Laser spherical aberration correction method and device

Abstract

The present invention discloses a laser spherical aberration correction method and device, and relates to the field of optical technology. The laser spherical aberration correction method is applied to an optical component, and the optical component includes a first diffraction element and a second diffraction element that are relatively parallel. The laser spherical aberration correction method includes: obtaining a first rotation angle of the first diffraction element and a second rotation angle of the second diffraction element; calculating a rotation angle difference according to the first rotation angle and the second rotation angle; calculating the total transmittance of the optical component according to the rotation angle difference; calculating a spherical aberration compensation coefficient according to the total transmittance to correct the spherical aberration of the laser. The technical solution of the present invention only requires two diffraction optical elements to achieve the adjustment of spherical aberration, and the laser spherical aberration correction method has a simple structure and is easy to integrate. It can achieve continuous spherical aberration correction or high-precision spherical aberration correction in a large range. Reduce equipment costs and improve equipment compatibility.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a laser spherical aberration correction method and a laser spherical aberration correction device. Background Art

[0002] In precision laser processing applications, the internal effects of the laser, the light beam passing through optical elements, dielectric materials, and environmental factors will inevitably introduce aberrations into the light beam, resulting in the degradation of the focused spot and affecting the final processing effect. Therefore, it is necessary to control and correct the aberration of the light beam, especially the on-axis point spherical aberration. Currently, the commonly used laser spherical aberration correction methods include liquid crystal spatial light modulator (SLM), deformable mirror, compensation mirror, wavefront correction film, etc.

[0003] SLM and deformable mirror can correct spherical aberration by loading compensation phase, but there are problems with zero-order diffraction and energy utilization, and the use of complex control devices is expensive and not conducive to large-scale industrial applications. Customized compensation mirrors, wavefront correction plates and other methods can only work in specific systems. Once the device changes, it needs to be redesigned and has poor compatibility. Summary of the invention

[0004] The main purpose of the present invention is to provide a laser spherical aberration correction method and a laser spherical aberration correction device, aiming to solve the technical problems of high cost and poor compatibility of spherical aberration correction equipment in the prior art.

[0005] To achieve the above object, the present invention proposes a laser spherical aberration correction method, which is applied to an optical component, wherein the optical component includes a first diffraction element and a second diffraction element that are relatively parallel. The laser spherical aberration correction method includes:

[0006] Acquire a first rotation angle of the first diffractive element and a second rotation angle of the second diffractive element;

[0007] Calculating a rotation angle difference according to the first rotation angle and the second rotation angle;

[0008] Calculating the total transmittance of the optical component according to the rotation angle difference;

[0009] The spherical aberration compensation coefficient is calculated according to the total transmittance to correct the spherical aberration of the laser.

[0010] In one embodiment, the step of calculating the total transmittance of the optical component according to the rotation angle difference includes:

[0011] Acquiring a first transmittance of the first diffraction element;

[0012] Acquiring a second transmittance of the second diffractive element;

[0013] Obtaining a constant coefficient according to the first transmittance and the second transmittance;

[0014] The total transmittance is calculated according to the constant coefficient and the rotation angle difference.

[0015] In one embodiment, the center points of the first diffraction element and the second diffraction element overlap with the optical axis of the laser, wherein when the first diffraction element rotates one circle relative to the second diffraction element with the optical axis as the rotation axis, there is an overlapping area on the projection surfaces of the first diffraction element and the second diffraction element in the direction of the optical axis;

[0016] The step of calculating the total transmittance according to the constant coefficient and the rotation angle difference comprises:

[0017] Establishing a polar coordinate system with the center point of the overlapping area as the origin, and obtaining the radial coordinate value of the pupil of the optical component;

[0018] Calculate the total transmittance according to the constant coefficient, the rotation angle difference, and the radial coordinate value;

[0019] The constant coefficient, the rotation angle difference, the radial coordinate value, and the total transmittance satisfy the following relationship:

[0020] ;

[0021] Wherein, T(r) is the total transmittance, θ is the rotation angle difference, β is the constant coefficient, r is the radial coordinate value, and i is an imaginary unit.

