R. Negres, C. Carr, I. Bass, D. Alessi, T. Laurence, K. Stanion, G. Guss, D. Cross, P. Wegner, C. Stolz
We investigate the optical damage performance of multi-layer dielectric (MLD) coatings suitable for use in high energy, large-aperture petawatt-class lasers. We employ small-area damage test methodologies to evaluate the damage resistance of various coatings as a function of deposition methods and coating materials under simulated use conditions. In addition, we demonstrate that damage initiation by raster scanning at lower fluences and growth threshold testing are required to estimate large-aperture optics’ performance.
{"title":"Characterization of laser-induced damage by picosecond pulses on multi-layer dielectric coatings for petawatt-class lasers","authors":"R. Negres, C. Carr, I. Bass, D. Alessi, T. Laurence, K. Stanion, G. Guss, D. Cross, P. Wegner, C. Stolz","doi":"10.1117/12.2195528","DOIUrl":"https://doi.org/10.1117/12.2195528","url":null,"abstract":"We investigate the optical damage performance of multi-layer dielectric (MLD) coatings suitable for use in high energy, large-aperture petawatt-class lasers. We employ small-area damage test methodologies to evaluate the damage resistance of various coatings as a function of deposition methods and coating materials under simulated use conditions. In addition, we demonstrate that damage initiation by raster scanning at lower fluences and growth threshold testing are required to estimate large-aperture optics’ performance.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"9632 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129972516","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}
M. Liessmann, L. Jensen, I. Balasa, M. Hunnekuhl, A. Büttner, P. Wessels, J. Neumann, D. Ristau
The growth of laser-induced contamination (LIC) on optical components in extraterrestrial missions is a known issue especially for the UV spectral region. The Laser Zentrum Hannover e.V. is responsible for the development of a pulsed laser-system operating at a wavelength of 266 nm for the ExoMars mission and for the qualification of used optics and materials regarding LIC. In this context, toluene was utilized which is an often used model contaminant in LIC studies. Test cycles based on the application of the two UV wavelengths 355 nm and 266 nm on fused silica substrates and ARcoated optics are conducted and the observed contamination effects are compared. This scaling allows for a rough estimate of the destructive influence of LIC on space optics degradation at 266 nm. Further tests will be performed with materials integrated into the ExoMars-laser-head under near-operation environmental conditions.
在地外任务中，光学元件的激光诱导污染(LIC)的增长是一个众所周知的问题，特别是在紫外光谱区域。汉诺威激光中心(Laser Zentrum Hannover e.V.)负责为ExoMars任务开发波长为266纳米的脉冲激光系统，并对使用过的光学器件和材料进行LIC认证。在这种情况下，使用了甲苯，这是在LIC研究中经常使用的模型污染物。将355nm和266nm两种紫外波长分别应用于熔融二氧化硅基片和ararcoated光学器件上进行了测试循环，并比较了观察到的污染效应。这种缩放可以粗略估计在266nm处LIC对空间光学退化的破坏性影响。在接近操作的环境条件下，将对集成到exomars -激光头中的材料进行进一步的测试。
{"title":"Scaling of laser-induced contamination growth at 266nm and 355nm","authors":"M. Liessmann, L. Jensen, I. Balasa, M. Hunnekuhl, A. Büttner, P. Wessels, J. Neumann, D. Ristau","doi":"10.1117/12.2194083","DOIUrl":"https://doi.org/10.1117/12.2194083","url":null,"abstract":"The growth of laser-induced contamination (LIC) on optical components in extraterrestrial missions is a known issue especially for the UV spectral region. The Laser Zentrum Hannover e.V. is responsible for the development of a pulsed laser-system operating at a wavelength of 266 nm for the ExoMars mission and for the qualification of used optics and materials regarding LIC. In this context, toluene was utilized which is an often used model contaminant in LIC studies. Test cycles based on the application of the two UV wavelengths 355 nm and 266 nm on fused silica substrates and ARcoated optics are conducted and the observed contamination effects are compared. This scaling allows for a rough estimate of the destructive influence of LIC on space optics degradation at 266 nm. Further tests will be performed with materials integrated into the ExoMars-laser-head under near-operation environmental conditions.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126806249","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}
M. Sozet, J. Néauport, E. Lavastre, N. Roquin, L. Gallais, L. Lamaignère
A rasterscan procedure is set to determine laser-induced damage densities in sub-picosecond regime at 1053nm on high-reflective coatings. Whereas laser-induced damage is usually considered deterministic in this regime, damage events occur on these structures for fluences lower than their intrinsic Laser-Induced Damage Threshold (LIDT). Damage densities are found to be high even for fluences as low as 20% of the LIDT. Scanning Electron Microscope observations of these “under threshold” damage sites evidence ejections of defects, embedded in the dielectric stack. It brings a new viewpoint for the qualification of optical components and for the optimization of manufacturing processes of coatings.
