Abstract The combination of diffractive optical elements or spatial light modulators with fully synchronized galvo scanners offers a possibility to scale up machining processes with ultra-short pulses to several 100 W of average power with minimal thermal impact. This will be demonstrated with the high-rate applications multi-pulse drilling on the fly and material removal with special intensity distributions up to an average power of 162 W and a removal rate of 16.5 mm3/min. Based on the experimental results strategies to achieve drilling rates of several 10,000 holes/s or removal rates of multiple 10 mm3/min will be discussed.
{"title":"High-rate laser processing with ultrashort laser pulses by combination of diffractive elements with synchronized galvo scanning","authors":"M. Gafner, S. Remund, M. Chaja, B. Neuenschwander","doi":"10.1515/aot-2021-0035","DOIUrl":"https://doi.org/10.1515/aot-2021-0035","url":null,"abstract":"Abstract The combination of diffractive optical elements or spatial light modulators with fully synchronized galvo scanners offers a possibility to scale up machining processes with ultra-short pulses to several 100 W of average power with minimal thermal impact. This will be demonstrated with the high-rate applications multi-pulse drilling on the fly and material removal with special intensity distributions up to an average power of 162 W and a removal rate of 16.5 mm3/min. Based on the experimental results strategies to achieve drilling rates of several 10,000 holes/s or removal rates of multiple 10 mm3/min will be discussed.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48972113","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. Abdou Ahmed, Christoph Roecker, A. Loescher, F. Bienert, Daniel Holder, R. Weber, V. Onuseit, T. Graf
Abstract Thin-disk multipass amplifiers represent one of the most powerful approaches to scale the average and peak powers of ultrafast laser systems. The present paper presents the amplification of picosecond and femtosecond pulses to average powers exceeding 2 and 1 kW, respectively. Second-harmonic generation in lithium-triborate crystals with powers higher than 1.4 kW and 400 W at a wavelength of 515 nm with picosecond and femtosecond pulse durations, respectively, are also reported. Furthermore, third-harmonic generation was demonstrated with output powers exceeding 250 W at a wavelength of 343 nm. Finally, processing of silicon, metals, and polycrystalline diamond with fs pulses at an average power of 1 kW is presented to demonstrate removal rates that are improved by orders of magnitude as compared to state-of-the-art techniques.
{"title":"High-power ultrafast thin-disk multipass amplifiers for efficient laser-based manufacturing","authors":"M. Abdou Ahmed, Christoph Roecker, A. Loescher, F. Bienert, Daniel Holder, R. Weber, V. Onuseit, T. Graf","doi":"10.1515/aot-2021-0047","DOIUrl":"https://doi.org/10.1515/aot-2021-0047","url":null,"abstract":"Abstract Thin-disk multipass amplifiers represent one of the most powerful approaches to scale the average and peak powers of ultrafast laser systems. The present paper presents the amplification of picosecond and femtosecond pulses to average powers exceeding 2 and 1 kW, respectively. Second-harmonic generation in lithium-triborate crystals with powers higher than 1.4 kW and 400 W at a wavelength of 515 nm with picosecond and femtosecond pulse durations, respectively, are also reported. Furthermore, third-harmonic generation was demonstrated with output powers exceeding 250 W at a wavelength of 343 nm. Finally, processing of silicon, metals, and polycrystalline diamond with fs pulses at an average power of 1 kW is presented to demonstrate removal rates that are improved by orders of magnitude as compared to state-of-the-art techniques.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41879937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Eidam, S. Breitkopf, O. Herrfurth, F. Stutzki, M. Kienel, S. Hädrich, C. Gaida, J. Limpert
Abstract State-of-the-art fiber-laser systems can deliver femtosecond pulses at average powers beyond the kilowatt level and multi-mJ pulse energies by employing advanced large-mode-area fiber designs, chirped-pulse amplification, and the coherent combination of parallel fiber amplifiers. By using sophisticated coherent phase control, one or even several output ports can be modulated at virtually arbitrary power levels and switching speeds. In addition, an all-fiber setup for GHz-burst generation is described allowing to access an even wider range of laser parameters. The combination of all these approaches together with the robustness, efficiency, and excellent beam quality inherent to fiber-laser technology has the potential to strongly improve existing materials-processing applications.
