A quasi-continuous green laser light emitting device and its use method

Abstract

The present invention proposes a quasi-continuous green laser light-emitting device and a method for using the same. The seed laser optical path includes a laser, which emits a seed laser; the seed laser is divided into a first laser and a second laser after passing through a polarization beam splitter; the second laser propagates at a ninety-degree angle to the first laser; the first optical path includes a first frequency-doubling crystal and a first dichroic mirror; the first laser forms a first frequency-doubling laser after passing through the first frequency-doubling crystal, and the first frequency-doubling laser is divided into a first useless laser and a first monochromatic laser after passing through the first dichroic mirror; the first monochromatic laser enters a polarization beam combiner; the second optical path includes a second frequency-doubling crystal, a second dichroic mirror, and a third dichroic mirror; the second laser forms a second frequency-doubling laser after passing through the second frequency-doubling crystal, and the second frequency-doubling laser is divided into a second useless laser and a second monochromatic laser after passing through the second dichroic mirror; the polarization beam combiner emits a synthesized laser. This technical solution uses a relatively low-priced red laser to obtain green laser light.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a quasi-continuous green laser light emitting device and a method for using the same. Background Art

[0002] Laser welding is a highly efficient and precise welding method that utilizes a high-energy-density laser beam as a heat source. It is a key application area for laser material processing technology. The laser welding process is a heat conduction process, whereby laser radiation heats the workpiece surface, which then diffuses internally through heat conduction. By controlling parameters such as the laser pulse width, energy, peak power, and repetition rate, the workpiece is melted, forming a specific molten pool. Due to its unique advantages, it has been successfully applied to the precision welding of micro and small parts.

[0003] Laser welding typically uses high-power continuous lasers, and for some precision thin-plate welding, infrared continuous lasers are often used. High-reflectivity copper has a very low cold absorption rate for 1µm-band lasers at room temperature (approximately 10%). However, as the temperature rises, the absorption rate gradually increases (to over 40%). Therefore, when using infrared continuous lasers to weld high-reflectivity copper, the absorption rate of the molten copper in the molten pool gradually increases. A large amount of heat is absorbed by the molten copper, and then splashes due to the high temperature, seriously affecting the welding quality. Therefore, laser welding of high-reflectivity copper usually requires blue or green lasers.

[0004] Among them, the wavelength of blue light is about 400nm, and it is usually formed by coupling multiple semiconductor blue light chips into optical fibers. It is expensive and has extremely poor beam quality. The light spot during welding is too large, making it unsuitable for precision welding applications.

[0005] Therefore, the field of laser welding technology urgently needs a quasi-continuous green laser for welding high-reflection copper materials. Summary of the Invention

[0006] In view of this, the present invention proposes a quasi-continuous green laser light-emitting device and its use method, which adopts a narrow-linewidth (spectral width less than 0.5nm) non-polarized (randomly polarized) continuous infrared laser as the front stage, adopts polarization splitting plus two-way LBO frequency doubling, and finally polarization synthesis of the converted green laser.

[0007] The technical solution of the present invention is implemented as follows: a quasi-continuous green laser light-emitting device, which includes a seed laser optical path, a polarization beam splitter, a first beam splitter path, a second beam splitter path, and a polarization beam combiner, wherein the seed laser optical path includes a laser, and the laser emits a seed laser; the seed laser is divided into a first laser and a second laser after passing through the polarization beam splitter; the first laser and the seed laser have the same propagation direction, and the second laser is ninety degrees to the propagation direction of the first laser; the first beam splitter path includes a first frequency-doubling crystal and a first dichroic mirror; the first laser forms a first frequency-doubling laser after passing through the first frequency-doubling crystal, and the first frequency-doubling laser is divided into a first useless laser and a first monochromatic laser after passing through the first dichroic mirror; the first monochromatic laser enters the polarization beam combiner; the second beam splitter path includes a second frequency-doubling crystal, a second dichroic mirror, and a third dichroic mirror; the second laser forms a second frequency-doubling laser after passing through the second frequency-doubling crystal, and the second frequency-doubling laser is divided into a second useless laser and a second monochromatic laser after passing through the second dichroic mirror; the second monochromatic laser is reflected by the third dichroic mirror and enters the polarization beam combiner; the polarization beam combiner emits a synthesized laser.

[0008] On the basis of the above technical solution, preferably, the polarization beam splitter is a red light polarization beam splitter, and the polarization beam combiner is a green light polarization beam combiner.

