Optical element laser cutting method and system

Abstract

The present invention relates to the field of laser cutting technology, and discloses a method and system for laser cutting of optical elements, comprising placing an optical element so that the second surface of a substrate faces the direction of laser incidence; configuring a central laser beam to focus inside the substrate and near the interface with the film layer; configuring an annular laser beam to focus inside the film layer, wherein the annular laser beam acts on the film layer to form an annular modified zone, wherein the annular modified zone inhibits the transfer of heat from the substrate to the film layer; controlling the pulse of the annular laser beam to be 0.1ms to 0.3ms earlier than the pulse of the central laser beam; and moving the optical element or synchronously moving the annular laser beam and the central laser beam along the cutting path to cut the optical element. The method and system of the present invention, through the coordination and timing control of dual laser beams, achieve active protection of the film layer during the laser cutting process, thereby improving the overall cutting quality and reliability.

Description

Technical Field

[0001] The present invention relates to the field of laser cutting technology, and in particular to a method and system for laser cutting of optical elements. Background Art

[0002] Laser cutting is used for precision cutting and microstructure processing of optical components. The precision cutting of composite optical components (composed of a substrate and functional film layers, such as anti-reflection films, reflective films, or green light films) has always faced major technical challenges. The core challenge lies in how to cut the substrate with high precision while avoiding peeling, cracking, or optical performance degradation of the film layer due to thermal stress or mechanical impact.

[0003] For example, the high temperatures (>1000°C) generated by laser cutting the substrate cause localized thermal expansion of the film through heat conduction. The different thermal expansion coefficients of the film and substrate create shear stress at the interface during rapid temperature rise, leading to delamination, damage, or warping of the film. Furthermore, stress waves generated by substrate cutting are transmitted to the film, causing microcracks to propagate within the film. Summary of the Invention

[0004] To this end, the purpose of the present invention is to solve the problems of interface peeling, damage and film warping caused by the different thermal expansion coefficients between the film layer and the substrate in the prior art, and to provide a laser cutting method and system for optical elements. Through the coordination and timing control of dual laser beams, active protection of the film layer is achieved during the laser cutting process, thereby improving the overall cutting quality and reliability.

[0005] In a first aspect, to solve the above technical problems, the present invention provides a method for laser cutting an optical element, wherein the optical element includes a substrate and a film layer attached to a first surface of the substrate, and the method includes:

[0006] The optical element is placed so that the second surface of the substrate faces the incident direction of the laser; the first surface and the second surface are two opposite surfaces in the thickness direction of the substrate;

[0007] Configuring a central laser beam to focus inside the substrate and near the interface between the film layer and the substrate;

[0008] An annular laser beam is configured to focus inside the film layer, with the central laser beam coinciding with the laser beam axis of the annular laser beam; the annular laser beam acts on the film layer to form an annular modified zone, wherein the annular modified zone inhibits heat transfer from the substrate to the film layer;

[0009] Controlling the pulse of the annular laser beam to be 0.1 ms to 0.3 ms ahead of the pulse of the central laser beam;

[0010] The optical element is moved or the annular laser beam and the central laser beam are synchronously moved along a cutting path to cut the optical element.

[0011] In one embodiment of the present invention, the annular laser beam is focused inside the film layer near the film-substrate interface; wherein the distance between the focus point and the interface is (1 / 3~1 / 2)×H, where H represents the thickness of the film layer.

[0012] In one embodiment of the present invention, the width of the annular modified zone is 20% to 40% of the thickness of the film layer.

[0013] In one embodiment of the present invention, an auxiliary laser beam is further configured, wherein the auxiliary laser beam is used to perform scanning annealing on the film layer within a range of 0.1 to 0.5 mm on both sides of the cutting path.

[0014] In one embodiment of the present invention, it further includes spraying cooling gas along the cutting path during the cutting process, and the spray angle θ of the cooling gas satisfies 20°≤θ≤60°; the spray angle θ is the angle between the spray center line and the laser beam axis.

[0015] In one embodiment of the present invention, the cooling gas is a mixture of argon and helium, and the volume of helium accounts for 10% to 30%.