{"title":"High-power ultrafast fiber lasers for materials processing","authors":"T. Eidam, S. Breitkopf, O. Herrfurth, F. Stutzki, M. Kienel, S. Hädrich, C. Gaida, J. Limpert","doi":"10.1515/aot-2021-0033","DOIUrl":"https://doi.org/10.1515/aot-2021-0033","url":null,"abstract":"Abstract State-of-the-art fiber-laser systems can deliver femtosecond pulses at average powers beyond the kilowatt level and multi-mJ pulse energies by employing advanced large-mode-area fiber designs, chirped-pulse amplification, and the coherent combination of parallel fiber amplifiers. By using sophisticated coherent phase control, one or even several output ports can be modulated at virtually arbitrary power levels and switching speeds. In addition, an all-fiber setup for GHz-burst generation is described allowing to access an even wider range of laser parameters. The combination of all these approaches together with the robustness, efficiency, and excellent beam quality inherent to fiber-laser technology has the potential to strongly improve existing materials-processing applications.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47346371","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}
Abstract Smoother surfaces after laser vision correction have been widely accepted as a factor for improving visual recovery regardless of the used technique (PRK, LASIK, or even SMILE). We tested the impact of laser beam truncation, dithering (expressing a continuous profile on a basis of lower resolution causing pixels to round up/down the number of pulses to be placed), and jitter (a controlled random noise (up to ±20 µm in either direction) added to the theoretical scanner positions) on residual smoothness after Poly(methyl methacrylate) (PMMA) ablations, using a close-to-Gaussian beam profile. A modified SCHWIND AMARIS system has been used providing a beam profile with the following characteristics: close-to-Gaussian beam profile with full width at half maximum (FWHM) of 540 µm, 1050 Hz. Laser parameters have been optimized following Invest. Ophthalmol. Vis. Sci., vol. 58, no. 4, pp. 2021–2037, 2017, the pulse energy has been optimized following Biomed. Opt. Express vol. 4, pp. 1422–1433, 2013. For the PMMA ablations, two configurations (with a 0.7 mm pinhole and 0.75 mJ and without pinhole and 0.9 mJ (for fluences of 329 mJ/cm2 and 317 mJ/cm2 and corneal spot volumes of 174 and 188 pl)) were considered, along with two types of lattices (with and without ordered dithering to select the optimum pulse positions), and two types of spot placement (with and without jitter). Real ablations on PMMA (ranging from −12D to +6D with and without astigmatism of up to 3D) completed the study setup. The effect of the 2 × 2 × 2 different configurations was analyzed based on the roughness in ablation estimated from the root mean square error in ablation. Truncation of the beam is negatively associated to a higher level of residual roughness; ordered dithering to select the optimum pulse positions is positively associated to a lower level of residual roughness; jitter is negatively associated to a higher level of residual roughness. The effect of dithering was the largest, followed by truncation, and jitter had the lowest impact on results. So that: Dithering approaches help to further minimize residual roughness after ablation; minimum (or no) truncation of the beam is essential to minimize residual roughness after ablation; and jitter shall be avoided to minimize residual roughness after ablation. The proposed model can be used for optimization of laser systems used for ablation processes at relatively low cost and would directly improve the quality of results. Minimum (or no) truncation of the beam is essential to minimize residual roughness after ablation. Ordered dithering without jitter helps to further minimize residual roughness after ablation. Other more complex dithering approaches may further contribute to minimize residual roughness after ablation.
