CN110540371A - CO2 laser scanning method applied to optical element film atomic defect repair - Google Patents
CO2 laser scanning method applied to optical element film atomic defect repair Download PDFInfo
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- CN110540371A CN110540371A CN201910820676.8A CN201910820676A CN110540371A CN 110540371 A CN110540371 A CN 110540371A CN 201910820676 A CN201910820676 A CN 201910820676A CN 110540371 A CN110540371 A CN 110540371A
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- laser
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- optical glass
- repair
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B11/00—Work holders not covered by any preceding group in the subclass, e.g. magnetic work holders, vacuum work holders
- B25B11/005—Vacuum work holders
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
- C03C23/0005—Other surface treatment of glass not in the form of fibres or filaments by irradiation
- C03C23/0025—Other surface treatment of glass not in the form of fibres or filaments by irradiation by a laser beam
Abstract
The invention relates to a CO2 laser scanning method applied to optical element film atomic-level defect repair, which adopts CO2 laser with the wavelength of 10.6 microns as a repair energy source, adopts an S-shaped or parallel scanning mode, scans an optical glass deposition layer by changing the laser power, the repetition frequency and the spot diameter, realizes the repair of defects such as a cavity, an E' color center, an oxygen vacancy, an oxygen connection, a non-bridge oxygen center, a peroxy group and the like in the optical glass deposition layer, and finally reduces the light absorption rate. The method of the invention adopts low-power laser energy for repair, does not damage the material, and does not change the surface appearance of the original material. The method is suitable for the nondestructive repair of the point defect of the optical glass deposition layer.
Description
Technical Field
The invention relates to the technical field of optical glass deposition layer defect repair, in particular to a CO2 laser scanning method applied to optical element film atomic-level defect repair.
Background
The optical element is in the field of ultraprecise optical elements with surface precision requirements of lambda/200 and surface roughness of less than 0.1nm, such as aerospace, medical treatment, national defense, astronomy, lasers and the like. An optical element formed by a fused quartz optical element substrate and thin film deposition layers such as SiO2, Al2O3 and HfO2 has good light transmittance, but the thin film has defects such as E' color center, dangling bond, overcoordination, oxygen vacancy, peroxy connection and the like, and although the defects can be eliminated by the traditional heat treatment, the surface shape precision and the surface roughness of the workpiece and the surface of the thin film are easy to change because the workpiece and the whole thin film can be subjected to heat treatment only, and the defects such as impurities and the like are introduced in the annealing process. Therefore, it is necessary to develop a novel defect repairing method to improve the atomic defects in the thin film and on the interface between the thin film and the substrate without changing the surface precision and the surface shape.
Disclosure of Invention
The present invention is to solve the above-mentioned deficiencies of the prior art and to provide a method for eliminating point defects of an optical glass deposition layer without affecting the existing surface topography and introducing new defects. The method adopts the technical means of cleaning, drying, CO2 laser scanning and low-power CO2 laser repeated scanning repair to realize the nondestructive repair of the point defects of the optical glass deposition layer.
The technical scheme adopted by the invention for solving the technical problems is as follows:
A CO2 laser scanning method for repairing the atomic defects of optical element film features that the CO2 laser with critical energy density is used to scan the clean surface of optical element film, and the atomic defects in the optical element film and at the interface between optical element film and substrate are repaired under the action of local heat to increase the binding force between film and substrate.
further, the CO2 laser repair method specifically comprises the following steps:
Firstly, in a ten thousand-level clean room, dust-free cloth is adopted to dip cleaning liquid, and optical glass is wiped in a single direction until dust cannot be found by naked eyes;
secondly, blowing the cleaned surface by adopting a normal-temperature mode of a blower until the cleaned surface is dry;
Fixing the dried optical glass on a CO2 laser processing platform in a vacuum adsorption mode to ensure that the surface to be repaired is opposite to the laser direction;
Fourthly, turning on a laser source, adjusting laser power, laser spot diameter and repetition frequency, introducing a laser scanning track graph, positioning a scanning starting point, and starting CO2 laser irradiation repair;
And fifthly, reducing the laser power, keeping the other parameters unchanged, keeping the track graph of the laser scanning unchanged, positioning the original scanning starting point as a new scanning starting point, and performing secondary irradiation repair.
