Steven T. Yang, Michael R. Greenberg, Eric Cunningham, Mikael D. Martinez, R. Negres, T. Spinka, Stavros G. Demos, Amy L. Rigatti
The Matter in Extreme Conditions Upgrade (MEC-U) project is a major upgrade to the MEC instrument of the LINAC Coherent Light Source (LCLS) X-ray free electron laser (XFEL) user facility at SLAC National Accelerator Laboratory. The envisioned MEC upgrade will significantly enhance the capabilities of the pump laser sources in current MEC experimental station, boosting the energy of the nanosecond shock driver from 100 J to the kJ level, and increasing the power and repetition rate of the short pulse laser from 25 TW at 5 Hz to 1 PW at 10 Hz rate. Building such high energy/power pump laser systems presents challenges to minimize and mitigate against laser-induced optical damage. As part of the system design, we have identified the optics at high-risk to damage and we have designed the laser systems to mitigate against these damage risks to ensure sustained facility operation.
{"title":"Optical damage considerations in the design of the matter in extreme condition upgrade (MEC-U) laser systems","authors":"Steven T. Yang, Michael R. Greenberg, Eric Cunningham, Mikael D. Martinez, R. Negres, T. Spinka, Stavros G. Demos, Amy L. Rigatti","doi":"10.1117/12.2685218","DOIUrl":"https://doi.org/10.1117/12.2685218","url":null,"abstract":"The Matter in Extreme Conditions Upgrade (MEC-U) project is a major upgrade to the MEC instrument of the LINAC Coherent Light Source (LCLS) X-ray free electron laser (XFEL) user facility at SLAC National Accelerator Laboratory. The envisioned MEC upgrade will significantly enhance the capabilities of the pump laser sources in current MEC experimental station, boosting the energy of the nanosecond shock driver from 100 J to the kJ level, and increasing the power and repetition rate of the short pulse laser from 25 TW at 5 Hz to 1 PW at 10 Hz rate. Building such high energy/power pump laser systems presents challenges to minimize and mitigate against laser-induced optical damage. As part of the system design, we have identified the optics at high-risk to damage and we have designed the laser systems to mitigate against these damage risks to ensure sustained facility operation.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239089","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}
Estimation of error bars on laser damage threshold measurements using only the fluence inaccuracy of the test laser unfortunately does not cover the full range of systematic errors in the laser damage protocol. A poor understanding of the actual measurement errors can lead to inaccurate conclusions or inadequate safety factors when designing laser systems. This Monte Carlo analysis focuses on improving the understanding of typical systematic errors of the ISO and raster scanning laser damage test protocols through modeling of the impact of fluence variations, laser beam pointing, and laser beam shape. The impact of increased test area and the magnitude of fluence increments between testing sites is also explored in an attempt to reduce systematic errors. Raster scanning tends to have significantly lower systematic errors than the ISO test. However, the raster scan protocol cannot measure unconditioned laser damage thresholds and has microscopy resolution limitations for pre and post irradiation inspection.