[0009] On the basis of the above technical solution, preferably, the laser is a narrow-band continuous laser or a single-frequency continuous laser or a nanosecond pulse laser or an ultrafast pulse laser.

[0010] On the basis of the above technical solution, preferably, the seed laser optical path further includes a laser amplifier and a laser collimation isolator, and the seed laser sequentially passes through the laser amplifier and the laser collimation isolator before entering the polarization beam splitter.

[0011] On the basis of the above technical solution, preferably, the first light splitting path further includes a first focusing lens, and the first laser enters the first frequency doubling crystal after passing through the first focusing lens.

[0012] On the basis of the above technical solution, preferably, the first light splitting path further includes a first collimating lens, and the first frequency-doubled laser enters the first dichroic mirror after passing through the first collimating lens.

[0013] On the basis of the above technical solution, preferably, the second light splitting path further includes a second focusing lens, and the second laser enters the second frequency doubling crystal after passing through the second focusing lens.

[0014] On the basis of the above technical solution, preferably, the second light splitting path further includes a second collimating lens, and the second frequency-doubled laser enters the second dichroic mirror after passing through the second collimating lens.

[0015] On the basis of the above technical solution, preferably, a red light high reflective mirror is further included, and the second laser light reflected by the red light high reflective mirror enters the second focusing lens.

[0016] On the basis of the above technical solution, preferably, it further comprises a first light-collecting tube and a second light-collecting tube, the first useless laser enters the first light-collecting tube, and the second useless laser enters the second light-collecting tube.

[0017] The quasi-continuous green laser light emitting device and its use method of the present invention have the following beneficial effects compared with the prior art:

[0018] (1) The laser uses a quasi-continuous random polarization laser. After passing through a laser amplifier and a polarization beam combiner, the peak power of the resulting synthetic laser is sufficiently high.

[0019] (2) Control the spectrum width within a narrow range through grating mode selection and nonlinear control;

[0020] (3) The infrared light is divided into two paths by using a first splitting path and a second splitting path. The first splitting path uses a first frequency doubling crystal, and the second splitting path uses a second frequency doubling crystal, thereby sharing the pressure of one frequency doubling crystal.

[0021] (4) Use a relatively low-cost red laser to produce green laser light. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a light path diagram of a quasi-continuous green laser light emitting device of the present invention;

[0024] Figure 2 This is a light path diagram of a quasi-continuous green laser light-emitting device of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] like Figure 1-2 As shown, a quasi-continuous green laser light emitting device includes a seed laser light path 1, a polarization beam splitter 2, a first beam splitting path 3, a second beam splitting path 4 and a polarization beam combiner 5.

[0027] Among them, the seed laser optical path 1, such as Figure 1 and Figure 2 As shown, it includes a laser 11, which emits a seed laser 121. The laser 11 can also be a narrowband continuous laser, a single-frequency continuous laser, a nanosecond pulse laser, or an ultrafast pulse laser. In this embodiment, the laser 11 takes a non-polarized continuous infrared laser with a spectral width less than 0.1nm as an example. The laser 11 adopts a standard continuous fiber oscillator structure, and the low-reflection grating near the output end adopts a narrowband grating. The spectral width of the seed laser 121 is less than 0.1nm. By adjusting the pump source current of the laser, a pulsed seed laser 121 is formed. The pulse width of the seed laser 121 is 50us~50ms, and the output peak power is about 10W; the laser 11 is used as the injection light source of the laser amplifier 12, and the line width is required to be less than 0.1nm. It can work in pulse modulation, and the pulse width and repetition frequency are adjustable.

[0028] In order to ensure that the seed laser 121 emitted by the laser 11 meets the requirements, as a preferred embodiment, the seed laser optical path 1 also includes a laser amplifier 12 and a laser collimation isolator 13. The seed laser 121 passes through the laser amplifier 12 and the laser collimation isolator 13 in sequence and then enters the polarization beam splitter 2. The laser amplifier 12 amplifies the input seed laser 121, amplifies the peak power to 1 kW to 3 kW, and amplifies the average power to 100 W to 500 W. The spectral width of the amplified seed laser 121 is controlled within 0.5 nm; the laser output by the laser amplifier 12 is output through the collimation isolator 13. The laser passes through the collimation isolator 13. On the one hand, the seed laser 121 is collimated and then output, and on the other hand, it is used to prevent part of the seed laser 121 reflected by the optical device from returning to the laser 11 and damaging the laser 11.