{"title":"Laser damage resistance of optical components in sub-picosecond regime in the infrared","authors":"M. Sozet, J. Néauport, E. Lavastre, N. Roquin, L. Gallais, L. Lamaignère","doi":"10.1117/12.2194286","DOIUrl":"https://doi.org/10.1117/12.2194286","url":null,"abstract":"A rasterscan procedure is set to determine laser-induced damage densities in sub-picosecond regime at 1053nm on high-reflective coatings. Whereas laser-induced damage is usually considered deterministic in this regime, damage events occur on these structures for fluences lower than their intrinsic Laser-Induced Damage Threshold (LIDT). Damage densities are found to be high even for fluences as low as 20% of the LIDT. Scanning Electron Microscope observations of these “under threshold” damage sites evidence ejections of defects, embedded in the dielectric stack. It brings a new viewpoint for the qualification of optical components and for the optimization of manufacturing processes of coatings.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"9 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129753270","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}
A. Zorila, A. Stratan, I. Dumitrache, L. Rusen, G. Nemeş
Data collected in real S-on-1 LIDT experiments performed with a nanosecond, 1064 nm automated station are used to calculate the damage probability with the ISO-recommended (conventional) method and the recently-suggested cumulative method. The damage probability points versus fluence for each type of calculation are fitted using both, linear and nonlinear curves. The resultant four data sets corresponding to each real experiment are used to compare important parameters as: statistical uncertainty of damage probability points, fitting errors, damage threshold fluences for actual number of pulses, and the extrapolated threshold fluences for very large number of pulses. We suggest and analyze also a limit case of the cumulative method, when the damage probability points are calculated for each interrogated site. Both, the recently-suggested cumulative method, and our limit case, look very promising.
{"title":"Analysis of cumulative versus ISO-recommended calculation of damage probability using a database of real S-on-1 tests","authors":"A. Zorila, A. Stratan, I. Dumitrache, L. Rusen, G. Nemeş","doi":"10.1117/12.2194303","DOIUrl":"https://doi.org/10.1117/12.2194303","url":null,"abstract":"Data collected in real S-on-1 LIDT experiments performed with a nanosecond, 1064 nm automated station are used to calculate the damage probability with the ISO-recommended (conventional) method and the recently-suggested cumulative method. The damage probability points versus fluence for each type of calculation are fitted using both, linear and nonlinear curves. The resultant four data sets corresponding to each real experiment are used to compare important parameters as: statistical uncertainty of damage probability points, fitting errors, damage threshold fluences for actual number of pulses, and the extrapolated threshold fluences for very large number of pulses. We suggest and analyze also a limit case of the cumulative method, when the damage probability points are calculated for each interrogated site. Both, the recently-suggested cumulative method, and our limit case, look very promising.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115004604","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}
M. Ghoumazi, N. Demagh, A. Adouane, B. Boubir, A. Daoui
In recent years, the rare earth ions and primarily Er played a crucial role in the development of the technology of optical telecommunications. The Emission of erbium ions at 1.53 microns is important for optical telecommunications because this emission corresponds to minimum mitigation of silica fibers which used as purpose to transport information. At first, we study the evolution of the signal powers and the pump powers along the propagation in the optical fiber amplifier Erbium doped. In addition, we study the variation of Erbium ions concentration for different spectroscopic parameters such as signal strength with (0, 1μW, 1mW) and the power of the pump going up 200 mW.
{"title":"Improved parametric spectroscopic performance of an optical fiber doped with erbium","authors":"M. Ghoumazi, N. Demagh, A. Adouane, B. Boubir, A. Daoui","doi":"10.1117/12.2194077","DOIUrl":"https://doi.org/10.1117/12.2194077","url":null,"abstract":"In recent years, the rare earth ions and primarily Er played a crucial role in the development of the technology of optical telecommunications. The Emission of erbium ions at 1.53 microns is important for optical telecommunications because this emission corresponds to minimum mitigation of silica fibers which used as purpose to transport information. At first, we study the evolution of the signal powers and the pump powers along the propagation in the optical fiber amplifier Erbium doped. In addition, we study the variation of Erbium ions concentration for different spectroscopic parameters such as signal strength with (0, 1μW, 1mW) and the power of the pump going up 200 mW.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128341971","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}
Control of the time duration of a laser pulse as it focuses spatially in a material provides a means for delaying the onset of nonlinear effects during propagation. We investigate simultaneous space-time focusing (SSTF) of femtosecond radially-chirped annular pulses in Kerr dielectrics. The energy and temporal chirp of pulses incident upon a grating-grating-lens system are varied in simulations that solve the unidirectional pulse propagation equation. This system is modeled by inserting transformations that act on the electric field obtained from propagation from one component to the next. The propagation is coupled to the time evolution of the free charge density as a function of space. The resulting “ionization tracks” are taken as a metric for predicting material modification and/or damage in bulk fused silica. As expected from linear-optical considerations, the temporal pre-chirp determines the overall pulse duration as the focusing annulus closes. We find in addition that, for a given pulse energy, the temporal pre-chirp also determines the on-axis intensity distribution as energy collapses onto the propagation axis. This effect determines how the local ionization-induced decrease in refractive index shifts energy in time relative to energy arriving on-axis from the spatially collapsing beam. The magnitude of the pre-chirp can thus control the spatial structure of ionization that may lead to material modification and/or damage.