遗憾的是，仅使用测试激光器的不准确通量来估算激光损伤阈值测量的误差条，并不能涵盖激光损伤协议中的全部系统误差。对实际测量误差的不了解会导致在设计激光系统时得出不准确的结论或安全系数不足。本蒙特卡洛分析侧重于通过对通量变化、激光束指向和激光束形状的影响进行建模，加深对 ISO 和光栅扫描激光损伤测试协议的典型系统误差的理解。此外，还探讨了增加测试区域和测试点之间通量增量的影响，以减少系统误差。光栅扫描的系统误差往往比 ISO 测试低得多。不过，光栅扫描协议无法测量无条件激光损伤阈值，并且在辐照前后检查时存在显微镜分辨率限制。
{"title":"Monte Carlo analysis of ISO and raster scan laser damage protocols: part 2","authors":"Christopher J. Stolz","doi":"10.1117/12.2684458","DOIUrl":"https://doi.org/10.1117/12.2684458","url":null,"abstract":"Estimation of error bars on laser damage threshold measurements using only the fluence inaccuracy of the test laser unfortunately does not cover the full range of systematic errors in the laser damage protocol. A poor understanding of the actual measurement errors can lead to inaccurate conclusions or inadequate safety factors when designing laser systems. This Monte Carlo analysis focuses on improving the understanding of typical systematic errors of the ISO and raster scanning laser damage test protocols through modeling of the impact of fluence variations, laser beam pointing, and laser beam shape. The impact of increased test area and the magnitude of fluence increments between testing sites is also explored in an attempt to reduce systematic errors. Raster scanning tends to have significantly lower systematic errors than the ISO test. However, the raster scan protocol cannot measure unconditioned laser damage thresholds and has microscopy resolution limitations for pre and post irradiation inspection.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239995","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}
K. Schaffers, Christopher J. Stolz, John J. Adams, R. Negres, M. Monticelli
Lawrence Livermore National Security’s (LLNS) National Ignition Facility (NIF) requires over 600 large crystals of KH2PO4 (KDP) and KH0.6D1.4PO4 (DKDP) for use in polarization rotation and frequency conversion assemblies. There are near term plans to increase the energy on NIF to 2.2 MJ and up to 3 MJ in future years. Managing optics’ damage is one critical aspect of achieving these aggressive goals. Frequency conversion crystals are being examined for readiness to meet the goals for higher energy operations. All aspects of the crystal fabrication process are being studied including growth, processing, laser conditioning, and mitigation to strengthen the crystals against damage. THG crystals have an approximately 10× lower exchange rate than fused silica optics, so unlike NIF fused silica optics which are micromachined to mitigate surface laser damage between recycle loops, THG crystals are refinished to remove surface laser damage. Given the long time to grow NIF size DKDP crystals (3 years) and the impact of THG thickness on frequency conversion, a good understanding of the evolution of the inventory is necessary. The number of damage sites that require laser blocking dictates the exchange rate of THG crystals. Understanding the difference between bulk and surface damage, is important to limit the number of blocked sites. Also, in preparation for higher power operations on NIF, the current KDP polarization rotators on half of the NIF beams are being exchanged with DKDP due to an ~5% reduction in absorption at 1053 nm thus reducing beam contrast in the NIF amplifiers.
{"title":"THGs for NIF operations (>2 MJ NIF operations)","authors":"K. Schaffers, Christopher J. Stolz, John J. Adams, R. Negres, M. Monticelli","doi":"10.1117/12.2684120","DOIUrl":"https://doi.org/10.1117/12.2684120","url":null,"abstract":"Lawrence Livermore National Security’s (LLNS) National Ignition Facility (NIF) requires over 600 large crystals of KH2PO4 (KDP) and KH0.6D1.4PO4 (DKDP) for use in polarization rotation and frequency conversion assemblies. There are near term plans to increase the energy on NIF to 2.2 MJ and up to 3 MJ in future years. Managing optics’ damage is one critical aspect of achieving these aggressive goals. Frequency conversion crystals are being examined for readiness to meet the goals for higher energy operations. All aspects of the crystal fabrication process are being studied including growth, processing, laser conditioning, and mitigation to strengthen the crystals against damage. THG crystals have an approximately 10× lower exchange rate than fused silica optics, so unlike NIF fused silica optics which are micromachined to mitigate surface laser damage between recycle loops, THG crystals are refinished to remove surface laser damage. Given the long time to grow NIF size DKDP crystals (3 years) and the impact of THG thickness on frequency conversion, a good understanding of the evolution of the inventory is necessary. The number of damage sites that require laser blocking dictates the exchange rate of THG crystals. Understanding the difference between bulk and surface damage, is important to limit the number of blocked sites. Also, in preparation for higher power operations on NIF, the current KDP polarization rotators on half of the NIF beams are being exchanged with DKDP due to an ~5% reduction in absorption at 1053 nm thus reducing beam contrast in the NIF amplifiers.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139241308","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. Paschel, M. Steinecke, T. Kellermann, K. Kiedrowski, A. Melninkaitis, M. Jupé, Andreas Wienke, Detlev Ristau
Quantizing nanolaminates are an interesting alternative to classical coating materials with greater independence of refractive index and the optical bandgap energy. This leads to more flexibility and considerable potential to increase the laser-induced damage threshold in the ultra-short pulse regime. The following study presents and compares the design choices, characterization, and LIDT testing of different quantizing nanolaminates for the ultraviolet spectral range to classical coating materials.