{"title":"Effect of laser beam truncation (pinhole), (ordered) dithering, and jitter on residual smoothness after poly(methyl methacrylate) ablations, using a close-to-Gaussian beam profile","authors":"Shwetabh Verma, J. Hesser, S. Arba-Mosquera","doi":"10.1515/aot-2021-0040","DOIUrl":"https://doi.org/10.1515/aot-2021-0040","url":null,"abstract":"Abstract Smoother surfaces after laser vision correction have been widely accepted as a factor for improving visual recovery regardless of the used technique (PRK, LASIK, or even SMILE). We tested the impact of laser beam truncation, dithering (expressing a continuous profile on a basis of lower resolution causing pixels to round up/down the number of pulses to be placed), and jitter (a controlled random noise (up to ±20 µm in either direction) added to the theoretical scanner positions) on residual smoothness after Poly(methyl methacrylate) (PMMA) ablations, using a close-to-Gaussian beam profile. A modified SCHWIND AMARIS system has been used providing a beam profile with the following characteristics: close-to-Gaussian beam profile with full width at half maximum (FWHM) of 540 µm, 1050 Hz. Laser parameters have been optimized following Invest. Ophthalmol. Vis. Sci., vol. 58, no. 4, pp. 2021–2037, 2017, the pulse energy has been optimized following Biomed. Opt. Express vol. 4, pp. 1422–1433, 2013. For the PMMA ablations, two configurations (with a 0.7 mm pinhole and 0.75 mJ and without pinhole and 0.9 mJ (for fluences of 329 mJ/cm2 and 317 mJ/cm2 and corneal spot volumes of 174 and 188 pl)) were considered, along with two types of lattices (with and without ordered dithering to select the optimum pulse positions), and two types of spot placement (with and without jitter). Real ablations on PMMA (ranging from −12D to +6D with and without astigmatism of up to 3D) completed the study setup. The effect of the 2 × 2 × 2 different configurations was analyzed based on the roughness in ablation estimated from the root mean square error in ablation. Truncation of the beam is negatively associated to a higher level of residual roughness; ordered dithering to select the optimum pulse positions is positively associated to a lower level of residual roughness; jitter is negatively associated to a higher level of residual roughness. The effect of dithering was the largest, followed by truncation, and jitter had the lowest impact on results. So that: Dithering approaches help to further minimize residual roughness after ablation; minimum (or no) truncation of the beam is essential to minimize residual roughness after ablation; and jitter shall be avoided to minimize residual roughness after ablation. The proposed model can be used for optimization of laser systems used for ablation processes at relatively low cost and would directly improve the quality of results. Minimum (or no) truncation of the beam is essential to minimize residual roughness after ablation. Ordered dithering without jitter helps to further minimize residual roughness after ablation. Other more complex dithering approaches may further contribute to minimize residual roughness after ablation.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45101999","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}
Abstract Materials processing with ultrafast lasers with pulse durations in the range between about 100 fs and 10 ps enable very promising and emerging high-tech applications. Moreover, the average power of such lasers is steadily increasing; multi kilowatt systems have been demonstrated in laboratories and will be ready for the market in the next few years, allowing a significantly increase in productivity. However, the implementation of ultrafast laser processes in applications is very challenging due to fundamental physical limitations. In this paper, the main limitations will be discussed. These include limitations resulting from the physical material properties such as the ablation depth and the optimal fluence, from processing parameters such as air-breakdown and heat accumulation, from the processing system such as thermal focus shift, and from legal regulations due to the potential emission of soft X-rays.
{"title":"The challenges of productive materials processing with ultrafast lasers","authors":"R. Weber, T. Graf","doi":"10.1515/aot-2021-0038","DOIUrl":"https://doi.org/10.1515/aot-2021-0038","url":null,"abstract":"Abstract Materials processing with ultrafast lasers with pulse durations in the range between about 100 fs and 10 ps enable very promising and emerging high-tech applications. Moreover, the average power of such lasers is steadily increasing; multi kilowatt systems have been demonstrated in laboratories and will be ready for the market in the next few years, allowing a significantly increase in productivity. However, the implementation of ultrafast laser processes in applications is very challenging due to fundamental physical limitations. In this paper, the main limitations will be discussed. These include limitations resulting from the physical material properties such as the ablation depth and the optimal fluence, from processing parameters such as air-breakdown and heat accumulation, from the processing system such as thermal focus shift, and from legal regulations due to the potential emission of soft X-rays.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44833432","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}
Abstract Bursts of GHz repetition rate pulses can significantly improve the ablation efficiency of femtosecond lasers. Depending on the process conditions, thermal mechanisms can be promoted and controlled. GHz ablation therefore combines thermal and non-thermal ablation mechanisms. With an optimal choice of the burst duration, the non-thermal ablation can be highly enhanced by a heating phase due to the first pulses in the burst. The GHz burst mode can be considered as a key function for the “agility” of new high-power lasers.