[0016] In one embodiment of the present invention, the method further includes adjusting the spray angle θ according to the curvature radius of the cutting path, which includes: if the curvature radius is greater than or equal to a first reference curvature radius, setting the spray angle θ to a fixed angle between 25° and 35°; if the curvature radius is greater than or equal to a second reference curvature radius and less than the first reference curvature radius, setting the spray angle θ according to the following method:

[0017] ;

[0018] If the curvature radius is smaller than the second reference curvature radius, the injection angle θ is set to a fixed angle between 55° and 60°;

[0019] It represents the first reference curvature radius, which is 4~6mm; r represents the actual curvature radius.

[0020] In one embodiment of the present invention, the method further includes obtaining the temperature of the annular modified zone; if the temperature of the annular modified zone exceeds the modification threshold temperature of the film layer, adjusting the flow rate of the cooling gas according to the following method:

[0021] ;

[0022] Q represents the cooling gas flow rate after adjustment; Q0 represents the cooling gas flow rate before adjustment; T represents the temperature of the annular reforming zone; Indicates the film modification threshold temperature; Indicates the flow gain coefficient, with a value of 0.3~0.6.

[0023] In one embodiment of the present invention, the film modification threshold temperature is determined by performing a step-by-step laser irradiation experiment on the film, and the highest temperature when the refractive index change rate of the film is less than or equal to 1% is the modification threshold temperature.

[0024] In a second aspect, based on the same inventive concept, the present invention provides an optical element laser cutting system for implementing the optical element laser cutting method, comprising:

[0025] A first pulsed laser generator is used to generate a central laser beam focused inside the substrate and close to the interface between the film layer and the substrate;

[0026] a second pulsed laser generator, configured to generate an annular laser beam focused inside the film layer, wherein the central laser beam coincides with the laser beam axis of the annular laser beam; the annular laser beam acts on the film layer to form an annular modified zone, wherein the annular modified zone inhibits heat transfer from the substrate to the film layer;

[0027] a controller connected to the first pulse laser generator and the second pulse laser generator, configured to control the pulse of the annular laser beam to be 0.1 ms to 0.3 ms earlier than the pulse of the central laser beam;

[0028] The motion platform is used for carrying the optical element and moving it along a cutting path to cut the optical element.

[0029] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0030] The optical element laser cutting method and system described in the present invention realizes active protection of the film layer during the laser cutting process through dual laser beam coordination and timing control, improves the overall cutting quality and reliability, and effectively solves the problems of interface peeling, damage and film warping caused by the different thermal expansion coefficients of the film layer and the substrate.

[0031] Among them, the annular laser beam is focused on the internal area of ​​the film layer, forming an annular modified zone in the film layer. This modified zone can effectively block the excessive transfer of heat generated during the cutting process of the central laser beam to the film layer, thereby significantly reducing the shear stress generated by the thermal expansion mismatch at the interface between the film layer and the substrate, avoiding interface cracking or film peeling.

[0032] The annular laser beam and the central laser beam are designed to coincide with each other in their axes. By controlling the sequence of pulse times, the annular laser beam is irradiated 0.1 to 0.3 ms earlier than the central laser beam. As a result, a thermal buffer zone is formed in the film before the central laser beam heats it. This thermal buffer mechanism reduces the instantaneous temperature rise of the film, minimizes thermal deformation of the film, and significantly reduces warping caused by non-uniform thermal expansion and contraction.

[0033] The central laser beam is focused inside the substrate, near the interface of the film layer, avoiding direct action on the film layer. This effectively decouples the cutting behavior of the substrate from the film layer thermally. In this way, while the substrate is effectively cut, the film layer is hardly affected by destructive heat, fundamentally solving the problem of film damage when cutting optical components. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 Schematic diagram of the structure of an optical element for laser cutting in an embodiment of the present invention;

[0036] Figure 2 Flowchart of the optical element laser cutting method in a preferred embodiment of the present invention;

[0037] Figure 3 4 is a block diagram of an optical element laser cutting system in a preferred embodiment of the present invention.

