Effects related to the use of high repetition rate lasers in ablation of metals (aluminum, copper, stainless steel) and silicon were investigated. The multi-pulse irradiation with the laser beam significantly lowered the ablation threshold and led to a relative increase in the ablation rate at the higher repetition rate. The reason of alteration could be accumulation of structural defects on the metal surface formed by irradiation with a laser of the sub-threshold fluence. The mean volumetric ablation rate in laser milling experiments was a non-linear function of the pulse energy. Plasma shielding was the main limiting factor in processing efficiency of metals with the high power picosecond lasers. Increasing the repetition rate keeping the pulse energy below the plasma formation threshold is a way to increase the efficiency of material removal with nanosecond lasers. Thermal management of the specimen could be a problem at high repetition rates because of the laser energy wasted in the bulk. The reduction in the ablation threshold by irradiation with a series of laser pulses might be useful in application of the high- repetition-rate lasers with the low pulse energy.
{"title":"Accumulation effects in laser ablation of metals with high-repetition-rate lasers","authors":"G. Račiukaitis, M. Brikas, P. Gečys, M. Gedvilas","doi":"10.1117/12.782937","DOIUrl":"https://doi.org/10.1117/12.782937","url":null,"abstract":"Effects related to the use of high repetition rate lasers in ablation of metals (aluminum, copper, stainless steel) and silicon were investigated. The multi-pulse irradiation with the laser beam significantly lowered the ablation threshold and led to a relative increase in the ablation rate at the higher repetition rate. The reason of alteration could be accumulation of structural defects on the metal surface formed by irradiation with a laser of the sub-threshold fluence. The mean volumetric ablation rate in laser milling experiments was a non-linear function of the pulse energy. Plasma shielding was the main limiting factor in processing efficiency of metals with the high power picosecond lasers. Increasing the repetition rate keeping the pulse energy below the plasma formation threshold is a way to increase the efficiency of material removal with nanosecond lasers. Thermal management of the specimen could be a problem at high repetition rates because of the laser energy wasted in the bulk. The reduction in the ablation threshold by irradiation with a series of laser pulses might be useful in application of the high- repetition-rate lasers with the low pulse energy.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126031639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The concept of power-scalable, high beam-quality diode pumped alkali lasers was introduced in 2003 [Krupke, US Patent No. 6,643,311; Opt. Letters, 28, 2336 (2003)]. Since then several laboratory DPAL devices have been reported on, confirming many of the spectroscopic, kinetic, and laser characteristics projected from literature data. This talk will present an overview of the DPAL concept, summarize key relevant properties of the cesium, rubidium, and potassium alkali vapor gain media so-far examined, outline power scaling considerations, and highlight results of published DPAL laboratory experiments.
{"title":"Diode pumped alkali lasers (DPALs): an overview","authors":"W. Krupke","doi":"10.1117/12.782466","DOIUrl":"https://doi.org/10.1117/12.782466","url":null,"abstract":"The concept of power-scalable, high beam-quality diode pumped alkali lasers was introduced in 2003 [Krupke, US Patent No. 6,643,311; Opt. Letters, 28, 2336 (2003)]. Since then several laboratory DPAL devices have been reported on, confirming many of the spectroscopic, kinetic, and laser characteristics projected from literature data. This talk will present an overview of the DPAL concept, summarize key relevant properties of the cesium, rubidium, and potassium alkali vapor gain media so-far examined, outline power scaling considerations, and highlight results of published DPAL laboratory experiments.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121214617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Lippert, L. Urech, R. Fardel, M. Nagel, C. Phipps, A. Wokaun
The application of energetic polymers has resulted in an increased thrust in micro laser plasma thrusters compared to standard polymers. In this study we tested a novel concept for micro laser plasma thrusters, i.e. the application of liquid polymeric fuels, by using polymer solutions of the energetic materials with different viscosity. Shadowgraphy experiments suggest that for higher viscosity solutions ablation without splashing is possible, indicating that liquids are applicable as fuels in laser plasma thrusters. First thrust measurements on a viscous polymer solution confirmed this by yielding a specific impulse similar to a solid material.