[0022] In one embodiment, the step of calculating the spherical aberration compensation coefficient according to the total transmittance includes:

[0023] Obtaining the radius of the overlapping area;

[0024] Calculating the spherical aberration compensation coefficient according to the radius of the overlapping area and the total transmittance;

[0025] The total transmittance, the radius, and the spherical aberration compensation coefficient satisfy the following relationship:

[0026] ;

[0027] Among them, W 040 is the spherical aberration compensation coefficient, R is the radius of the overlapping area, and λ is the wavelength of the laser.

[0028] In one embodiment, after the step of calculating the rotation angle difference according to the first rotation angle and the second rotation angle, the method further includes:

[0029] Calculating the diffraction efficiency of the optical component according to the rotation angle difference;

[0030] Obtaining an adjustment range of the rotation angle difference according to the diffraction efficiency;

[0031] The compensation interval of the spherical aberration compensation coefficient is calculated according to the adjustment interval.

[0032] In one embodiment, the step of calculating the diffraction efficiency of the optical component according to the rotation angle difference includes:

[0033] The rotation angle difference and the diffraction efficiency satisfy the following relationship:

[0034] ;

[0035] Wherein, η is the diffraction efficiency, and θ is the rotation angle difference.

[0036] In one embodiment, the step of obtaining the adjustment range of the rotation angle difference according to the diffraction efficiency includes:

[0037] Determining whether the diffraction efficiency is greater than a preset efficiency;

[0038] If the diffraction efficiency is greater than the preset efficiency, obtaining the rotation angle difference;

[0039] The obtained rotation angle difference is associated with an adjustment interval; the adjustment interval includes all corresponding rotation angle differences when the efficiency is greater than the preset efficiency.

[0040] In one embodiment, after the step of calculating the spherical aberration compensation coefficient according to the total transmittance, the method further includes:

[0041] Adjusting the spherical aberration of the laser according to the spherical aberration compensation coefficient and obtaining an adjustment result;

[0042] Determining whether the adjustment result is qualified;

[0043] If the adjustment result is unqualified, the process returns to the step of obtaining the first rotation angle of the first diffraction element and the second rotation angle of the second diffraction element until the adjustment result is qualified.

[0044] In one embodiment, the step of determining whether the adjustment result is qualified includes:

[0045] Determining whether the spot image adjusted by the optical component is consistent with a preset image;

[0046] If they are consistent, the adjustment result is qualified;

[0047] If not consistent, the adjustment result is unqualified.

[0048] In addition, in order to solve the above problems, the present invention also proposes a laser spherical aberration correction device, which is applied to the laser spherical aberration correction method as described above, and the spherical aberration correction device includes an adjustment component;

[0049] The adjustment component comprises a first diffraction element and a second diffraction element which are arranged opposite to each other, wherein the optical axis of the laser is perpendicular to the first diffraction element and the second diffraction element, and the center points of the first diffraction element and the second diffraction element are located on the optical axis, and the first diffraction element and the second diffraction element are arranged to rotate with the optical axis as a rotation axis;

[0050] Wherein, the first diffraction element and / or the second diffraction element are used to continuously adjust the spherical aberration of the laser when rotating.

[0051] The technical solution of the present invention only needs two optical diffraction elements to adjust the laser spherical aberration. The laser spherical aberration correction method has a simple structure and is easy to integrate. By selecting reasonable parameters, the spherical aberration can be continuously adjusted during the rotation of the first diffraction element and / or the second diffraction element, and by rotating to different angles, a wide range of continuous spherical aberration correction or high-precision spherical aberration correction can be achieved. The equipment cost is reduced and the compatibility of the equipment is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 the structures shown in these drawings without paying creative work.

[0053] Figure 1 It is a schematic diagram of the flow chart of the first embodiment of the laser spherical aberration correction method of the present invention;

[0054] Figure 2 It is a schematic diagram of the flow chart of the second embodiment of the laser spherical aberration correction method of the present invention;

[0055] Figure 3 It is a schematic diagram of the flow chart of the third embodiment of the laser spherical aberration correction method of the present invention;

[0056] Figure 4 It is a schematic diagram of the flow chart of the fourth embodiment of the laser spherical aberration correction method of the present invention;

[0057] Figure 5 It is a schematic diagram of the flow chart of the fifth embodiment of the laser spherical aberration correction method of the present invention;

[0058] Figure 6 It is a schematic diagram of the structure of the optical components in the laser spherical aberration correction device of the present invention;

[0059] Figure 7 It is a schematic diagram of the overlapping area of ​​the optical components in the laser spherical aberration correction device of the present invention;

[0060] Figure 8 A phase distribution diagram of a diffraction element in an embodiment of a laser spherical aberration correction method of the present invention;

[0061] Fig. 9 for Figure 8 Phase distribution of the diffraction element and the corresponding spherical aberration phase diagram;

[0062] Fig.10 A phase distribution diagram of a diffraction element in another embodiment of the laser spherical aberration correction method of the present invention;

[0063] Fig.11 for Fig.10 Phase distribution of the diffraction element and the corresponding spherical aberration phase diagram.

