The temperature distribution of a slightly absorbing optical thin film atop a glass substrate subjected to a laser pulse train of pulse duration 1ns is derived from the classical heat equation. The critical fluence defined by the point at which thermal damage occurs is derived and the dependence of laser induced damage threshold (LIDT) on repetition rate, pulse duration, wavelength, thermal properties, beam and optic dimensions is discussed. A comparison is made between the theoretical LIDT and well known experimentally observed scaling laws for both Gaussian and ”Top-Hat” pulse profiles. It is found that the ratio of beam to optic diameter is an important parameter in LIDT determination. Larger substrates are found to have a lower LIDT and it is suggested that LIDT follows an inverse scaling rule with respect to repetition rate.
{"title":"Thermal laser induced damage in optical coatings due to an incident pulse train","authors":"Ryan McGuigan, H. Kessler","doi":"10.1117/12.2600793","DOIUrl":"https://doi.org/10.1117/12.2600793","url":null,"abstract":"The temperature distribution of a slightly absorbing optical thin film atop a glass substrate subjected to a laser pulse train of pulse duration 1ns is derived from the classical heat equation. The critical fluence defined by the point at which thermal damage occurs is derived and the dependence of laser induced damage threshold (LIDT) on repetition rate, pulse duration, wavelength, thermal properties, beam and optic dimensions is discussed. A comparison is made between the theoretical LIDT and well known experimentally observed scaling laws for both Gaussian and ”Top-Hat” pulse profiles. It is found that the ratio of beam to optic diameter is an important parameter in LIDT determination. Larger substrates are found to have a lower LIDT and it is suggested that LIDT follows an inverse scaling rule with respect to repetition rate.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132619213","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}
Zican Yang, H. Xu, Jian Cheng, Linjie Zhao, Mingjun Chen, Jinghe Wang, C. Tan, Yaguo Li, Zhichao Liu
During the grinding and polishing processes of hard-brittle fused silica optics, the defects would be inevitably formed on the finished surface. Fused silica has a high absorption coefficient for far-infrared lasers, which makes the CO2 laser processing to be the potential repairing technology for machining-induced defects on fused silica surfaces. In this work, using a low-power CO2 laser, a new repairing method to heal the machining-induced micro-defects on the surface of fused silica is proposed. Then, based on the nonlinear thermodynamic parameters of fused silica material, a thermal transfer model under CO2 laser irradiation and a dynamic defect healing model were established. On basis of that, the influence of CO2 laser parameters on the maximum surface temperature and the temperature distribution inside the silica material was investigated. It is found that, under the low-power and near-continuous CO2 laser irradiation, the maximum melting depth can be obtained under the non-evaporative condition. The defect healing process under various laser powers was explored as well. It is found that the defects would be more difficult to be healed under a laser with higher-power, smaller beam size or shorter pulse width. This work can provide theoretical guidance for the determination of the optimal parameters in the laser healing process and the optical manufacturing strategies of fused silica optics.
{"title":"Investigation on the influence of the CO2 laser parameters on the defect healing process of fused silica","authors":"Zican Yang, H. Xu, Jian Cheng, Linjie Zhao, Mingjun Chen, Jinghe Wang, C. Tan, Yaguo Li, Zhichao Liu","doi":"10.1117/12.2618826","DOIUrl":"https://doi.org/10.1117/12.2618826","url":null,"abstract":"During the grinding and polishing processes of hard-brittle fused silica optics, the defects would be inevitably formed on the finished surface. Fused silica has a high absorption coefficient for far-infrared lasers, which makes the CO2 laser processing to be the potential repairing technology for machining-induced defects on fused silica surfaces. In this work, using a low-power CO2 laser, a new repairing method to heal the machining-induced micro-defects on the surface of fused silica is proposed. Then, based on the nonlinear thermodynamic parameters of fused silica material, a thermal transfer model under CO2 laser irradiation and a dynamic defect healing model were established. On basis of that, the influence of CO2 laser parameters on the maximum surface temperature and the temperature distribution inside the silica material was investigated. It is found that, under the low-power and near-continuous CO2 laser irradiation, the maximum melting depth can be obtained under the non-evaporative condition. The defect healing process under various laser powers was explored as well. It is found that the defects would be more difficult to be healed under a laser with higher-power, smaller beam size or shorter pulse width. This work can provide theoretical guidance for the determination of the optimal parameters in the laser healing process and the optical manufacturing strategies of fused silica optics.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123931949","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}
Laser users desire optics that not only have a high laser induced damage threshold (LIDT), but also perform consistently over time. In fact, some aerospace and military applications can require long lifetime optics for remote environments where replacement is untenable. UV laser optics are susceptible to slow performance degradation with exposure to sub- Laser Induced Damage Threshold UV laser light due to the process of UV fatigue. Although UV fatigue of optics is well documented, the mechanisms are not well understood. Design and construction of a UV lifetime testbed to investigate the mechanisms of UV fatigue, preliminary results, and future directions are presented.
