CN212229325U - Laser beam focusing system of coupling water beam optical fiber - Google Patents
Laser beam focusing system of coupling water beam optical fiber Download PDFInfo
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- CN212229325U CN212229325U CN202020937792.6U CN202020937792U CN212229325U CN 212229325 U CN212229325 U CN 212229325U CN 202020937792 U CN202020937792 U CN 202020937792U CN 212229325 U CN212229325 U CN 212229325U
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Abstract
The utility model discloses a laser beam focusing system of coupling water beam optic fibre has set up phase place board (6), and laser beam (3) after reflection, collimation expand the back and carry out the phase modulation at phase place board (6) and regenerate no diffraction light beam, can reduce the sidelobe effect of no diffraction light beam to improve the central facula energy density of light beam, both improved the quality of light beam and improved the coupling efficiency of water beam-light beam; a positive/negative axicon lens combination unit (7) is arranged to generate a light beam after phase modulation into a non-diffraction light beam with a small central light spot and a long collimation area, so that the difficulty of coupling with a water beam optical fiber in a subsequent stage is reduced.
Description
Technical Field
The utility model relates to a water guide laser processing technology field, concretely relates to laser beam focusing system of coupling water beam optic fibre.
Background
The water-guided laser is a technology for conducting laser beams by using a water beam optical fiber, because the refractive index of water is greater than that of air, when a focused beam meets the critical condition of total reflection at the interface of air and liquid of the water beam, the formed water beam optical fiber can limit the focused beam totally reflected inside the water beam, the focused beam is transmitted to the surface of a workpiece to be processed along the water beam optical fiber due to the total reflection effect inside the water beam, and the micro water beam impacts the workpiece to remove materials and cools the workpiece while the laser ablates and melts the surface of the workpiece, so that the workpiece is processed.
The water-guided laser processing technology has the problems of high part processing cost and high water beam-light beam coupling difficulty, and the prior art solves the problems by using a mode of generating a non-diffraction light beam by using a single positive axis pyramid mirror aiming at the situation, and can overcome the problems of high focusing difficulty and aberration because the non-diffraction light beam is close to the minimum divergence angle of a parallel light beam, the focal depth range is large, the central light spot is small, so that the coupling difficulty of the water beam-light beam is reduced, but the cone angle of the single axis pyramid mirror is usually 1-5 degrees, the processing precision requirement is high, the processing error is easy to distort the non-diffraction light beam, the focusing difficulty of the single axis pyramid mirror with small taper is high in the installation process, the abrasion of the cone angle easily influences the light beam quality, and meanwhile, the energy utilization rate is low due to the side lobe.
Therefore, a laser beam focusing system for coupling a water beam fiber is to be provided, which can improve the quality of the light beam and the coupling efficiency of the water beam and the light beam, and can reduce the coupling difficulty of the water beam and the light beam.
SUMMERY OF THE UTILITY MODEL
The utility model provides a laser beam focusing system of coupling water beam optic fibre provides hardware support and structural support for solving the problem that "the light beam quality is poor, water beam-light beam coupling efficiency is low, water beam-light beam coupling degree of difficulty is big" that exists among the prior art.
The utility model discloses a technical problem is solved to following technical scheme:
a laser beam focusing system of a coupling water beam optical fiber comprises a controller, a laser transmitter, a reflector, a laser beam collimation and beam expansion unit, a phase plate and a positive/negative axicon combination unit; the laser beam collimation and beam expansion unit, the phase plate and the positive/negative axicon combination unit are coaxially arranged;
the laser transmitter transmits laser beams to the reflector under the control of the controller, and the laser beams are incident to the phase plate for phase modulation after being collimated and expanded by the laser beam collimating and expanding unit;
the positive/negative axicon lens combination unit consists of a negative axicon lens and a positive axicon lens, and the light beam after phase modulation by the phase plate passes through the negative axicon lens and the positive axicon lens and then is coupled with an external water beam optical fiber.
Further, the negative axicon and the positive axicon have the same refractive index.
Furthermore, the negative axicon and the positive axicon are attached and mounted and coaxially arranged.