[0064] Description of Figure Numbers:

[0065] 10. First diffraction element; 20. Second diffraction element.

[0066] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0067] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0069] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0070] The present invention discloses a laser spherical aberration correction method, which is applied to an optical component. The optical component comprises a first diffraction element 10 and a second diffraction element 20 which are arranged relatively parallel.

[0071] Please refer to Figure 1 , Figure 1 This is a flow chart of the first embodiment of the laser spherical aberration correction method of the present invention, which specifically includes the following steps:

[0072] Step S10: acquiring a first rotation angle of the first diffractive element and a second rotation angle of the second diffractive element;

[0073] Step S20: calculating a rotation angle difference according to the first rotation angle and the second rotation angle;

[0074] Step S30: calculating the total transmittance of the optical component according to the rotation angle difference;

[0075] Step S40: calculating the spherical aberration compensation coefficient according to the total transmittance.

[0076] The light source is a laser, and the laser beam is irradiated toward the optical component. The first diffraction element 10 and the second diffraction element 20 are both planar, and the shape can be selected as a square or a circle, and are placed parallel to each other and at a certain interval. The interval between the first diffraction element 10 and the second diffraction element 20 is less than 0.5 mm. The light beam is perpendicular to the first diffraction element 10 and the second diffraction element 20, and the optical axis of the light source passes through the center point of the first diffraction element 10 and the center point of the second diffraction element 20 in sequence.

[0077] The substrate of the optical component is an optically transparent material such as glass, fused quartz, plastic, zinc selenide, etc. The surface has a specially designed microstructure that can modulate the wavefront phase of the light beam. Please refer to Figure 6By rotating the first diffraction element 10 or the second diffraction element 20 with the optical axis as the rotation axis, the phase distribution thereof can be changed, thereby realizing continuous adjustment of the spherical aberration of the laser beam. The total transmittance of the optical component can be obtained by measuring when constructing the first diffraction element 10 and the second diffraction element 20.

[0078] As an embodiment, in a system with a known spherical aberration coefficient, the spherical aberration compensation coefficient corresponding to the rotation angle difference can be directly calculated by the total transmittance. The spherical aberration can be corrected by adjusting the rotation angle difference to the corresponding angle. Thus, the first diffraction element and / or the second diffraction element can be quickly rotated to the corresponding position. This embodiment can also be used to measure the adjustment range of the optical component when the optical component is just manufactured.

[0079] As another embodiment, in a laser system with an unknown spherical aberration coefficient, when the spherical aberration coefficient is within an adjustable range, the laser beam emitted by the system is directed toward the optical component, and the light spot output from the optical component is observed, and the first diffraction element 10 and / or the second diffraction element 20 is continuously rotated until the optimal imaging effect of the light spot is found, and the first diffraction element 10 and the second diffraction element 20 are fixed at the current rotation angle, and the current angle of the first diffraction element 10 and the second diffraction element 20 is the correction position of the laser system.

[0080] The technical solution of the present invention only needs two optical diffraction elements to adjust the spherical aberration. The laser spherical aberration correction method has a simple structure and is easy to integrate. By selecting reasonable parameters, the spherical aberration can be continuously adjusted during the rotation of the first diffraction element 10 and / or the second diffraction element 20, and by rotating to different angles, a wide range of continuous spherical aberration correction or high-precision spherical aberration correction can be achieved. The equipment cost is reduced and the compatibility of the equipment is improved.

[0081] For further information, please refer to Figure 2 , Figure 2 This is a flow chart of the second embodiment of the laser spherical aberration correction method of the present invention, step S30 includes:

[0082] Step S31: obtaining a first transmittance of the first diffraction element;

[0083] Step S32: obtaining a second transmittance of the second diffraction element;

[0084] Step S33: obtaining a constant coefficient according to the first transmittance and the second transmittance;

[0085] Step S34: calculating the total transmittance according to the constant coefficient and the rotation angle difference.