{"title":"Ultraviolet fatigue testing of laser optics","authors":"M. Dabney, B. Arnold, Cyrus Rashvand","doi":"10.1117/12.2598678","DOIUrl":"https://doi.org/10.1117/12.2598678","url":null,"abstract":"Laser users desire optics that not only have a high laser induced damage threshold (LIDT), but also perform consistently over time. In fact, some aerospace and military applications can require long lifetime optics for remote environments where replacement is untenable. UV laser optics are susceptible to slow performance degradation with exposure to sub- Laser Induced Damage Threshold UV laser light due to the process of UV fatigue. Although UV fatigue of optics is well documented, the mechanisms are not well understood. Design and construction of a UV lifetime testbed to investigate the mechanisms of UV fatigue, preliminary results, and future directions are presented.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126892057","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. Lamaignère, C. Bouyer, M. Veinhard, R. Parreault, J. Natoli
The paper aims to compare the results obtained with the same laser source with a large beam and with small beams. These latest were shaped from phase objects implemented to obtain several small beams from a single larger beam. The consistency of the results from both sets of measurements is shown. It validates the assumptions made and the specific mathematical treatments implemented to establish the link between the two approaches. It also validates and strengthens the approach developed from the rasterscan procedure used to measure damage densities from the scanning with beams of small dimensions. This shows that small beam tests are reasonably representative of tests carried out with large beams.
{"title":"Laser damage metrology with small and large beams on a unique testbed","authors":"L. Lamaignère, C. Bouyer, M. Veinhard, R. Parreault, J. Natoli","doi":"10.1117/12.2598918","DOIUrl":"https://doi.org/10.1117/12.2598918","url":null,"abstract":"The paper aims to compare the results obtained with the same laser source with a large beam and with small beams. These latest were shaped from phase objects implemented to obtain several small beams from a single larger beam. The consistency of the results from both sets of measurements is shown. It validates the assumptions made and the specific mathematical treatments implemented to establish the link between the two approaches. It also validates and strengthens the approach developed from the rasterscan procedure used to measure damage densities from the scanning with beams of small dimensions. This shows that small beam tests are reasonably representative of tests carried out with large beams.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130378704","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}
Jian Cheng, Dinghuai Yang, Li Lai, Mingjun Chen, Jinghe Wang, Hao Yang, Linjie Zhao, Qi Liu, Wenyu Ding, Zhichao Liu
Potassium dihydrogen phosphate (KDP) crystal has been regarded as the solely irreplaceable component in laser-driven inertial confinement fusion (ICF) facilities. Nevertheless, the laser-induced damage on KDP crystal surfaces under highenergy laser irradiation considerably restricts the output power of ICF facilities. The laser damage event on KDP surface is an extremely complex process, among which the non-heat initial energy deposition is regarded as the major absorbed energy source, determining the subsequent thermal damage process and final damage morphology. The initial energy deposition process is a non-heat stage, where the plasmas are generated from ionization processes under intense laser irradiation. However, there is still no available model that can well reproduce the dynamic interaction behaviors between the high-energy laser and plasmas in the initial energy deposition process, resulting in the laser-induced damage mechanisms on KDP crystal surface still not fully revealed. In this work, a Particle-In-Cell (PIC) model is established to investigate the initial dynamic damage behaviors of KDP crystals under intense laser irradiation. On basis of this model, the crater formation process and the particle ejection dynamics involved in the laser damage event are reproduced. The reproduced characteristic parameters of laser damage craters on KDP input and output surfaces, and the obtained particle ejection angles are consistent with the previously reported laser damage morphology, which verifies the effectiveness of the established PIC model. This work could provide theoretical means for investigating the initial energy deposition process and also offer further insights in understanding the laser-induced damage mechanisms of KDP crystal components.
