Water-jet guided laser focusing lens

Abstract

The invention relates to a laser focusing lens, belongs to the technical field of optics, is used for focusing water-guided laser, and aims at solving the problems that a traditional focusing lens is short in focal length, large in focusing light spot and low in focusing light spot quality.

Description

Technical Field

[0001] This invention patent relates to the field of optical technology, and specifically to a laser focusing lens. Background Art

[0002] The basic principle of water-guided laser is that the water beam totally reflects to guide the laser light source. The laser beam is focused by a focusing system onto the nozzle at the bottom of the coupling water cavity, coupled with a hair-thin water beam and undergoes total reflection at the water-air interface (the water beam is the water optical fiber) to achieve laser conduction. The laser beam irradiates the workpiece to ablate and remove materials in a melting and vaporization manner. At the same time, the liquid supply system injects into the coupling cavity at a pressure of 5 to 60 MPa. It realizes total reflection output together with the laser through a nozzle with a diameter generally of 20 to 150 μm. The performance of water-guided laser technology is different from that of traditional lasers. First, the cylindrical water jet guides the laser, so the cutting surface is steep, and the working distance can exceed 10 cm. Such a long working distance cannot be achieved by expensive focusing control optical devices. The research and development of this equipment will fill the domestic gap in high-end laser low-damage, high-precision, and high-efficiency processing machine tools, provide "hard core force" for enterprise technological innovation and industrial upgrading, achieve green processing, and improve the "soft power" in health and safety competition. Water-guided laser equipment is widely used in the high-precision, high-efficiency, and low-damage processing of difficult-to-process materials such as high-melting-point, high-brittle-hardness, and high-melting-point-difference composite materials in the fields of IC, MEMS, 3C products, LED, photovoltaic, etc., especially for the strategic third-generation semiconductor material SiC in chip manufacturing.

[0003] However, to form a stable water beam optical fiber requires a water jet with stable pressure. Such a water jet has a very small diameter, which requires the imaging spot diameter to be small enough. Due to the spherical aberration of traditional convex lenses that cannot be effectively corrected, it is difficult to meet the coupling requirements for the size of the focused spot. Therefore, it is necessary to break through the optical technology of using traditional focusing lenses in laser processing, solve the problem of great difficulty in water-light coupling in water-guided laser, improve the coupled laser power, system robustness and coordination, and enable a leapfrog improvement in the product quality and production efficiency of the processing manufacturing industry.

[0004] Therefore, those skilled in the art have provided a laser focusing lens to solve the problems existing in the focused spot proposed in the above background art. Content of the Invention Patent

[0005] This invention patent provides a laser focusing lens to solve technical problems, aiming to solve the problem that the focusing distance of the laser cutting head is short and cannot meet the requirement of the small focused spot needed for water-guided laser coupling.

[0006] The technical solution of this invention patent to solve the above technical problems is as follows: A laser focusing lens, including a lens barrel, one end of the lens barrel is provided with a hollow connecting rod which can be connected to a standard collimating and beam expanding lens, and one end of the lens barrel is provided with a connecting rod for connecting to a collimating and beam expanding system.

[0007] The beneficial effects of this invention patent are:

[0008] 1. The system length is shorter, and it can be more easily integrated into the laser cutting head system. 2. The spherical aberration correction design is beneficial to achieving the minimum imaging spot.

[0009] Based on the above technical solution, this invention patent can also be improved as follows.

[0010] Further, the inner wall of the lens barrel is provided with internal threads, and the outer wall of the focusing lens is provided with slidable external threads that match the internal threads on the inner wall of the second lens barrel.

[0011] Further, the collimating lens is a plano-convex lens with positive optical power, and the convex surface faces the object side.

[0012] Further, the beam expanding lens is a plano-concave lens with negative optical power, and the concave surface faces the image side.

[0013] Further, the focusing lens is a plano-convex lens with positive optical power, and the convex surface faces the object side.

[0014] Further, the total length of the focusing lens group is 13.37 mm. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of this invention patent;

[0016] Figure 2 It is a cross-sectional view of this invention patent.