Further, the reflector is arranged in front of the laser emitter, and a laser beam emitted by the laser emitter forms an angle of 45 degrees with an axis of the reflector.
Further, the mirror surface of the reflector is plated with a reflecting film.
Furthermore, the laser beam collimation and beam expansion unit consists of a first collimation and beam expansion lens and a second collimation and beam expansion lens; the first collimation beam expander and the second collimation beam expander form an inverted telescope structure and are virtually confocal.
Furthermore, the phase plate is of an annular structure, and the phase of the phase plate is a binary phase 0/pi.
Further, the outer diameter of the phase plate is larger than the diameter of the emergent light beam of the laser beam collimation and beam expansion unit.
Further, the wavelength of the laser beam is 532nm or 1064 nm.
Furthermore, the laser beam is a pulse laser, the pulse width of the pulse laser is 5ns-50ns, the power of the pulse laser is 50W-500W, and the frequency range is 20kHz-200 kHz.
Compared with the prior art, the method has the following characteristics:
1. the hardware is provided with a phase plate, laser beams are subjected to phase modulation on the phase plate after being reflected, collimated and expanded and then are regenerated into non-diffracted beams, the side lobe effect of the non-diffracted beams can be reduced, the central light spot energy density of the beams is improved, the beam quality is improved, the coupling efficiency of the water beams and the beams is improved, a positive/negative axicon lens combination unit is also arranged, the non-diffracted beams with small central light spots and long collimation areas are generated from the beams subjected to phase modulation, and the difficulty of coupling with the water beam optical fibers in the subsequent stage is reduced;
2. the non-diffraction laser beam with small central light spot and long collimation area is obtained by using the negative axicon lens and the positive axicon lens which are attached, have the same refractive index and are coaxially arranged, and the reliability is higher compared with the method of obtaining the non-diffraction laser beam by using only a single positive axicon lens.
Drawings
Fig. 1 is a schematic structural diagram of the present invention.
Fig. 2 is a structural parameter diagram of the positive/negative axicon lens combination unit.
Fig. 3 is a diagram of the structure and phase characteristics of the phase plate.
The reference numbers in the figures are:
1. a controller; 2. a laser transmitter; 3. a laser beam; 4. a reflective mirror; 5. a laser beam collimation and expansion unit; 5-1, a first collimating beam expander; 5-2, a second collimating beam expander; 6. a phase plate; 7. A positive/negative axicon lens combination unit; 7-1, a negative axicon; 7-2, a positive axis pyramid mirror.
Detailed Description
The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples.
A laser beam focusing system of a coupling water beam optical fiber comprises a controller 1, a laser emitter 2, a reflector 4, a laser beam collimation and beam expansion unit 5, a phase plate 6 and a positive/negative axicon lens combination unit 7; the laser beam collimation and beam expansion unit 5, the phase plate 6 and the positive/negative axicon combination unit 7 are coaxially arranged; the laser emitter 2 emits a laser beam 3 to the reflector 4 under the control of the controller 1, and the laser beam 3 is collimated and expanded by the laser beam collimation and expansion unit 5 and then enters the phase plate 6 for phase modulation; the positive/negative axicon lens combination unit 7 consists of a negative axicon lens 7-1 and a positive axicon lens 7-2, and the light beam after phase modulation by the phase plate 6 passes through the negative axicon lens 7-1 and the positive axicon lens 7-2 and then is coupled with an external water beam optical fiber. The structure schematic diagram of the utility model is shown in figure 1.
The controller 1 is a core component of a hardware structure, and is used for controlling the laser emitter 2 and setting parameters of the laser beam 3, so that the laser emitter 2 emits the laser beam 3 meeting the parameter requirements. The laser emitter 2 is controlled by the controller 1, and emits a laser beam 3 meeting the parameter requirement according to the control instruction of the controller 1.
The wavelength of the laser beam 3 is 532nm or 1064 nm. The laser beam 3 is pulse laser, the pulse width of the pulse laser is 5ns-50ns, the power is 50W-500W, and the frequency range is 20kHz-200 kHz.