{"title":"Particle simulation of the initial dynamic damage behaviors of KDP crystals under intense laser irradiation","authors":"Jian Cheng, Dinghuai Yang, Li Lai, Mingjun Chen, Jinghe Wang, Hao Yang, Linjie Zhao, Qi Liu, Wenyu Ding, Zhichao Liu","doi":"10.1117/12.2618830","DOIUrl":"https://doi.org/10.1117/12.2618830","url":null,"abstract":"Potassium dihydrogen phosphate (KDP) crystal has been regarded as the solely irreplaceable component in laser-driven inertial confinement fusion (ICF) facilities. Nevertheless, the laser-induced damage on KDP crystal surfaces under highenergy laser irradiation considerably restricts the output power of ICF facilities. The laser damage event on KDP surface is an extremely complex process, among which the non-heat initial energy deposition is regarded as the major absorbed energy source, determining the subsequent thermal damage process and final damage morphology. The initial energy deposition process is a non-heat stage, where the plasmas are generated from ionization processes under intense laser irradiation. However, there is still no available model that can well reproduce the dynamic interaction behaviors between the high-energy laser and plasmas in the initial energy deposition process, resulting in the laser-induced damage mechanisms on KDP crystal surface still not fully revealed. In this work, a Particle-In-Cell (PIC) model is established to investigate the initial dynamic damage behaviors of KDP crystals under intense laser irradiation. On basis of this model, the crater formation process and the particle ejection dynamics involved in the laser damage event are reproduced. The reproduced characteristic parameters of laser damage craters on KDP input and output surfaces, and the obtained particle ejection angles are consistent with the previously reported laser damage morphology, which verifies the effectiveness of the established PIC model. This work could provide theoretical means for investigating the initial energy deposition process and also offer further insights in understanding the laser-induced damage mechanisms of KDP crystal components.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131276223","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}
Camille Petite, Jeanne Graisset, A. Moreau, H. Krol, C. Grèzes-besset, J. Lumeau, L. Gallais
The increase of continuous wave laser power is an important topic in various industrial and defense applications. One of the important limitation is due to optical coatings. In order to study this absorption, it is of prime importance to measure and determine the origin of this absorption. We have developed a LIT system (LIT) to perform low-absorption measurement at 1.07 μm. A multipass setup was realized and calibrated with a sensitivity of a few ppm and a ten times better accuracy is demonstrated. Then, this instrument was used to study single layers made with different materials and deposited by PIAD and multilayer components.
{"title":"Low absorption metrology of thin film optical components for high power continuous wave lasers","authors":"Camille Petite, Jeanne Graisset, A. Moreau, H. Krol, C. Grèzes-besset, J. Lumeau, L. Gallais","doi":"10.1117/12.2642761","DOIUrl":"https://doi.org/10.1117/12.2642761","url":null,"abstract":"The increase of continuous wave laser power is an important topic in various industrial and defense applications. One of the important limitation is due to optical coatings. In order to study this absorption, it is of prime importance to measure and determine the origin of this absorption. We have developed a LIT system (LIT) to perform low-absorption measurement at 1.07 μm. A multipass setup was realized and calibrated with a sensitivity of a few ppm and a ten times better accuracy is demonstrated. Then, this instrument was used to study single layers made with different materials and deposited by PIAD and multilayer components.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"509 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134023151","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}
E. Field, B. Galloway, M. Geissel, D. Kletecka, P. Rambo, I. Smith, J. Porter
Antireflection coatings, containing alternating layers of hafnia (HfO2) and silica (SiO2), were deposited using electron beam (e-beam) evaporation for use in laser operations at 532 nm and 1064 nm in the nanosecond regime. The e-beam evaporation process produces coatings that are porous and therefore absorb water from the ambient environment. Consequently, humidity may affect the spectral performance of the coatings, and the laser damage resistance of the coatings may be affected as well. The purpose of this study was to compare the laser-induced damage thresholds of the antireflection coatings measured in the ambient environment at 0% and 40.5% relative humidity. At 1064 nm, the laserinduced damage thresholds at 0% and 40.5% relative humidity were almost the same. However, at 532 nm, the laserinduced damage thresholds at 40.5% relative humidity were nearly twice as high as those measured at 0% relative humidity. This indicates that humidity can inhibit lower-fluence precursors that would lead to laser damage at 532 nm in the nanosecond regime, thereby improving the durability of the coatings in a humid environment.