[0038] Description of the accompanying drawings: 10-substrate, 20-film layer. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0040] The purpose of the embodiments of the present invention is to solve the problems of interface peeling, damage and film warping caused by the different thermal expansion coefficients of the film layer and the substrate during laser cutting of composite optical elements. Figure 1 As shown, the optical element to be laser cut includes a substrate 10 and a film layer 20 attached to the first surface of the substrate 10. The first surface is one surface in the thickness direction of the substrate, and the other surface in the thickness direction is the second surface.

[0041] Example 1: Reference Figure 2 As shown, an embodiment of the present invention discloses a method for laser cutting an optical element, comprising:

[0042] S100, placing the optical element so that the second surface of the substrate faces the incident direction of the laser;

[0043] S200, configuring a central laser beam to focus inside the substrate and near the film-substrate interface; configuring an annular laser beam to focus inside the film, with the central laser beam and the laser beam axis of the annular laser beam coinciding; the annular laser beam acts on the film to form an annular modified zone, the annular modified zone inhibiting heat transfer from the substrate to the film;

[0044] S300, controlling the pulse of the annular laser beam to be 0.1 ms to 0.3 ms earlier than the pulse of the central laser beam;

[0045] S400 , moving the optical element or synchronously moving the annular laser beam and the central laser beam along a cutting path to cut the optical element.

[0046] In specific application scenarios, the optical element with a film layer is fixed on a controllable motion platform to ensure that the film layer faces downward and the second surface of the substrate faces upward, that is, toward the direction of laser incidence; the optical element can be fixed with the help of vacuum adsorption or mechanical clamping to ensure the stability and precise positioning of the optical element during the cutting process; at the same time, it provides a basis for precise control of the focusing depth, which is conducive to the formation of an ideal thermal stress distribution of the laser energy inside the substrate.

[0047] The central laser beam vaporizes the substrate material with high energy. It uses a 355nm wavelength ultraviolet laser beam, which is suitable for transparent substrates such as fused quartz and borosilicate glass. The power is 5~20W, the pulse frequency is 50~100kHz, the pulse width is 10~100ns, and the energy density is 5~10J / cm 2 Focusing position: inside the substrate, ensuring that the interface is not directly damaged when the substrate is cut; the focusing position is close to the film-substrate interface, for example, the focusing depth is about 10~50um away from the film interface, so that the cutting behavior of the substrate is thermally effectively decoupled from the film. In this way, while the substrate is effectively cut, the film is almost not affected by destructive heat, fundamentally solving the problem of film damage when cutting optical components.

[0048] Ring laser beam is used for film modification. It uses an infrared laser beam with a wavelength of 1064nm. It is suitable for deep film layers (greater than 3um) or highly reflective film systems (such as metal coatings). The power is 1~5W, the pulse width is 5~50ns, and the pulse width is 100~500kHz, the pulse width is 5~50ns, and the energy density is 0.5~3J / cm 2The energy density ratio of the central laser beam to the annular laser beam is 3:1 to 5:1; the focal position is within the film layer. The annular laser beam focuses on the inner area of ​​the film layer, forming an annular modified zone within the film layer. This modified zone effectively blocks excessive heat transfer from the central laser beam during cutting to the film layer, significantly reducing the shear stress generated by thermal expansion mismatch at the interface between the film layer and the substrate, thereby preventing interfacial cracking or film delamination.

[0049] The mechanism by which the annular laser beam acts on the inside of the film to form an annular modified zone is as follows:

[0050] The spot of the annular laser beam is distributed in a hollow ring shape, and its energy is concentrated in the annular area, causing the film material to undergo amorphization (such as SiO2 film from crystalline to amorphous state) or grain refinement (such as Ta2O5 grain size reduced from 50nm to 10nm), or both simultaneously. The concentrated energy causes the local temperature to rise to the softening point of the film material, but below the vaporization point. Thermal stress induces atomic rearrangement to form a densified structure. The thermal conductivity of this densified structure is reduced to 40% to 60% of the original film layer, acting as a heat diffusion barrier, thereby inhibiting the transfer of heat from the cutting substrate to the film layer. It should be noted that this densification structure only increases the density of the film layer, without any quality loss.