[0086] Please refer to Figure 6, the center points of the first diffractive element 10 and the second diffractive element 20 overlap with the optical axis. Figure 7 When the first diffraction element 10 rotates one circle relative to the second diffraction element 20 with the optical axis as the rotation axis, there is an overlapping area A.

[0087] The overlapping area A is a circle, and a coordinate system is established with the center of the overlapping area A as the origin. When constructing the first diffraction element and the second diffraction element, their transmittance functions satisfy the following relationship respectively:

[0088] ;

[0089] Wherein, T1(r) is the first transmittance, T2(r) is the second transmittance. Wherein β is a constant coefficient. For a diffractive optical element, once β is determined, it is a fixed value.

[0090] The coordinate system established with the center of the overlapping area A as the origin can be calculated: ;

[0091] The phase transmittance functions of the first diffractive element 10 and the second diffractive element 20 are inverted, so the two can use the same phase function, thereby reducing the cost and error of processing. When in use, two identical diffractive optical elements are placed facing each other to achieve the designed effect.

[0092] It should be noted that the function floor[f] is a floor rounding function.

[0093] The total transmittance function is calculated by using the representation function of the first transmittance and the representation function of the second transmittance. When the first diffraction element 10 and / or the second diffraction element 20 are rotated so that the rotation angle difference between them is θ, the total transmittance function satisfies the following expression:

[0094] Expression 1: ;

[0095] Wherein, T(r) is the total transmittance, and θ is the rotation angle difference.

[0096] In aberration theory, the wave phase difference of the third-order spherical aberration satisfies the following relationship:

[0097] Expression 2: ;

[0098] Among them, W 040 is the spherical aberration compensation coefficient, SA(r) is the wave phase difference, λ is the wavelength of the light beam, r is the radial coordinate value of the pupil of the optical component, and R is the radius of the overlapping area A.

[0099] It should be noted that the optical component has a pupil. For example, the pupil can be a circular frame of the optical component.

[0100] When performing calculations, a polar coordinate system is established with the center of the overlapping area A as the origin. Figure 7 In the polar coordinate system, R is the radial coordinate value of the radius of the overlapping area A, and r is the radial coordinate value of the pupil of the optical component.

[0101] It can be understood that, because the optical system is circularly symmetric, the polar coordinate value of the pupil does not need to consider the angle, and the radial coordinate value of the polar coordinate can be taken.

[0102] When the conditions are met When the total transmittance function of the first diffraction element 10 and the second diffraction element 20 can be calculated by the spherical aberration compensation coefficient W 040 That is, when the rotation angle difference between the first diffraction element 10 and the second diffraction element 20 is θ, the spherical aberration compensation coefficient is W 040 .

[0103] Therefore, by substituting the conversion, expression 1 is compared with expression 2 to make it satisfy the condition , then the total transmittance, the wave phase difference and the spherical aberration compensation coefficient satisfy the following expression:

[0104] Expression 3: ;

[0105] The total transmittance function of the first diffractive element 10 and the second diffractive element 20 can compensate for the spherical aberration coefficient W 040 That is, when the rotation angle difference between the first diffraction element 10 and the second diffraction element 20 is θ, the spherical aberration compensation coefficient is W 040 .

[0106] To facilitate calculation, transform expression 3 to obtain the following expression:

[0107] Expression 4: .

[0108] Therefore, the corresponding spherical aberration compensation coefficient can be calculated by substituting the rotation angle difference θ into Expression 4.

[0109] For further information, please refer to Figure 3 , Figure 3 This is a flow chart of the third embodiment of the laser spherical aberration correction method of the present invention. After step S20, the following steps are also included:

[0110] Step S50: calculating the diffraction efficiency of the optical component according to the rotation angle difference;

[0111] Step S60: obtaining an adjustment range of the rotation angle difference according to the diffraction efficiency;

[0112] Step S70: calculating the compensation interval of the spherical aberration compensation coefficient according to the adjustment interval.