{"title":"Laser damage comparisons of E-beam evaporated HfO2/SiO2 antireflection coatings at 0% and 40% relative humidity for 532 nm and 1064 nm","authors":"E. Field, B. Galloway, M. Geissel, D. Kletecka, P. Rambo, I. Smith, J. Porter","doi":"10.1117/12.2598613","DOIUrl":"https://doi.org/10.1117/12.2598613","url":null,"abstract":"Antireflection coatings, containing alternating layers of hafnia (HfO2) and silica (SiO2), were deposited using electron beam (e-beam) evaporation for use in laser operations at 532 nm and 1064 nm in the nanosecond regime. The e-beam evaporation process produces coatings that are porous and therefore absorb water from the ambient environment. Consequently, humidity may affect the spectral performance of the coatings, and the laser damage resistance of the coatings may be affected as well. The purpose of this study was to compare the laser-induced damage thresholds of the antireflection coatings measured in the ambient environment at 0% and 40.5% relative humidity. At 1064 nm, the laserinduced damage thresholds at 0% and 40.5% relative humidity were almost the same. However, at 532 nm, the laserinduced damage thresholds at 40.5% relative humidity were nearly twice as high as those measured at 0% relative humidity. This indicates that humidity can inhibit lower-fluence precursors that would lead to laser damage at 532 nm in the nanosecond regime, thereby improving the durability of the coatings in a humid environment.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116782915","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}
Simin Zhang, A. Davenport, N. Talisa, Joseph R. Smith, C. Menoni, V. Gruzdev, E. Chowdhury
The interaction of ultrafast laser pulses and dielectric materials has been under intensive research for improvement of laser induced damage of optics for high intensity lasers. A 2D model based on Keldysh photoionization and finite-different time-domain (FDTD) algorithm are used to simulate the ionization processes in multilayer interference coatings, taking nonlinear photoionization, impact ionization, and plasma collision into account. Simulation and experimental results of bulk fused silica with different pulse durations and angles of incidence are compared and discussed. We also simulated the interaction of a 40-layer SiO2/Ta2O5 high reflective interference coating designed for 45° angle of incidence and a p-polarized 5-fs pulse at a wavelength of 800 nm, and the damage threshold of the coating is estimated.
{"title":"2D dynamic ionization simulation from ultrashort pulses in multilayer dielectric interference coatings","authors":"Simin Zhang, A. Davenport, N. Talisa, Joseph R. Smith, C. Menoni, V. Gruzdev, E. Chowdhury","doi":"10.1117/12.2571081","DOIUrl":"https://doi.org/10.1117/12.2571081","url":null,"abstract":"The interaction of ultrafast laser pulses and dielectric materials has been under intensive research for improvement of laser induced damage of optics for high intensity lasers. A 2D model based on Keldysh photoionization and finite-different time-domain (FDTD) algorithm are used to simulate the ionization processes in multilayer interference coatings, taking nonlinear photoionization, impact ionization, and plasma collision into account. Simulation and experimental results of bulk fused silica with different pulse durations and angles of incidence are compared and discussed. We also simulated the interaction of a 40-layer SiO2/Ta2O5 high reflective interference coating designed for 45° angle of incidence and a p-polarized 5-fs pulse at a wavelength of 800 nm, and the damage threshold of the coating is estimated.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123980676","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}
C. Lacombe, Guillaume Hallo, M. Sozet, P. Fourtillan, R. Diaz, S. Vermersch, J. Néauport
The Laser MegaJoule (LMJ) is a 176-beamlines facility, located at the CEA CESTA near Bordeaux (France). It is designed to deliver about 1.4 MJ of ultraviolet laser energy on targets set in vacuum chamber, for high energy density physics experiments, including fusion experiments. The commissioning of the seven first bundles of height beams is achieved since November 2019 and the commissioning of next bundles is on the way. For performance requirements, it is important to follow final optics behavior. Moreover, for questions of manufacturability, ease of maintenance and cost, the understanding and the improvement of vacuum windows laser damage resistance are of main importance. The MDCC (Center Chamber Diagnostic System) is thus operating since November 2018 on the LMJ facility. It consists in a high resolution CCD camera combined with a predefined focus set of optics. The resolution of this system is about 100μm with a working distance of 8 m. This system can perform 3 functions: damage detection on the vacuum window surface, the measurement of the spatial profile on the vacuum window plane and of final optics transmission.