[0051] The central laser beam is focused on the substrate side of the film-substrate interface with an energy density of 5~10J / cm 2 The substrate is partially vaporized, and the high-pressure steam generated by the vaporization pushes the film layer to be neatly peeled off along the modified area instead of directly vaporizing the film layer.

[0052] The pulse of the annular laser beam is 0.1ms to 0.3ms ahead of the pulse of the central laser beam. In other words, the annular laser beam pre-irradiates the internal area of ​​the film layer 0.1 to 0.3ms ahead of the central laser beam. As a result, a thermal buffer area is formed in the film layer before the central laser beam heats it. This thermal buffer mechanism reduces the instantaneous temperature rise of the film layer, reduces the thermal deformation of the film layer, and significantly reduces the warping of the film layer caused by non-uniform thermal expansion and contraction.

[0053] The optical element laser cutting method described in the present invention realizes active protection of the film layer during the laser cutting process through the coordination and timing control of dual laser beams, improves the overall cutting quality and reliability, and effectively solves the problems of interface peeling, film warping and damage caused by the different thermal expansion coefficients of the film layer and the substrate.

[0054] During laser cutting, the energy absorbed by the substrate is mainly transmitted to the film layer through the film layer-substrate interface. In order to maximize the blocking of the heat diffusion path, the annular laser beam in the embodiment of the present invention is focused at a distance within the film layer and close to the film layer-substrate interface. The area near the interface is the area with the strongest bonding force between the film layer and the substrate. The modification of the annular laser beam here can preferentially weaken the bonding force, making it easier for the steam pressure of the subsequent central laser beam to push the film layer to be cut.

[0055] Specifically, the distance between the focus point of the annular laser beam and the interface is (1 / 3 to 1 / 2) × H, where H represents the film thickness. 1 / 3 × H is optimal, close enough to the interface to block heat flow and maximize the heat diffusion path. Finite element analysis shows that when the focus depth is less than 1 / 4 of the thickness, the substrate temperature rises by more than 10%. When the focus depth exceeds 1 / 2 of the thickness, the thermal blocking effect decreases sharply.

[0056] Before processing, the thickness H of the optical component's film layer is non-contactly measured using optical interferometry or ellipsometers. This thickness data is recorded and input as the basis for laser focus depth control. The laser control system automatically calculates the focus depth of the annular laser beam based on the measured film thickness H. For example, if the film thickness H = 3μm, the focus depth is set to 1μm to 1.5μm. A high-numerical-aperture focusing lens system or spatial light modulator is used to precisely control the focus depth of the annular laser beam.

[0057] By properly setting the modified zone width, a continuous and stable thermal buffer zone can be formed within the film, suppressing local stress concentration and heat conduction. A larger width enhances the modified zone's ability to suppress heat flow, making it suitable for applications with higher heat loads or thicker films. A smaller width narrows the modified zone, minimizing the impact on the film's overall performance and preserving its optical consistency. In an embodiment of the present invention, the width of the annular modified zone ranges from 20% to 40% of the film thickness. A modified zone width of 20% × H is suitable for thinner films with high optical performance requirements, maximizing optical performance. A modified zone width of 40% × H is suitable for thicker films or materials with high thermal conductivity, providing a stronger thermal buffer and suppression, effectively reducing temperature rise beneath the film. The modified zone's increased mechanical stability helps maintain cutting path continuity and film integrity. By flexibly selecting the modified zone width, a balance can be achieved between film protection and cutting efficiency, meeting the combined requirements of film integrity and thermal control in different application scenarios.