{"title":"GHz femtosecond processing with agile high-power laser","authors":"É. Audouard, G. Bonamis, C. Hönninger, E. Mottay","doi":"10.1515/aot-2021-0029","DOIUrl":"https://doi.org/10.1515/aot-2021-0029","url":null,"abstract":"Abstract Bursts of GHz repetition rate pulses can significantly improve the ablation efficiency of femtosecond lasers. Depending on the process conditions, thermal mechanisms can be promoted and controlled. GHz ablation therefore combines thermal and non-thermal ablation mechanisms. With an optimal choice of the burst duration, the non-thermal ablation can be highly enhanced by a heating phase due to the first pulses in the burst. The GHz burst mode can be considered as a key function for the “agility” of new high-power lasers.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43199175","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}
Abstract Micro structuring of surfaces is of great interest for various applications, e.g. for the tooling industry, the printing industry and for consumer goods. In suitable mass production applications, such as injection molding or roll-to-roll processing for various markets, the final product could be equipped with new properties, such as hydrophilic behavior, adjustable gloss level, soft-touch behavior, light management properties etc. To generate functionalities at reasonable cost, embossing dies can be augmented with additional micro/nano-scale structure using laser ablation technologies. Despite the availability of ultrashort pulsed (USP) high power lasers (up to several hundred watts), it is still a challenge to structure large areas, as required on embossing rolls, in an acceptable processing time for industrial production. In terms of industrial implementation, direct digital transfer is a limiting factor for ultrahigh resolution. Shorter machining times by further increasing spot or workpiece motion are limited. Enlarging the ablation diameter, and thus the tool diameter, delivers a higher ablation rate with the comparable ablation quality, but entails a reduction in resolution. While maintaining the achieved state-of-the-art performance, upscaling of single modulated lasers provides a less demanding way to increase productivity. In the processing of steel surfaces, an increase in material removal can also be achieved by using pulse burst. In this work, the parallel process of single modulated multi laser sources is compared with a laser source split by diffractive optical elements (DOE) for applications in a cylinder micro patterning system. A newly developed highly compact ps laser with repetition rates up to 8 MHz and an average power of 300 or 500 W was divided into 8 or 16 parallel beamlets by a DOE. The ablation rate of each approach was investigated by typical microstructures on copper surfaces. At surface speeds of 10 m/s and a resolution of 5080 dpi, an ablation rate of up to 27 mm³/min was achieved. Different functional surface geometries were realized on an embossing roll as master, which is used for replication of the structures in roll-to-roll processes. Functional structures, such as friction reduction, improved soft touch or light guiding elements on large surfaces are demonstrated.
