In the femtosecond regime laser damage thresholds are determined by the electric field distribution within the optical components. Especially, for radiation sources with integrated frequency conversion the simultaneous presence of photons with different frequencies introduces additional ionization channels in optical materials by cross excitation and other effects. In this work we report on the pulse delay dependency of the LIDT of HR390/780nm mirrors under simultaneous exposure to fundamental and second harmonic femtosecond radiation. We perform Son1-tests according to ISO 21254 with the addition of a second harmonic pulse at different fixed pulse energies. To determine the influence of the cross excitation between fundamental and second harmonic radiation, these tests are repeated for different time delays between the two pulses. For the 1on1, single wavelength femtosecond LIDT testing, the Keldysh theory in combination with the Drude Model has been proven to reasonably describe the time dependent electron density in the conduction band, and hence the LIDT. We extend these approaches to the determination of the LIDT for the case of simultaneous interactions of photons of two separate wavelengths.
{"title":"Delay dependency of two-pulse femtosecond laser damage","authors":"M. Gyamfi, P. Jürgens, L. Jensen, D. Ristau","doi":"10.1117/12.2194778","DOIUrl":"https://doi.org/10.1117/12.2194778","url":null,"abstract":"In the femtosecond regime laser damage thresholds are determined by the electric field distribution within the optical components. Especially, for radiation sources with integrated frequency conversion the simultaneous presence of photons with different frequencies introduces additional ionization channels in optical materials by cross excitation and other effects. In this work we report on the pulse delay dependency of the LIDT of HR390/780nm mirrors under simultaneous exposure to fundamental and second harmonic femtosecond radiation. We perform Son1-tests according to ISO 21254 with the addition of a second harmonic pulse at different fixed pulse energies. To determine the influence of the cross excitation between fundamental and second harmonic radiation, these tests are repeated for different time delays between the two pulses. For the 1on1, single wavelength femtosecond LIDT testing, the Keldysh theory in combination with the Drude Model has been proven to reasonably describe the time dependent electron density in the conduction band, and hence the LIDT. We extend these approaches to the determination of the LIDT for the case of simultaneous interactions of photons of two separate wavelengths.","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":"126811645","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 present our results of a fundamental simulation of a periodic grating structure formation on a copper target during the femtosecond-pulse laser damage process, and compare our results to recent experiment. The particle-in-cell (PIC) method is used to model the initial laser heating of the electrons, a two-temperature model (TTM) is used to model the thermalization of the material, and a modified PIC method is employed to model the atomic transport leading to a damage crater morphology consistent with experimental grating structure formation. This laser-induced periodic surface structure (LIPSS) is shown to be directly related to the formation of surface plasmon polaritons (SPP) and their interference with the incident laser pulse.
{"title":"First principles simulation of laser-induced periodic surface structure using the particle-in-cell method","authors":"Robert A. Mitchell, D. Schumacher, E. Chowdhury","doi":"10.1117/12.2195006","DOIUrl":"https://doi.org/10.1117/12.2195006","url":null,"abstract":"We present our results of a fundamental simulation of a periodic grating structure formation on a copper target during the femtosecond-pulse laser damage process, and compare our results to recent experiment. The particle-in-cell (PIC) method is used to model the initial laser heating of the electrons, a two-temperature model (TTM) is used to model the thermalization of the material, and a modified PIC method is employed to model the atomic transport leading to a damage crater morphology consistent with experimental grating structure formation. This laser-induced periodic surface structure (LIPSS) is shown to be directly related to the formation of surface plasmon polaritons (SPP) and their interference with the incident laser pulse.","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":"115313020","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}
In calculations of ultrafast laser-induced ionization the treatment of fundamental mechanisms such as photoionization and the Kerr effect are treated in isolation using monochromatic perturbative approaches. Such approaches are often questionable for pulses of ultrashort duration and multi-chromatic spectra. In this work we address this issue by solving the quantum optical Bloch equations in a 3D quasi-momentum space and show how to couple this model to ultrashort pulse propagation in dielectrics. This approach self-consistently couples a quantum calculation of the photoionization yield, the photoionization current, and the current from free-carriers with the traditional Kerr effect (self-focusing and self phase modulation) without resort to a perturbative treatment. The material band structure is taken in the tight binding limit and is periodic in the crystal momentum space. As this model makes no assumption about the pulse spectrum, we examine the laser-material interaction of strongly chirped pulses and multi-color multi-pulse schemes of laser-induced material modification. These results are compared to those predicted by standard treatments, such as the Keldysh model of photoionization, for pulses of ultrashort duration.
