Water-guided laser coupling device

Abstract

This invention belongs to the field of water-guided laser processing technology, specifically relating to a water-guided laser coupling device. The water-guided laser coupling device of this invention includes: an aperture, a 4f system, and a liquid nozzle arranged sequentially along the laser propagation path; the laser beam is focused by the aperture and the 4f system onto the laser entrance of the liquid nozzle and exits from the liquid ejection port of the nozzle. This water-guided laser coupling device first uses the aperture to block stray light and prevent beam deviation from damaging the nozzle; then, the 4f system images the laser beam into the water column of the liquid nozzle. The 4f system can accurately image the light field distribution at the aperture onto the nozzle. As long as the light field distribution at the aperture remains unchanged, the image will not change, so the size and position of the laser spot at the nozzle will not change due to variations in the laser output beam. Compared to fiber optic transmission, by using free-space laser transmission, the beam quality remains unchanged, and the depth of focus is significantly improved compared to fiber optic coupling.

Description

Technical Field

[0001] This utility model belongs to the field of water-guided laser processing technology, specifically relating to a water-guided laser coupling device. Background Technology

[0002] Water-guided laser processing technology is an innovative precision machining method that combines laser and water jet. By coupling a laser beam into a micrometer-sized water column, the total internal reflection property of water guides the laser energy, achieving high-precision processing with low thermal damage. The coupling mechanism between the laser and the water column is as follows: the laser needs to be coupled into an optical fiber, which is then transmitted over a relatively long distance to a cutting head near the processing table. After being focused by the optical lens of the cutting head, it enters a water-filled coupling cavity. The high-pressure water flow forms a stable micrometer-sized water jet (with a diameter as small as 30 micrometers). The laser undergoes total internal reflection at the water-air interface and is transmitted along the water column to the workpiece surface. The water column is similar to a "liquid optical fiber," which avoids the energy divergence problem caused by changes in focusing distance in traditional laser processing, enabling stable transmission over long distances (such as 10 cm and above).

[0003] In existing technologies, the advantage of using fiber optic transmission is that it avoids the laser output beam deflection during transmission, which could burn out the nozzle. However, it also has some disadvantages. For example, fiber optics cannot withstand high power for extended periods in the green light band, easily experiencing power attenuation. Furthermore, the beam quality output through fiber optics deteriorates significantly, resulting in a very short focal depth when focused onto the nozzle, making it impossible to couple into smaller nozzles. Specifically, the current mainstream fiber core diameter is 150µm, which is multimode fiber. After the laser is coupled into the fiber, it is transmitted in multimode, with a minimum exit divergence angle controllable to around 70mrad. This means that the beam quality deteriorates significantly after transmission through the fiber. The spot size after collimation and refocusing onto the nozzle is typically 30µm, corresponding to a focal depth (Rayleigh distance) of 86µm. The nozzle must be at least twice the size of the focal spot for safety; therefore, the current mainstream nozzle (i.e., water column diameter) is around 60µm. Further reducing the focal spot size would require an even narrower focal depth, making coupling into the nozzle even more difficult. Utility Model Content

[0004] The purpose of this invention is to provide a water-guided laser coupling device to solve the technical problem of deteriorated beam quality caused by using optical fiber to transmit laser in the prior art.

[0005] This application provides a water-guided laser coupling device, comprising: an aperture, a 4f system, and a liquid nozzle arranged sequentially along the laser propagation path; The laser is focused by an aperture and a 4f system onto the laser inlet of the liquid nozzle and then emitted from the liquid outlet of the liquid nozzle.

[0006] In one embodiment of this application, the aperture is a pinhole aperture.

[0007] In one embodiment of this application, the 4f system includes a first lens and a second lens with focal lengths of 3f and f, respectively; The light propagation distance from the aperture to the first lens is 3f, the light propagation distance from the first lens to the second lens is 4f, and the light propagation distance from the second lens to the laser inlet of the liquid nozzle is f.

[0008] In one embodiment of this application, the water-guided laser coupling device includes a laser delivery module and a cutting head module; The laser delivery module includes the aperture and the first lens, as well as several reflectors; The cutting head module includes several reflectors, the second lens, and the liquid nozzle.

[0009] In one embodiment of this application, the liquid nozzle includes: A water chamber is used to hold liquids. A laser entrance port, located at one end of the water chamber, is used to allow the laser beam to enter the water chamber; and A liquid jet nozzle, located at the other end of the water chamber, is used to eject laser and liquid.

