Elliptical bessel cutter head apparatus

Abstract

The application discloses an elliptical Bessel cutting head device, a direct drive motor is connected with a two-dimensional translation table through an adapter, the two-dimensional translation table is fixed with the cutting head through an adapter block, and the cutting head can be driven to rotate and move in two dimensions; the cutting head comprises a diffraction type conical lens and a focusing mirror arranged along an optical path, and the diffraction type conical lens and the focusing mirror are used for shaping a Gaussian distributed laser beam into an elliptical Bessel distributed light beam; the surface of the diffraction type conical lens element is provided with a microstructure, and the microstructure is in the form of an annular grating structure; the elliptical Bessel light beam is shaped by using the diffraction type conical lens with an elliptical distribution and the focusing mirror, and the Gaussian distributed ultrashort pulse laser is shaped into the elliptical Bessel light beam, and cracks along the direction of the long axis of the ellipse are guided out on sapphire and glass; the cutting head is rotated along a pattern tangent angle, and machining of an arbitrary pattern is realized, and oblique cracks generated in ordinary Bessel beam machining are avoided. The laser transmission efficiency is improved, and the structure is very compact.

Description

TECHNICAL FIELD

[0001] The application relates to an elliptical Bessel cutting head device for shaping a Gaussian distribution of an ultrashort pulse laser into an elliptical Bessel distribution, and belongs to the field of laser processing. BACKGROUND

[0002] Ordinary Bessel beams are prone to produce oblique cracks when processing anisotropic sapphire. Patent No. CN212587848U discloses a laser device which adopts a light blocking strip and other modulation devices to obtain an elliptical cutting beam perpendicular to the modulation device, and controls the cutting direction by rotating the modulation device axially; however, the light blocking strip blocks part of the light beam, thereby reducing the processing energy.

[0003] The application adopts a diffraction type conical lens with an elliptical distribution of no blockage and high transmittance, and combines a focusing mirror to obtain an elliptical Bessel beam, so that cracks along the long axis direction of the ellipse are guided in sapphire and glass, the cutting head is rotated along the tangent angle of the pattern, and processing of an arbitrary pattern is realized. SUMMARY

[0004] The application aims to overcome the deficiencies in the prior art and provide an elliptical Bessel cutting head device.

[0005] The application achieves the above-mentioned purpose by the following technical scheme.

[0006] The elliptical Bessel cutting head device is characterized in that a direct drive motor is connected to a two-dimensional translation table through an adapter, the two-dimensional translation table fixes the cutting head through an adapter block, and the cutting head can be driven to rotate and move in two dimensions; the cutting head comprises a diffraction type conical lens and a focusing mirror arranged along an optical path, and the diffraction type conical lens and the focusing mirror shape a laser beam with a Gaussian distribution into a beam with an elliptical Bessel distribution.

[0007] Further, the elliptical Bessel cutting head device, wherein the surface of the diffraction type conical lens element has a microstructure, the microstructure is a ring-shaped grating structure, and the relationship between the grating period d and the cone angle gamma is:

[0008] d = lambda / sin[gamma(n-1)]

[0009] In the formula, lambda is the wavelength of the laser, and n is the refractive index of the material.

[0010] The cone angle gamma ranges from 0.5 degrees to 20 degrees, and the corresponding top angle ranges from 179 degrees to 140 degrees.

[0011] Further, the elliptical Bessel cutting head device, wherein the microstructure is a ring-shaped grating structure of G order, G is an integer, the width of G steps in each period is d / G, and the relative phases of the G steps in each period successively form a first term 0, a last term 2(G-1)pi / G and a common difference of 2pi / G.

[0012] Further, the elliptical Bessel cutting head device, wherein the microstructure is a G-order annular grating structure, G is an integer, G steps in each period form an arithmetic sequence with a first term of 0, a last term of (G-1)λ / [G(n-1)] and a tolerance of λ / [G(n-1)], and n is a material refractive index.

[0013] Further, the elliptical Bessel cutting head device, wherein the material of the diffractive conic lens is fused quartz glass, BK7 glass or S-LAH64 glass, and the refractive indices of the fused quartz glass, BK7 glass and S-LAH64 glass at 1064 nm at room temperature are 1.4496, 1.5066 and 1.7688 respectively.