Further, the optical glass includes fused silica glass, K9 or BK 7.
furthermore, the optical glass deposition layer material comprises SiO2, HfO2 or Al2O3, and the thickness of the deposition layer is 10-1000 nm.
Further, the defects of the optical glass deposition layer refer to point defects generated during the deposition of the optical glass deposition layer, including an E' core, an oxygen core, a hydroxyl group or a peroxy group.
Further, in the first step, the cleaning solution refers to absolute ethyl alcohol and acetone.
further, in the third step, vacuum adsorption means that a workbench with a vacuum adsorption function is adopted to adsorb the optical glass, and the vacuum degree is 20-60 kPa.
further, in the fourth step, the parameters related to the CO2 laser are as follows: the wavelength is 10.6 mu m, the power is 4-20W, the frequency is 1-200 kHz, the pulse width is 2-1000 mu s, and the diameter of a light spot is 1-5 mm.
further, in the fourth step, the scanned track patterns are S-shaped tracks and parallel tracks, and the relevant track parameters are as follows: the distance between adjacent tracks is 50-80% of the diameter of the light spot, the area formed by scanning the tracks is 1.01-1.1 times of the surface to be repaired, the speed adopted by scanning is 5-50mm/s, and the defocusing amount is 0.1-2 mm.
Compared with the prior art, the invention has the following characteristics:
1. Ethanol or acetone is adopted, dust-free cloth is used for cleaning, a blower is used for drying the surface, the operation is simple, the method is reliable, and the surface of the optical glass cannot be damaged in any form by normal-temperature operation;
2. CO2 laser irradiation lower than the damage threshold of the optical glass deposition layer is adopted, so that new residual stress cannot be introduced, new damage cannot be caused, and the method is an effective repair mode;
3. The optical glass is fixed in a vacuum adsorption mode, so that the operation is convenient, no clamping force is generated, and the method is more suitable for processing precise optical glass;
4. The CO2 laser scanning motion track adopts S-shaped and parallel motion modes, and the scanning is uniform and simple and easy to implement. The scanning area is larger than the surface to be repaired of the optical glass, so that the quality is prevented from being unstable in the initial stage and the end stage of laser scanning, the parameter adjustment difficulty is reduced, and the repairing effect is improved;
5. in the first scanning, residual stress is possibly generated due to temperature rise caused by heat absorption of the defects, the potential residual stress can be conveniently eliminated by slowly cooling through the second low-power scanning, and the operation process is simple and easy to implement.
drawings
Fig. 1 is a schematic diagram of CO2 laser scanning repair in relation to the present invention.
fig. 2 is a schematic diagram of the CO2 laser irradiation motion trajectory according to the present invention.
in fig. 1, 1 is a CO2 laser source, 2 is a laser beam, 3 is a spectroscope, 4 is a reflector, 5 lenses, 6 is an optical glass deposition layer, 7 is optical glass, 8 is a movable vacuum adsorption platform, 9 is a vacuum pump, 10 is a power meter, and 11 is a control system.
In fig. 2, 12 is an S-shaped track and 13 is a parallel track.
Detailed Description
The invention will be further explained with reference to the drawings
the CO2 laser repairing method for the defects of the optical glass deposition layer is suitable for nondestructive repair of point defects of optical glass with the substrate being fused quartz glass, K9 and BK7, the deposition layer being made of SiO2, HfO2 and Al2O3, and the deposition layer being 10-1000 nm thick.
The principle and basis of the invention are as follows: the CO2 laser with good directionality, good monochromatic light and good coherence is focused on the surface of a workpiece to be processed through a lens, has high energy, and the energy is transmitted to the surface of a material to be processed through photons to increase the temperature of the surface of the workpiece. Meanwhile, due to the light absorption effect of the defects, the obtained energy is the most, so that the atom activity at the defects is the highest, the atom positions are changed and restored to a normal state, and the broken chemical bonds are reconnected, so that the point defects are repaired. The CO2 laser can realize accurate control of time and space, control heat on the surface of a workpiece, control energy density below film damage, scan the optical glass deposition, further eliminate point defects in the deposition layer, and improve the light transmittance of the optical glass deposition layer.
