CN115502552A - Bessel laser processing head with double focal depth - Google Patents
Bessel laser processing head with double focal depth Download PDFInfo
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- CN115502552A CN115502552A CN202211108220.7A CN202211108220A CN115502552A CN 115502552 A CN115502552 A CN 115502552A CN 202211108220 A CN202211108220 A CN 202211108220A CN 115502552 A CN115502552 A CN 115502552A
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- liquid crystal
- light
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- bessel
- crystal flat
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/0648—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising lenses
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- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Laser Beam Processing (AREA)
Abstract
A double depth of focus Bessel laser machining head comprising an axicon for converting an incident laser beam into a Bessel beam and a lens group for focusing the beam onto a machining surface, a beam translation ring being provided between the axicon and the lens group; the cone lens is a liquid crystal flat cone lens, the liquid crystal flat cone lens converts an incident laser beam into two divergent and convergent annular light beams, and the two annular light beams enter the lens group after passing through the light beam translation ring, so that focal depth regions of the two annular light beams are spliced together. The Bessel laser processing head with double focal depth provided by the invention can form longer focal depth under the condition of giving the same laser characteristics by matching the liquid crystal flat cone lens with the light beam translation ring, and the maximum focal depth can be twice of that of a common laser processing head, so that the synchronous improvement of the cutting processing efficiency and the processing quality can be realized.
Description
Technical Field
The invention relates to the technical field of laser processing equipment, in particular to a Bessel laser processing head with double focal depth.
Background
The laser processing is a processing process in which a laser beam acts on the surface of an object to change the shape or the property of the object, and the essence is that the laser transmits energy to a processed material to cause the physical or chemical change of the processed material, so that the purpose of processing is achieved. The laser processing technology mainly has the application forms of laser cutting, laser marking, laser welding, laser engraving, laser punching and the like, and plays an important role in the industries of machine manufacturing, automobiles, aerospace, electronic chips, buildings and the like.
In a laser cutting apparatus, one of the most important core components of a laser processing head, and at present, the most used laser processing head is a bessel laser processing head, as shown in fig. 1, the principle of which is to convert an incident laser beam 1 into an annular beam by a refractive type axicon 2, generate a bessel beam near the focal point of the axicon, and then focus the bessel beam on a processing surface by a lens group 3 for cutting processing. The focal depth of a common Bessel laser processing head is short, when a product with the thickness larger than the focal depth is cut, multiple scanning and cutting operations are required, and the processing efficiency is low; and the coincidence of the scanning paths in each cutting process needs to be ensured, and high technical requirements on the operation precision are also provided.
In view of this, the present application aims to provide a bessel laser processing head with a long focal depth, which can reach twice the focal depth of a common laser processing head, and improve the cutting efficiency and the cutting quality.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the Bessel laser processing head with double focal depth, under the condition of the same laser characteristics, the focal depth of the Bessel laser processing head is twice that of a common laser processing head, and the synchronous improvement of the cutting processing efficiency and the processing quality can be realized.
The technical scheme of the invention is as follows: a double depth of focus Bessel laser machining head comprising an axicon for converting an incident laser beam into a Bessel beam and a lens group for focusing the beam onto a machining surface, a beam translation ring being provided between the axicon and the lens group; the cone lens is a liquid crystal flat cone lens, the liquid crystal flat cone lens converts an incident laser beam into two divergent annular light beams and two convergent annular light beams, the two annular light beams enter the lens group after passing through the light beam translation ring, and finally the focal depth areas of the two annular light beams are spliced together.
Further, the liquid crystal flat cone lens comprises a substrate and a liquid crystal layer arranged between the two substrates.