[0010] In one embodiment of this application, the wavelength range of the laser is from infrared to ultraviolet.

[0011] In one embodiment of this application, the diameter of the water column ejected from the liquid jet nozzle is not less than 30 μm.

[0012] The beneficial effects of this utility model are: Unlike existing technologies, this application provides a water-guided laser coupling device, comprising: an aperture, a 4f system, and a liquid nozzle arranged sequentially along the laser propagation path; the laser is focused by the aperture and the 4f system onto the laser inlet of the liquid nozzle and exits from the liquid outlet of the liquid nozzle. This water-guided laser coupling device first uses the aperture to block stray light and prevent beam deviation from damaging the nozzle; then, the 4f system images the light into the water column of the liquid nozzle. The 4f system accurately images the light field distribution at the aperture onto the nozzle. As long as the light field distribution at the aperture remains unchanged, the image will not change. Therefore, the size and position information of the light spot at the nozzle will not change due to variations in the laser output beam.

[0013] In other words, compared to fiber optic transmission, the water-guided laser coupling device of this invention can solve the technical problems of poor beam quality, short focal depth of the focused beam, low coupling efficiency, and short fiber life caused by fiber optic laser transmission in the prior art. This overcomes the problem of nozzle burnout and improves the power and energy density of the water-guided laser. It also solves the problem of nozzle burnout caused by changes in the size and directionality of the laser output beam, which are easily affected by changes in the size and position of the focused spot on the nozzle in the free-space direct focusing method (without an aperture and 4F system).

[0014] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention are realized and obtained through the structures particularly pointed out in the description and the accompanying drawings.

[0015] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a preferred embodiment of the water-guided laser coupling device of the present invention; Figure 2 This is a schematic diagram of a liquid nozzle according to a preferred embodiment of the present invention.

[0018] In the picture: Aperture 1, 4f system 2, first lens 21, second lens 22, liquid nozzle 3, laser inlet 31, liquid jet outlet 32, water chamber 33, reflector 4, laser delivery module 100, cutting head module 200. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0020] This application provides a water-guided laser coupling device, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0021] See Figure 1 and Figure 2 In one embodiment, the water-guided laser coupling device includes: an aperture 1, a 4f system 2, and a liquid nozzle 3 arranged sequentially along the laser propagation path; the laser is focused by the aperture 1 and the 4f system 2 onto the laser inlet 31 of the liquid nozzle 3 and emitted from the liquid outlet 32 ​​of the liquid nozzle 3.

[0022] In this embodiment, the laser 300 emits laser light. The water-guided laser coupling device first uses an aperture 1 to block stray light and prevent beam deviation from damaging the liquid nozzle 3. Then, it images the light into the water column of the liquid nozzle 3 through a 4f system 2. The 4f system 2 can accurately image the light field distribution at the aperture 1 onto the nozzle. As long as the light field distribution at the aperture 1 remains unchanged, the image will not change. Therefore, the size and position information of the light spot at the nozzle will not change due to changes in the output laser beam. In other words, compared to fiber optic transmission, the water-guided laser coupling device in this embodiment uses free-space laser transmission, so the beam quality does not change, and the depth of focus is significantly improved compared to fiber optic coupling. It avoids the use of fiber optics, increases the service life, and achieves smaller water column coupling.

[0023] Optionally, the aperture 1 is a pinhole aperture.

[0024] Furthermore, the 4f system 2 includes a first lens 21 and a second lens 22; the light propagation distance from the aperture 1 to the first lens 21 is 3f, the light propagation distance from the first lens 21 to the second lens 22 is 4f, and the light propagation distance from the second lens 22 to the laser inlet 31 of the liquid nozzle 3 is f.

[0025] Optionally, the water-guided laser coupling device includes a laser delivery module 100 and a cutting head module 200; the laser delivery module 100 includes the aperture 1 and the first lens 21, as well as a plurality of reflectors 4; the cutting head module 200 includes a plurality of reflectors 4, the second lens 22, and the liquid nozzle 3.

[0026] In this embodiment, the function of the plurality of reflectors 4 is to reflect the light emitted from the first lens 21 to the second lens 22. Optionally, the laser delivery module 100 may have a housing or box, and the aperture 1, the first lens 21, and the plurality of reflectors 4 may be installed inside the housing. Similarly, the cutting head module 200 may also have a housing or box, and the plurality of reflectors 4, the second lens 22, and the liquid nozzle 3 may all be installed inside the housing.