{"title":"Materials for laser propulsion: \"liquid\" polymers","authors":"T. Lippert, L. Urech, R. Fardel, M. Nagel, C. Phipps, A. Wokaun","doi":"10.1117/12.782867","DOIUrl":"https://doi.org/10.1117/12.782867","url":null,"abstract":"The application of energetic polymers has resulted in an increased thrust in micro laser plasma thrusters compared to standard polymers. In this study we tested a novel concept for micro laser plasma thrusters, i.e. the application of liquid polymeric fuels, by using polymer solutions of the energetic materials with different viscosity. Shadowgraphy experiments suggest that for higher viscosity solutions ablation without splashing is possible, indicating that liquids are applicable as fuels in laser plasma thrusters. First thrust measurements on a viscous polymer solution confirmed this by yielding a specific impulse similar to a solid material.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133991536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the many challenges faced by laser propulsion is the long-term performance of the propellant. The chemical changes that can take place at the propellant surface during ablation can greatly modify the in-flight performance characteristics. For stable regimes for propulsion, such chemical action should be minimized. A TEA (Transverse Electrical discharge in gas at Atmospheric pressure) CO2 laser of 10.6 μm wavelength, 300 ns pulse length, and up to 20 J pulse energy was used to ablate several types of polymer targets with a range of observable chemical changes at the surface following ablation. After 10 subsequent shots, the target samples were measured using Attenuated Total Reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy then compared to unablated samples of the same polymer. An analysis of the results was made with an emphasis on laser propulsion applications, with a comparison of the propulsion performance of the targets, specifically regarding the ablated mass per spot area (Δma). Chemical reaction pathways for combustion and vaporization are discussed on the basis of the differences observed in the FTIR spectra, and the consequences for using such materials as laser propulsion propellants are explored.
{"title":"Reflection Fourier transform infrared spectroscopy of polymer targets for CO2 laser ablation","authors":"J. Sinko, C. A. Schlecht","doi":"10.1117/12.782436","DOIUrl":"https://doi.org/10.1117/12.782436","url":null,"abstract":"One of the many challenges faced by laser propulsion is the long-term performance of the propellant. The chemical changes that can take place at the propellant surface during ablation can greatly modify the in-flight performance characteristics. For stable regimes for propulsion, such chemical action should be minimized. A TEA (Transverse Electrical discharge in gas at Atmospheric pressure) CO2 laser of 10.6 μm wavelength, 300 ns pulse length, and up to 20 J pulse energy was used to ablate several types of polymer targets with a range of observable chemical changes at the surface following ablation. After 10 subsequent shots, the target samples were measured using Attenuated Total Reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy then compared to unablated samples of the same polymer. An analysis of the results was made with an emphasis on laser propulsion applications, with a comparison of the propulsion performance of the targets, specifically regarding the ablated mass per spot area (Δma). Chemical reaction pathways for combustion and vaporization are discussed on the basis of the differences observed in the FTIR spectra, and the consequences for using such materials as laser propulsion propellants are explored.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131742117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Zhigilei, E. Leveugle, A. Sellinger, J. Fitz-Gerald
Coarse-grained molecular dynamics simulations are performed to investigate the origins of the surface features observed in films deposited by the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. The simulations of MAPLE are performed for polymer concentrations up to 6 wt.% and a broad range of laser fluences. The polymer molecules are found to be ejected only in the ablation regime and are always incorporated into polymer-matrix clusters/droplets generated in the process of the explosive disintegration of the overheated matrix. The entanglement of the polymer molecules facilitates the formation of intricate elongated viscous droplets that can be related to the complex morphologies observed in polymer films deposited by MAPLE. The effect of dynamic molecular redistribution in the ejected matrix-polymer droplets, leading to the generation of transient "molecular balloons" in which polymer-rich surface layers enclose the volatile matrix material, has been identified as the mechanism responsible for the formation of characteristic wrinkled polymer structures observed experimentally in films deposited by MAPLE.