{"title":"Self-consistent modeling of photoionization and the Kerr effect in bulk solids","authors":"J. Gulley, T. Lanier","doi":"10.1117/12.2195293","DOIUrl":"https://doi.org/10.1117/12.2195293","url":null,"abstract":"In calculations of ultrafast laser-induced ionization the treatment of fundamental mechanisms such as photoionization and the Kerr effect are treated in isolation using monochromatic perturbative approaches. Such approaches are often questionable for pulses of ultrashort duration and multi-chromatic spectra. In this work we address this issue by solving the quantum optical Bloch equations in a 3D quasi-momentum space and show how to couple this model to ultrashort pulse propagation in dielectrics. This approach self-consistently couples a quantum calculation of the photoionization yield, the photoionization current, and the current from free-carriers with the traditional Kerr effect (self-focusing and self phase modulation) without resort to a perturbative treatment. The material band structure is taken in the tight binding limit and is periodic in the crystal momentum space. As this model makes no assumption about the pulse spectrum, we examine the laser-material interaction of strongly chirped pulses and multi-color multi-pulse schemes of laser-induced material modification. These results are compared to those predicted by standard treatments, such as the Keldysh model of photoionization, for pulses of ultrashort duration.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131806018","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. Papernov, A. Kozlov, J. Oliver, C. Smith, L. Jensen, D. Ristau, S. Günster, H. Mädebach
The role of thin-film interfaces in the near-ultraviolet absorption and pulsed-laser–induced damage was studied for ion-beam–sputtered coatings comprised of HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage threshold were measured for a one-wave (355-nm)–thick HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO2 film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thinfilm interfaces, as compared to HfO2 film material. The relevance of obtained absorption data to coating near-ultraviolet, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film, in agreement with data recently reported for similarly designed electron-beam–deposited coatings. The results are explained through the similarity of interfacial film structure and structure formed during the co-deposition of HfO2 and SiO2 materials.
{"title":"The role of film interfaces in near-ultraviolet absorption and pulsed-laser damage in ion-beam-sputtered coatings based on HfO2/SiO2 thin-film pairs","authors":"S. Papernov, A. Kozlov, J. Oliver, C. Smith, L. Jensen, D. Ristau, S. Günster, H. Mädebach","doi":"10.1117/12.2196654","DOIUrl":"https://doi.org/10.1117/12.2196654","url":null,"abstract":"The role of thin-film interfaces in the near-ultraviolet absorption and pulsed-laser–induced damage was studied for ion-beam–sputtered coatings comprised of HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage threshold were measured for a one-wave (355-nm)–thick HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO2 film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thinfilm interfaces, as compared to HfO2 film material. The relevance of obtained absorption data to coating near-ultraviolet, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film, in agreement with data recently reported for similarly designed electron-beam–deposited coatings. The results are explained through the similarity of interfacial film structure and structure formed during the co-deposition of HfO2 and SiO2 materials.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115208600","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. Jupé, M. Lappschies, L. Jensen, K. Starke, D. Ristau, A. Melninkaitis, V. Sirutkaitis, I. Cravetchi, W. Rudolph
A modified IBS-process was used to create mixtures of oxide coating materials. The process allows to manufacture new designs, whereas the important optical and electronic properties of the material can be varied in a wide range. Especially for ultra short pulse applications, higher damage thresholds can be achieved. In this paper, LIDT measurements of mixed and pure single layers are presented. The coatings were investigated at different wavelengths and in a wide pulse duration range. The results of the measurements confirm the empirical law of the linear LIDT dependency on the absorption gap. Based on this empirical law, the Refractive Index StEps Down (RISED) concept was developed. From the data of the single layer measurements, an optimization of RISED optical components in the fs-regime will lead to even higher damage thresholds. Particularly, for high reflecting mirrors the damage threshold could be doubled for different dielectric coating materials. Additionally, the paper presents a theoretical analysis of the stack LIDT on the basis of the single layer properties.