量子化纳米层压材料是经典涂层材料的一种有趣替代品，它的折射率和光带隙能量具有更大的独立性。这将带来更大的灵活性，并具有在超短脉冲条件下提高激光诱导损伤阈值的巨大潜力。以下研究介绍并比较了紫外光谱范围内不同量化纳米层压材料与传统涂层材料的设计选择、表征和 LIDT 测试。
{"title":"Bandgap energy of quantizing nanolaminates and its relation to the laser-induced damage threshold in the ultraviolet","authors":"S. Paschel, M. Steinecke, T. Kellermann, K. Kiedrowski, A. Melninkaitis, M. Jupé, Andreas Wienke, Detlev Ristau","doi":"10.1117/12.2685250","DOIUrl":"https://doi.org/10.1117/12.2685250","url":null,"abstract":"Quantizing nanolaminates are an interesting alternative to classical coating materials with greater independence of refractive index and the optical bandgap energy. This leads to more flexibility and considerable potential to increase the laser-induced damage threshold in the ultra-short pulse regime. The following study presents and compares the design choices, characterization, and LIDT testing of different quantizing nanolaminates for the ultraviolet spectral range to classical coating materials.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139241501","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}
Many damage morphologies are possible following irradiation of materials with an intense laser beam. We present ultrafast time-resolved microscopic imaging of materials immediately following laser-matter interaction. In the case of transparent, brittle materials such imaging allows monitoring of multiple resultant processes such as shockwaves, induced stress, crack, and others. We present an optical system for such imaging and examples of several studies completed. Imaging shockwaves produced from impulsive absorption of intense light provides insight into shockwave speed and intensity. Imaging of crack evolution over time allows for understanding of the driving forces behind crack initiation and growth. Time-resolved imaging of visible emissions provides a timescale of radiative relaxation mechanisms and images the extension of cracks during and following bursts of multiple ultrafast pulses helps to understand the enhancement of crack growth under pulse bursts.
{"title":"Shockwave and crack monitoring following nonlinear absorption with picosecond time-resolved microscopic imaging","authors":"Matthew R. Ross, Jue Wang","doi":"10.1117/12.2685245","DOIUrl":"https://doi.org/10.1117/12.2685245","url":null,"abstract":"Many damage morphologies are possible following irradiation of materials with an intense laser beam. We present ultrafast time-resolved microscopic imaging of materials immediately following laser-matter interaction. In the case of transparent, brittle materials such imaging allows monitoring of multiple resultant processes such as shockwaves, induced stress, crack, and others. We present an optical system for such imaging and examples of several studies completed. Imaging shockwaves produced from impulsive absorption of intense light provides insight into shockwave speed and intensity. Imaging of crack evolution over time allows for understanding of the driving forces behind crack initiation and growth. Time-resolved imaging of visible emissions provides a timescale of radiative relaxation mechanisms and images the extension of cracks during and following bursts of multiple ultrafast pulses helps to understand the enhancement of crack growth under pulse bursts.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240011","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}
J. Vanda, Martin Mydlář, Priyadarshani Narayanasamy, Hana Turcicova, Radek Poboril, J. Brajer, T. Mocek
For most of the laser applications is optics equipped with antireflective coatings must. Therefore, laser damage resistance and stability at high energies of used components is a key performance limiting factor at the large portion of the user cases. In UV region, issue of laser damage is particularly enhanced as many optical materials tends to degrade at longer exposure and any contamination may accelerate that. In the following paper will be disseminated laser damage performance of selected commercially available optical windows equipped with AR coatings, designed for high-power lasers in UV region. Damage threshold measured with mm-size laser beam will be compared and influence of the long exposure to ultrashort pulses will be considered.