{"title":"Molecular dynamics simulation study of the ejection of polymer molecules and generation of molecular balloons in matrix-assisted pulsed laser evaporation","authors":"L. Zhigilei, E. Leveugle, A. Sellinger, J. Fitz-Gerald","doi":"10.1117/12.782524","DOIUrl":"https://doi.org/10.1117/12.782524","url":null,"abstract":"Coarse-grained molecular dynamics simulations are performed to investigate the origins of the surface features observed in films deposited by the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. The simulations of MAPLE are performed for polymer concentrations up to 6 wt.% and a broad range of laser fluences. The polymer molecules are found to be ejected only in the ablation regime and are always incorporated into polymer-matrix clusters/droplets generated in the process of the explosive disintegration of the overheated matrix. The entanglement of the polymer molecules facilitates the formation of intricate elongated viscous droplets that can be related to the complex morphologies observed in polymer films deposited by MAPLE. The effect of dynamic molecular redistribution in the ejected matrix-polymer droplets, leading to the generation of transient \"molecular balloons\" in which polymer-rich surface layers enclose the volatile matrix material, has been identified as the mechanism responsible for the formation of characteristic wrinkled polymer structures observed experimentally in films deposited by MAPLE.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134038628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Ueno, G. Soumagne, T. Suganuma, T. Yabu, M. Moriya, H. Komori, T. Abe, A. Endo, A. Sumitani
We are developing a laser produced plasma light source for high volume manufacturing (HVM) EUV lithography. The light source is based on a high power, high repetition rate CO2 laser (10.6μm) system, a tin (Sn) target and a magnetic ion guiding for Sn treatment. We evaluated the characteristics of Sn debris generated by a CO2 laser produced plasma. Experiments were performed with bulk Sn-plate targets and Mo/Si multilayer mirror samples were used for debris analysis. We observed very thin and uniform Sn layers of nano/sub-nano size debris particles. The layer deposition rate at 120mm from the plasma is, without magnetic field, about 30nm per million shots. The fast Sn ion flux was measured with Faraday cups and the signal decreased by more than 3 orders of magnitude on application of a magnetic field of 1T. The Sn deposition on the Mo/Si multilayer mirror decreased in small magnetic field space by a factor of 5. In a large magnetic field space, the effectiveness of the magnetic guiding of Sn ions is examined by monitoring the fast Sn ions. The ion flux from a Sn plasma was confined along the magnetic axis with a maximum magnetic field of 2T.
{"title":"Magnetic field for efficient exhaustion of CO2 laser-produced Sn plasma in EUV light source","authors":"Y. Ueno, G. Soumagne, T. Suganuma, T. Yabu, M. Moriya, H. Komori, T. Abe, A. Endo, A. Sumitani","doi":"10.1117/12.782475","DOIUrl":"https://doi.org/10.1117/12.782475","url":null,"abstract":"We are developing a laser produced plasma light source for high volume manufacturing (HVM) EUV lithography. The light source is based on a high power, high repetition rate CO2 laser (10.6μm) system, a tin (Sn) target and a magnetic ion guiding for Sn treatment. We evaluated the characteristics of Sn debris generated by a CO2 laser produced plasma. Experiments were performed with bulk Sn-plate targets and Mo/Si multilayer mirror samples were used for debris analysis. We observed very thin and uniform Sn layers of nano/sub-nano size debris particles. The layer deposition rate at 120mm from the plasma is, without magnetic field, about 30nm per million shots. The fast Sn ion flux was measured with Faraday cups and the signal decreased by more than 3 orders of magnitude on application of a magnetic field of 1T. The Sn deposition on the Mo/Si multilayer mirror decreased in small magnetic field space by a factor of 5. In a large magnetic field space, the effectiveness of the magnetic guiding of Sn ions is examined by monitoring the fast Sn ions. The ion flux from a Sn plasma was confined along the magnetic axis with a maximum magnetic field of 2T.