[0058] Furthermore, it also includes configuring an auxiliary laser beam, which is used to perform scanning annealing on the film layer within the range of 0.1~0.5mm on both sides of the cutting path. In specific application scenarios, wavelengths with high absorption by the film layer and low absorption by the substrate (such as 355nm for SiO2 film or 1064nm for glass substrate) are preferably selected, and the energy density is 10%~30% of the central laser beam. The purpose of pre-annealing treatment by the auxiliary laser beam is to eliminate the residual stress of the film layer by low-temperature annealing within the range of 0.1~0.5mm on both sides of the cutting path, thereby reducing the thermal sensitivity during subsequent cutting. The mechanism of action is: heating to the glass transition temperature of the film material, promoting the rearrangement of atoms in the film layer, and filling microcracks / voids. At the same time, a gradual temperature gradient is formed on the periphery of the cutting area to prevent the heat of the main cutting laser from suddenly diffusing to the untreated area.

[0059] Furthermore, in order to cool down and remove slag, the laser cutting system is usually equipped with a cooling gas injection device to inject cooling gas along the cutting path. The injected cooling gas reduces the temperature of the heat-affected zone through forced convection heat transfer. At the same time, the gas injection can blow away the melt generated by the laser to prevent re-solidification and cause edge burrs. In conventional laser cutting, gas injection is mostly used at a coaxial (0°) or vertical angle (90°) for slag removal or oxidation prevention in metal cutting. The optical element laser cutting method of the embodiment of the present invention also includes injecting cooling gas along the cutting path during the cutting process. The injection angle is different from the conventional angle. The cooling gas is injected at an inclined angle. The injection angle θ of the cooling gas satisfies 20°≤θ≤60°, and the injection angle θ supports dynamic adjustment; the injection angle θ is the angle between the injection centerline and the axis of the laser beam.

[0060] Specifically, when the injection angle θ is 20°~45°, the cooling gas forms a directional airflow barrier along the cutting path, preferentially cooling the area about to be acted upon by the laser, reducing heat accumulation in the film layer before laser irradiation. Compared with the same-direction injection at 0°, the gas lags behind the laser action point, and the cooling effect is delayed. When the injection angle θ is 46°~60°, the larger-angle injection can push the melt and plasma produced by the cutting back to the cut area to avoid the slag re-attaching to the edge of the film layer and causing secondary thermal damage. When the injection angle θ is less than 20°, the gas cannot effectively cover the cutting side wall, and the heat of the substrate is conducted to cause the edge of the film layer to heat up; when the injection angle θ is greater than 60°, the vertical component of the airflow is too large, blowing the film layer in the uncut area, causing vibration or local uneven cooling. 20°≤θ≤60° can balance the needs of lateral cooling (protecting the film layer) and longitudinal penetration (cooling the substrate).

[0061] The cooling gas is a mixture of argon and helium, with helium accounting for 10% to 30% by volume. Helium's high thermal conductivity accelerates heat transfer and reduces the temperature of the heat-affected zone. Argon's high density maintains the impact of the airflow, ensuring melt removal. By adjusting the helium volume percentage to 10% to 30%, a balance between cooling efficiency and melt removal is achieved.

[0062] Furthermore, the method further includes adjusting the spray angle θ according to the curvature radius of the cutting path, which includes: further including adjusting the spray angle θ according to the curvature radius of the cutting path, which includes:

[0063] If the curvature radius is greater than or equal to the first reference curvature radius, the injection angle θ is set to a fixed angle between 25° and 35°;

[0064] If the curvature radius is greater than or equal to the second reference curvature radius and smaller than the first reference curvature radius, the injection angle θ is set according to the following method:

[0065] ;

[0066] The first reference curvature radius is 4~6mm; r represents the actual curvature radius;

[0067] If the curvature radius is smaller than the second reference curvature radius, the injection angle θ is set to a fixed angle between 55° and 60°.

[0068] In specific application scenarios, the first and second base curvature radii can be set to 5mm and 3mm, respectively. When the curvature radius is greater than or equal to 5mm, it approaches a straight line segment to ensure a balance between stable cooling and slag removal, and a fixed angle between 25° and 35° is determined. The optimal injection angle θ is 30°. When the curvature radius is less than 5mm and greater than or equal to 3mm, the injection angle increases linearly with the decrease in the curvature radius, reaching a maximum of 45°. When the curvature radius is less than 3mm, it approaches an acute angle area, requiring maximum sidewall cooling, and the injection angle θ is determined to be fixed between 55° and 60°.

