Surface bulging type defocus lens machining method based on femtosecond laser

Abstract

The invention belongs to the technical field of femtosecond laser processing, and particularly relates to a femtosecond laser-based surface bulging out-of-focus lens processing method, which is used for processing a micro-lens array with the out-of-focus amount continuously changing from the eye side to the temporal side based on a plurality of bulging units. The cavity structure is machined below the bulging unit based on multiple laser control, the cavity structure provides a preset transformation foundation for subsequent secondary machining, the bulging unit is conveniently converted into a micropore structure, and after conversion is completed, the light transmittance does not obviously change. Under the condition that the light transmittance meets the requirement, the vision correction defocus lens which better meets the requirement for the real defocus amount of the retina and can prolong the service cycle after secondary processing is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of femtosecond laser processing, and particularly relates to a surface bulging type defocus lens processing method based on femtosecond laser. BACKGROUND

[0002] The bulging microlens defocus lens is a special designed myopia prevention lens, mainly used for delaying the myopia progression of children and adolescents. The core principle is to form a peripheral defocus signal through the micro lens array on the lens (usually distributed in the peripheral area), so as to inhibit the excessive growth of the eye axis, and achieve the effect of controlling the development of myopia; the existing such lens depends on the mold mechanical pressing to form the surface bulging structure, the curvature distribution is rigid, and the error is > ± 0.75D. At the same time, the bulging unit has consistent curvature, and cannot adapt to the asymmetric defocus demand of the retina. At the same time, due to the fixed structure, the replacement cycle of the existing bulging microlens defocus lens is short.

[0003] If laser irradiation is used to process the bulging structure, local high temperature will be generated in the processing area, which will cause the molecular chain of the resin to break, so that the light transmittance decays by > 15%, which is higher than the ISO standard requirement of < 5%, and the bulging height consistency is poor, with an error of up to ± 20 μm. In the continuous / long pulse laser processing, the thermal accumulation effect of the laser causes the carbonization of the material, so that the surface roughness Ra is > 1.0 μm, which cannot meet the requirement of the optical transparency of the ophthalmic lens (Ra < 0.1 μm); at the same time, the infrared waveband femtosecond laser can only realize surface ablation or modification, lacks the precise generation ability of the internal cavity (cavity position error > ± 5 μm), and cannot control the air pressure gradient to match the curvature function. SUMMARY

[0004] Therefore, the application provides a surface bulging type defocus lens processing method based on femtosecond laser, which adopts a micro lens array composed of multiple bulging unit groups, the defocus amount of which continuously changes from the eye side to the temporal side, and processes a cavity structure under the bulging unit based on multiple controls, so as to convert the bulging unit into a micro hole structure, and the light transmittance does not change obviously after the conversion. The application realizes a vision correction defocus lens which can meet the real defocus amount demand of the retina and prolong the service life after secondary processing, under the condition that the light transmittance meets the requirement.

[0005] In order to realize the above technical purpose, the specific technical scheme adopted by the application is as follows: The surface of the defocus lens is provided with a micro lens array composed of multiple bulging unit groups; the defocus amount of the micro lens array continuously increases from the eye side to the temporal side; the lower substrate of at least a part of the bulging unit is pre-provided with a cavity; and the cavity supports the conversion of the bulging unit into a micro hole lens after the secondary laser irradiation processing; The method for processing at least one part of the bulging unit is: processing the cavity inside the substrate of the lens; when the cavity is formed, the surface of the substrate above the cavity is deformed to form the bulging unit; The method for processing the cavity includes: inducing a non-equilibrium plasma under the surface of the substrate of the lens based on a femtosecond laser, triggering a predetermined position of the substrate to occur gaseous decomposition to form a sealed empty package based on a multi-photon absorption effect, and generating the sub-micron cavity inside the lens by adjusting the time sequence difference between the electron relaxation time and the lattice heat transfer time when the lens is irradiated by the femtosecond laser; Wherein: the diameter of the sealed empty package generated by single femtosecond pulse laser irradiation of the lens is not greater than 0.5-5 μm; the cavity is formed after multiple expansions of the empty package based on multiple femtosecond pulse laser irradiations; and the air pressure inside the empty package is dynamically controlled based on the cumulative number of laser pulses during the expansion of the empty package.