[0029] After passing through the polarization beam splitter 2, the seed laser 121 is split into a first laser 122 and a second laser 123. After passing through the polarization beam splitter 2, the first laser 122 is emitted, and the propagation direction of the first laser 122 and the seed laser 121 is the same. The second laser 123 is reflected by the polarization beam splitter 2 and then emitted, and the propagation direction of the second laser 123 and the first laser 122 is 90 degrees. Since both the laser 11 and the laser amplifier 12 use non-polarization-maintaining optical fiber, the polarization state of the seed laser 121 is randomly polarized. Since the polarization beam splitter 2 uses a red light polarization beam splitter, the randomly polarized seed laser 121 is split into the first laser 122 and the second laser 123 after passing through the polarization beam splitter 2, and the first laser 122 and the second laser 123 have orthogonal polarization states.

[0030] The first split light path 3, such as Figure 1 and Figure 2As shown, it includes a first frequency doubling crystal 31 , a first dichroic mirror 32 , a first focusing lens 33 and a first collimating lens 34 .

[0031] The first laser 122 passes through the first focusing lens 33 and enters the first frequency-doubling crystal 31. In this embodiment, the first frequency-doubling crystal 31 is a lithium triborate crystal, which is a double-frequency crystal. The first frequency-doubling crystal 31 can also be a triple-frequency crystal or a quadruple-frequency crystal with a suitable wavelength according to actual needs. In order to avoid wasting the first laser 122 entering the first frequency-doubling crystal 31, the first focusing lens 33 is first used to converge the first laser 122.

[0032] After converging, the first laser beam 122 passes through the first frequency-doubling crystal 31 to form a first frequency-doubled laser beam 124. The first frequency-doubled laser beam 124 passes through the first collimating lens 34 and enters the first dichroic mirror 32. The first frequency-doubled laser beam 124 includes frequency-doubled green laser light and unfrequency-doubled infrared light. Therefore, after passing through the first dichroic mirror 32, the first frequency-doubled laser beam 124 is divided into a first useless laser beam 125 and a first monochromatic laser beam 126. The first useless laser beam 125 is unfrequency-doubled infrared light, and the first monochromatic laser beam 126 is frequency-doubled green laser light. The first useless laser beam 125 passes through the first dichroic mirror 32 and is emitted. The first monochromatic laser beam 126 is reflected by the first dichroic mirror 32 and is emitted.

[0033] A red light high reflective mirror 7 is also included. Since the first laser 122 and the second laser 123 are in orthogonal polarization states, in order to reduce the volume of the entire structure, the second laser 123 is reflected by the red light high reflective mirror 7 and then enters the second focusing lens 44.

[0034] After passing through the second focusing lens 44, the second laser beam 123 enters the second frequency-doubling crystal 41. In this embodiment, the second frequency-doubling crystal 41 is a doubled-frequency crystal of lithium triborate. Alternatively, a tripled-frequency crystal or a quadrupled-frequency crystal with an appropriate wavelength may be selected as needed. After passing through the second frequency-doubling crystal 41, the second laser beam 123 forms a second frequency-doubling laser beam 127. The second frequency-doubling laser beam 127 passes through the second collimating lens 45 and enters the second dichroic mirror 42. The second frequency-doubling laser beam 127 comprises frequency-doubled green laser light and un-frequency-doubled infrared light. After passing through the second dichroic mirror 42, the second frequency-doubling laser beam 127 is divided into a second unused laser beam 128 and a second monochromatic laser beam 129. The second unused laser beam 128 is un-frequency-doubled infrared light, while the second monochromatic laser beam 129 is frequency-doubled green laser light. The second unused laser beam 128 passes through the second dichroic mirror 42 and is directly emitted. The second monochromatic laser beam 129 is reflected by the second dichroic mirror 42 and reaches the third dichroic mirror 43.

[0035] The second monochromatic laser 129 is reflected by the third dichroic mirror 43 and then enters the polarization beam combiner 5 . The first monochromatic laser 126 also enters the polarization beam combiner 5 . The polarization beam combiner 5 finally emits a combined laser 130 .

[0036] The device further includes a first light-collecting tube 61 and a second light-collecting tube 62. The first unwanted laser light 125 enters the first light-collecting tube 61, and the second unwanted laser light 128 enters the second light-collecting tube 62. Since the first unwanted laser light 125 and the second unwanted laser light 128 are infrared lasers, infrared lasers are not required for welding in this technical solution, and therefore infrared lasers are considered useless lasers in this technical solution. Since infrared laser light emits radiation when it enters the natural world, affecting people's normal lives, the first and second light-collecting tubes 61 and 62 are used to collect the radiation, thereby preventing the infrared laser light from causing light pollution to the environment after it is emitted.