{"title":"Mixed oxide coatings for advanced fs-laser applications","authors":"M. Jupé, M. Lappschies, L. Jensen, K. Starke, D. Ristau, A. Melninkaitis, V. Sirutkaitis, I. Cravetchi, W. Rudolph","doi":"10.1117/12.753730","DOIUrl":"https://doi.org/10.1117/12.753730","url":null,"abstract":"A modified IBS-process was used to create mixtures of oxide coating materials. The process allows to manufacture new designs, whereas the important optical and electronic properties of the material can be varied in a wide range. Especially for ultra short pulse applications, higher damage thresholds can be achieved. In this paper, LIDT measurements of mixed and pure single layers are presented. The coatings were investigated at different wavelengths and in a wide pulse duration range. The results of the measurements confirm the empirical law of the linear LIDT dependency on the absorption gap. Based on this empirical law, the Refractive Index StEps Down (RISED) concept was developed. From the data of the single layer measurements, an optimization of RISED optical components in the fs-regime will lead to even higher damage thresholds. Particularly, for high reflecting mirrors the damage threshold could be doubled for different dielectric coating materials. Additionally, the paper presents a theoretical analysis of the stack LIDT on the basis of the single layer properties.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128021079","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 Gaussian profile beam has been de rigeur for damage threshold measurements for decades. This paper formulates the cumulative probability of damage (CPD) curve for the Gaussian and an arbitrary distribution of defects in fluence (intensity) space. It is seen that the CPD for the Gaussian is relatively insensitive to the underlying distribution of defects. The CPD is reformulated for a flat top distribution and shown to be far more influenced by the underlying defect distribution. The paper concludes with a discussion of the relationship between the defect distribution, sample size, threshold and measured threshold, for both the Gaussian and flat top profiles. It will be shown than the CPD for Gaussian beams increases with increasing fluence regardless of the distributions of the defects in fluence. The Flat Top CPD will only increase with increasing defect density.
{"title":"The relationship between laser fluence profile and the cumulative probability of damage curve","authors":"J. Arenberg","doi":"10.1117/12.753054","DOIUrl":"https://doi.org/10.1117/12.753054","url":null,"abstract":"The Gaussian profile beam has been de rigeur for damage threshold measurements for decades. This paper formulates the cumulative probability of damage (CPD) curve for the Gaussian and an arbitrary distribution of defects in fluence (intensity) space. It is seen that the CPD for the Gaussian is relatively insensitive to the underlying distribution of defects. The CPD is reformulated for a flat top distribution and shown to be far more influenced by the underlying defect distribution. The paper concludes with a discussion of the relationship between the defect distribution, sample size, threshold and measured threshold, for both the Gaussian and flat top profiles. It will be shown than the CPD for Gaussian beams increases with increasing fluence regardless of the distributions of the defects in fluence. The Flat Top CPD will only increase with increasing defect density.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121968168","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. Schwarz, P. Rambo, M. Geissel, D. Headley, M. Ramsey, B. Atherton
Optical properties of various thin films such as Nitrocellulose, Mylar, and Polyimide were investigated with respect to their application as laser debris shields. Studies on optical and spectral transmission quality, absorption, stress induced birefringence, and damage threshold have been performed. Scalability to large apertures was also considered. Studies were performed of how focusing geometry, target alignment, and mechanical components can help mitigate target debris traveling back to the focusing optic.
{"title":"Studies on thin films as short pulse laser debris shields","authors":"J. Schwarz, P. Rambo, M. Geissel, D. Headley, M. Ramsey, B. Atherton","doi":"10.1117/12.752605","DOIUrl":"https://doi.org/10.1117/12.752605","url":null,"abstract":"Optical properties of various thin films such as Nitrocellulose, Mylar, and Polyimide were investigated with respect to their application as laser debris shields. Studies on optical and spectral transmission quality, absorption, stress induced birefringence, and damage threshold have been performed. Scalability to large apertures was also considered. Studies were performed of how focusing geometry, target alignment, and mechanical components can help mitigate target debris traveling back to the focusing optic.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"6720 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129937976","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 observe that by conditioning DKDP using 500 ps laser pulses, the bulk damage threshold becomes essentially equivalent to the surface damage threshold. We report here the findings of our study of laser initiated output surface damage on 500 ps laser conditioned DKDP for test pulses at 351 nm, 3 ns. The relation between surface damage density and damaging fluence (ρ(Φ)) is presented for the first time and the morphologies of the surface sites are discussed. The results of this study suggest a surface conditioning effect resulting from exposure to 500 ps laser pulses.