[0006] Further, in order to make the specifications of the bulging unit meet the defocus amount requirements, the geometric constraints of the bulging unit satisfy the following formula:

[0007] In the formula, R is the radius of curvature of the bulging unit, D is the diameter of the bulging unit, H is the height of the bulging unit bulging the surface of the lens Further, in order to make the diopter of the bulging unit more accurate, the diopter of the bulging unit satisfies:

[0008] In the formula, D is the diopter of the bulging unit, and n is the refractive index of the substrate, is the diffraction correction term of the cavity;

[0009] Wherein, λ is the wavelength of visible light, is a calibrated correction coefficient, D is the diameter of the cavity, is the axial depth of the cavity itself, is an attenuation constant determined by the material of the substrate.

[0010] Furthermore, in order to process the cavity more rationally and ensure that it still meets the light transmittance requirements after secondary processing, during the cavity forming process, the cavity is nucleated by a femtosecond pulsed laser in the near-infrared band, the initial plasma is induced by a laser with a single pulse energy of 2-200 μJ, the expansion of the cavity is controlled by a femtosecond pulsed laser in the green or ultraviolet band, and the size of the cavity is precisely controlled by a femtosecond pulsed laser with a single pulse energy of 1-50 μJ.

[0011] Furthermore, when processing the cavity, the parameters of the femtosecond pulsed laser satisfy the following:

[0012] In the formula, E This refers to the single-pulse energy of a femtosecond pulsed laser. The pulse value of a femtosecond pulsed laser for focusing a single-point dwell area in laser processing. This represents the axial scanning spacing of the femtosecond pulse laser. The scanning speed of the femtosecond pulsed laser. This is the reference scanning speed for femtosecond pulsed lasers. and All of these are attenuation constants determined by the material of the substrate.

[0013] Furthermore, to accommodate different lens substrates, after the cavity is formed, a bulging unit naturally forms above the cavity. The height of the bulging unit and the parameters of the laser pulse satisfy the following formula:

[0014] in The bulging efficiency coefficient of the substrate is expressed in µm. 3 / µJ.

[0015] Furthermore, in order to improve processing efficiency, the cavity is formed by irradiation with a femtosecond pulse laser with 10-100 pulses.

[0016] Furthermore, for ease of control, the cavity is spherical or an ellipsoid of revolution; when the cavity is spherical, = When the cavity is an ellipsoid of revolution, This represents the equatorial diameter of the cavity. This indicates the length of the cavity's axis of rotation.

[0017] Furthermore, to avoid accumulating errors, the laser pulse spot is monitored using a vision system during the machining of the cavity; the vision system is equipped with an artificial intelligence model to support the monitoring.

[0018] By adopting the above technical solution, the present invention can also bring the following beneficial effects: This invention proposes a calculation method that correlates the position of the cavity with the refractive power of the bulging unit. By establishing a mathematical model, the correspondence between the position of the cavity and the change in refractive power is quantified, providing a theoretical basis for lens design and optimization. This invention, starting from the attenuation constant of the material, proposes a method for controlling various parameters of the laser pulse during cavity processing. This method enables sub-micron level control, achieving high-precision and high-transparency optical processing effects, and is suitable for precision lens manufacturing and micro / nano fabrication. During continuous / long-pulse laser processing, it avoids the thermal accumulation effect of the laser that leads to material carbonization, resulting in a surface roughness Ra < 1.0 μm, which meets the optical transparency requirements of ophthalmic lenses (Ra < 0.1 μm). Simultaneously, the processing method of this invention has the ability to precisely generate internal cavities and can control the air pressure gradient to match the curvature function.