Further, the phase modulation of the incident light by the liquid crystal layer based on the fast axis alignment of the liquid crystal molecules meets the following requirements:
a) When the incident light is right-handed circularly polarized light, the polarization state is converted into left-handed circularly polarized light after being modulated by the liquid crystal flat cone lens, the left-handed circularly polarized light carries a focusing cone phase, a non-diffraction region is formed after focusing, the light beam generated in the region has Bessel light beam characteristics, and annular light beams are formed after continuous transmission;
b) When the incident light is left-handed circularly polarized light, the polarization state is converted into right-handed circularly polarized light after being modulated by the liquid crystal flat cone lens, and the right-handed circularly polarized light carries a divergent cone phase, and an annular light beam is directly formed after diffraction;
c) When the incident light is linearly polarized light, the left and right circular polarization components of the incident light are modulated by the liquid crystal flat cone lens to respectively obtain focused and divergent cone phases, and the focused and divergent cone phases are respectively diverged and directly diverged, and divergence and convergence angles are equal;
d) When the incident light is elliptical polarized light, the left and right circular polarization components have different amplitudes, the diffraction process of the transmitted light is the same as that of the incident light when linearly polarized light is incident, but the intensity of the transmitted light is related to the ellipticity;
e) When the incident light is unpolarized light, it is a superposition of all the above.
Furthermore, the light beam translation ring is annular plate glass with a conical through hole in the center.
Furthermore, the side of the light beam translation ring with the smaller diameter of the conical through hole is opposite to the liquid crystal flat conical lens.
Further, the light beam translation ring is taperedThe taper of the through hole is related to the divergence angle (deflection angle) of the liquid crystal panel cone lens to the light, so that the convergent light beam generated by the liquid crystal panel cone lens conversion just completely passes through the taper through hole at the center of the light beam translation ring without being influenced, and the divergent light beam generated by the liquid crystal panel cone lens conversion completely passes through the ring body of the light beam translation ring to be integrally translated and spliced with the convergent light beam into a whole. According to the diffraction formula of the grating, when the light beam is normally incident:
(ii) a Wherein θ is a deflection angle, λ is a wavelength, p is a period along a radial direction, and deflection angles corresponding to different periods are:
。
further, when the beam translation ring works, the thickness and the light translation distance of the beam translation ring satisfy the following formula:
wherein n is the refractive index of the material, alpha is the refraction angle, theta is the deflection angle of the liquid crystal flat cone lens, and l is the distance of downward translation of the light beam.
Furthermore, the installation position of the light beam translation ring is behind the focus of the liquid crystal flat cone lens, and the converged light beams pass through the light beam translation ring after passing through the focus.
Further, the lens group structure comprises two lenses, and the two lenses are both convex lenses. Preferably, the two convex lenses form a 4f structure.
Compared with the prior art, the invention has the beneficial effects that: the Bessel laser processing head with double focal depth provided by the invention can form longer focal depth under the condition of giving the same laser characteristics by matching the liquid crystal flat cone lens with the light beam translation ring, and the maximum focal depth can be twice of that of a common laser processing head, so that the synchronous improvement of the cutting processing efficiency and the processing quality can be realized.
Drawings
FIG. 1 is a schematic view of a prior art Bessel laser machining head;
figure 2 is a schematic view of a bessel laser machining head of the present invention;
FIG. 3 is a schematic diagram of the liquid crystal flat axicon lens of example 1 of the present invention acting on right-handed circularly polarized light;
FIG. 4 is a schematic view of a liquid crystal flat axicon lens applied to left-handed circularly polarized light in example 1 of the present invention;
FIG. 5 is a schematic view showing a case where a liquid crystal flat axicon is applied to linearly polarized light in example 1 of the present invention;
FIG. 6 is a schematic view of a beam translation ring in embodiment 1 of the present invention;
FIG. 7 is a schematic view showing the operation of the light beam translation ring in embodiment 1 of the present invention;
in the figure: 1-laser beam, 11-divergent beam, 12-convergent beam, 2-refraction type conical lens, 3-lens group, 4-beam translation ring and 5-liquid crystal flat conical lens.
Detailed Description
The present invention will be described in further detail below with reference to specific examples, wherein methods or features not specifically described are known in the art.
Example 1
As shown in fig. 2 to 7, the present embodiment is a double focal depth bessel laser processing head, which includes a liquid crystal flat axicon 5 and a lens group 3, and a beam translation ring 4 is disposed between the liquid crystal flat axicon 5 and the lens group 3; the liquid crystal flat cone lens 5 can convert the incident laser beam 1 into two annular light beams including a divergent light beam 11 and a convergent light beam 12, and the two annular light beams enter the lens group 3 after passing through the light beam translation ring 4, so that focal depth regions of the two annular light beams are spliced together.
