being provided with a deflection gear block (10), and the side wall of the adjustment bracket (9) being provided with a rotation column (18) rotatably connected to the inner side wall of the inner sleeve (1); The spur gear block (6) is slidably connected in the limiting portion (2) and meshingly connected with the deflection gear block (10). A boss (11) is installed on the surface of the spur gear block (6). The boss (11) is located in the rotating guide groove (8) and is slidably arranged relative to the adjustment sleeve (7). When the adjustment sleeve (7) rotates around the axis of the inner sleeve (1), the boss (11) moves in the rotating guide groove (8) to pull the spur gear block (6) to slide along the limiting portion (2).

9. The laser beam expander according to the method for quickly adjusting astigmatism according to claim 8, characterized in that: The adjusting sleeve (7) is fixedly sleeved with an outer sleeve (12); The side wall of the inner sleeve (1) is provided with a limit slide groove (13), and a plurality of steel balls (14) are provided in the limit slide groove (13). A plurality of top screws (15) are fixedly mounted on the outer sleeve (12), and each top screw (15) is respectively provided corresponding to each steel ball (14), and an elastic member (16) is fixedly connected between each top screw (15) and each steel ball (14).

10. The laser beam expander according to the method for quickly adjusting astigmatism as claimed in claim 8, characterized in that: The surface of the inner sleeve (1) is provided with scales (17); The travel of the boss (11) in the rotating guide groove (8) is divided equally according to the scale (17), and after being divided equally, it is divided into two parts, one of which is used to display the deflection angle of the prism (3), the first reflector (4) or the second reflector (5), and the other part is used to limit the rotation of the adjustment sleeve (7).

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