[0069] Furthermore, overheating of the modified zone may cause the densified structure to collapse, and thermal stress concentration may induce radial cracks in the film layer. To address this problem, the optical element laser cutting method according to an embodiment of the present invention further includes obtaining the temperature of the annular modified zone; if the temperature of the annular modified zone exceeds the modification threshold temperature of the film layer, adjusting the flow rate of the cooling gas according to the following method:

[0070] ;

[0071] Q represents the cooling gas flow rate after adjustment; Q0 represents the cooling gas flow rate before adjustment; T represents the temperature of the annular reforming zone; Indicates the film modification threshold temperature; Indicates the flow gain coefficient, with a value of 0.3~0.6.

[0072] In specific application scenarios, during the laser cutting process, the temperature of the annular modified zone is measured by an infrared thermal imager and compared with the predetermined modification threshold temperature. If the temperature of the modified zone exceeds the modification threshold temperature, the cooling gas flow rate is increased to enhance cooling and prevent overheating of the modified zone; and the cooling gas flow rate is dynamically adjusted based on a certain method to ensure that the modified zone is always in the optimal temperature window to stabilize the thermal conductivity.

[0073] According to the cooling gas flow rate adjustment formula, the flow rate increase and the over-temperature amplitude (T- ) is proportional to; the denominator Normalization processing eliminates the influence of material differences; flow gain coefficient Boundary control is performed, and the value is less than or equal to 0.6 to prevent turbulence caused by sudden flow changes.

[0074] Specifically, the film modification threshold temperature T* is the maximum tolerable temperature of the film material without significant degradation of optical properties, which is determined by performing a step-by-step laser irradiation experiment on the film, and the highest temperature when the refractive index change rate of the film is less than or equal to 1% is the modification threshold temperature.

[0075] In the specific implementation process, a laser source, a temperature control platform, a refractive index measuring instrument and a film sample are required. The energy density gradient is from 0.1J / cm 2 Initially, 0.05 J / cm 2 The step size was increased until visible damage to the film was observed. Five pulses were applied at each energy density. The steady-state temperature was recorded with an infrared thermometer, and the refractive index of the irradiated area was measured with an ellipsometer. The highest temperature corresponding to the refractive index change of 1% or less was defined as the modification threshold temperature.

[0076] Example 2: Reference Figure 3 As shown, an embodiment of the present invention discloses an optical element laser cutting system for implementing the optical element laser cutting method, comprising:

[0077] A first pulsed laser generator is used to generate a central laser beam focused inside the substrate and close to the interface between the film layer and the substrate;

[0078] a second pulsed laser generator, configured to generate an annular laser beam focused inside the film layer, wherein the central laser beam coincides with the laser beam axis of the annular laser beam; the annular laser beam acts on the film layer to form an annular modified zone, wherein the annular modified zone inhibits heat transfer from the substrate to the film layer;

[0079] a controller connected to the first pulse laser generator and the second pulse laser generator, configured to control the pulse of the annular laser beam to be 0.1 ms to 0.3 ms earlier than the pulse of the central laser beam;

[0080] The motion platform is used for carrying the optical element and moving it along a cutting path to cut the optical element.

[0081] The optical element laser cutting system described in the embodiment of the present invention is based on the same inventive concept as the above embodiment 1 and is used to execute the optical element laser cutting method in embodiment 1. The two have the same technical effects and will not be described in detail here.

[0082] In summary, the optical element laser cutting method and system described in the embodiments of the present invention realize active protection of the film layer during the laser cutting process through the coordination and timing control of dual laser beams, improve the overall cutting quality and reliability, and effectively solve the interface peeling, damage and film warping problems caused by the different thermal expansion coefficients of the film layer and the substrate.