[0017] In the drawings, the list of components represented by each reference numeral is as follows:

[0018] 1. Lens barrel; 2. Hollow connecting rod; 3. Protective glass 4a. Convex surface of plano-convex focusing lens; 4b. Plane of plano-convex focusing lens; 5 Meniscus lens 5a Meniscus lens 5b Meniscus lens 6. Focusing lens; 6a. Convex surface of focusing lens; 6b. Spherical surface of focusing lens; 7 Protective window; 8. Connection buckle Figure 3 It is a simulation diagram of the focusing effect of this invention patent Figure 4 It is an interference diagram of this invention patent Detailed Description of the Invention

[0019] The principles and features of the present invention patent will be described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention patent.

[0020] Example 1

[0021] As Figure 1-2 shown, this embodiment provides a laser focusing lens, including a first lens barrel 1. One end of the lens barrel 1 is provided with a connecting buckle 8, and the other end of the lens barrel 1 has a thread. The first lens of the focusing lens group is close to the object surface inside the lens barrel. In this embodiment, the curvature radius of the spherical surface 4a is 43.93 mm, the thickness is 3.2 mm, N-BK7 glass is used, the curvature radius of the plane 4b is infinity, and N-BK7 glass is used. The curvature radius of 5a of the second lens is 128.195 mm, the thickness is 1.8 mm, and the curvature radius of 5b is 22.423. The curvature radius of the spherical surface 6a of the third lens of the lens group is 23 mm, the thickness is 6 mm, the glass material used is Fused Silica, and the curvature radius of the plane 6b is infinity.

[0022] Preferably, in this embodiment, the inner wall of the lens barrel 1 is also provided with an internal thread and a mounting hole, which is convenient for the staff to cooperate with the laser collimating / beam expanding lens for installation.

[0023] Preferably, in this embodiment, the focusing lens 1 is also a plano-convex lens with positive optical power, and the convex surface faces the object side, and a spherical surface is adopted, aiming to eliminate spherical aberration and improve the collimation imaging quality.

[0024] Preferably, in this embodiment, the beam expanding lens 5 is also a plano-concave lens with negative optical power, and the concave surface faces the image side. The beam expanding lens 5 adopts a Galilean structure, and the concave mirror plays a role in diverging and expanding the beam. The concave surface faces the image side, which can avoid the laser from reflecting back into the laser.

[0025] Preferably, in this embodiment, the focusing lens 3 is also a plano-convex lens with positive optical power, and the convex surface faces the object side, mainly focusing the diverged light beam.

[0026] Preferably, in this embodiment, the total thickness of the lenses is also less than 14 mm, the structure is simple and compact, the weight is light, the volume is small, it is easy to carry and easy to realize standardized mass production.

[0027] In this embodiment, during use, the distance between the spherical surface of the collimating lens / beam expander and the focusing lens can be 10 mm to the collimation focal length of the collimating lens. After the laser beam is collimated by the collimating lens, it is expanded by the beam expander or not expanded. When the light beam enters the focusing lens for focusing, the focusing lens group is manually twisted to move the focusing lens group back and forth on the inner wall of the lens barrel, thereby realizing fine adjustment of the light spot and focal length, and obtaining a small focusing light spot at different positive and negative defocus distances, as Figure 3 shown.

Claims

1. A laser focusing lens, characterized in that: The lens comprises a lens barrel, a lens group and a protective window.

2. The laser focusing lens according to claim 1, characterized in that: The inner wall of the lens barrel is provided with an internal thread, and the outer wall of the focusing lens is provided with an external thread that can be matched with a standard component of a beam expansion and collimation lens group.

3. The laser focusing lens according to any one of claims 1 to 3, characterized in that: The lens 1 is a plano-convex lens with positive refractive power, with the convex surface facing the object.

4. The laser focusing lens according to any one of claims 1 to 3, characterized in that: The lens 2 is a meniscus lens with negative optical power, and the side with a larger curvature radius faces the object.

5. The laser focusing lens according to any one of claims 1 to 3, characterized in that: The lens 3 is a plano-convex lens with positive optical power, and the convex surface faces the object side.

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