An adjustable dual-wavelength laser processing system

Abstract

The present invention discloses an adjustable dual-wavelength laser processing system, comprising a laser for emitting polarization-maintaining narrow-linewidth infrared laser light. A QBH fiber output head, a first collimating convex lens, a half-wave plate, a second focusing convex lens, a nonlinear crystal, a third collimating convex lens, and a dual-wavelength welding processing head are sequentially arranged along the transmission direction of the infrared laser light emitted by the laser. In the present invention, the deflection direction of the fundamental frequency light entering the nonlinear crystal can be changed by rotating the half-wave plate, thereby changing the frequency doubling efficiency generated by the nonlinear crystal and further adjusting the power ratio of the green light and infrared light in the laser light emitted from the nonlinear crystal. In the present invention, the fundamental frequency infrared laser and the frequency doubling green light are not separated; only one laser is required to generate laser light of two wavelengths, achieving dual-wavelength composite processing, greatly simplifying the dual-wavelength processing head structure and reducing production costs.

Description

Technical Field

[0001] The present invention relates to the field of lasers, and in particular to an adjustable dual-wavelength laser processing system. Background Art

[0002] Copper is one of the most widely used metal materials in modern industrial processing. Its industrial chain terminal demand covers more than 30 sub-industries such as aerospace, high-speed trains, smart terminals, electronic communications, and automobiles. It is the main indicator of high-end industrial applications. At present, 1-micron infrared fiber lasers are widely used for welding. Because copper has weak absorption of lasers in this band, there are shortcomings such as large spatter and uncontrollable penetration depth in the copper material welding process. Copper has advantages such as high absorption rate and high energy coupling efficiency for visible light laser welding such as green light. Figure 2 As shown, the sensitivity to material surface quality is reduced, spatter-free heat conduction welding can be achieved, and the welding process is more stable.

[0003] Therefore, the use of an infrared-green dual-beam hybrid welding process can significantly reduce weld spatter and improve weld quality. However, this hybrid welding process currently requires at least two lasers: one producing blue-green light and one producing infrared light in the fiber laser band. This process has drawbacks such as large footprint, complex welding head structure, high cost, and significant dual-beam composite losses, hindering widespread and effective adoption in the industrial market. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes an adjustable dual-wavelength laser processing system.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A tunable dual-wavelength laser processing system includes a laser for emitting polarization-maintaining narrow-linewidth infrared laser light. A QBH fiber output head, a collimating and focusing system, a nonlinear crystal, a third collimating convex lens, and a processing head are sequentially arranged along the transmission direction of the infrared laser light emitted by the laser. The collimating and focusing system includes a first collimating convex lens and a second focusing convex lens, with a rotatable half-wave plate disposed between the first collimating convex lens and the second focusing convex lens.

[0007] The linearly polarized infrared laser emitted by the laser is output after passing through the QBH collimating output head and enters the collimating convex lens 1 to become the first parallel light. The polarization direction of the first parallel light is rotated after passing through the 1 / 2 wave plate, and is focused by the focusing convex lens 2 to enter the nonlinear crystal. The polarization direction of the infrared polarized light forms an angle a with the fast axis or slow axis of the nonlinear crystal, 0≤a≤90; the nonlinear crystal frequency-doubles the fundamental frequency light to produce green laser; the residual fundamental frequency infrared laser and the frequency-doubled green laser pass through the collimating convex lens 3 to form the second parallel light, which enters the processing head and acts on the workpiece surface after being emitted through the processing head to achieve processing; the power ratio of the infrared laser and the green laser is adjusted by rotating the 1 / 2 wave plate.

[0008] As a further improvement, the wavelength range of the green laser is 480-550nm, and the wavelength range of the infrared laser is 960-1100nm. Among them, 480nm is already a cyan wavelength, but in the field of laser processing, it is still classified as a green laser due to the wavelength absorption characteristics of metals.

[0009] As a further improvement, the laser is a fundamental frequency infrared laser, which has the characteristics of narrow line width and linear polarization output.

[0010] As a further improvement, the 1 / 2 wave plate is connected to a servo motor, which drives the 1 / 2 wave plate to rotate to adjust the angle of the 1 / 2 wave plate.

[0011] As a further improvement, the workpiece is made of nonferrous metal, and the nonferrous metal has a reflectivity higher than 90% to 960-1100nm infrared laser and an absorptivity higher than 40% to 480-550nm green laser.

[0012] In a further improvement, the non-ferrous metals include copper and aluminum.

[0013] As a further improvement, the frequency doubling crystal includes but is not limited to KTP, RTP, BBO, LBO, LN nonlinear crystals, and periodically poled nonlinear crystals.

[0014] The beneficial effects of the present invention are:

[0015] 1. Existing dual-wavelength composite processing applications require two lasers: a blue-green laser and an infrared fiber laser. The blue-green laser and the infrared laser are combined in the processing head and used to process high-reflective materials. During the processing, high-reflective materials such as copper have a relatively high absorption rate for blue-green lasers, which easily forms a molten pool. The melted metal material has an increased absorption rate for the infrared band. Therefore, the dual-wavelength method can effectively utilize high-power infrared lasers with high beam quality for processing, while avoiding the shortcomings of blue-green lasers such as low power, high cost, and poor beam quality. Since the present invention does not need to separate green light and infrared light, only one laser is needed to generate lasers of two wavelengths, realizing dual-wavelength composite processing, greatly simplifying the welding head structure and reducing production costs.