[0113] In this embodiment, the spherical aberration can be continuously adjusted by rotating the first diffraction element 10 and / or the second diffraction element 20. At different rotation angles, the diffraction efficiency of the first diffraction element 10 and the second diffraction element 20 is derived by Bernet, and the relationship between the 0th order diffraction efficiency and the rotation angle, the rotation angle difference and the diffraction efficiency satisfy the following relationship:

[0114] Expression 5: ;

[0115] Wherein, η is the diffraction efficiency. Each rotation angle difference has its corresponding diffraction efficiency. It can be understood that, under normal circumstances, the value range of the first rotation angle difference is 0°~360°, that is, the difference range generated during the second diffraction element rotates one circle relative to the first diffraction element.

[0116] The diffraction efficiency corresponding to each rotation angle difference is calculated respectively, and can be reflected on the line graph for clear display. The angles whose corresponding diffraction efficiency meets the requirements within the range of 0°~360° are selected and combined to form an angle interval, that is, the adjustment interval. The rotation angle difference within the adjustment interval is then substituted into Expression 4 to calculate the maximum spherical aberration compensation coefficient and the minimum spherical aberration compensation coefficient, thereby further obtaining the compensation interval of the spherical aberration compensation coefficient.

[0117] For further information, please refer to Figure 4 , Figure 4 This is a flow chart of a fourth embodiment of the laser spherical aberration correction method of the present invention, step S60 includes:

[0118] Step S61: determining whether the diffraction efficiency is greater than a preset efficiency;

[0119] Step S62: if the diffraction efficiency is greater than the preset efficiency, obtaining the rotation angle difference;

[0120] Step S63: establishing an adjustment interval according to all the rotation angle differences obtained.

[0121] In this embodiment, for example, the preset efficiency is set to 80%. When the rotation angle difference is limited to change between (-π / 2, π / 2), the total diffraction efficiency is greater than 81%, which means that the rotation angle difference in the range of (-π / 2, π / 2) satisfies the adjustment effect, so (-π / 2, π / 2) is the adjustment interval of the optical component. When the rotation angle difference is not limited, it is calculated according to a rotation from 0° to 360°. When there are multiple adjustment intervals, they are calculated separately according to the multiple adjustment intervals.

[0122] Substitute the angle within the adjustment range into Expression 4 to calculate the spherical aberration coefficient W at this time 040 In (-βR 4 λ / 4, -βR 4 λ / 4) is continuously adjustable. Therefore, (-βR 4 λ / 4, -βR 4 λ / 4) is the compensation interval of the optical component. Correspondingly, when there are multiple adjustment intervals, multiple compensation intervals are formed by calculating them respectively according to the multiple adjustment intervals.

[0123] For further information, please refer to Figure 5 , Figure 5 This is a flow chart of the fifth embodiment of the laser spherical aberration correction method of the present invention. After step S40, the method further includes:

[0124] Step S80: adjusting the spherical aberration of the laser according to the spherical aberration compensation coefficient and obtaining an adjustment result;

[0125] Step S90: judging whether the adjustment result is qualified;

[0126] Step S100: If the adjustment result is unqualified, return to step S20 until the adjustment result is qualified.

[0127] In this embodiment, a system with an unknown spherical aberration coefficient is taken as an example. The light beam is adjusted in real time by rotating the first diffraction element 10 and the second diffraction element 20, and the light spot formed by the light beam after passing through the optical component is observed at the same time.

[0128] The first diffraction element 10 and the second diffraction element 20 are rotated in real time until the best imaging effect of the light spot is found. When the light spot meets the adjusted effect, and the first diffraction element 10 and the second diffraction element 20 are fixed at the current rotation angle, the current angle of the first diffraction element 10 and the second diffraction element 20 is the correction position of the light source.

[0129] Specifically, step S90 includes:

[0130] Step S91: determining whether the spot image adjusted by the optical component is consistent with a preset image;

[0131] Step S92: If they are consistent, the adjustment result is qualified;

[0132] Step S93: If not consistent, the adjustment result is unqualified.

[0133] As an embodiment, for the adjustable spherical aberration correction device with a laser wavelength of λ=532nm, the aperture D=20mm includes two diffractive optical elements whose substrate material is fused quartz. When the first diffractive element 10 is kept stationary and the second diffractive element 20 is rotated between (-π / 4, π / 4), the spherical aberration coefficient of the device is continuously adjustable between (-5λ, 5λ). The phase distribution diagram of the two diffractive optical elements is shown in FIG. Figure 8 The total phase distribution of the overlapping parts of the two diffractive optical elements corresponding to different rotation angles and the corresponding spherical aberration phase reference Fig. 9 The sensitivity of spherical aberration adjustment is 0.11λ / °.