{"title":"Calculation of nonlinear optical damage from space-time-tailored pulses in dielectrics","authors":"T. Lanier, J. Gulley","doi":"10.1117/12.2195299","DOIUrl":"https://doi.org/10.1117/12.2195299","url":null,"abstract":"Control of the time duration of a laser pulse as it focuses spatially in a material provides a means for delaying the onset of nonlinear effects during propagation. We investigate simultaneous space-time focusing (SSTF) of femtosecond radially-chirped annular pulses in Kerr dielectrics. The energy and temporal chirp of pulses incident upon a grating-grating-lens system are varied in simulations that solve the unidirectional pulse propagation equation. This system is modeled by inserting transformations that act on the electric field obtained from propagation from one component to the next. The propagation is coupled to the time evolution of the free charge density as a function of space. The resulting “ionization tracks” are taken as a metric for predicting material modification and/or damage in bulk fused silica. As expected from linear-optical considerations, the temporal pre-chirp determines the overall pulse duration as the focusing annulus closes. We find in addition that, for a given pulse energy, the temporal pre-chirp also determines the on-axis intensity distribution as energy collapses onto the propagation axis. This effect determines how the local ionization-induced decrease in refractive index shifts energy in time relative to energy arriving on-axis from the spatially collapsing beam. The magnitude of the pre-chirp can thus control the spatial structure of ionization that may lead to material modification and/or damage.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131714165","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}
Klaus Mann, B. Schäfer, M. Stubenvoll, K. Hentschel, M. Zenz
We demonstrate the feasibility of passive compensation of the thermal lens effect in fused silica optics, placing suitable optical materials with negative dn/dT in the beam path of a high power near IR fiber laser. Following a brief overview of the involved mechanisms, photo-thermal absorption measurements with a Hartmann-Shack sensor are described, from which coefficients for surface/coating and bulk absorption in various materials are determined. Based on comprehensive knowledge of the 2D wavefront deformations resulting from absorption, passive compensation of thermally induced aberrations in complex optical systems is possible, as illustrated for an F-Theta objective. By means of caustic measurements during high-power operation we are able to demonstrate a 60% reduction of the focal shift in F-Theta lenses through passive compensation.
{"title":"Measurement and compensation of wavefront deformations and focal shifts in high-power laser optics","authors":"Klaus Mann, B. Schäfer, M. Stubenvoll, K. Hentschel, M. Zenz","doi":"10.1117/12.2196160","DOIUrl":"https://doi.org/10.1117/12.2196160","url":null,"abstract":"We demonstrate the feasibility of passive compensation of the thermal lens effect in fused silica optics, placing suitable optical materials with negative dn/dT in the beam path of a high power near IR fiber laser. Following a brief overview of the involved mechanisms, photo-thermal absorption measurements with a Hartmann-Shack sensor are described, from which coefficients for surface/coating and bulk absorption in various materials are determined. Based on comprehensive knowledge of the 2D wavefront deformations resulting from absorption, passive compensation of thermally induced aberrations in complex optical systems is possible, as illustrated for an F-Theta objective. By means of caustic measurements during high-power operation we are able to demonstrate a 60% reduction of the focal shift in F-Theta lenses through passive compensation.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116282180","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}
Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation’s ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface contaminants, nano-scale scratches, bumps, particles and other asperities under low energy physical sputtering conditions. ANAB may be used to remove a precisely controlled, uniform thickness of material without any increase of surface roughness, regardless of the total amount of material removed. The ANAB process does not involve the use of slurries or other abrasive polishing compounds and therefore does not require any post process cleaning. ANAB can be integrated as an in-situ surface preparation method for other process steps in the uninterrupted fabrication of optical devices.
