CN110768096A - High-power and high-roundness industrial laser - Google Patents
High-power and high-roundness industrial laser Download PDFInfo
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- CN110768096A CN110768096A CN201911028559.4A CN201911028559A CN110768096A CN 110768096 A CN110768096 A CN 110768096A CN 201911028559 A CN201911028559 A CN 201911028559A CN 110768096 A CN110768096 A CN 110768096A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
- H01S3/109—Frequency multiplication, e.g. harmonic generation
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Abstract
The invention relates to a high-power high-roundness industrial laser, in particular to a high-power high-roundness industrial laser, which comprises: the invention relates to a laser cavity rear cavity mirror, a laser working medium, a pumping laser diode, a Q switch, a spectroscope, a frequency doubling crystal, a frequency tripling crystal, a resonant cavity mirror, a laser fundamental wave 1/2 wave plate turning mirror and a synthesis mirror, compared with the prior art, the invention has the following beneficial effects: 1. the reliability of the ultraviolet laser is realized; 2. the stability of the ultraviolet laser is realized; 3. and the spot roundness of the ultraviolet laser is improved.
Description
Technical Field
The invention relates to an industrial laser, in particular to a high-power and high-roundness industrial laser.
Background
The ultraviolet laser has short wavelength, small focusing light spot and large photon energy, can directly destroy the molecular bonds of a plurality of non-metallic materials in the material processing process to realize cold processing, and has smooth material edges and small carbonization.
The diode-pumped 355nm ultraviolet laser has the advantages of good beam quality, high efficiency, good power stability, high reliability, convenient use, small volume and the like, and is widely applied to the fields of precision material processing, photoetching, spectral analysis, medical treatment, scientific research and the like.
Diode-pumped high-power (>8W)355nm ultraviolet laser is realized by performing intracavity or extracavity frequency doubling on fundamental frequency infrared laser with the wavelength of 1064nm, and then performing corresponding mode frequency tripling (sum frequency) on partial fundamental frequency light and 532nm green light generated by frequency doubling.
The frequency doubling and frequency tripling are both nonlinear conversion processes of laser in an optical nonlinear crystal. Compared with an in-cavity nonlinear conversion mode, the laser focusing light spot outside the cavity is smaller, the requirement on the surface coating of the optical nonlinear crystal is higher, and therefore the crystal is easier to damage. Companies such as foreign coherence (Coherent) and spectrum Physics (Spectra-Physics) adopt such nonlinear conversion methods. The method is characterized in that the nonlinear crystal is shifted to limit the working time of the working point on the surface of the crystal, so that the laser can work stably and reliably for a long time. However, this method has very high requirements for controlling the crystal position movement (the laser has only one optimal orientation position relative to the nonlinear crystal), and generally needs precise position detection and discrimination, and the system control is complicated. In order to realize high-efficiency frequency doubling and frequency tripling, the ratio of the numbers of 1064nm infrared laser and 532nm green light photons entering the frequency tripling nonlinear crystal is 1:1, and actually, the numbers of the laser photons with two wavelengths are difficult to reach the ratio, so that the nonlinear conversion efficiency is influenced.
For the intracavity mode, because the light intensity in the cavity of the laser is improved by one order of magnitude compared with the light intensity outside the cavity, compared with the nonlinear conversion mode outside the cavity, the ultraviolet laser output with the same efficiency and the same power is realized, and the requirement of the mode on the surface coating of the nonlinear crystal is much lower than that of the nonlinear crystal in the mode outside the cavity, so the service life of the crystal is longer. The mode generally has no infrared laser output cavity, the green light and the ultraviolet laser outside the output cavity can be regarded as equivalent loss of the infrared laser resonant cavity, and the high nonlinear conversion efficiency can be achieved by optimizing parameters such as optical and mechanical dimensions of the nonlinear crystal. However, because multiple wavelengths (infrared 808nm, 1064nm, green 532nm, and ultraviolet 355nm) interact with each other simultaneously in the laser cavity, energy exchange occurs between them, and the exchange is also easily affected by external conditions (such as heat dissipation of the laser crystal, quality of the beam focused by coupling of the pump laser, etc.); meanwhile, the nonlinear frequency doubling and frequency tripling crystals need adjustment of more than three degrees of freedom and temperature adjustment, so that high-stability and reliable operation is more difficult to realize compared with an outside-cavity mode.