[0134] As another embodiment, for the adjustable spherical aberration correction device with a laser wavelength of λ=343nm, the aperture D=30mm, comprises two diffractive optical elements whose substrate material is fused quartz. When the first diffractive element 10 is kept stationary and the second diffractive element 20 is rotated between (-π / 4, π / 4), the spherical aberration coefficient of the device is continuously adjustable between (-λ, λ). The phase distribution diagram of the two diffractive optical elements is shown in FIG. Fig.10 The total phase distribution of the overlapping parts of the two diffractive optical elements corresponding to different rotation angles and the corresponding spherical aberration phase reference Fig.11 The sensitivity of spherical aberration adjustment is 0.022λ / °.

[0135] In addition, to solve the above problems, the present invention also proposes a laser spherical aberration correction device, which is applied to the laser spherical aberration correction method as mentioned above, and the spherical aberration correction device includes an adjustment component, and the adjustment component includes a first diffraction element 10 and a second diffraction element 20 that are relatively arranged, wherein the optical axis of the light source is perpendicular to the first diffraction element 10 and the second diffraction element 20, and the center points of the first diffraction element 10 and the second diffraction element 20 are located on the optical axis, and the first diffraction element 10 and the second diffraction element 20 are arranged to rotate with the optical axis as the center; wherein the first diffraction element 10 and / or the second diffraction element 20 are used to continuously adjust the spherical aberration of the light beam of the light source when rotating.

[0136] The light source is a laser, and the laser beam is irradiated toward the optical component. The first diffraction element 10 and the second diffraction element 20 are both planar, and the shape can be selected as a square or a circle, and are placed parallel to each other and at a certain interval. The interval between the first diffraction element 10 and the second diffraction element 20 is less than 0.5 mm. The light beam is perpendicular to the first diffraction element 10 and the second diffraction element 20, and the optical axis of the light source passes through the center point of the first diffraction element 10 and the center point of the second diffraction element 20 in sequence.

[0137] The substrate of the optical component is an optically transparent material such as glass, fused quartz, plastic, zinc selenide, etc. The surface has a specially designed microstructure that can modulate the wavefront phase of the light beam. Please refer to Figure 6 By rotating the first diffraction element 10 or the second diffraction element 20 with the optical axis as the rotation axis, the phase distribution thereof can be changed, thereby realizing continuous adjustment of the spherical aberration of the light beam. The total transmittance of the optical component can be obtained by measuring when constructing the first diffraction element 10 and the second diffraction element 20.

[0138] As an embodiment, in a system with a known spherical aberration coefficient, the spherical aberration compensation coefficient corresponding to the rotation angle difference can be directly calculated by the total transmittance. The spherical aberration can be corrected by adjusting the rotation angle difference to the corresponding angle. Thus, the first diffraction element and / or the second diffraction element can be quickly rotated to the corresponding position. This embodiment can also be used to measure the adjustment range of the optical component when the optical component is just manufactured.

[0139] As another embodiment, in a system with an unknown spherical aberration coefficient, when the spherical aberration coefficient is within an adjustable range, the laser beam emitted by the light source is directed toward the optical component, and the light spot output from the optical component is observed, and the first diffraction element 10 and / or the second diffraction element 20 is continuously rotated until the optimal imaging effect of the light spot is found, and the first diffraction element 10 and the second diffraction element 20 are fixed at the current rotation angle, and the current angle of the first diffraction element 10 and the second diffraction element 20 is the correction position of the light source.

[0140] The technical solution of the present invention only needs two optical diffraction elements to adjust the spherical aberration. The laser spherical aberration correction method has a simple structure and is easy to integrate. By selecting reasonable parameters, the spherical aberration can be continuously adjusted during the rotation of the first diffraction element 10 and / or the second diffraction element 20, and by rotating to different angles, a wide range of continuous spherical aberration correction or high-precision spherical aberration correction can be achieved. The equipment cost is reduced and the compatibility of the equipment is improved.