在大多数激光应用中，光学元件都必须配备抗反射涂层。因此，在大部分用户案例中，所用元件在高能量下的抗激光损伤性和稳定性是限制其性能的关键因素。在紫外线区域，激光损伤问题尤为突出，因为许多光学材料在长时间暴露下会发生降解，而任何污染都可能加速这种降解。以下论文将介绍为紫外区大功率激光器设计的、配备 AR 涂层的部分市售光学窗口的激光损伤性能。本文将比较用毫米级激光束测量的损伤阈值，并考虑超短脉冲长时间照射的影响。
{"title":"An overview on laser damage performance of current AR-coated windows at 343 nm and ultrashort pulses","authors":"J. Vanda, Martin Mydlář, Priyadarshani Narayanasamy, Hana Turcicova, Radek Poboril, J. Brajer, T. Mocek","doi":"10.1117/12.2686252","DOIUrl":"https://doi.org/10.1117/12.2686252","url":null,"abstract":"For most of the laser applications is optics equipped with antireflective coatings must. Therefore, laser damage resistance and stability at high energies of used components is a key performance limiting factor at the large portion of the user cases. In UV region, issue of laser damage is particularly enhanced as many optical materials tends to degrade at longer exposure and any contamination may accelerate that. In the following paper will be disseminated laser damage performance of selected commercially available optical windows equipped with AR coatings, designed for high-power lasers in UV region. Damage threshold measured with mm-size laser beam will be compared and influence of the long exposure to ultrashort pulses will be considered.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240157","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}
Joshua McCauley, Xiaochuan Ji, M. Jupé, Jinlong Zhang, Andreas Wienke, Detlev Ristau
Nonlinear absorption is mainly governed by mechanisms involving excitation processes of electrons. Typically, two phenomena are considered when discussing nonlinear absorption; the multiphoton absorption where multiple photons interact directly with a single electron, and tunnel ionization, where the high electric field results in a shifting of the bandgap allowing an electron to tunnel into the conduction band. Electrons in the conduction band can be accelerated through the absorption of further photons until they obtain enough energy to excite further electrons to the conduction band, leading to runaway absorption and finally damage of the sample. By laser calorimetric measurement of the nonlinear absorption, it is expected that the laser damage threshold can be predicted without damaging the optic. Before accurate predictions can be made, the process must be thoroughly characterized and understood. The nonlinear behavior of the absorption was demonstrated with potential increases in absorption of an order of magnitude. Initial results show a noticeable impact of contaminants, though a nonlinear response is still observed.