The device used by the invention comprises the following working processes: the vacuum pump 9 controls the vacuum degree of the movable vacuum adsorption platform 8, the power meter 10 detects laser power and judges whether the laser light source 1 works normally, and the control system 11 controls relevant parameters of the laser light source 1 and the movable vacuum adsorption platform 8. Firstly, a laser 1 emits a laser beam 2, part of the laser beam enters a power meter 10 through the action of a spectroscope 3, most of the laser beam is emitted to a reflector 4 and then reflected to a lens 5, and the laser beam 1 irradiates an optical glass deposition layer 6 for laser repair under the focusing action of the lens 5.
Example 1
And performing CO2 laser repair on the point defects of the optical glass deposition layer, wherein the base material is fused quartz, the deposition layer material is SiO2, and the thickness of the deposition layer is 1000 nm. The experiment was performed in a ten thousand grade clean room. Firstly, uniformly dripping absolute ethyl alcohol on dust-free cloth, then wiping the settled layer in a single direction by using the dust-free cloth, and not using the wiped dust-free cloth until no dust exists on the surface of the settled layer under the light reflection. And then dried by a blower. And finally, placing the optical glass on the movable vacuum adsorption platform 8, ensuring that the optical glass 7 is close to the movable vacuum adsorption platform 8, ensuring that the optical glass deposition layer 6 is just opposite to the laser beam, opening the vacuum pump 9, and ensuring that the vacuum degree of the vacuum adsorption platform 8 is 30 kPa. The laser parameters are adjusted by the control system 11: laser power is 12W, repetition frequency is 10kHz, pulse width is 300 mus, lens 5 is adjusted to enable the diameter of a light spot to be 1mm, scanning speed is 1000mm/S, track interval is 2mm, the size of a track exceeds 1% of fused quartz, and scanning is conducted by adopting an S-shaped track 1 irradiation mode in the figure 2. And after the scanning is finished, adjusting the laser power to be 6W, keeping the other parameters unchanged, and re-irradiating by adopting the same method. The experimental result shows that after irradiation, the light transmittance of the fused quartz deposition layer is improved by about 5% in a visible light wave band.
Example 2, the optical glass deposition layer is subjected to defect CO2 laser repair, the base material is K9, the deposition layer material is Al2O3, and the thickness of the deposition layer is 300 nm. The experiment was performed in a ten thousand grade clean room. Firstly, uniformly dripping absolute ethyl alcohol on dust-free cloth, then wiping the settled layer in a single direction by using the dust-free cloth, and not using the wiped dust-free cloth until no dust exists on the surface of the settled layer under the light reflection. And then dried by a blower. And finally, placing the optical glass on the movable vacuum adsorption platform 8, ensuring that the optical glass 7 is close to the movable vacuum adsorption platform 8, ensuring that the optical glass deposition layer 6 is just opposite to the laser beam, opening the vacuum pump 9, and ensuring that the vacuum degree of the vacuum adsorption platform 8 is 40 kPa. The laser parameters are adjusted by the control system 11: laser power is 16W, repetition frequency is 3kHz, pulse width is 300 mus, lens 5 is adjusted to enable spot diameter to be 2mm, scanning speed is 300mm/s, track interval is 1.5mm, track exceeds fused quartz size by 1%, and scanning is conducted in a parallel track 2 irradiation mode in the graph 2. And after the scanning is finished, adjusting the laser power to be 8W, keeping the other parameters unchanged, and re-irradiating by adopting the same method. The experimental result shows that after irradiation, the light transmittance of the fused quartz deposition layer is improved by about 8% in a visible light wave band.
The repairing method of the invention has no influence on the surface shape of the surface. The cleaning and drying method adopted in the defect repairing process step does not introduce new defects, does not corrode optical glass, and is environment-friendly and pollution-free; through the heat conduction of low energy, can adjust the relative motion position of atom, and then repair the defect, can effectively improve the luminousness, reduce the absorptivity, and then improve corresponding optical element's life-span. Defects in the deposition layer can be eliminated by the second low-power irradiation in the first laser irradiation due to the phenomenon of residual stress and the like possibly existing in the heat absorption phenomenon, and the method is simple to operate, safe and reliable; the size of the optical glass is not limited, local repair can be carried out, and the repair range is greatly improved. The method can make up for the defects in the deposition process, expand the application range of the technology and have good social and practical values.