[0016] 2. Existing green lasers typically use frequency-doubled lasers, which contain bandpass filters that separate the green and infrared light in the output laser. The green light enters the processing head for processing, while the infrared light is absorbed as waste light, wasting some power. In the present invention, the output laser (including green and infrared light) enters the processing head directly, eliminating waste light and resulting in a high output photoelectric conversion rate.

[0017] 3. In the present invention, the deflection direction of the laser entering the nonlinear crystal can be changed by rotating the 1 / 2 wave plate, thereby changing the frequency doubling efficiency generated by the nonlinear crystal and adjusting the power ratio of the green light and infrared light in the laser emitted from the nonlinear crystal. This makes the power of the dual wavelengths in the output laser of the system adjustable, greatly improving the processing flexibility and processing accuracy, making it adaptable to a wider range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described with reference to the accompanying drawings, but the contents in the drawings do not constitute any limitation to the present invention.

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 Schematic diagram of the absorption rate of different non-ferrous metals to lasers of different wavelengths. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0022] Example 1

[0023] like Figure 1The tunable dual-wavelength laser processing system shown in the figure includes a laser 1, a QBH collimating output head 2, a collimating convex lens 3, a focusing convex lens 4, a 1 / 2 wave plate 5, a nonlinear crystal 6, a collimating convex lens 7 and a processing head 8 in sequence along the laser emission direction.

[0024] The laser is preferably a polarization-maintaining narrow-linewidth laser. The laser outputs a linearly polarized 1μm-band infrared laser, which is output after passing through the QBH collimation output head and entering the collimating convex lens 1 to become parallel light. After the parallel light passes through the 1 / 2 wave plate, the linear polarization direction of the laser rotates, causing it to produce an angle with the fast axis or slow axis of the nonlinear crystal (the angle range varies between 0 and 90 degrees. By changing the value of the angle, the efficiency of the nonlinear effect can be changed, thereby adjusting the power ratio of the two wavelengths in the output laser). After that, it is focused by the focusing convex lens and enters the nonlinear crystal to achieve frequency doubling of the infrared laser. Because the frequency doubling efficiency is limited, the light emitted from the nonlinear crystal contains 1μm-band infrared laser and 500nm-band green laser. The emitted laser passes through the collimating convex lens 3 to form parallel light, and finally enters the processing head. After being emitted by the processing head, it acts on the surface of the workpiece to achieve processing.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A tunable dual-wavelength laser processing system, comprising a laser (1) for emitting polarization-maintaining narrow-linewidth infrared laser light, characterized in that: A QBH collimating output head (2), a collimating focusing system, a nonlinear crystal (6), a collimating convex lens three (7), and a processing head (8) are sequentially arranged along the transmission direction of the infrared laser emitted by the laser (1); the collimating focusing system comprises a collimating convex lens one (3) and a focusing convex lens sheet (4); a rotatable 1 / 2 wave plate (5) is arranged between the collimating convex lens one (3) and the focusing convex lens sheet (4); The linearly polarized infrared laser emitted by the laser (1) passes through the QBH collimating output head (2) and is output, and enters the collimating convex lens 1 (3) to become the first parallel light. The polarization direction of the first parallel light rotates after passing through the 1 / 2 wave plate (5), and is focused by the focusing convex lens (4) and enters the nonlinear crystal (6). The polarization direction of the infrared polarized light and the fast axis or slow axis of the nonlinear crystal (6) form an angle a, 0≤a≤90; the nonlinear crystal (6) doubles the fundamental frequency light to produce green laser; the residual fundamental frequency infrared laser and the doubled frequency green laser pass through the collimating convex lens 3 (7) to form the second parallel light, and the second parallel light enters the processing head (8), and after being emitted by the processing head, acts on the surface of the workpiece to achieve processing; the power ratio of the infrared laser and the green laser is adjusted by rotating the 1 / 2 wave plate (5).

2. The tunable dual-wavelength laser processing system according to claim 1, wherein: The wavelength range of the green laser is 480-550 nm, and the wavelength range of the infrared laser is 960-1100 nm.

3. The tunable dual-wavelength laser processing system according to claim 1, wherein: The laser (1) is a fundamental frequency infrared laser, which has the characteristics of narrow line width and linear polarization output.

4. The tunable dual-wavelength laser processing system according to claim 1, wherein: The 1 / 2 wave plate (5) is connected to a servo motor, and the servo motor drives the 1 / 2 wave plate (5) to rotate to adjust the angle of the 1 / 2 wave plate (5).

5. The tunable dual-wavelength laser processing system according to claim 1, wherein: The workpiece is made of non-ferrous metal, and the non-ferrous metal has a reflectivity of higher than 90% for 960-1100 nm infrared laser and an absorptivity of higher than 40% for 480-550 nm green laser.

6. The tunable dual-wavelength laser processing system according to claim 5, characterized in that: The non-ferrous metals include copper and aluminum.

7. The tunable dual-wavelength laser processing system according to claim 1, wherein: The nonlinear crystal (6) includes but is not limited to KTP, RTP, BBO, LBO, LN nonlinear crystals, and periodically poled nonlinear crystals.

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