{"title":"Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing","authors":"S. Kirkpatrick, M. Walsh, R. Svrluga, M. Thomas","doi":"10.1117/12.2196545","DOIUrl":"https://doi.org/10.1117/12.2196545","url":null,"abstract":"Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation’s ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface contaminants, nano-scale scratches, bumps, particles and other asperities under low energy physical sputtering conditions. ANAB may be used to remove a precisely controlled, uniform thickness of material without any increase of surface roughness, regardless of the total amount of material removed. The ANAB process does not involve the use of slurries or other abrasive polishing compounds and therefore does not require any post process cleaning. ANAB can be integrated as an in-situ surface preparation method for other process steps in the uninterrupted fabrication of optical devices.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114410286","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}
Dam-be Douti, M. Chrayteh, S. Monneret, M. Commandré, L. Gallais
Laser Induced Damage Thresholds and morphologies of damage sites on thin films samples irradiated by sub-ps pulses are studied based on experimental and numerical studies. Experiments are conducted with 500fs pulses at 1030nm and 343nm and the irradiated sites are analyzed with phase imaging, AFM and SEM. The results are compared to simulations of energy deposition in the films based on the Single Rate Equation taking account transient optical properties of the films. Results suggest that a critical absorbed energy as a damage criterion give consistent results both with the measured LIDT and the observed damage morphologies.
{"title":"Analysis of energy deposition and damage mechanisms in single layers of HfO2 and Nb2O5 submitted to 500fs pulses","authors":"Dam-be Douti, M. Chrayteh, S. Monneret, M. Commandré, L. Gallais","doi":"10.1117/12.2195005","DOIUrl":"https://doi.org/10.1117/12.2195005","url":null,"abstract":"Laser Induced Damage Thresholds and morphologies of damage sites on thin films samples irradiated by sub-ps pulses are studied based on experimental and numerical studies. Experiments are conducted with 500fs pulses at 1030nm and 343nm and the irradiated sites are analyzed with phase imaging, AFM and SEM. The results are compared to simulations of energy deposition in the films based on the Single Rate Equation taking account transient optical properties of the films. Results suggest that a critical absorbed energy as a damage criterion give consistent results both with the measured LIDT and the observed damage morphologies.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116227107","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}
S. Demos, R. Negres, R. Raman, M. Feit, K. Manes, A. Rubenchik
Laser induced damage (breakdown) initiated on the exit surface of transparent dielectric materials using nanosecond pulses creates a volume of superheated material reaching localized temperatures on the order of 1 eV and pressures on the order of 10 GPa or larger. This leads to material ejection and the formation of a crater. The volume of this superheated material depends largely on the laser parameters such as fluence and pulse duration. To elucidate the material behaviors involved, we examined the morphologies of the ejected superheated material particles and found distinctive morphologies. We hypothesize that these morphologies arise from the difference in the structure and physical properties (such as the dynamic viscosity and presence of instabilities) of the superheated material at the time of ejection of each individual particle. Some of the ejected particles are on the order of 1 µm in diameter and appear as “droplets”. Another subgroup appears to have stretched, foam-like structure that can be described as material globules interconnected via smaller in diameter columns. Such particles often contain nanometer size fibers attached on their surface. In other cases, only the globules have been preserved suggesting that they may be associated with a collapsed foam structure under the dynamic pressure as it traverses in air. These distinct features originate in the structure of the superheated material during volume boiling just prior to the ejection of the particles.
{"title":"Morphology of ejected debris from laser super-heated fused silica following exit surface laser-induced damage","authors":"S. Demos, R. Negres, R. Raman, M. Feit, K. Manes, A. Rubenchik","doi":"10.1117/12.2195501","DOIUrl":"https://doi.org/10.1117/12.2195501","url":null,"abstract":"Laser induced damage (breakdown) initiated on the exit surface of transparent dielectric materials using nanosecond pulses creates a volume of superheated material reaching localized temperatures on the order of 1 eV and pressures on the order of 10 GPa or larger. This leads to material ejection and the formation of a crater. The volume of this superheated material depends largely on the laser parameters such as fluence and pulse duration. To elucidate the material behaviors involved, we examined the morphologies of the ejected superheated material particles and found distinctive morphologies. We hypothesize that these morphologies arise from the difference in the structure and physical properties (such as the dynamic viscosity and presence of instabilities) of the superheated material at the time of ejection of each individual particle. Some of the ejected particles are on the order of 1 µm in diameter and appear as “droplets”. Another subgroup appears to have stretched, foam-like structure that can be described as material globules interconnected via smaller in diameter columns. Such particles often contain nanometer size fibers attached on their surface. In other cases, only the globules have been preserved suggesting that they may be associated with a collapsed foam structure under the dynamic pressure as it traverses in air. These distinct features originate in the structure of the superheated material during volume boiling just prior to the ejection of the particles.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123042470","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}
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