[0037] The following describes a method for using a quasi-continuous green laser light emitting device of the present invention:

[0038] S1, adjustment of seed laser 121:

[0039] The laser 11 emits a red seed laser 121 . The power of the seed laser 121 is amplified by the laser amplifier 12 and then passes through the laser collimation isolator 13 before entering the polarization beam splitter 2 .

[0040] S2, the adjusted spectrophotometry of the seed laser 121:

[0041] The adjusted seed laser 121 passes through the polarization beam splitter 2 and is split into a first laser 122 and a second laser 123 , wherein the first laser 122 and the second laser 123 are in orthogonal polarization states.

[0042] The first laser beam 122 enters the first splitting path 3 , and the second laser beam enters the second splitting path 4 .

[0043] S3, acquisition of green laser light in the first split light path 3:

[0044] After passing through the first focusing lens 33, the first laser 122 enters the first frequency-doubling crystal 31. The first focusing lens 33 converges the first laser 122. The converged first laser 122 passes through the first frequency-doubling crystal 31 to form a first frequency-doubled laser 124. The first frequency-doubled laser 124 passes through the first collimating lens 34 and enters the first dichroic mirror 32. The first frequency-doubled laser 124 includes frequency-doubled green laser light and unfrequency-doubled infrared light. Therefore, after passing through the first dichroic mirror 32, the first frequency-doubled laser 124 is divided into a first useless laser 125 and a first monochromatic laser 126. The first useless laser 125 is unfrequency-doubled infrared light, and the first monochromatic laser 126 is frequency-doubled green laser light.

[0045] S4, acquisition of green laser light in the second split light path 4:

[0046] The second laser 123 is reflected by the red light high-reflection mirror 7 and enters the second focusing lens 44. The second laser 123 passes through the second focusing lens 44 and enters the second frequency-doubling crystal 41. The second laser 123 passes through the second frequency-doubling crystal 41 to form a second frequency-doubling laser 127. The second frequency-doubling laser 127 passes through the second collimating lens 45 and enters the second dichroic mirror 42. The second frequency-doubling laser 127 includes a frequency-doubled green laser and an infrared light that has not been frequency-doubled. After passing through the second dichroic mirror 42, the second frequency-doubling laser 127 is divided into a second useless laser 128 and a second monochromatic laser 129. The second useless laser 128 is an infrared light that has not been frequency-doubled, and the second monochromatic laser 129 is a frequency-doubled green laser.

[0047] S5, recycling of useless laser:

[0048] The first unnecessary laser beam 125 enters the first light-collecting tube 61 , and the second unnecessary laser beam 128 enters the second light-collecting tube 62 .

[0049] S6, emission of green laser:

[0050] The second monochromatic laser 129 is reflected by the third dichroic mirror 43 and then enters the polarization beam combiner 5 . The first monochromatic laser 126 also enters the polarization beam combiner 5 . The polarization beam combiner 5 then emits a combined laser 130 .

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A quasi-continuous green laser light emitting device, comprising a seed laser light path (1), a polarization beam splitter (2), a first beam splitting path (3), a second beam splitting path (4) and a polarization beam combiner (5), wherein: The seed laser optical path (1) comprises a laser (11), wherein the laser (11) emits a seed laser (121); The seed laser (121) is divided into a first laser (122) and a second laser (123) after passing through a polarization beam splitter (2); the first laser (122) and the seed laser (121) propagate in the same direction, and the second laser (123) and the first laser (122) propagate at a 90-degree angle. It is characterized in that: the first light splitting path (3) includes a first frequency doubling crystal (31) and a first dichroic mirror (32); The first laser (122) passes through the first frequency-doubling crystal (31) to form a first frequency-doubling laser (124), and the first frequency-doubling laser (124) passes through the first dichroic mirror (32) to be divided into a first useless laser (125) and a first monochromatic laser (126); The first monochromatic laser (126) finally enters the polarization beam combiner (5); The second light splitting path (4) includes a second frequency doubling crystal (41), a second dichroic mirror (42) and a third dichroic mirror (43); The second laser (123) passes through the second frequency-doubling crystal (41) to form a second frequency-doubling laser (127), and the second frequency-doubling laser (127) passes through the second dichroic mirror (42) to be divided into a second useless laser (128) and a second monochromatic laser (129); The second monochromatic laser (129) is reflected by the third dichroic mirror (43) and finally enters the polarization beam combiner (5); The polarization beam combiner (5) emits a synthesized laser (130); The seed laser optical path (1) further includes a laser amplifier (12) and a laser collimation isolator (13); the seed laser (121) sequentially passes through the laser amplifier (12) and the laser collimation isolator (13) and then enters the polarization beam splitter (2); The first light splitting path (3) further includes a first focusing lens (33), and the first laser (122) enters the first frequency doubling crystal (31) after passing through the first focusing lens (33); The first light splitting path (3) further includes a first collimating lens (34), and the first frequency-doubled laser (124) enters the first dichroic mirror (32) after passing through the first collimating lens (34); It also includes a red light high-reflection mirror (7), and the second light splitting path (4) also includes a second focusing lens (44). The second laser (123) reflected by the red light high-reflection mirror (7) passes through the second focusing lens (44) and then enters the second frequency-doubling crystal (41). The second light splitting path (4) further includes a second collimating lens (45), and the second frequency-doubled laser (127) passes through the second collimating lens (45) and then enters the second dichroic mirror (42); It also includes a first light-collecting tube (61) and a second light-collecting tube (62), wherein the first useless laser light (125) enters the first light-collecting tube (61) and the second useless laser light (128) enters the second light-collecting tube (62).