The reliable and stable output of high-power ultraviolet laser with the power of more than 8W is realized, 1064nm infrared fundamental frequency laser is required to be capable of generating high-power base film oscillation with high beam quality, a laser crystal has thermal lens and thermal birefringence effect as small as possible, and meanwhile, in order to realize the best nonlinear polarization matching, the ultraviolet nonlinear crystal and green light nonlinear crystal are required to be convenient to adjust.
CN205543662U, a utility model patent named uv laser discloses such a technical solution: the utility model provides an ultraviolet laser, a first pump laser light source; a second pump laser light source; a first lens; a second lens; a laser crystal module; an infrared laser total reflection mirror; an acousto-optic Q switch; the frequency tripling crystal module comprises a frequency tripling crystal and a frequency tripling crystal seat, wherein the frequency tripling crystal is fixed on the frequency tripling crystal seat, and three rotational degrees of freedom of the frequency tripling crystal can be adjusted through the frequency tripling crystal seat; the frequency doubling crystal module comprises a frequency doubling crystal and a frequency doubling crystal seat, the frequency doubling crystal is fixed on the frequency doubling crystal seat, and three rotational degrees of freedom of the frequency doubling crystal can be adjusted through the frequency doubling crystal seat; a mirror tail; a green light absorption cell for absorbing green laser light; the pump laser light emitted by the first pump laser light source enters the laser crystal module through the first lens, and the pump laser light emitted by the second pump laser light source enters the laser crystal module through the second lens; the pump laser emitted by the first pump laser light source and the pump laser emitted by the second pump laser light source generate fundamental mode oscillation in the laser crystal module and output fundamental frequency laser, the infrared laser total reflection mirror reflects the fundamental frequency laser to the acousto-optic Q switch, and the acousto-optic Q switch modulates continuous fundamental frequency laser into pulse fundamental frequency laser and outputs the pulse fundamental frequency laser; the pulse fundamental frequency laser sequentially passes through the triple frequency crystal and the double frequency crystal and then is reflected back to the double frequency crystal by a reflecting tail mirror; the double frequency crystal generates green laser and outputs the green laser to the triple frequency crystal, and the triple frequency crystal generates ultraviolet laser; the green laser which is not converted into the ultraviolet laser in the frequency tripling crystal is emitted into the green light absorption cell and is absorbed by the green light absorption cell. The technical scheme mainly solves the problems of 1, reducing the thermal resistance of the heat dissipation thermal coupling of the laser crystal and accelerating the heat dissipation of the laser crystal. 2. The double frequency crystal and the triple frequency crystal are working substances for generating green light and ultraviolet light, and because polarization matching in the double frequency process and the triple frequency process is involved, in order to achieve the optimal frequency doubling and sum frequency efficiency, three rotational degrees of freedom of the two crystals and adjustment of three rotational directions are required to be finely adjusted besides the adjustment of the matching temperature of the two crystals, and a crystal seat is required to be fixed after each crystal is adjusted to prevent dislocation. Generally, two crystals are adjusted on the same mounting base, and fastening screws are loosened during adjustment and then fastened after adjustment. However, the adjusted crystal position is changed, the other two degrees of freedom are affected when one degree of freedom is adjusted, the crystal is difficult to adjust to the optimal position and fasten all the time, and the method is very tedious and time-consuming. Meanwhile, because one crystal mounting seat is shared, the adjustment of one crystal can affect the other crystal, and the effect can be achieved only by repeatedly debugging, so that a lot of time is wasted. The utility model discloses a technical scheme structure that reveals is complicated, complex operation. Is not suitable for industrial large-scale application.
Fig. 2 discloses a prior ultraviolet laser, wherein 010, 030 are laser resonator cavity mirrors, 010 is a laser fundamental wave high reflection mirror, and the design has the advantages of simplicity and directness, and the defects that a frequency tripling crystal 017 is easy to damage (especially the upper end of the frequency tripling crystal upwards increases the antireflection film layer) when the ultraviolet power exceeds more than 5w, and the service life is short. In some designs, the ultraviolet emergent surface of the triple frequency doubling crystal is made into a Brewster surface, a dielectric film layer is not adopted, and the Brewster surface still has a damage phenomenon under the ultraviolet laser power.
Thus, there is a need for improvements and enhancements to the prior art.
Disclosure of Invention
The Q-switch ultraviolet laser is mainly limited by the damage threshold of a nonlinear crystal, the ultraviolet power is generally between 6 and 8w, the reliability and stability of the laser exceeding 10w are extremely challenging and expensive, while many applications such as ultraviolet micromachining, cutting and the like have great demands on the high-power ultraviolet laser, and the roundness of an ultraviolet laser spot is another extremely challenging.