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133307512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electric oxygen iodine laser (EOIL) offers a vastly more practical, implementable, and safer alternative to its predecessor, the chemical oxygen iodine laser (COIL), particularly for airborne or other mobile military applications. Despite its promise and after 25 years effort, numerous laboratories around the world have not succeeded in providing the known basic physical requirements needed to electrically convert O2 into O2(a1Δ) with the fractional yields and efficiencies needed to make a practical laser. Hence, as of this date, the world record power generated from an EOIL device is only 6.5 watts. In this paper, a 30% conversion from O2 into O2(a1Δ) operating at substantial oxygen mass flow rates (0.090 moles O2/sec at 50 torr) and 40% electrical efficiency is reported. The O2(a1Δ) flow stream being produced carries 2400 watts. Gain measurements are currently in progress, to be followed shortly by power extraction. Current conditions imply that initial power extraction could push beyond 1 KW. Efforts to date have failed to generate substantial laser power because critical criteria have not been met. In order to achieve good O2(a1Δ) fractional yield, it is normally mandatory to impart on the order of 100 KJ/mole O2 while efficiently removing the waste heat energy from the generator so that less than a few hundred degrees Kelvin rise occurs due to gas heating. The generator must be excited by an electric field on the order of 10 Td. This is far below glow potential; hence, a fully externally sustained plasma generation technique is required. Ionization is supplied by means of applying short (tens of nanosecond) pulses to the O2(a1Δ) generator at 50,000 PPS, which are on the order of ten times breakdown potential. This enables a quasi-steady adjustable DC current to flow through the generator, being conducted by application of a DC, 10 to 14 Td pump E-field. This field is independently tunable. The result is that up to 180 KJ/mole O2 gets imparted to the gas by means of the 6 KW sub-breakdown pump field, while another 2700 watts is applied to the controlled avalanche field. The generator consists of 24 each, 1 cm diameter tubes that are submerged in rapidly circulating cold fluorinert. Heat is efficiently removed so that that the gas temperature, initially 273°K, raises only by 125°K, as evidenced by spectrographic analysis of the fine structure of O2(b1Σ) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O2 to O2(a1Δ) has been achieved. Fortuitously, neither excited O atom production nor O2(b1Σ) production is visible in the spectra of the higher pressure, best yield runs. Essentially all other spectral lines are dwarfed in comparison the O2(a1Δ) line. Energy normally partitioned to O2(b1Σ) and apparently O atoms now feeds into O2(a1Δ) directly, enabling electrical efficiency to exceed 40%. As a continuation of this work, an I2 disassociating mixing section - then subsequently a 20 cm transverse M = 2.5
{"title":"Latest developments toward the demonstration of a KW-class EOIL laser","authors":"A. E. Hill","doi":"10.1117/12.782656","DOIUrl":"https://doi.org/10.1117/12.782656","url":null,"abstract":"The electric oxygen iodine laser (EOIL) offers a vastly more practical, implementable, and safer alternative to its predecessor, the chemical oxygen iodine laser (COIL), particularly for airborne or other mobile military applications. Despite its promise and after 25 years effort, numerous laboratories around the world have not succeeded in providing the known basic physical requirements needed to electrically convert O2 into O2(a1Δ) with the fractional yields and efficiencies needed to make a practical laser. Hence, as of this date, the world record power generated from an EOIL device is only 6.5 watts. In this paper, a 30% conversion from O2 into O2(a1Δ) operating at substantial oxygen mass flow rates (0.090 moles O2/sec at 50 torr) and 40% electrical efficiency is reported. The O2(a1Δ) flow stream being produced carries 2400 watts. Gain measurements are currently in progress, to be followed shortly by power extraction. Current conditions imply that initial power extraction could push beyond 1 KW. Efforts to date have failed to generate substantial laser power because critical criteria have not been met. In order to achieve good O2(a1Δ) fractional yield, it is normally mandatory to impart on the order of 100 KJ/mole O2 while efficiently removing the waste heat energy from the generator so that less than a few hundred degrees Kelvin rise occurs due to gas heating. The generator must be excited by an electric field on the order of 10 Td. This is far below glow potential; hence, a fully externally sustained plasma generation technique is required. Ionization is supplied by means of applying short (tens