The reflector 4 is arranged in front of the laser emitter 2, and the laser beam 3 emitted by the laser emitter 2 forms an angle of 45 degrees with the axis of the reflector 4. The mirror surface of the reflector 4 faces the laser emitter 2, and the mirror surface of the reflector 4 is coated with a reflecting film to increase the reflectivity of the laser beam 3 and reduce energy loss.
The laser beam collimation and beam expansion unit 5 consists of a first collimation and beam expansion lens 5-1 and a second collimation and beam expansion lens 5-2; the first collimation beam expander 5-1 and the second collimation beam expander 5-2 form an inverted telescope structure and are virtually confocal. The first collimating beam expander 5-1 and the second collimating beam expander 5-2 can complete the function of collimating and expanding beams as long as the parameters are matched, generally, the first collimating beam expander 5-1 is provided with a plano-concave lens, the second collimating beam expander 5-2 is provided with a plano-convex lens, or both the first collimating beam expander 5-1 and the second collimating beam expander 5-2 can be provided with convex lenses, but the arrangement mode of the two is not limited to the above description.
The utility model discloses in, first collimation expands beam expander 5-1 for input negative lens, and second collimation beam expander 5-2 is the positive lens of output, and input negative lens is the virtually confocal structure with the positive lens of output, and input negative lens sends a virtual focus light beam to output positive lens, expands the beam by the positive lens outgoing collimation of output, accomplishes the collimation and expands the beam function.
Multiple of beam expansion
Wherein f is2To output the focal length of the positive lens, f1Is the focal length of the input negative lens.
Wherein r is21To output the front radius of curvature, r, of the positive lens22Is the rear radius of curvature of the output positive lens;
wherein r is11To input the front radius of curvature, r, of the negative lens12Is the input negative lens back radius of curvature. The parallel laser beam 3 is incident to the laser beam collimation and beam expansion unit 5, after the beam is expanded by the input negative lens and the output positive lens, the laser beam 3 is emitted in parallel, the diameter of the laser beam 3 is increased, the divergence angle is reduced, and the collimation degree of the laser beam 3 is improved. If the diameter of the laser beam 3 is 4mm and the beam expansion multiple K of the laser beam collimation and beam expansion unit 5 is 5, the diameter of the beam incident on the phase plate 6 is 20 mm.
The phase plate 6 is used for phase modulation of the light beam after alignment and beam expansion so that the positive/negative axicon lens combination unit 7 generates a diffraction-free light beam with small central light spot and long alignment area, andthe generated diffraction-free light beam has the characteristics of small side lobe effect and high energy density of a central light spot. The phase plate 6 is a ring structure, and the phase of the phase plate 6 is set to a binary phase 0/pi by plating or grooving, that is, the phase of the collimated and expanded light beam leads or lags the phase pi through different areas of the phase plate 6. The structure and phase characteristics of the phase plate 6 are shown in fig. 3. In FIG. 3, r1Denotes the ring diameter, r, of the 1 st ring of the phase plate 62Denotes the ring diameter, r, of the 2 nd ring of the phase plate 63Denotes the ring diameter, r, of the 3 rd ring of the phase plate 64Denotes the ring diameter, r, of the 4 th ring of the phase plate 65The ring diameter of the 5 th ring of the phase plate 6 is shown. The parameters of the phase plate 6 include the number of rings, the ring diameter, the phase, the ring depth and the resulting phase modulation function. In addition, the outer diameter of the phase plate 6 is larger than the diameter of the outgoing beam of the laser beam collimation and expansion unit 5.
The utility model discloses if only adopt just negative/positive axicon lens combination unit 7 to generate no diffraction light beam, then the side lobe effect is serious, and central facula energy density is low, consequently, adds phase plate 6 and solves above-mentioned problem. The phase plate 6 adopts a binary phase 0/pi to align the light beam after direct expansion for wave front phase modulation, the subsequent modulation generates an amplitude transmittance function of the non-diffracted light beam, the amplitude transmittance function is utilized to modulate the light field with the transmittance of 0, side lobes are inhibited, the light beam with the transmittance of non-0 is subjected to interference superposition, the energy density distribution of the non-diffracted light beam is improved, the setting mode of the binary phase 0/pi of the phase plate 6 is seen, the side lobe effect of the non-diffracted light beam is reduced, the quality of the light beam is improved, and the coupling efficiency of the water beam and the light beam is also improved.