[0019] This invention takes the ratio between the bulging volume of the material and the laser energy as its starting point, and correlates the relationship between various parameters of the laser spot and the bulging height. By establishing a mathematical model, it realizes the accurate prediction and optimized control of laser processing parameters, thereby improving the controllability and repeatability of the bulging unit and cavity forming. This invention uses a vision system equipped with an artificial intelligence module to monitor the laser spot in real time, enabling dynamic deviation control during the processing and avoiding the accumulation of errors. It can also correct the processing path online, further improving processing accuracy and process stability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of a surface bulging defocus lens processing method based on femtosecond laser in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the surface-bulging defocus lens in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the bulging unit in a specific embodiment of the present invention. Detailed Implementation

[0022] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0023] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0024] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0025] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The illustrations only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0027] In one embodiment of the present invention, a method for processing a surface-bulging defocused lens based on femtosecond laser is proposed. The defocused lens has a microlens array composed of multiple bulging units on its surface. The defocusing amount of the microlens array increases continuously from the eye to the temporal region. At least a portion of the bulging units have a pre-set cavity in the lens substrate below them. The cavity supports the transformation of the bulging units into microporous lenses after secondary laser irradiation processing. The principle is that the cavity serves as the substrate for secondary processing, based on the physical process of the interaction between the femtosecond laser and the material, and the guiding and confining effect of the cavity structure on the laser energy. Specifically: Preset function of the cavity: The cavity is preset in the lens substrate below the bulging unit (see...). Figure 2 and Figure 3 (The cavity structure). During secondary laser irradiation, the cavity provides a controllable "starting point," allowing laser energy to be precisely applied to the cavity boundaries, avoiding starting the process from scratch and efficiently converting the bulging unit into a microporous lens. Energy control and transmittance optimization: During secondary processing, laser parameters (such as pulse energy and scanning speed) are dynamically adjusted based on the cavity dimensions according to formulas, ensuring minimal material removal. The document emphasizes that the transmittance change rate after conversion is <5%, because the cavity size (diameter 5-200μm) and processing precision (surface roughness Ra <0.1μm) reduce light scattering and maintain optical uniformity.

[0028] Physical mechanism: The presence of the cavity reduces the energy barrier for material removal. The internal air pressure of the laser-induced cavity is dynamically controlled by the cumulative number of pulses, allowing secondary processing to precisely expand the cavity diameter or deepen its depth, forming a microporous structure without damaging the surrounding substrate.

[0029] The processing method for at least a portion of the bulging units in this embodiment (mostly located in the temporal region, where the defocus requirement of the lens is higher to meet the human eye's corrective defocus requirements) is as follows: the cavity is processed inside the substrate of the lens; during the forming of the cavity, the surface of the substrate above the cavity is deformed and protrudes to form the bulging unit; The method for processing the cavity includes: Based on the femtosecond laser inducing non-equilibrium plasma under the substrate surface of the lens, gaseous decomposition of the substrate is triggered at a predetermined location based on the multiphoton absorption effect; During laser irradiation, the submicron-scale cavity is generated inside by adjusting the timing difference between the electronic relaxation time and the lattice heat transfer time. Wherein: the diameter of the sealed void generated by a single laser pulse is no greater than 0.5-5μm, and the cavity is formed after multiple void expansions; during the processing of the cavity, the air pressure of the cavity is dynamically controlled based on the cumulative number of laser pulses.

[0030] The timing difference between the electronic relaxation time and the lattice heat transfer time in this embodiment relates to the non-thermal equilibrium mechanism of femtosecond laser processing and is a key control method achieved through subsequent processing formulas, as explained in detail below: Physical background: Femtosecond pulsed lasers have extremely short durations (e.g., 270 fs), much shorter than electron relaxation time (the time it takes for electrons to release energy after absorption) and lattice heat transfer time (the time it takes for heat to diffuse within a material). By controlling the laser parameters and utilizing this time difference, energy can be preferentially absorbed by electrons, forming a non-equilibrium plasma, while the lattice does not have enough time to heat up, thus avoiding thermal damage.

[0031] Among them, single pulse energy E Pulse count N pulse Scanning speed v These parameters collectively control the timing of electron-lattice interactions. For example, a lower scan rate... v It allows for longer energy deposition times to match electronic relaxation; while the cumulative pulse count regulates heat transfer to avoid carbonization (the specification mentions that the traditional method achieves Ra>1.0μm, while this method achieves Ra<0.1μm).