{"title":"Determining the bandgap dependence of nonlinear absorption and laser induced damage threshold through numerical simulation and experiment","authors":"Joshua McCauley, Xiaochuan Ji, M. Jupé, Jinlong Zhang, Andreas Wienke, Detlev Ristau","doi":"10.1117/12.2685160","DOIUrl":"https://doi.org/10.1117/12.2685160","url":null,"abstract":"Nonlinear absorption is mainly governed by mechanisms involving excitation processes of electrons. Typically, two phenomena are considered when discussing nonlinear absorption; the multiphoton absorption where multiple photons interact directly with a single electron, and tunnel ionization, where the high electric field results in a shifting of the bandgap allowing an electron to tunnel into the conduction band. Electrons in the conduction band can be accelerated through the absorption of further photons until they obtain enough energy to excite further electrons to the conduction band, leading to runaway absorption and finally damage of the sample. By laser calorimetric measurement of the nonlinear absorption, it is expected that the laser damage threshold can be predicted without damaging the optic. Before accurate predictions can be made, the process must be thoroughly characterized and understood. The nonlinear behavior of the absorption was demonstrated with potential increases in absorption of an order of magnitude. Initial results show a noticeable impact of contaminants, though a nonlinear response is still observed.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139242016","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, Kyle P. Kafka, Christopher Smith, Marek Stehlik, Sarah Olandt, Stavros G. Demos, Amy L. Rigatti
This year’s competition proposed to survey the state-of-the-art broadband, near-IR multilayer dielectric (MLD) mirrors designed for ultra-short, pulsed laser applications. The requirements for the coatings were a minimum reflection of 99.5% at 45-degree incidence angle for S-polarization from 830 nm to 1010 nm and group delay dispersion (GDD) < ± 50 fs2. The participants in this effort selected the coating materials, coating design, and deposition method. Samples were damage tested at a single testing facility to enable direct comparison among the participants using a 25 ± 5 fs OPCPA laser system operating at 5 Hz. A double blind test assured sample and submitter anonymity. The damage performance results, sample rankings, details of the deposition processes, coating materials and substrate cleaning methods are shared here. We found that multilayer coatings using tantala and/or hafnia as high index materials were top performers within several coating deposition groups. Specifically, dense coatings by ion-beam sputtering (IBS), magnetron sputtering (MS), and electron-beam ion assisted deposition (e-beam IAD) exhibited highest damage initiation onset (LIDT) while e-beam coatings were low performers. In addition, damage growth onset (LDGT) was also examined and the results are reported here for all samples as this performance metric plays an important role in establishing the safe operational conditions for larger aperture, ultrashort pulsed lasers. Lastly, not all coating samples in the survey met the GDD requirements stated above and associated measurements are discussed in the context of the present and past competitions focused on similar broadband, near-IR MLD coatings.
{"title":"Broadband, 920-nm mirror thin film damage competition","authors":"R. Negres, Kyle P. Kafka, Christopher Smith, Marek Stehlik, Sarah Olandt, Stavros G. Demos, Amy L. Rigatti","doi":"10.1117/12.2685127","DOIUrl":"https://doi.org/10.1117/12.2685127","url":null,"abstract":"This year’s competition proposed to survey the state-of-the-art broadband, near-IR multilayer dielectric (MLD) mirrors designed for ultra-short, pulsed laser applications. The requirements for the coatings were a minimum reflection of 99.5% at 45-degree incidence angle for S-polarization from 830 nm to 1010 nm and group delay dispersion (GDD) < ± 50 fs2. The participants in this effort selected the coating materials, coating design, and deposition method. Samples were damage tested at a single testing facility to enable direct comparison among the participants using a 25 ± 5 fs OPCPA laser system operating at 5 Hz. A double blind test assured sample and submitter anonymity. The damage performance results, sample rankings, details of the deposition processes, coating materials and substrate cleaning methods are shared here. We found that multilayer coatings using tantala and/or hafnia as high index materials were top performers within several coating deposition groups. Specifically, dense coatings by ion-beam sputtering (IBS), magnetron sputtering (MS), and electron-beam ion assisted deposition (e-beam IAD) exhibited highest damage initiation onset (LIDT) while e-beam coatings were low performers. In addition, damage growth onset (LDGT) was also examined and the results are reported here for all samples as this performance metric plays an important role in establishing the safe operational conditions for larger aperture, ultrashort pulsed lasers. Lastly, not all coating samples in the survey met the GDD requirements stated above and associated measurements are discussed in the context of the present and past competitions focused on similar broadband, near-IR MLD coatings.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239155","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 first demonstration of fusion in the laboratory required the National Ignition Facility (NIF) to leverage its novel approach to laser-induced damage; managing laser-induced damage rather than avoiding it. Accepting regular damage to the laser’s final optics allows the NIF to deliver about 300% higher energy on its targets. This mode of operation is made viable by a unique optics maintenance strategy and a variety of damage management and mitigation. We will review the prominent damage mitigation and management technologies which are classified in three categories: Damage Initiation Prevention, Damage Management, and Damage Repair. Examples of these technologies are the Fused Silica Debris Shield, AI driven damage detection, and the CO2 mitigation cone, respectively. We introduce a simple empirical model which both quantifies individual and combined impacts of the technologies on NIF’s optics usage.