[0141] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A laser spherical aberration correction method, characterized in that: The laser spherical aberration correction method is applied to an optical component, wherein the optical component comprises a first diffraction element and a second diffraction element which are arranged relatively parallel to each other; The laser spherical aberration correction method comprises: Acquire a first rotation angle of the first diffractive element and a second rotation angle of the second diffractive element; Calculating a rotation angle difference according to the first rotation angle and the second rotation angle; Acquiring a first transmittance of the first diffraction element; Acquiring a second transmittance of the second diffractive element; Obtaining a constant coefficient according to the first transmittance and the second transmittance; The center points of the first diffraction element and the second diffraction element overlap with the optical axis of the laser, and when the first diffraction element rotates one circle relative to the second diffraction element with the optical axis as the rotation axis, there is an overlapping area on the projection surfaces of the first diffraction element and the second diffraction element in the direction of the optical axis; Establishing a polar coordinate system with the center point of the overlapping area as the origin, and obtaining the radial coordinate value of the pupil of the optical component; Calculate the total transmittance according to the constant coefficient, the rotation angle difference, and the radial coordinate value; The constant coefficient, the rotation angle difference, the radial coordinate value, and the total transmittance satisfy the following relationship: ； Wherein, T(r) is the total transmittance, θ is the rotation angle difference, β is the constant coefficient, r is the radial coordinate value, and i is the imaginary unit; Obtaining the radius of the overlapping area; Calculating a spherical aberration compensation coefficient according to the radius of the overlapping area and the total transmittance to correct the spherical aberration of the laser; When the conditions are met When , the total transmittance, the radius and the spherical aberration compensation coefficient satisfy the following relationship: ； Among them, W 040 is the spherical aberration compensation coefficient, R is the radius of the overlapping area, and λ is the wavelength of the laser; SA(r) is the wave phase difference of the third-order spherical aberration, and the wave phase difference of the third-order spherical aberration satisfies the following relationship: W 040 is the spherical aberration compensation coefficient, SA(r) is the wave phase difference, and r is the radial coordinate value of the pupil of the optical component.

2. The laser spherical aberration correction method according to claim 1, characterized in that: After the step of calculating the rotation angle difference according to the first rotation angle and the second rotation angle, the method further includes: Calculating the diffraction efficiency of the optical component according to the rotation angle difference; Obtaining an adjustment range of the rotation angle difference according to the diffraction efficiency; The compensation interval of the spherical aberration compensation coefficient is calculated according to the adjustment interval.

3. The laser spherical aberration correction method according to claim 2, characterized in that: The step of calculating the diffraction efficiency of the optical component according to the rotation angle difference comprises: The rotation angle difference and the diffraction efficiency satisfy the following relationship: ； Wherein, η is the diffraction efficiency, and θ is the rotation angle difference.

4. The laser spherical aberration correction method according to claim 2, characterized in that: The step of obtaining the adjustment range of the rotation angle difference according to the diffraction efficiency comprises: Determining whether the diffraction efficiency is greater than a preset efficiency; If the diffraction efficiency is greater than the preset efficiency, obtaining the rotation angle difference; An adjustment interval is established according to all the obtained rotation angle differences.

5. The laser spherical aberration correction method according to claim 1, characterized in that: After the step of calculating the spherical aberration compensation coefficient according to the total transmittance, the method further includes: Adjusting the spherical aberration of the laser according to the spherical aberration compensation coefficient and obtaining an adjustment result; Determining whether the adjustment result is qualified; If the adjustment result is unqualified, the process returns to the step of obtaining the first rotation angle of the first diffraction element and the second rotation angle of the second diffraction element until the adjustment result is qualified.

6. The laser spherical aberration correction method according to claim 5, characterized in that: The step of judging whether the adjustment result is qualified comprises: Determining whether the spot image adjusted by the optical component is consistent with a preset image; If they are consistent, the adjustment result is qualified; If not consistent, the adjustment result is unqualified.

7. A laser spherical aberration correction device, characterized in that: The spherical aberration correction device is applied to the laser spherical aberration correction method according to any one of claims 1 to 6, and the spherical aberration correction device comprises an adjustment component; The adjustment component comprises a first diffraction element and a second diffraction element which are arranged opposite to each other, wherein the optical axis of the laser is perpendicular to the first diffraction element and the second diffraction element, and the center points of the first diffraction element and the second diffraction element are located on the optical axis, and the first diffraction element and the second diffraction element are arranged to rotate with the optical axis as a rotation axis; Wherein, the first diffraction element and / or the second diffraction element are used to continuously adjust the spherical aberration of the laser when rotating.

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