[0032] Implementation method: In practice, the laser first uses the near-infrared band (1010-1070nm) to induce plasma nucleation (dominated by electron relaxation), and then switches to the green / ultraviolet band (510-550nm) to control the void expansion (limited by lattice heat transfer). The timing difference is dynamically optimized through formula parameters. The femtosecond laser-based surface-bulging defocus lens processing method provided in this embodiment directly fabricates a cavity under the lens substrate, and the passively protruding surface substrate automatically forms bulging units. In this embodiment, each bulging unit is set with a curvature that increases as it moves further away from the center of the eye, thus the defocus amount changes continuously. This defocus amount distribution is more suitable for the defocus amount requirements of the human retina, resulting in better correction.

[0033] In this embodiment, a cavity is provided in the lens substrate below some or all of the bulging units, and the cavity is coaxial with the bulging unit; generally, the bulging units located on the periphery of the microlens array are preferably provided with cavities.

[0034] The cavity in this embodiment can serve as a base for secondary processing. Secondary processing can transform the bulging unit into a microporous structure in its original position, allowing for the resetting of the defocus amount based on the same lens after the patient's axial length grows, thereby extending the service life of the defocus lens of this invention. This embodiment first measures the patient's retinal map; the retinal map is divided into multiple regions, and the defocus requirement for each region is measured. Based on the defocus requirement, the radius of curvature of each bulging unit is set, and the radius of curvature is obtained using the following formula:

[0035] in The radius of curvature (mm) of the bulging unit is given. The diameter (mm) of the bulging unit. The height of the bulging unit is (µm).

[0036] In some embodiments, to make the refractive power of the bulging unit more accurate, the present invention considers the influence of the refractive index and diffraction of the lens substrate on the refractive power of the bulging unit, thereby ensuring that the refractive power of the bulging unit satisfies:

[0037] in Let n be the refractive power of the bulging unit, and n be the refractive index of the lens substrate. This is a correction term for cavity diffraction.

[0038] in, Visible light wavelength The correction factor is the one used for calibration. The diameter of the cavity is [missing information]. The diameter of the cavity is [missing information]. The axial depth of the cavity itself (the axial length of the cavity itself, not the length of the cavity from the lens base). The attenuation constant (used to quantify the cavity depth h) is determined by the material of the lens substrate. c The attenuation scale of the effect on diffraction can be understood as the attenuation depth of the diffraction effect, in μm.

[0039] In this embodiment, the cavity is spherical or ellipsoidal in shape, and when embedded under the lens substrate, the axis of rotation is parallel to the lens axis. When the cavity is spherical, h c = When the cavity is an ellipsoid of revolution, h represents the equatorial diameter of the cavity. c This indicates the length of the cavity's axis of rotation.

[0040] To process the cavity more efficiently and ensure it still meets the transmittance requirements after secondary or multiple processing steps, the cavity is formed by using near-infrared laser pulses to nucleate the cavity, inducing initial plasma with laser pulses of 2-200 μJ per pulse, controlling the expansion of the cavity with green or ultraviolet pulses, and precisely controlling the size of the cavity with laser pulses of 1-50 μJ per pulse.

[0041] When machining the cavity, the parameters of the laser pulse satisfy:

[0042] in, E The energy of a single femtosecond laser pulse (µJ) The number of pulses that remain at a single point during focused spot processing. The axial scanning spacing is (µm). The scanning speed of the light spot is (mm / s). For reference scanning speed (mm / s), and Both are attenuation constants determined by the material of the lens substrate (representing the ratio of cavity diameter to attenuation constant and the ratio of cavity depth to attenuation constant, respectively, representing the efficiency of the substrate material in generating cavities and the efficiency and control of material processing in the depth direction under unit laser energy density). The above formula for single-pulse energy... E Pulse count Scanning speed These parameters collectively control the timing of electron-lattice interactions. For example, a lower scan rate... This allows for longer energy deposition times to match electronic relaxation; while the cumulative pulse count regulates heat transfer and avoids carbonization (Ra>1.0μm in traditional methods, Ra<0.1μm in this embodiment).