[0014] Further, the elliptical Bessel cutting head device, wherein G≥2.

[0015] Further, the elliptical Bessel cutting head device, wherein the diffractive conic lens is coated.

[0016] The elliptical equation, the major axis and the minor axis radii are a and ell×a respectively, and ell represents the roundness of the ellipse, 0%<ell≤100%;

[0017]

[0018] The major axis radius a at the coordinates (x, y),

[0019]

[0020] The step size Δ=d / G of the coordinates x and y, G represents the order, and the matrix length M is:

[0021]

[0022] R represents the radius of the diffractive conic lens element, and the coordinates x and y are formed by an arithmetic sequence with a first term of -(M-1)Δ / 2, a tolerance of Δ and a last term of (M-1)Δ / 2;

[0023] The elliptical Bessel phase Φ,

[0024]

[0025] Converted into the rectangular coordinate system,

[0026]

[0027] The phase is congruent to 2pi, and in each period width d, according to the order G, the phase is divided into G segment regions, and in each period, the region depth constitutes an arithmetic sequence with the first term of 0, the last term of (G-1)l / [G(n-1)], and the tolerance of l / [G(n-1)]; the phase diagram is split into log2G sub-diagrams according to the order, and 2, 4, 8 and 16 orders are 1st, 2nd, 3rd and 4th coating, photoetching, etching and cleaning processes respectively.

[0028] Compared with the prior art, the present application has remarkable advantages and beneficial effects, which are embodied in the following aspects.

[0029] ① The present application adopts the diffraction type conical lens with elliptical distribution, combines with the focusing mirror, shapes the Gaussian distributed ultra-short pulse laser into the elliptical Bessel beam, and leads out the crack along the elliptical long axis direction on the sapphire and glass; the cutting head is rotated along the tangent angle of the pattern, so that the machining of any pattern is realized, and the oblique crack generated by the machining of the ordinary Bessel beam is avoided.

[0030] ② The collimating lens and the light blocking strip and other modulation devices are omitted, so that the laser transmission efficiency is improved, and the structure is relatively compact.

[0031] ③ The diffraction type conical lens has high transmission efficiency and controllable quality repeatability.

[0032] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 : the structural schematic diagram of the device of the present application;

[0035] Figure 2 : the principle schematic diagram of the cutting head;

[0036] Figure 3 : the phase diagram of the elliptical diffraction conical lens with 100% roundness;

[0037] Figure 4 : the phase diagram of the elliptical diffraction conical lens with 90% roundness. DETAILED DESCRIPTION

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, directional and ordinal terms are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] like Figure 1 As shown, the elliptical Bezier cutting head device has a direct drive motor (DD motor) 5 connected to a two-dimensional translation stage 3 via an adapter 4. The two-dimensional translation stage 3 fixes the cutting head 1 via an adapter block 2, screws, and set screws, and can drive the cutting head 1 to rotate and perform two-dimensional translational movements. The cutting head 1 includes a diffractive conical lens 12 and a focusing lens 13 arranged along the optical path, which shape the Gaussian distributed laser beam 11 into an elliptical Bezier distributed beam 14.

[0041] The diffractive conical lens 12 is suitable for wavelengths λ of 1064nm, 1030nm, 532nm, and 515nm. The beam is a short-pulse laser with a pulse width range of 0.1–100ps.

[0042] An elliptical Bezier beam guides cracks along the major axis of an ellipse in sapphire and glass. The cutting head rotates at the angle of the pattern tangent to achieve the processing of arbitrary patterns.

[0043] The diffractive cone lens 12 is made of fused silica glass, BK7 glass, or S-LAH64 glass.

[0044] Microstructures were fabricated on the surface of a diffractive conical lens element 12 using a phase modulator interference lithography apparatus and an inductively coupled plasma etching apparatus.

[0045] The microstructure exhibits a ring-shaped grating structure, and the relationship between the grating period d and the cone angle γ is as follows:

[0046] d = λ / sin[γ(n-1)]

[0047] In the formula, λ is the wavelength of laser, and n is the refractive index of the material; the refractive index is related to the material and wavelength, etc.