{"title":"Dealing with LMJ final optics damage: post-processing and models","authors":"C. Lacombe, Guillaume Hallo, M. Sozet, P. Fourtillan, R. Diaz, S. Vermersch, J. Néauport","doi":"10.1117/12.2571074","DOIUrl":"https://doi.org/10.1117/12.2571074","url":null,"abstract":"The Laser MegaJoule (LMJ) is a 176-beamlines facility, located at the CEA CESTA near Bordeaux (France). It is designed to deliver about 1.4 MJ of ultraviolet laser energy on targets set in vacuum chamber, for high energy density physics experiments, including fusion experiments. The commissioning of the seven first bundles of height beams is achieved since November 2019 and the commissioning of next bundles is on the way. For performance requirements, it is important to follow final optics behavior. Moreover, for questions of manufacturability, ease of maintenance and cost, the understanding and the improvement of vacuum windows laser damage resistance are of main importance. The MDCC (Center Chamber Diagnostic System) is thus operating since November 2018 on the LMJ facility. It consists in a high resolution CCD camera combined with a predefined focus set of optics. The resolution of this system is about 100μm with a working distance of 8 m. This system can perform 3 functions: damage detection on the vacuum window surface, the measurement of the spatial profile on the vacuum window plane and of final optics transmission.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"23 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129108373","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. Negres, C. Stolz, G. Batavičiūtė, A. Melninkaitis
This year’s competition aimed to survey state-of-the-art visible high reflectors in the nanosecond pulse length regime. The requirements for the coatings were a minimum reflection of 99.5% at 0 degrees incidence angle light at 532-nm. The choice of coating materials, design, and deposition method were left to the participants. Laser damage testing was performed at a single testing facility using the raster scanning test protocol with a 6-ns pulse length laser system operating at 100 Hz in a single-longitudinal mode. A double blind test assured sample and submitter anonymity. The damage performance results (LIDT), sample rankings, details of the deposition processes, coating materials and substrate cleaning methods are shared. We found that hafnia/silica multilayer coatings deposited by all five deposition methods surveyed were the most damage resistant within their group under these test conditions. In addition, hafnia/alumina/silica designs deposited performed second best.
{"title":"532-nm, nanosecond laser mirror thin film damage competition","authors":"R. Negres, C. Stolz, G. Batavičiūtė, A. Melninkaitis","doi":"10.1117/12.2566691","DOIUrl":"https://doi.org/10.1117/12.2566691","url":null,"abstract":"This year’s competition aimed to survey state-of-the-art visible high reflectors in the nanosecond pulse length regime. The requirements for the coatings were a minimum reflection of 99.5% at 0 degrees incidence angle light at 532-nm. The choice of coating materials, design, and deposition method were left to the participants. Laser damage testing was performed at a single testing facility using the raster scanning test protocol with a 6-ns pulse length laser system operating at 100 Hz in a single-longitudinal mode. A double blind test assured sample and submitter anonymity. The damage performance results (LIDT), sample rankings, details of the deposition processes, coating materials and substrate cleaning methods are shared. We found that hafnia/silica multilayer coatings deposited by all five deposition methods surveyed were the most damage resistant within their group under these test conditions. In addition, hafnia/alumina/silica designs deposited performed second best.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116266322","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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