{"title":"Analysis of output surface damage resulting from single 351 nm, 3 ns pulses on sub-nanosecond laser conditioned KD2PO4 crystals","authors":"J. Jarboe, J. Adams, R. Hackel","doi":"10.1117/12.752957","DOIUrl":"https://doi.org/10.1117/12.752957","url":null,"abstract":"We observe that by conditioning DKDP using 500 ps laser pulses, the bulk damage threshold becomes essentially equivalent to the surface damage threshold. We report here the findings of our study of laser initiated output surface damage on 500 ps laser conditioned DKDP for test pulses at 351 nm, 3 ns. The relation between surface damage density and damaging fluence (ρ(Φ)) is presented for the first time and the morphologies of the surface sites are discussed. The results of this study suggest a surface conditioning effect resulting from exposure to 500 ps laser pulses.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124648942","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}
F. Wagner, A. Hildenbrand, J. Natoli, M. Commandré, F. Théodore, H. Albrecht
The laser damage probability of nonlinear optical crystals depends on many different factors. In addition to the fabrication process (crystal growth, cutting, polishing, coating) the damage threshold of non-linear crystals is influenced by the usage of the crystal. The anisotropy of material properties like the complex refractive index, the mechanical yield strength and the polarizability may cause anisotropy of the Laser Induced Damage Threshold (LIDT). The LIDT may depend on the propagation direction or the polarization of the light. Anisotropy in the LIDT has in fact been observed in different crystals. The dependency of the KDP-LIDT on the propagation direction and its independence on the polarization direction reported by Burnham et al. is an example that is not yet fully understood. For KTP it has been evidenced by Hu et al. that the grey-tracking threshold is polarization dependent. In this contribution we discuss the bulk laser damage resistance of two isomorphous non-linear crystals: KTiOPO4 (KTP) and RbTiOPO4 (RTP). All tests are performed using a nanosecond laser at 1064nm wavelength. For both crystals all polarization and propagation directions parallel to the principal axes have been tested. In addition we investigated two typical devices: two types of Pockels cells in RTP and a SHG-cut crystal in KTP. The results are analyzed on the basis of an anisotropic sensitivity of the crystal to the electric field and the efficiency of second harmonic generation.
{"title":"Laser damage investigation in KTiOPO4 (KTP) and RbTiOPO4 (RTP) crystals: threshold anisotropy and the influence of SHG","authors":"F. Wagner, A. Hildenbrand, J. Natoli, M. Commandré, F. Théodore, H. Albrecht","doi":"10.1117/12.752895","DOIUrl":"https://doi.org/10.1117/12.752895","url":null,"abstract":"The laser damage probability of nonlinear optical crystals depends on many different factors. In addition to the fabrication process (crystal growth, cutting, polishing, coating) the damage threshold of non-linear crystals is influenced by the usage of the crystal. The anisotropy of material properties like the complex refractive index, the mechanical yield strength and the polarizability may cause anisotropy of the Laser Induced Damage Threshold (LIDT). The LIDT may depend on the propagation direction or the polarization of the light. Anisotropy in the LIDT has in fact been observed in different crystals. The dependency of the KDP-LIDT on the propagation direction and its independence on the polarization direction reported by Burnham et al. is an example that is not yet fully understood. For KTP it has been evidenced by Hu et al. that the grey-tracking threshold is polarization dependent. In this contribution we discuss the bulk laser damage resistance of two isomorphous non-linear crystals: KTiOPO4 (KTP) and RbTiOPO4 (RTP). All tests are performed using a nanosecond laser at 1064nm wavelength. For both crystals all polarization and propagation directions parallel to the principal axes have been tested. In addition we investigated two typical devices: two types of Pockels cells in RTP and a SHG-cut crystal in KTP. The results are analyzed on the basis of an anisotropic sensitivity of the crystal to the electric field and the efficiency of second harmonic generation.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133618695","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}
Transmission, absorption and laser induced fluorescence (LIF) measurements were performed to reveal the applicability of different grade CaF2 for 248 nm laser applications. No emission from self-trapped excitions could be found in LIF measurements after irradiation with 100k pulses for all grades. Therefore, three-photon excitation could be excluded up to 1 J/cm2. Whereas emission at 420 nm and partially the double-peak at 313/333 nm could be found in LIF measurements. UV-VIS difference spectra did not show any absorption bands after 248 nm irradiation of the samples. Optical elements from CaF2 promise high life expectancy at 248 nm if a standard laser polish is used and hot spots are avoided.
{"title":"248 nm high fluence irradiation of CaF2 crystals","authors":"A. Burkert, D. Keutel, U. Natura","doi":"10.1117/12.752813","DOIUrl":"https://doi.org/10.1117/12.752813","url":null,"abstract":"Transmission, absorption and laser induced fluorescence (LIF) measurements were performed to reveal the applicability of different grade CaF2 for 248 nm laser applications. No emission from self-trapped excitions could be found in LIF measurements after irradiation with 100k pulses for all grades. Therefore, three-photon excitation could be excluded up to 1 J/cm2. Whereas emission at 420 nm and partially the double-peak at 313/333 nm could be found in LIF measurements. UV-VIS difference spectra did not show any absorption bands after 248 nm irradiation of the samples. Optical elements from CaF2 promise high life expectancy at 248 nm if a standard laser polish is used and hot spots are avoided.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131092616","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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