[0048] The cone angle γ ranges from 0.5° to 20°, and the corresponding apex angle ranges from 179° to 140°.

[0049] The refractive indices of fused silica glass, BK7 glass and S-LAH64 glass at 1064 nm are 1.4496, 1.5066 and 1.7688 respectively at room temperature.

[0050] The annular grating structures of the diffractive cone lens element are different at different orders. The annular grating structure of the microstructure is G order, G is an integer, the width of G steps in each period is d / G, and the relative phases of the G steps in each period form an arithmetic sequence with the first term 0, the last term 2(G-1)π / G and the common difference 2π / G. The relative depths of the G steps in each period form an arithmetic sequence with the first term 0, the last term (G-1)λ / [G(n-1)] and the common difference λ / [G(n-1)], n is the refractive index of the material; G≥2;

[0051] The diffractive cone lens 12 is coated;

[0052] The ellipse equation has a major axis radius a and a minor axis radius ell×a, and ell represents the roundness of the ellipse, 0%<ell≤100%;

[0053]

[0054] The major axis radius a at the coordinates (x, y) is:

[0055]

[0056] The step length Δ of the coordinates x and y is d / G, G represents the order, and the matrix length M is:

[0057]

[0058] In the formula, R represents the radius of the diffractive cone lens element, the coordinates x and y are formed by an arithmetic sequence with the first term -(M-1)Δ / 2, the common difference Δ and the last term (M-1)Δ / 2;

[0059] The elliptical Bessel phase Φ is:

[0060]

[0061] Convert to the rectangular coordinate system,

[0062]

[0063] The phase is congruent to 2π, and each period width d is divided into G segments according to the order G, and the depth of each period region forms an arithmetic sequence with the first term of 0, the last term of (G-1)λ / [G(n-1)], and the tolerance of λ / [G(n-1)]. The phase diagram is divided into log2G sub-diagrams according to the order, and the 2, 4, 8, and 16 orders are 1st, 2nd, 3rd, and 4th coating, photoetching, etching, and cleaning processes, respectively.

[0064] As shown in Figure 2 , the 10ps laser beam 11 of Gaussian distribution passes through the diffraction cone lens 12 and the focusing mirror 13, and is shaped into an elliptical Bessel beam 14.

[0065] The cone angle is 1°, and the wavelength λ is 1064nm. The corresponding grating period is 135.6μm. For convenience of display, a 4th-order grating is used, and each pixel width is 33.9μm. The pixel sizes of the DOEs with diameters of 25.4mm and 1.27mm are 749×749 and 37×37, respectively. For convenience of display, the DOE with a diameter of 1.27mm is used for description. The calculation of the DOE with a diameter of 25.4mm is the same, and the calculation of the DOE with other cone angles is also the same. The phase diagrams of the elliptical diffraction cone lenses with roundnesses of 100% and 90% are shown in Figure 3 、 Figure 4 The phase diagram of the elliptical diffraction cone lens with a roundness of 100% is center-symmetric, and there are 4 periods in the x and y directions. The phase diagram of the elliptical diffraction cone lens with a roundness of 90% is non-center-symmetric, and there are 4 and 5 periods in the horizontal and vertical directions, respectively. The points with the same phase form an ellipse. There are 4 gray scales in each period, and the phases are 0, 2π / 4, 2π / 4, and 3π / 4, respectively. Fused quartz is used as the material, and the corresponding step depths are 0, 592nm, 1183nm, and 1775nm, respectively.

[0066] The phase diagram is irradiated multiple times by etching. Before each etching, the lens is cleaned with isopropyl alcohol and dried with N2, and then a chromium layer is deposited to prevent ion beam deviation caused by charge deposition. Then, a positive photoresist is deposited.

[0067] The photoresist is irradiated by a phase modulator interference lithography device: NanoCrystal. The line width range is 100nm to 10um, the processing width is 300mm×300mm, the speed is 50-300mm / s, the mask plate can be quickly processed on the photoresist, and the pixel width is 33.9μm by multi-line irradiation processing. An ICP (inductively coupled plasma) device is used for ion beam etching. The etching gas is a mixture of trifluoromethane CHF3, argon Ar, and oxygen O2, and the flow rates are 200, 20, and 5sccm (standard cubic centimeter per minute), respectively. After etching the glass, the chromium layer is removed by a solution.