of nanosecond) pulses to the O2(a1Δ) generator at 50,000 PPS, which are on the order of ten times breakdown potential. This enables a quasi-steady adjustable DC current to flow through the generator, being conducted by application of a DC, 10 to 14 Td pump E-field. This field is independently tunable. The result is that up to 180 KJ/mole O2 gets imparted to the gas by means of the 6 KW sub-breakdown pump field, while another 2700 watts is applied to the controlled avalanche field. The generator consists of 24 each, 1 cm diameter tubes that are submerged in rapidly circulating cold fluorinert. Heat is efficiently removed so that that the gas temperature, initially 273°K, raises only by 125°K, as evidenced by spectrographic analysis of the fine structure of O2(b1Σ) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O2 to O2(a1Δ) has been achieved. Fortuitously, neither excited O atom production nor O2(b1Σ) production is visible in the spectra of the higher pressure, best yield runs. Essentially all other spectral lines are dwarfed in comparison the O2(a1Δ) line. Energy normally partitioned to O2(b1Σ) and apparently O atoms now feeds into O2(a1Δ) directly, enabling electrical efficiency to exceed 40%. As a continuation of this work, an I2 disassociating mixing section - then subsequently a 20 cm transverse M = 2.5","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117042338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We perform a comparison study of periodic structures on the surfaces of three different noble metals, Cu, Ag, and Au, following femtosecond laser radiation. Under identical experimental conditions, laser-induced surface patterns show distinctly different level of morphological clearness on the three different metals. Simply calculations based on metal melting fail to explain the pattern differences. We show that our observation result from the competition of two ultrafast processes, electron-phonon energy coupling and hot electron diffusion, following femtosecond laser heating of metals.
{"title":"Dynamics of femtosecond laser-induced periodic surface structures on metals","authors":"Jincheng Wang, Chunlei Guo","doi":"10.1117/12.782743","DOIUrl":"https://doi.org/10.1117/12.782743","url":null,"abstract":"We perform a comparison study of periodic structures on the surfaces of three different noble metals, Cu, Ag, and Au, following femtosecond laser radiation. Under identical experimental conditions, laser-induced surface patterns show distinctly different level of morphological clearness on the three different metals. Simply calculations based on metal melting fail to explain the pattern differences. We show that our observation result from the competition of two ultrafast processes, electron-phonon energy coupling and hot electron diffusion, following femtosecond laser heating of metals.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114723804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The AEgis Technologies Group and RTI International are developing microsensors for High Energy Laser (HEL) diagnostic applications. The conformal sensor array will measure the irradiance profile of an incident laser beam, and concomitant rise in surface temperature of the target. The open mesh architecture allows 90% of the beam to impact the surface. A critical part of this program is developing a protective coating that ensures sensor survivability at high irradiance levels for operational lifetimes on the order of 10 seconds. The protective coating must transmit a measurable amount of light to the irradiance sensor. We have conducted experiments to evaluate candidate heat shield materials. In the first round of experiments, a 10kW CO2 laser was used to irradiate pure materials, including metals and carbon foils. Although many of the metal foils were perforated by the laser, no significant amount of material was ablated away. In fact, most of the test samples gained mass, presumably due to oxidation. Analysis of high speed video shows that once the metal melted, surface tension caused the molten metal to coalesce into droplets around the rim of the hole. The second and third rounds of testing, conducted with a 3kW, 1.07μm fiber laser, included samples of highly reflective metals and ceramics, standard plasma-sprayed coatings, and multilayer stacks. We have also measured the performance of temperature sensors and irradiance sensors fabricated from nanoparticle solutions deposited by advanced printing technology and have completed a preliminary investigation of high temperature adhesives.