[0043] Furthermore, to accommodate different lens substrates, after the cavity is formed, a bulging unit naturally forms above the cavity. The height of the bulging unit and the parameters of the laser pulse satisfy the following formula:

[0044] in The bulging efficiency coefficient of the substrate is expressed in µm. 3 / µJ.

[0045] Among the above formulas, the method for controlling various parameters of the laser pulse during cavity processing is proposed, starting from the attenuation constant of the material. This method enables sub-micron level control, achieving high-precision and high-transparency optical processing effects, and is suitable for precision lens manufacturing and micro / nano processing. During continuous / long-pulse laser processing, the thermal accumulation effect of the laser is avoided, which leads to material carbonization, resulting in a surface roughness Ra < 1.0 μm, meeting the optical transparency requirements of ophthalmic lenses (Ra < 0.1 μm). At the same time, the processing method of this invention has the ability to accurately generate internal cavities and can control the air pressure gradient to match the curvature function.

[0046] This invention takes the ratio between the bulging volume of the material and the laser energy as its starting point, and correlates the relationship between various parameters of the laser spot and the bulging height. By establishing a mathematical model, it realizes the accurate prediction and optimized control of laser processing parameters, thereby improving the controllability and repeatability of the bulging unit and cavity forming. This embodiment employs a five-axis galvanometer femtosecond laser processing system. A non-equilibrium plasma is induced beneath the surface of a resin / PC lens using a femtosecond laser, triggering gaseous material decomposition via multiphoton absorption. By controlling the time difference between electron relaxation time and lattice heat transfer time, a submicron-level sealed cavity is generated within the material. The diameter of the cavity processed by a single pulse is controlled to not exceed 0.5-5 μm. The internal gas pressure of the cavity is dynamically controlled by the cumulative number of laser pulses, processing one cavity based on 10-100 pulses. Simultaneously, the surface bulge height is matched with the curvature function, controlling the error to ±3 μm.

[0047] When performing secondary processing on the cavity, it is done based on the data from the initial processing, and femtosecond pulsed laser technology is also used.

[0048] In some embodiments, for ease of processing and optical feature calculation, the cavity of the present invention is configured as spherical or ellipsoidal.

[0049] In some embodiments, to avoid accumulating errors, the spot of the laser pulse is monitored based on a vision system equipped with an artificial intelligence model.

[0050] The artificial intelligence model in this embodiment performs real-time monitoring during laser pulse processing of the cavity. Based on the feedback of plasma luminescence intensity in the video data of the vision system, it monitors the laser pulse. If there is a deviation, it performs real-time focus depth compensation to ensure that the position error of the cavity is <±0.5μm.

[0051] Overall processing steps: A femtosecond laser system (pulse width 270 fs, wavelength 515 nm, repetition rate 50 kHz) was used to fabricate a cavity structure inside a PC lens with a refractive index of 1.60 (diameter 65 mm, center thickness 1.5 mm, surface Ra < 0.01 μm). The plasma cavity was induced by multiphoton absorption: nucleation was triggered by a single pulse of 20-40 μJ in the near-infrared band (1010-1070 nm), and expansion was modulated by 1-50 μJ in the green band (510-550 nm). The cavity parameters conformed to the formula... and Empirical formula for bulge height Achieve target refractive power The height error is ±3μm; the five-axis galvanometer system integrates the Grove Vision AI module (1000fps frame rate) to monitor plasma emission in real time. When the cavity position deviation is >0.5μm, it triggers focus depth compensation within 10ms (range 5-200μm); verified by white light interferometer, a 100μJ pulse generates a cavity with a diameter of (3.2±0.3)μm, the curvature of the bulging unit matches the asymmetric function, the transmittance attenuation is <0.5%, and the surface roughness Ra is <0.1μm.