[0027] Optionally, the liquid nozzle 3 includes: a water chamber 33 for containing liquid; a laser inlet 31 disposed at one end of the water chamber 33 for allowing laser light to enter the water chamber; and a liquid ejection port 32 disposed at the other end of the water chamber 33 for ejecting laser light and liquid.

[0028] In one application scenario, for a laser with M2=10, the laser output beam is 900um, the aperture diameter of aperture 1 is 900um, the focal length of the first lens 21 is f=900mm, and the focal length of the second lens 22 is 30mm. The 4f system composed of these two lenses has a magnification of 30 times (900mm / 30mm). Therefore, the diameter of the light spot transmitted by aperture 1 and imaged onto the nozzle by the 4f system is 30um (900um / 30 times). That is, when the light spot focused on the nozzle by the water-guided laser coupling device of this embodiment is 30um, the corresponding focal depth (Rayleigh distance) is 1320um, which is 15 times higher than that of the fiber coupling method.

[0029] Furthermore, for the above application scenarios, if the M2 of the laser is changed to 1, i.e., the common fundamental mode laser, and the other parameters of the system remain unchanged, the spot focused on the nozzle by the water-guided laser coupling device is still 30um, and the corresponding focal depth (Rayleigh distance) is 1320um multiplied by 10, i.e., 13200um, which is 150 times higher than that of the fiber coupling method.

[0030] This invention relates to a water-guided laser coupling device that can cover the laser wavelength from infrared to ultraviolet. Currently, optical fibers, due to material limitations, cannot transmit ultraviolet light for extended periods. However, this application utilizes free-space transmission, allowing ultraviolet lasers to be stably and reliably coupled into a water column. The water column diameter produced by the nozzle can reach as low as 30µm, half the 60µm diameter of current fiber optic transmission coupling devices. Under the same coupling power, the energy density of the water column is doubled, improving processing efficiency and capability. For fiber optic transmission, with a mainstream water column diameter of 80µm, the coupling efficiency is generally only 85%, and the maximum coupling power is only around 100W. This invention's water-guided laser coupling device can achieve a coupling efficiency of 95% and a coupling power exceeding 500W.

[0031] It should be noted that all the devices (parts whose specific structures are not specified) selected in this application are general standard parts or parts known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0032] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation", "connection" and "linking" should be interpreted broadly, for example, they can be fixed connections, detachable connections, or integral connections.

[0033] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification.

Claims

1. A water-guided laser coupling device, characterized by, include: An aperture (1), a 4f system (2), and a liquid nozzle (3) are arranged sequentially along the laser propagation path. The laser is focused by the aperture (1) and the 4f system (2) onto the laser inlet (31) of the liquid nozzle (3) and emitted from the liquid outlet (32) of the liquid nozzle (3).

2. The water-guided laser coupling device according to claim 1, characterized in that, The aperture (1) is a pinhole aperture.

3. The water-guided laser coupling device according to claim 1, characterized in that, The 4f system (2) includes a first lens (21) and a second lens (22) with focal lengths of 3f and f, respectively; The light propagation distance from the aperture (1) to the first lens (21) is 3f, the light propagation distance from the first lens (21) to the second lens (22) is 4f, and the light propagation distance from the second lens (22) to the laser inlet (31) of the liquid nozzle (3) is f.

4. The water-guided laser coupling device according to claim 3, characterized in that, The water-guided laser coupling device includes a laser delivery module (100) and a cutting head module (200). The laser delivery module (100) includes the aperture (1) and the first lens (21), as well as a plurality of reflectors (4). The cutting head module (200) includes several reflectors (4), the second lens (22) and the liquid nozzle (3).

5. The water-guided laser coupling device according to claim 1, characterized in that, The liquid nozzle (3) includes: Water chamber (33), used to contain liquid; A laser entrance (31) is located at one end of the water chamber (33) for allowing laser light to enter the water chamber; and A liquid jet nozzle (32) is located at the other end of the water chamber (33) for supplying laser and liquid ejection.

6. The water-guided laser coupling device according to claim 1, characterized in that, The wavelength range of the laser is from infrared to ultraviolet.

7. The water-guided laser coupling device according to claim 1, characterized in that, The diameter of the water column ejected from the liquid jet nozzle (32) is not less than 30 μm.

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