[0068] In summary, the application adopts the diffraction type conical lens with elliptical distribution, combines the focusing mirror, shapes the Gaussian distributed ultra-short pulse laser into the elliptical Bessel beam, and guides the crack along the elliptical long axis direction on the sapphire and glass; the cutting head is rotated along the pattern tangent angle, the processing of any pattern is realized, and the oblique crack generated by the ordinary Bessel beam processing is avoided.

[0069] The collimating lens and the light blocking strip and other modulation devices are omitted, the laser transmission efficiency is improved, and the structure is relatively compact; the diffraction type conical lens has high transmission efficiency and controllable quality.

[0070] The above merely describes the preferred embodiments of the application and is not used to limit the application, and the application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application. It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0071] The above merely describes the preferred embodiments of the application and is not used to limit the application, and the application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application. It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0072] It should be noted that, in the present document, the relative terms such as first and second and the like are used merely to differentiate one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element(s).

Claims

1. An elliptical Bézier cutting head apparatus, characterized by: The direct drive motor (5) is connected with the two-dimensional translation table (3) through the adapter (4), the two-dimensional translation table (3) is fixed with the cutting head (1) through the adapter block (2), and the cutting head (1) can be driven to rotate and move in two dimensions; the cutting head (1) comprises a diffraction type conical lens (12) and a focusing mirror (13) arranged along an optical path, and a Gaussian distributed laser beam (11) is shaped into an elliptical Bessel distributed light beam (14); The diffractive conical lens (12) element surface has a microstructure, the microstructure is in the form of an annular grating structure, and the grating period d is in a relationship with the conical angle Gamma ​ d = Lambda / sin[ Gamma ( n -1)] wherein Lambda is the laser wavelength, n is the material refractive index; Conical angle Gamma The range is 0.5° to 20°, and the corresponding vertex angle range is 179° to 140°. The microstructure is G The annular grating structure has G is an integer, and each period has G The width of each step is d / G Each period has G The relative phases of the steps successively form an arithmetic sequence with a first term of 0, a last term of 2( G -1)π / G , and a tolerance of 2π / G .

2. The elliptical Bézier cutting head apparatus of claim 1, wherein: The microstructure is G a stepped annular grating structure, G is an integer, and each period has G a relative depth of the steps forms an arithmetic sequence with the first term being 0, the last term being G -1 Lambda / G ( n -1)] and a tolerance of Lambda / [ G ( n -1)]. n is the refractive index of the material.

3. The elliptical Bézier cutting head apparatus of claim 1, wherein: The material of the diffraction type conical lens (12) is fused quartz glass, BK7 glass or S-LAH64 glass, and the refractive indexes of the fused quartz glass, the BK7 glass and the S-LAH64 glass at 1064 nm are 1.4496, 1.5066 and 1.7688 respectively at room temperature.

4. The elliptical Bézier cutting head apparatus of claim 1 or 2, wherein: G ≥ 2。 5. The elliptical Bézier cutting head apparatus of claim 1, wherein: The diffraction type conical lens (12) is coated; The equation of the ellipse, with the radii of the major and minor axes being respectively... a and Ell x a , ell Indicates the roundness of an ellipse, 0% < ell ≤100%; coordinate( x , y Major axis radius at ) a , coordinate x and y Step size Δ= d / G , G Indicates the order and length of the matrix. M for: R Represents the radius of the diffractive conical lens element, coordinates x and y All by -( M -1)Δ / 2 is the first term, Δ is the tolerance, ( M -1)Δ / 2 is an arithmetic sequence with the last term as the first term; Elliptical bessel phase Phi , a ∈ [0, R ]; Convert to rectangular coordinate system, Phase is congruent to 2π, each cycle width d In accordance with the order G Divided into G Segment area, each cycle area depth constitutes the first term is 0, the last term is G -1)λ / [ G ( n -1)] and the tolerance is Lambda / [ G ( n -1)] arithmetic sequence; phase diagram according to the order is split into log2 G Subgraph, 2, 4, 8, 16 order respectively 1, 2, 3 and 4 times of coating, photoetching, etching and cleaning process.

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