Claims (9)
1. A CO2 laser scanning method for repairing atomic defects of optical element film is characterized in that the method is to scan the surface of a clean optical element film by CO2 laser with critical energy density, repair the atomic defects in the optical element film and at the interface between the optical element film and a substrate under the action of local heat, and improve the bonding force between the film and the substrate interface, wherein the critical energy density is higher than the electron transition of a defect structure and lower than the energy of surface morphology deformation.
2. The scanning method according to claim 1, wherein the step of CO2 laser repair is specifically:
Firstly, in a ten thousand-level clean room, dust-free cloth is adopted to dip cleaning liquid, and optical glass is wiped in a single direction until dust cannot be found by naked eyes;
secondly, blowing the cleaned surface by adopting a normal-temperature mode of a blower until the cleaned surface is dry;
Fixing the dried optical glass on a CO2 laser processing platform in a vacuum adsorption mode to ensure that the surface to be repaired is opposite to the laser direction;
fourthly, turning on a laser source, adjusting laser power, laser spot diameter and repetition frequency, introducing a laser scanning track graph, positioning a scanning starting point, and starting CO2 laser irradiation repair;
and fifthly, reducing the laser power, keeping the other parameters unchanged, keeping the track graph of the laser scanning unchanged, positioning the original scanning starting point as a new scanning starting point, and performing secondary irradiation repair.
3. A scanning method according to claim 2, characterized in that said optical glass comprises fused silica glass, K9 or BK 7.
4. The scanning method of claim 2, wherein the optical glass deposition layer comprises SiO2, HfO2 or Al2O3, and the thickness of the deposition layer is 10-1000 nm.
5. A scanning method according to claim 2 wherein the defects in the deposited layer of optical glass are point defects generated during the deposition of the deposited layer of optical glass, including E' centers, oxygen centers, hydroxyl groups or peroxy groups.
6. The scanning method according to claim 2, wherein the cleaning solution in the first step is absolute ethanol and acetone.
7. The scanning method according to claim 2, wherein in the third step, the vacuum adsorption is performed by adsorbing the optical glass by using a stage having a vacuum adsorption function, and the degree of vacuum is 20 to 60 kPa.
8. The scanning method according to claim 2, wherein in the fourth step, the parameters related to the CO2 laser are as follows: the wavelength is 10.6 mu m, the power is 4-20W, the frequency is 1-200 kHz, the pulse width is 2-1000 mu s, and the diameter of a light spot is 1-5 mm.
9. The scanning method according to claim 2, wherein in the fourth step, the scanned track patterns are S-shaped tracks and parallel tracks, and the associated track parameters are: the distance between adjacent tracks is 50-80% of the diameter of the light spot, the area formed by scanning the tracks is 1.01-1.1 times of the surface to be repaired, the speed adopted by scanning is 5-50mm/s, and the defocusing amount is 0.1-2 mm.
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| CN201910820676.8A CN110540371A (en) | 2019-08-29 | 2019-08-29 | CO2 laser scanning method applied to optical element film atomic defect repair |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114394764A (en) * | 2021-12-31 | 2022-04-26 | 中建材蚌埠玻璃工业设计研究院有限公司 | Repairing method for repairing edge of flexible glass |
| CN116282865A (en) * | 2022-11-25 | 2023-06-23 | 中国工程物理研究院激光聚变研究中心 | Online removing system and method for high-energy radiation defects of optical element |
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Cited By (2)
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| CN114394764A (en) * | 2021-12-31 | 2022-04-26 | 中建材蚌埠玻璃工业设计研究院有限公司 | Repairing method for repairing edge of flexible glass |
| CN116282865A (en) * | 2022-11-25 | 2023-06-23 | 中国工程物理研究院激光聚变研究中心 | Online removing system and method for high-energy radiation defects of optical element |
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