{"title":"Evaluation of materials for on-board laser diagnostics","authors":"J. Luke, David Thomas, Jay S. Lewis, C. Phipps","doi":"10.1117/12.782754","DOIUrl":"https://doi.org/10.1117/12.782754","url":null,"abstract":"The AEgis Technologies Group and RTI International are developing microsensors for High Energy Laser (HEL) diagnostic applications. The conformal sensor array will measure the irradiance profile of an incident laser beam, and concomitant rise in surface temperature of the target. The open mesh architecture allows 90% of the beam to impact the surface. A critical part of this program is developing a protective coating that ensures sensor survivability at high irradiance levels for operational lifetimes on the order of 10 seconds. The protective coating must transmit a measurable amount of light to the irradiance sensor. We have conducted experiments to evaluate candidate heat shield materials. In the first round of experiments, a 10kW CO2 laser was used to irradiate pure materials, including metals and carbon foils. Although many of the metal foils were perforated by the laser, no significant amount of material was ablated away. In fact, most of the test samples gained mass, presumably due to oxidation. Analysis of high speed video shows that once the metal melted, surface tension caused the molten metal to coalesce into droplets around the rim of the hole. The second and third rounds of testing, conducted with a 3kW, 1.07μm fiber laser, included samples of highly reflective metals and ceramics, standard plasma-sprayed coatings, and multilayer stacks. We have also measured the performance of temperature sensors and irradiance sensors fabricated from nanoparticle solutions deposited by advanced printing technology and have completed a preliminary investigation of high temperature adhesives.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131494414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Poprawe, A. Gillner, D. Hoffmann, J. Gottmann, Welf Wawers, W. Schulz
In recent years new generations of precision lasers have been demonstrated and are increasingly available on an industrial level. For example high beam quality and diffraction limited Fiber lasers, Slab lasers, Disk lasers and still Rod lasers are used very successfully. This paper focuses on - ns and μs drilling of shaped holes by helical drilling1 - drilling of extreme aspect ratios in dielectrics/glass by ns-slab lasers2 - nm-size periodic structuring of polymers by interferometric approaches - ablation by ns- and ps-pulses for metal moulds - generation of waveguide structures in glass by fs-pulses.3 On the laboratory scale a next generation of diffraction limited short pulse lasers is at the horizon.4 In particular, ps-lasers at multi-hundred watts of average power with repetition rates of several MHz,2 fs-lasers at 400W2 average power and green, frequency doubled lasers at 200W are under construction. At the short end of pulses, attosecond lasers have been demonstrated and themselves shall open a new domain of interaction of light and matter5.
{"title":"High speed high precision ablation from ms to fs","authors":"R. Poprawe, A. Gillner, D. Hoffmann, J. Gottmann, Welf Wawers, W. Schulz","doi":"10.1117/12.785225","DOIUrl":"https://doi.org/10.1117/12.785225","url":null,"abstract":"In recent years new generations of precision lasers have been demonstrated and are increasingly available on an industrial level. For example high beam quality and diffraction limited Fiber lasers, Slab lasers, Disk lasers and still Rod lasers are used very successfully. This paper focuses on - ns and μs drilling of shaped holes by helical drilling1 - drilling of extreme aspect ratios in dielectrics/glass by ns-slab lasers2 - nm-size periodic structuring of polymers by interferometric approaches - ablation by ns- and ps-pulses for metal moulds - generation of waveguide structures in glass by fs-pulses.3 On the laboratory scale a next generation of diffraction limited short pulse lasers is at the horizon.4 In particular, ps-lasers at multi-hundred watts of average power with repetition rates of several MHz,2 fs-lasers at 400W2 average power and green, frequency doubled lasers at 200W are under construction. At the short end of pulses, attosecond lasers have been demonstrated and themselves shall open a new domain of interaction of light and matter5.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131628246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：