[0052] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for processing a surface-extruding defocus lens based on femtosecond laser, characterized in that, The surface of the defocus lens is provided with a microlens array composed of a plurality of bulging units; a cavity is pre-set in the lens substrate below at least a part of the bulging units; the cavity supports the bulging unit to be converted into a microporous lens after secondary femtosecond laser irradiation processing; The processing method of the bulging unit provided with the cavity in the lens substrate below is that the cavity is processed in the substrate of the lens based on femtosecond laser; when the cavity is formed, the surface of the lens substrate above the cavity is deformed and protruded to form the bulging unit; The method for processing the cavity is that a non-equilibrium plasma is induced below the substrate surface based on femtosecond laser, and a closed empty package is formed by triggering gaseous decomposition of a predetermined position of the substrate based on multi-photon absorption effect; the closed empty package is expanded to form the cavity after multiple cumulative irradiations of femtosecond laser; during the expansion of the empty package, the air pressure inside the empty package is dynamically controlled based on the cumulative pulse number of femtosecond pulse laser; The gaseous decomposition is realized by adjusting the time difference between the electron relaxation time and the lattice heat transfer time during femtosecond laser irradiation; The diameter of the closed empty package generated by single femtosecond pulse laser irradiation of the lens is not greater than 0.5-5 μm; The defocus amount of the microlens array continuously increases from the ocular part to the temporal part.

2. The femtosecond laser-based surface-extrusion type defocusing lens processing method according to claim 1, characterized by, When the cavity is processed, the cavity is nucleated based on femtosecond pulse laser in the near-infrared waveband, the initial plasma is induced based on laser with single pulse energy of 2-200 μJ, the expansion of the empty package is regulated based on femtosecond pulse laser in the green or ultraviolet waveband, and the size of the cavity is fine controlled based on femtosecond pulse laser with single pulse energy of 1-50 μJ.

3. The femtosecond laser-based surface-extrusion type defocusing lens processing method according to claim 1, characterized by, When the cavity is processed, the parameters of femtosecond pulse laser satisfy the following formula: wherein, is the diameter of the cavity, is the axial depth of the cavity itself, E is the single pulse energy of the femtosecond pulsed laser, is the number of pulses of the femtosecond pulsed laser for a single point processing of the focused spot, is the axial scanning pitch of the femtosecond pulsed laser, is the scanning speed of the spot of the femtosecond pulsed laser, is the reference scanning speed of the femtosecond pulsed laser, and are both attenuation constants determined by the material of the substrate.

4. The femtosecond laser-based surface-extruded, defocusing lens machining method according to claim 3, characterized by, After the cavity is formed, the bulging unit is naturally formed above the cavity, and the height of the bulging unit and the parameters of femtosecond pulse laser satisfy the following formula: wherein is the bulging efficiency factor of the substrate in µm 3 / µJ.

5. The femtosecond laser-based surface-extruded, defocusing lens machining method according to claim 4, characterized in that, The cavity is formed based on 10-100 times of femtosecond pulse laser irradiation.

6. The femtosecond laser-based surface-extruded, defocusing lens machining method according to claim 3, characterized by, The cavity is spherical or spheroidal; when the cavity is spherical, ; when the cavity is spheroidal, denotes the diameter of the equatorial circle of the spheroid, denotes the length of the rotation axis of the spheroid.

7. The femtosecond laser-based surface-extruded, defocusing lens machining method according to claim 1, characterized by, When the cavity is processed, the spot of femtosecond pulse laser is monitored based on a vision system; the vision system is configured with an artificial intelligence model to support the monitoring.

8. The femtosecond laser-based surface-extruded, defocusing lens machining method according to claim 3, characterized by, The geometric constraints of the bulging unit satisfy the following formula: wherein R is the radius of curvature of the protrusion unit, D is the diameter of the protrusion unit, H is the height of the protrusion unit protruding the lens surface.

9. The femtosecond laser-based surface-extruded, defocusing lens machining method according to claim 8, characterized in that, The diopter of the bulging unit satisfies the following formula: wherein D is the dioptric power of the protrusion unit, n is the refractive index of the substrate, D is the dioptric power of the protrusion unit, n is the refractive index of the substrate, wherein is a wavelength of visible light, is a correction factor for calibration, is an attenuation constant determined by the material of the substrate.

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