[0083] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for laser cutting an optical element, wherein the optical element comprises a substrate and a film layer attached to a first surface of the substrate, characterized in that: The method includes, The optical element is placed so that the second surface of the substrate faces the incident direction of the laser; the first surface and the second surface are two opposite surfaces in the thickness direction of the substrate; Configuring a central laser beam to focus inside the substrate and near the interface between the film layer and the substrate; configuring an annular laser beam to focus inside the film layer, with the central laser beam coinciding with the laser beam axis of the annular laser beam; The annular laser beam acts on the film layer to form an annular modified zone, and the annular modified zone inhibits the heat of the substrate from being transferred to the film layer; Controlling the pulse of the annular laser beam to be 0.1 ms to 0.3 ms ahead of the pulse of the central laser beam; The optical element is moved or the annular laser beam and the central laser beam are synchronously moved along a cutting path to cut the optical element.

2. The optical element laser cutting method according to claim 1, wherein: The annular laser beam is focused in the film layer near the film layer-substrate interface; wherein the distance between the focus point and the interface is (1 / 3~1 / 2)×H, where H represents the thickness of the film layer.

3. The optical element laser cutting method according to claim 1, wherein: The width of the annular modified zone is 20% to 40% of the thickness of the film layer.

4. The optical element laser cutting method according to any one of claims 1 to 3, characterized in that: The method further includes configuring an auxiliary laser beam, wherein the auxiliary laser beam is used to perform scanning annealing on the film layer within a range of 0.1 to 0.5 mm on both sides of the cutting path.

5. The optical element laser cutting method according to claim 1, wherein: It also includes spraying cooling gas along the cutting path during the cutting process, and the spray angle θ of the cooling gas satisfies 20°≤θ≤60°; the spray angle θ is the angle between the spray center line and the laser beam axis.

6. The optical element laser cutting method according to claim 5, wherein: The cooling gas is a mixture of argon and helium, and the volume of helium accounts for 10% to 30%.

7. The optical element laser cutting method according to claim 5, wherein: The method further includes adjusting the spray angle θ according to the curvature radius of the cutting path, which includes: If the curvature radius is greater than or equal to the first reference curvature radius, the injection angle θ is set to a fixed angle between 25° and 35°; If the curvature radius is greater than or equal to the second reference curvature radius and smaller than the first reference curvature radius, the injection angle θ is set according to the following method: ； If the curvature radius is smaller than the second reference curvature radius, the injection angle θ is set to a fixed angle between 55° and 60°; It represents the first reference curvature radius, which is 4~6mm; r represents the actual curvature radius.

8. The optical element laser cutting method according to claim 5 or 7, characterized in that: Also includes, obtaining the temperature of the annular modification zone; If the temperature of the annular modification zone exceeds the modification threshold temperature of the film layer, the flow rate of the cooling gas is adjusted according to the following method: ； Q represents the cooling gas flow rate after adjustment; Q0 represents the cooling gas flow rate before adjustment; T represents the temperature of the annular reforming zone; Indicates the film modification threshold temperature; Indicates the flow gain coefficient, with a value of 0.3~0.

6.

9. The optical element laser cutting method according to claim 8, wherein: The modification threshold temperature of the film layer is determined by performing a step-by-step laser irradiation experiment on the film layer, and the highest temperature when the refractive index change rate of the film layer is less than or equal to 1% is the modification threshold temperature.

10. An optical element laser cutting system, configured to implement the optical element laser cutting method according to any one of claims 1 to 9, characterized in that: include, A first pulsed laser generator is used to generate a central laser beam focused inside the substrate and close to the interface between the film layer and the substrate; a second pulsed laser generator, configured to generate an annular laser beam focused inside the film layer, wherein the central laser beam coincides with the laser beam axis of the annular laser beam; The annular laser beam acts on the film layer to form an annular modified zone, and the annular modified zone inhibits the heat of the substrate from being transferred to the film layer; a controller connected to the first pulse laser generator and the second pulse laser generator, configured to control the pulse of the annular laser beam to be 0.1 ms to 0.3 ms earlier than the pulse of the central laser beam; The motion platform is used for carrying the optical element and moving it along a cutting path to cut the optical element.

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