In the utility model discloses in, the refracting index of negative axicon 7-1 and positive axicon 7-2 can be the same, also can be different, the utility model discloses a to obtain better cone angle matching effect, negative axicon 7-1 and positive axicon 7-2 use the same refracting index. The negative axicon 7-1 and the positive axicon 7-2 are mounted in a fitting mode or processed by integrated geometric polishing and photoetching and are coaxially arranged. The positive/negative axicon combination unit 7 can be made of BK7 or K9 materials.
Equivalent cone angle theory of positive/negative axicon combination unit 7Computing
Wherein n is the refractive index of the negative axicon 7-1 and the positive axicon 7-2, R1Diameter of the outgoing beam of the negative axicon 7-1, R2Diameter, R, of incident beam of regular axicon 7-21≈R2，γ1Is the cone angle, gamma, of the negative axial pyramid 7-12Is the cone angle of the right-axis pyramid mirror 7-2, gamma is gamma2-γ1Is the equivalent cone angle of the positive/negative axicon combination unit 7. The cone angle of the positive axicon 7-2 is larger than that of the negative axicon 7-1, and the cone angle matching is carried out when the negative axicon 7-1 and the positive axicon 7-2 are combined.
Analysis was performed with the beam propagating along the Z direction: if the wavelength of the laser beam 3 is 532nm, the radius of the beam incident to the positive/negative axicon combination unit 7 is 10mm, the cone angle range of the positive axicon 7-2 is 5 ° -15 °, the cone angle range of the negative axicon 7-1 is 1 ° -15 °, and the cone angle of the positive axicon 7-2 is set to γ2The cone angle of the negative axicon 7-1 is gamma when the angle is 10 degrees1If the equivalent taper angle γ of the positive/negative axicon combination unit 7 is 1 °, i.e., 10 ° -9 ° -1 °, and if the refractive indices n of the negative axicon 7-1 and the positive axicon 7-2 are both 1.5, the negative axicon 7-1 and the positive axicon 7-2 are formed by
Calculating the maximum undiffracted beam area ZmaxApproximately 1146mm, made of
Calculating the diameter d of the central spot of the non-diffracted beam0≈46.7μm，r0The radius of the central spot of the diffraction-free beam is represented, the focused light angle theta is 0.5 degrees calculated by theta-gamma (n-1), the diameter range of the coupling water beam optical fiber in the water guide laser is 50-200 mu m, and the incident angle of the optical fiber, which meets the critical condition of total reflection of the water beam optical fiber, of the light incident to the inlet end face of the water beam optical fiber is equal to
Wherein n isaIs the refractive index of air, nwAs the refractive index of water, the analysis shows that theta is less than 41.25 degrees, which indicates that the reflection angle formed at the total reflection interface is larger than the critical angle of total reflection by 48.75 degrees (90-41.25 degrees), and the water beam-light beam coupling tolerance is high, and the water beam-light beam coupling difficulty is low.
In the prior art, only a single positive axis pyramid mirror is used for generating a non-diffracted light beam, the non-diffracted light beam has the advantages that the non-diffracted light beam is close to a minimum divergence angle of a parallel light beam, the length of a maximum non-diffracted light beam area reaches dozens of millimeters or even hundreds of millimeters, the focal depth range and a central light spot are small, the problems of high focusing difficulty and aberration are solved, and the coupling difficulty of a water beam and the light beam in water-guided laser is reduced. And the utility model discloses a just/negative axis pyramid mirror modular unit 7 has not only reduced the coupling degree of difficulty of water beam-light beam in the water conservancy diversion laser, has still reduced the machining precision requirement of unipolar pyramid mirror, has reduced the influence that machining error produced the distortion to no diffraction light beam, has reduced the influence of the unipolar pyramid mirror adjustment degree of difficulty and operation in to beam transmission characteristic because of cone angle wearing and tearing, has solved the problem that no diffraction light beam causes energy utilization low because of the side lobe effect well, improves no diffraction light beam quality and entire system's reliability.