In this embodiment, the liquid crystal panel axicon 5 includes a substrate and a liquid crystal layer disposed between the two substrates. The phase modulation of the liquid crystal layer on incident light based on the fast axis orientation of liquid crystal molecules meets the following requirements:
a) When the incident light is right-handed circularly polarized light, the polarization state is converted into left-handed circularly polarized light after being modulated by the liquid crystal flat cone lens 5, the left-handed circularly polarized light carries a focusing cone phase, a section of diffraction-free area is formed after focusing, the light beam generated in the area has Bessel light beam characteristics, and annular light beams are formed after continuous transmission; as shown in fig. 3;
b) When the incident light is left-handed circularly polarized light, the polarization state is converted into right-handed circularly polarized light after being modulated by the liquid crystal flat cone lens 5, and the right-handed circularly polarized light carries a divergent cone phase, and an annular light beam is directly formed after diffraction; as shown in fig. 4;
c) When the incident light is linearly polarized light, the left and right circular polarization components of the incident light are modulated by the liquid crystal flat cone lens 5 to respectively obtain focused and divergent cone phases, and the focused and divergent cone phases are respectively divergent and directly divergent, and the divergent and convergent angles are equal; as shown in fig. 5;
d) When the incident light is elliptical polarized light, the left and right circular polarization components have different amplitudes, the diffraction process of the transmitted light is the same as that of the incident light when linearly polarized light is incident, but the intensity of the transmitted light is related to the ellipticity;
e) When the incident light is unpolarized light, it is a superposition of all the above. It follows that the incident laser beam in this embodiment must be linearly polarized.
In this embodiment, the beam translation ring 4 is a piece of annular plate glass with a tapered through hole in the center. The side of the light beam translation ring 4 with the smaller diameter of the conical through hole is opposite to the liquid crystal flat conical lens 5. According to the grating diffraction formula, when the light beam is normally incident:
(ii) a Wherein theta is a deflection angle, lambda is a wavelength, p is a period along the radial direction, and the deflection angles corresponding to different periods are as follows:
。
in this embodiment, when the beam translation ring 4 works, the light translation distance and the thickness thereof satisfy the following formula:
wherein n is the refractive index of the material of the light beam translation ring 4, α is the refraction angle, θ is the deflection angle of the liquid crystal flat-plate axicon 5, and l is the distance of downward translation of the light beam.
In this embodiment, the taper of the tapered through hole on the light beam translation ring 4 is associated with the divergence angle (deflection angle) of the liquid crystal panel axicon 5 to the light, so that the convergent light beam 12 generated by the liquid crystal panel axicon 5 just completely passes through the tapered through hole at the center of the light beam translation ring 4 without being affected, and the divergent light beam 11 generated by the liquid crystal panel axicon 5 just completely passes through the light beam translation ring 4 to be translated integrally, and is spliced with the convergent light beam 12 into a whole. More specifically, the beam translation ring 4 is installed behind the focal point of the liquid crystal flat cone lens 5, and the converged light beam 12 passes through the focal point and then passes through the beam translation ring 4.
In this embodiment, the lens assembly 3 includes two lenses, and both the two lenses are convex lenses. The two convex lenses form a 4f structure. In some embodiments, angle e and angle C may be equal.
The present invention is not limited to the above embodiments, and various combinations and modifications of the above technical features may be provided for those skilled in the art, and modifications, variations, equivalents, or uses of the structure or method of the present invention in other fields without departing from the spirit and scope of the present invention are included in the protection scope of the present invention.
Claims (10)
1. A double focal depth bessel laser processing head comprising a cone lens for converting an incident laser beam into a bessel beam and a lens group for focusing the beam onto a processing surface, characterized in that: a beam translation ring is arranged between the cone lens and the lens group; the cone lens is a liquid crystal flat cone lens, the liquid crystal flat cone lens converts an incident laser beam into two divergent and convergent annular light beams, and the two annular light beams enter the lens group after passing through the light beam translation ring, so that focal depth regions of the two annular light beams are spliced together.