The infrared pulse is divided into two groups, two groups are mutually orthogonal in orientation on the nonlinear conversion crystal, namely one group carries out intracavity frequency tripling on the horizontal polarization infrared, the other group carries out frequency tripling on the vertical polarization infrared, and the output two beams of frequency tripling pulse light beams are orthogonal in polarization and also in roundness. After synthesis, the ultraviolet light spot obtained contains polarization in two directions and has better roundness. Meanwhile, the method makes full use of unpolarized infrared pulses.
The technical scheme of the invention is as follows: an ultraviolet laser, comprising: a laser cavity rear cavity mirror, a laser working medium, a pump laser diode, a Q switch, a spectroscope, a frequency doubling crystal, a frequency tripling crystal, a resonant cavity mirror, a laser fundamental wave 1/2 wave plate turning mirror and a synthesis mirror, the spectroscope comprises a first spectroscope and a second spectroscope, the frequency doubling crystal comprises a first frequency doubling crystal and a second frequency doubling crystal, the frequency tripling crystal comprises a first frequency tripling crystal and a second frequency tripling crystal, the resonant cavity mirror comprises a first resonant cavity mirror and a second resonant cavity mirror, the turning mirrors comprise a first turning mirror and a second turning mirror, the laser working medium corresponds to the pumping laser diode, the laser fundamental wave beam is divided into two beams by the first spectroscope, one beam passes through the first frequency doubling crystal and the first frequency tripling crystal, and then part of the beam is converted into frequency tripling ultraviolet laser which is output as a first ultraviolet laser beam through the first resonant cavity mirror; and the other beam of partial laser fundamental wave beam reflected by the second beam splitter is reflected by the first turning mirror, the polarization direction is rotated by 90 degrees by the laser fundamental wave 1/2 wave plate, then the partial laser fundamental wave energy is converted into triple frequency laser through the second double frequency crystal and the second triple frequency crystal, the triple frequency laser is output as a second ultraviolet laser beam through the second resonant cavity mirror, and the first ultraviolet laser beam passes through the second turning mirror and then is synthesized into a third ultraviolet laser beam through the ultraviolet laser synthesis mirror and the second ultraviolet laser beam.
Further, the crystal orientation of the second frequency doubling crystal and the second frequency tripling crystal is orthogonal or rotated by 90 degrees relative to the first frequency doubling crystal and the first frequency tripling crystal.
Further, 1/4 wave plates of a pair of ultraviolet laser beams are inserted into the third ultraviolet laser beam optical path.
Compared with the prior art, the invention has the beneficial effects that: 1. the reliability of the ultraviolet laser is realized; 2. the stability of the ultraviolet laser is realized; 3. and the spot roundness of the ultraviolet laser is improved.
Drawings
FIG. 1: the invention has a structure schematic diagram;
FIG. 2: the structure of the existing laser is schematically shown.
Detailed Description
As shown in fig. 1, 050 is a laser cavity rear cavity mirror, a laser fundamental wave high-reflection mirror, 051 is a laser working medium, 052 is a pump laser diode, 053 is a driving current of the pump laser diode 052, 054 is an acousto-optic Q switch, 055 is a radio frequency drive of the acousto-optic Q switch 054, and 059 is a first beam splitter. A laser fundamental wave beam 077 is divided into two beams by a first beam splitter 059, wherein one beam 078 is partially converted into frequency tripling ultraviolet laser after passing through a first frequency tripling crystal 065 and a first frequency tripling crystal 066 and is output through a first resonant cavity mirror 072, and the output first ultraviolet laser beam is 081; the other laser fundamental wave beam 079 is reflected to the first turning mirror 057 through the second beam splitter 056 and then reflected, the laser fundamental wave 1/2 wave plate 058 rotates the polarization direction by 90 degrees, then passes through the second frequency doubling crystal 0651 and the second frequency tripling crystal 0661, part of the laser fundamental wave energy is converted into frequency tripling laser, and is output as a second ultraviolet laser beam 082 through the second resonator mirror 0721.
In fig. 1, 068,070,060 and 059 are angle control parts of frequency doubling and frequency tripling crystals 065, 066, 059 and 061, and 067,069,060 and 062 are temperature control driving parts corresponding to the frequency doubling and frequency tripling crystals 065, 066, 059 and 061.
The second frequency doubling crystal 059, the crystal orientation of the second frequency doubling crystal 061 is orthogonal or rotated 90 ° with respect to the first frequency doubling crystal 065 and the first frequency doubling crystal 066, so that the deflection direction of the second ultraviolet laser beam 082, the spot circle direction and the first ultraviolet laser beam 081 are also exactly orthogonal, i.e. are in a 90 ° direction with respect to each other.