{"title":"Fusion enabling laser-induced damage reduction, management, and repair strategies at the National Ignition Facility","authors":"C. W. Carr","doi":"10.1117/12.2688417","DOIUrl":"https://doi.org/10.1117/12.2688417","url":null,"abstract":"The first demonstration of fusion in the laboratory required the National Ignition Facility (NIF) to leverage its novel approach to laser-induced damage; managing laser-induced damage rather than avoiding it. Accepting regular damage to the laser’s final optics allows the NIF to deliver about 300% higher energy on its targets. This mode of operation is made viable by a unique optics maintenance strategy and a variety of damage management and mitigation. We will review the prominent damage mitigation and management technologies which are classified in three categories: Damage Initiation Prevention, Damage Management, and Damage Repair. Examples of these technologies are the Fused Silica Debris Shield, AI driven damage detection, and the CO2 mitigation cone, respectively. We introduce a simple empirical model which both quantifies individual and combined impacts of the technologies on NIF’s optics usage.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239212","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}
Gregory S. Demos, Brittany N. Hoffman, J. Lambropoulos, Marcela Mireles
We explore the laser-damage behavior of gallium alloy-based liquid metal mirrors for their potential to provide higherdamage- threshold performance. One of the key advantages of using liquid metal mirrors is the self-healing potential following perturbations arising from exposure to high-power laser pulses. In this work, key performance metrics, such as reflectivity and the laser-damage initiation mechanism and initiation threshold, were investigated using fused-silica cells filled with three different Ga liquid metal alloys. The results suggest that irreversible modification (damage) under 355- nm, 6-ns pulses are associated with the formation of gallium oxide, taking place at a fluence significantly higher than that for damage initiation in conventional metal mirrors. This exploratory work is the first of its kind and highlights the strong performance of gallium alloy metal mirrors.
我们探索了基于镓合金的液态金属反射镜的激光损伤行为，以发现其提供更高损伤阈值性能的潜力。使用液态金属反射镜的主要优势之一是在受到高功率激光脉冲干扰后具有自我修复的潜力。在这项工作中，使用填充了三种不同 Ga 液体金属合金的熔融石英电池研究了反射率、激光损伤起始机制和起始阈值等关键性能指标。结果表明，在 355 nm、6 ns 脉冲下发生的不可逆改性（损伤）与氧化镓的形成有关，其发生的通量明显高于传统金属反射镜的损伤起始通量。这项探索性工作在同类研究中尚属首次，凸显了镓合金金属镜的强大性能。
{"title":"Exploring self-healing liquid metal mirrors for high-power laser applications","authors":"Gregory S. Demos, Brittany N. Hoffman, J. Lambropoulos, Marcela Mireles","doi":"10.1117/12.2685176","DOIUrl":"https://doi.org/10.1117/12.2685176","url":null,"abstract":"We explore the laser-damage behavior of gallium alloy-based liquid metal mirrors for their potential to provide higherdamage- threshold performance. One of the key advantages of using liquid metal mirrors is the self-healing potential following perturbations arising from exposure to high-power laser pulses. In this work, key performance metrics, such as reflectivity and the laser-damage initiation mechanism and initiation threshold, were investigated using fused-silica cells filled with three different Ga liquid metal alloys. The results suggest that irreversible modification (damage) under 355- nm, 6-ns pulses are associated with the formation of gallium oxide, taking place at a fluence significantly higher than that for damage initiation in conventional metal mirrors. This exploratory work is the first of its kind and highlights the strong performance of gallium alloy metal mirrors.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139242487","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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