2. The Bessel laser processing head of claim 1 wherein the liquid crystal plate axicon comprises a substrate and a liquid crystal layer disposed between the two substrates.
3. The Bessel laser processing head of claim 2, wherein the phase modulation of the incident light by the liquid crystal layer based on the fast axis orientation of the liquid crystal molecules satisfies the following requirements: a) When the incident light is right-handed circularly polarized light, the polarization state is converted into left-handed circularly polarized light after being modulated by the liquid crystal flat cone lens, the left-handed circularly polarized light carries a focusing cone phase, a non-diffraction area is formed after focusing, and light beams generated in the area have Bessel light beam characteristics and are continuously transmitted to form annular light beams; b) When the incident light is left-handed circularly polarized light, the polarization state is converted into right-handed circularly polarized light after being modulated by the liquid crystal flat cone lens, and the right-handed circularly polarized light carries a divergent cone phase, and an annular light beam is directly formed after diffraction; c) When the incident light is linearly polarized light, the left and right circular polarization components of the incident light are modulated by the liquid crystal flat cone lens to respectively obtain focused and divergent cone phases, and the focused and divergent cone phases are respectively diverged and directly diverged, and divergence and convergence angles are equal; d) When the incident light is elliptically polarized light, the left and right circular polarization components have different amplitudes, the diffraction process of the transmitted light is the same as that of the incident linearly polarized light, but the intensity of the transmitted light is related to the ellipticity; e) When the incident light is unpolarized, the above conditions are superimposed.
4. The Bessel laser machining head as claimed in claim 3 wherein the beam translation ring is an annular flat glass with a tapered through hole in the center.
5. The Bessel laser processing head as claimed in claim 4, wherein the side of the beam translation ring where the diameter of the tapered through hole is smaller is opposed to the liquid crystal plate axicon.
6. The Bessel laser processing head as claimed in claim 5, wherein the taper of the tapered through hole on the beam translation ring is related to the divergence angle of the liquid crystal flat cone lens to the light, so that the taper of the tapered through hole is parallel to the ray of the diverging light beam generated by the liquid crystal flat cone lens.
7. The bessel laser machining head as claimed in claim 4 wherein the beam translation ring is operative such that the thickness and the ray translation distance satisfy the following equation:
wherein n is the refractive index of the material, alpha is the refraction angle, theta is the deflection angle of the liquid crystal flat cone lens, and l is the distance of the up-and-down translation of the light beam.
8. The Bessel laser processing head as claimed in claim 7, wherein the beam translation ring is installed near the focus of the liquid crystal flat cone lens, so that the convergent beam generated by the liquid crystal flat cone lens conversion just passes through the cone-shaped through hole at the center of the beam translation ring without being influenced, and the divergent beam generated by the liquid crystal flat cone lens conversion just passes through the beam translation ring to be translated integrally and spliced with the convergent beam into a whole.
9. The Bessel laser machining head of claim 1 wherein the lens set arrangement comprises two convex lenses.
10. The Bessel laser processing head as claimed in claim 9, wherein the lens group structure is a 4f structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211108220.7A CN115502552A (en) | 2022-09-13 | 2022-09-13 | Bessel laser processing head with double focal depth |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211108220.7A CN115502552A (en) | 2022-09-13 | 2022-09-13 | Bessel laser processing head with double focal depth |
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| CN115502552A true CN115502552A (en) | 2022-12-23 |
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| CN202211108220.7A Pending CN115502552A (en) | 2022-09-13 | 2022-09-13 | Bessel laser processing head with double focal depth |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116079229A (en) * | 2023-03-07 | 2023-05-09 | 长沙麓邦光电科技有限公司 | Point ring laser processing system and processing method thereof |
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2022
- 2022-09-13 CN CN202211108220.7A patent/CN115502552A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116079229A (en) * | 2023-03-07 | 2023-05-09 | 长沙麓邦光电科技有限公司 | Point ring laser processing system and processing method thereof |
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