{"title":"Multi beam microprocessing for printing and embossing applications with high power ultrashort pulsed lasers","authors":"S. Bruening, A. Gillner, K. Du","doi":"10.1515/aot-2021-0025","DOIUrl":"https://doi.org/10.1515/aot-2021-0025","url":null,"abstract":"Abstract Micro structuring of surfaces is of great interest for various applications, e.g. for the tooling industry, the printing industry and for consumer goods. In suitable mass production applications, such as injection molding or roll-to-roll processing for various markets, the final product could be equipped with new properties, such as hydrophilic behavior, adjustable gloss level, soft-touch behavior, light management properties etc. To generate functionalities at reasonable cost, embossing dies can be augmented with additional micro/nano-scale structure using laser ablation technologies. Despite the availability of ultrashort pulsed (USP) high power lasers (up to several hundred watts), it is still a challenge to structure large areas, as required on embossing rolls, in an acceptable processing time for industrial production. In terms of industrial implementation, direct digital transfer is a limiting factor for ultrahigh resolution. Shorter machining times by further increasing spot or workpiece motion are limited. Enlarging the ablation diameter, and thus the tool diameter, delivers a higher ablation rate with the comparable ablation quality, but entails a reduction in resolution. While maintaining the achieved state-of-the-art performance, upscaling of single modulated lasers provides a less demanding way to increase productivity. In the processing of steel surfaces, an increase in material removal can also be achieved by using pulse burst. In this work, the parallel process of single modulated multi laser sources is compared with a laser source split by diffractive optical elements (DOE) for applications in a cylinder micro patterning system. A newly developed highly compact ps laser with repetition rates up to 8 MHz and an average power of 300 or 500 W was divided into 8 or 16 parallel beamlets by a DOE. The ablation rate of each approach was investigated by typical microstructures on copper surfaces. At surface speeds of 10 m/s and a resolution of 5080 dpi, an ablation rate of up to 27 mm³/min was achieved. Different functional surface geometries were realized on an embossing roll as master, which is used for replication of the structures in roll-to-roll processes. Functional structures, such as friction reduction, improved soft touch or light guiding elements on large surfaces are demonstrated.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44867178","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. Petelin, Luka Černe, Jaka Mur, V. Agrež, Jernej Jan Kočica, J. Schille, U. Loeschner, R. Petkovšek
Abstract In this manuscript we present a true pulse-on-demand laser design concept using two different approaches. First, we present a fiber master oscillator power amplifier (MOPA) based quasi-continuous wave (CW) laser, working at high modulation bandwidths, for generation of nanosecond pulses. Second, we present a hybrid chirped pulse amplification (CPA)-based laser, combining a chirped-pulse fiber amplifier and an additional solid-state amplifier, for generation of femtosecond pulses. The pulse-on-demand operation is achieved without an external optical modulator/shutter at high-average powers and flexible repetition rates up to 40 MHz, using two variants of the approach for near-constant gain in the amplifier chain. The idler and marker seed sources are combined in the amplifier stages and separated at the out using either wavelength-based separation or second harmonic generation (SHG)-generation-based separation. The nanosecond laser source is further applied to high throughput processing of thin film materials. The laser is combined with a resonant scanner, using the intrinsic pulse-on-demand operation to compensate the scanner’s sinusoidal movement. We applied the setup to processing of indium tin oxide (ITO) and metallic films on flexible substrates.
{"title":"Pulse-on-demand laser operation from nanosecond to femtosecond pulses and its application for high-speed processing","authors":"J. Petelin, Luka Černe, Jaka Mur, V. Agrež, Jernej Jan Kočica, J. Schille, U. Loeschner, R. Petkovšek","doi":"10.1515/aot-2021-0020","DOIUrl":"https://doi.org/10.1515/aot-2021-0020","url":null,"abstract":"Abstract In this manuscript we present a true pulse-on-demand laser design concept using two different approaches. First, we present a fiber master oscillator power amplifier (MOPA) based quasi-continuous wave (CW) laser, working at high modulation bandwidths, for generation of nanosecond pulses. Second, we present a hybrid chirped pulse amplification (CPA)-based laser, combining a chirped-pulse fiber amplifier and an additional solid-state amplifier, for generation of femtosecond pulses. The pulse-on-demand operation is achieved without an external optical modulator/shutter at high-average powers and flexible repetition rates up to 40 MHz, using two variants of the approach for near-constant gain in the amplifier chain. The idler and marker seed sources are combined in the amplifier stages and separated at the out using either wavelength-based separation or second harmonic generation (SHG)-generation-based separation. The nanosecond laser source is further applied to high throughput processing of thin film materials. The laser is combined with a resonant scanner, using the intrinsic pulse-on-demand operation to compensate the scanner’s sinusoidal movement. We applied the setup to processing of indium tin oxide (ITO) and metallic films on flexible substrates.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49492692","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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