In the electrical field, technical solutions relating to parameter setting and control execution necessarily involve computer programs, but if the computer programs involved are prior art, or are simply calculations, comparisons and controls, the technical solutions should not be considered to involve improvements of the computer programs. In the present invention, it is clear from the specification that the technical solution provides hardware support and structural support for solving the problems of "poor light beam quality, low coupling efficiency of water beam-light beam, and great difficulty of water beam-light beam coupling" existing in the prior art, that is, only making contributions on hardware and structure for solving the corresponding technical problems, what is claimed is only the relevant description of hardware and structure, and it is common knowledge known to those skilled in the art that an external computer program is used by the controller 1, a control instruction is sent to the control end of the controlled object, and the controlled object starts the internal circuit according to the control instruction and makes corresponding feedback, and it should not be considered as an improvement related to the computer program, therefore, the present invention does not relate to the improvement of the computer program.
Claims (10)
1. A laser beam focusing system coupled to a water beam fiber, comprising:
the device comprises a controller (1), a laser transmitter (2), a reflector (4), a laser beam collimation and expansion unit (5), a phase plate (6) and a positive/negative axicon combination unit (7); the laser beam collimation and expansion unit (5), the phase plate (6) and the positive/negative axicon combination unit (7) are coaxially arranged;
the laser emitter (2) emits a laser beam (3) to the reflector (4) under the control of the controller (1), and the laser beam (3) enters the phase plate (6) for phase modulation after being collimated and expanded by the laser beam collimating and expanding unit (5);
the positive/negative axicon lens combination unit (7) consists of a negative axicon lens (7-1) and a positive axicon lens (7-2), and the light beam after phase modulation by the phase plate (6) passes through the negative axicon lens (7-1) and the positive axicon lens (7-2) and then is coupled with an external water beam optical fiber.
2. The laser beam focusing system of claim 1, wherein: the negative axicon (7-1) and the positive axicon (7-2) have the same refractive index.
3. The laser beam focusing system of claim 1, wherein: the negative axicon (7-1) and the positive axicon (7-2) are attached and coaxially arranged.
4. The laser beam focusing system of claim 1, wherein:
the reflecting mirror (4) is arranged in front of the laser emitter (2), and a laser beam (3) emitted by the laser emitter (2) forms an angle of 45 degrees with the axis of the reflecting mirror (4).
5. The laser beam focusing system of claim 1, wherein: the mirror surface of the reflector (4) is plated with a reflecting film.
6. The laser beam focusing system of claim 1, wherein:
the laser beam collimation and beam expansion unit (5) consists of a first collimation and beam expansion lens (5-1) and a second collimation and beam expansion lens (5-2); the first collimation beam expander (5-1) and the second collimation beam expander (5-2) form an inverted telescope structure and are virtually confocal.
7. The laser beam focusing system of claim 1, wherein: the phase plate (6) is of an annular structure, and the phase of the phase plate (6) is a binary phase 0/pi.
8. The laser beam focusing system of claim 1, wherein: the outer diameter of the phase plate (6) is larger than the diameter of the emergent light beam of the laser beam collimation and expansion unit (5).
9. The laser beam focusing system of claim 1, wherein: the wavelength of the laser beam (3) is 532nm or 1064 nm.
10. The system of claim 9, wherein: the laser beam (3) is pulse laser, the pulse width of the pulse laser is 5ns-50ns, the power of the pulse laser is 50W-500W, and the frequency range is 20kHz-200 kHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020937792.6U CN212229325U (en) | 2020-05-28 | 2020-05-28 | Laser beam focusing system of coupling water beam optical fiber |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020937792.6U CN212229325U (en) | 2020-05-28 | 2020-05-28 | Laser beam focusing system of coupling water beam optical fiber |
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| Publication Number | Publication Date |
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| CN212229325U true CN212229325U (en) | 2020-12-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202020937792.6U Expired - Fee Related CN212229325U (en) | 2020-05-28 | 2020-05-28 | Laser beam focusing system of coupling water beam optical fiber |
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- 2020-05-28 CN CN202020937792.6U patent/CN212229325U/en not_active Expired - Fee Related
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Granted publication date: 20201225 Termination date: 20210528 |