The ultraviolet laser synthesizing mirror 076 transmits the second ultraviolet laser beam 082 completely, and reflects the first ultraviolet laser beam 081 polarized orthogonally to the second ultraviolet laser beam 082 completely, so that the first ultraviolet laser beam 081 passes through the second turning mirror 075, passes through the ultraviolet laser synthesizing mirror 076, and is synthesized with the second ultraviolet laser beam 082 into a third ultraviolet laser beam 085.
The power of the ultraviolet laser beam 081,082 is controlled at 6-8w level, so that the stable working life of frequency tripling crystals 066 and 061 can be greatly prolonged, and the power of the synthesized ultraviolet laser beam can reach about 15w level, thereby meeting the requirements of many ultraviolet laser applications. Meanwhile, the synthesized third ultraviolet laser beam 085 has better spot roundness, has two components with mutually orthogonal polarization, has certain superiority in many polarization-sensitive applications, and can also be used for converting the two ultraviolet laser beams 081,082 into lights with same-frequency polarization by inserting 1/4 wave plates of a pair of ultraviolet laser beams into the light path of the third ultraviolet laser beam 085.
Although embodiments of the present invention have been shown and described, it will be understood that the embodiments described above are illustrative and should not be construed as limiting the invention, and that those skilled in the art can make changes, modifications, substitutions and alterations to the embodiments described above without departing from the spirit and scope of the invention, and that such changes, modifications, substitutions and alterations in combination are intended to be included within the scope of the invention.
Claims (3)
1. A high power, high roundness industrial laser, comprising: a laser cavity rear cavity mirror, a laser working medium, a pump laser diode, a Q switch, a spectroscope, a frequency doubling crystal, a frequency tripling crystal, a resonant cavity mirror, a laser fundamental wave 1/2 wave plate turning mirror and a synthesis mirror, the spectroscope comprises a first spectroscope and a second spectroscope, the frequency doubling crystal comprises a first frequency doubling crystal and a second frequency doubling crystal, the frequency tripling crystal comprises a first frequency tripling crystal and a second frequency tripling crystal, the resonant cavity mirror comprises a first resonant cavity mirror and a second resonant cavity mirror, the turning mirrors comprise a first turning mirror and a second turning mirror, the laser working medium corresponds to the pumping laser diode, the laser fundamental wave beam is divided into two beams by the first spectroscope, one beam passes through the first frequency doubling crystal and the first frequency tripling crystal, and then part of the beam is converted into frequency tripling ultraviolet laser which is output as a first ultraviolet laser beam through the first resonant cavity mirror; and the other beam of partial laser fundamental wave beam reflected by the second beam splitter is reflected by the first turning mirror, the polarization direction is rotated by 90 degrees by the laser fundamental wave 1/2 wave plate, then the partial laser fundamental wave energy is converted into triple frequency laser through the second double frequency crystal and the second triple frequency crystal, the triple frequency laser is output as a second ultraviolet laser beam through the second resonant cavity mirror, and the first ultraviolet laser beam passes through the second turning mirror and then is synthesized into a third ultraviolet laser beam through the ultraviolet laser synthesis mirror and the second ultraviolet laser beam.
2. A high power, high circularity industrial laser according to claim 1, wherein: the crystal orientation of the second frequency doubling crystal and the second frequency tripling crystal is orthogonal or rotated by 90 degrees relative to the first frequency doubling crystal and the first frequency tripling crystal.
3. A high power, high circularity industrial laser according to claim 1, wherein: an 1/4 wave plate for a pair of ultraviolet laser beams is inserted into the third ultraviolet laser beam optical path.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911028559.4A CN110768096A (en) | 2019-10-28 | 2019-10-28 | High-power and high-roundness industrial laser |
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| CN201911028559.4A CN110768096A (en) | 2019-10-28 | 2019-10-28 | High-power and high-roundness industrial laser |
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| CN110768096A true CN110768096A (en) | 2020-02-07 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114204394A (en) * | 2021-11-03 | 2022-03-18 | 中国科学院微电子研究所 | Orthogonal polarization dual-wavelength laser with adjustable proportion |
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2019
- 2019-10-28 CN CN201911028559.4A patent/CN110768096A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114204394A (en) * | 2021-11-03 | 2022-03-18 | 中国科学院微电子研究所 | Orthogonal polarization dual-wavelength laser with adjustable proportion |
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Application publication date: 20200207 |