2. A quasi-continuous green laser light emitting device according to claim 1, characterized in that: The polarization beam splitter (2) is a red light polarization beam splitter, and the polarization beam combiner (5) is a green light polarization beam combiner.

3. The quasi-continuous green laser emitting device according to claim 1, characterized in that: The laser (11) is a narrowband continuous laser, a single-frequency continuous laser, a nanosecond pulse laser, or an ultrafast pulse laser.

4. A method for using a quasi-continuous green laser light emitting device, characterized in that: Using the quasi-continuous green laser light emitting device according to claim 1, The following steps are involved: S1, adjustment of seed laser (121): The laser (11) is started, and the laser emits a red seed laser (121). The power of the seed laser (121) is amplified by the laser amplifier (12), passes through the laser collimation isolator (13), and then enters the polarization beam splitter (2). S2, the adjusted spectroscopic result of the seed laser (121): The adjusted seed laser (121) passes through a polarization beam splitter (2) and is then split into a first laser (122) and a second laser (123), wherein the first laser (122) and the second laser (123) are in orthogonal polarization states; The first laser (122) enters the first splitting path (3), and the second laser enters the second splitting path (4); S3, acquisition of green laser light in the first split light path (3): The first laser (122) passes through the first focusing lens (33) and enters the first frequency doubling crystal (31). The first focusing lens (33) converges the first laser (122). The converged first laser (122) passes through the first frequency doubling crystal (31) to form a first frequency doubling laser (124). The first frequency doubling laser (124) passes through the first collimating lens (34) and enters the first dichroic mirror (32). The first frequency doubling laser (124) includes a frequency-doubled green laser and an infrared light that has not been frequency-doubled. Therefore, the first frequency doubling laser (124) passes through the first dichroic mirror (32) and is divided into a first useless laser (125) and a first monochromatic laser (126). The first useless laser (125) is an infrared light that has not been frequency-doubled, and the first monochromatic laser (126) is a frequency-doubled green laser. S4, acquisition of green laser light in the second split light path (4): The second laser (123) is reflected by the red light high reflective mirror (7) and enters the second focusing lens (44). The second laser (123) passes through the second focusing lens (44) and enters the second frequency doubling crystal (41). The second laser (123) passes through the second frequency doubling crystal (41) to form a second frequency doubling laser (127). The second frequency doubling laser (127) passes through the second collimating lens (45) and enters the second dichroic mirror (42). The second frequency doubling laser (127) includes a green laser after frequency doubling and infrared light that has not been frequency doubling. The second frequency doubling laser (127) passes through the second dichroic mirror (42) and is divided into a second useless laser (128) and a second monochromatic laser (129). The second useless laser (128) is infrared light that has not been frequency doubling, and the second monochromatic laser (129) is a green laser after frequency doubling. S5, recycling of useless laser: The first useless laser light (125) enters the first light-collecting tube (61), and the second useless laser light (128) enters the second light-collecting tube (62); S6, emission of green laser: The second monochromatic laser (129) is reflected by the third dichroic mirror (43) and enters the polarization beam combiner (5), and the first monochromatic laser (126) enters the polarization beam combiner (5); the polarization beam combiner (5) emits a synthesized laser (130).

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