Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Diagnostics (Basel) ; 11(11)2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34829478

RESUMO

Abdominal aortic aneurysms (AAA) may remain clinically silent until they enlarge and patients present with a potentially lethal rupture. This necessitates early detection and elective treatment. The goal of this study was to develop an easy-to-train algorithm which is capable of automated AAA screening in CT scans and can be applied to an intra-hospital environment. Three deep convolutional neural networks (ResNet, VGG-16 and AlexNet) were adapted for 3D classification and applied to a dataset consisting of 187 heterogenous CT scans. The 3D ResNet outperformed both other networks. Across the five folds of the first training dataset it achieved an accuracy of 0.856 and an area under the curve (AUC) of 0.926. Subsequently, the algorithms performance was verified on a second data set containing 106 scans, where it ran fully automated and resulted in an accuracy of 0.953 and an AUC of 0.971. A layer-wise relevance propagation (LRP) made the decision process interpretable and showed that the network correctly focused on the aortic lumen. In conclusion, the deep learning-based screening proved to be robust and showed high performance even on a heterogeneous multi-center data set. Integration into hospital workflow and its effect on aneurysm management would be an exciting topic of future research.

2.
Magn Reson Med ; 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34652819

RESUMO

PURPOSE: To design and manufacture a pelvis phantom for magnetic resonance (MR)-guided prostate interventions, such as MRGB (MR-guided biopsy) or brachytherapy seed placement. METHODS: The phantom was designed to mimic the human pelvis incorporating bones, bladder, prostate with four lesions, urethra, arteries, veins, and six lymph nodes embedded in ballistic gelatin. A hollow rectum enables transrectal access to the prostate. To demonstrate the feasibility of the phantom for minimal invasive MRI-guided interventions, a targeted inbore MRGB was performed. The needle probe was rectally inserted and guided using an MRI-compatible remote controlled manipulator (RCM). RESULTS: The presented pelvis phantom has realistic imaging properties for MR imaging (MRI), computed tomography (CT) and ultrasound (US). In the targeted inbore MRGB, a prostate lesion was successfully hit with an accuracy of 3.5 mm. The experiment demonstrates that the limited size of the rectum represents a realistic impairment for needle placements. CONCLUSION: The phantom provides a valuable platform for evaluating the performance of MRGB systems. Interventionalists can use the phantom to learn how to deal with challenging situations, without risking harm to patients.

3.
J Imaging ; 7(3)2021 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-34460700

RESUMO

The reconstruction of computed tomography (CT) images is an active area of research. Following the rise of deep learning methods, many data-driven models have been proposed in recent years. In this work, we present the results of a data challenge that we organized, bringing together algorithm experts from different institutes to jointly work on quantitative evaluation of several data-driven methods on two large, public datasets during a ten day sprint. We focus on two applications of CT, namely, low-dose CT and sparse-angle CT. This enables us to fairly compare different methods using standardized settings. As a general result, we observe that the deep learning-based methods are able to improve the reconstruction quality metrics in both CT applications while the top performing methods show only minor differences in terms of peak signal-to-noise ratio (PSNR) and structural similarity (SSIM). We further discuss a number of other important criteria that should be taken into account when selecting a method, such as the availability of training data, the knowledge of the physical measurement model and the reconstruction speed.

4.
Artigo em Inglês | MEDLINE | ID: mdl-34460343

RESUMO

Pharmacotherapy is essential in palliative medicine. Besides potential benefits, pharmacotherapy also poses potential risks that need to be minimized for patient safety. Pharmacists can play an important role in identifying, solving, and avoiding drug-related problems (DRPs). The aim of this study was to evaluate pharmaceutical interventions on safety of drug therapy in patients in an inpatient palliative care unit. All patients admitted to a palliative care unit over a 12-month period were screened for eligibility (ie, life expectancy >4 weeks). To identify and assess DRPs, patients' pharmacotherapy was evaluated by a pharmacist according to various aspects (eg, drug selection, dose selection, or treatment duration according to the Pharmaceutical Care Network Europe classification for DRPs). During the 12-month period, 41 patients were included. Patients received a median of 11 (range, 1-22) different drugs. Overall, 207 DRPs were documented (median 5 DRPs/patient). After recording a DRP, the pharmacist directly intervened 290 times in order to solve the DRP, which was successful in 181/207 (88%). Clinically relevant DRPs are common in palliative medicine. The systematic assessment can support therapy decisions. This can result in optimized drug therapy, subsequently having a positive effect on symptom control and quality of life.

5.
Radiologe ; 61(9): 829-838, 2021 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-34251481

RESUMO

CLINICAL/METHODOLOGICAL ISSUE: Multiparametric magnetic resonance imaging (mpMRI) of the prostate plays a crucial role in the diagnosis and local staging of primary prostate cancer. STANDARD RADIOLOGICAL METHODS: Image-guided biopsy techniques such as MRI-ultrasound fusion not only allow guidance for targeted tissue sampling of index lesions for diagnostic confirmation, but also improve the detection of clinically significant prostate cancer. METHODOLOGICAL INNOVATIONS: Minimally invasive, focal therapies of localized prostate cancer complement the treatment spectrum, especially for low- and intermediate-risk patients. PERFORMANCE: In patients of low and intermediate risk, MR-guided, minimally invasive therapies could enable local tumor control, improved functional outcomes and possible subsequent therapy escalation. Further study results related to multimodal approaches and the application of artificial intelligence (AI) by machine and deep learning algorithms will help to leverage the full potential of focal therapies for prostate cancer in the upcoming era of precision medicine. ACHIEVEMENTS: Completion of ongoing randomized trials comparing each minimally invasive therapy approach with established whole-gland procedures is needed before minimally invasive therapies can be implemented into existing treatment guidelines. PRACTICAL RECOMMENDATIONS: This review article highlights minimally invasive therapies of prostate cancer and the key role of mpMRI for planning and conducting these therapies.


Assuntos
Inteligência Artificial , Neoplasias da Próstata , Humanos , Biópsia Guiada por Imagem , Imageamento por Ressonância Magnética , Masculino , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/cirurgia
6.
Int J Comput Assist Radiol Surg ; 16(8): 1277-1285, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33934313

RESUMO

PURPOSE: Sparsity of annotated data is a major limitation in medical image processing tasks such as registration. Registered multimodal image data are essential for the diagnosis of medical conditions and the success of interventional medical procedures. To overcome the shortage of data, we present a method that allows the generation of annotated multimodal 4D datasets. METHODS: We use a CycleGAN network architecture to generate multimodal synthetic data from the 4D extended cardiac-torso (XCAT) phantom and real patient data. Organ masks are provided by the XCAT phantom; therefore, the generated dataset can serve as ground truth for image segmentation and registration. Realistic simulation of respiration and heartbeat is possible within the XCAT framework. To underline the usability as a registration ground truth, a proof of principle registration is performed. RESULTS: Compared to real patient data, the synthetic data showed good agreement regarding the image voxel intensity distribution and the noise characteristics. The generated T1-weighted magnetic resonance imaging, computed tomography (CT), and cone beam CT images are inherently co-registered. Thus, the synthetic dataset allowed us to optimize registration parameters of a multimodal non-rigid registration, utilizing liver organ masks for evaluation. CONCLUSION: Our proposed framework provides not only annotated but also multimodal synthetic data which can serve as a ground truth for various tasks in medical imaging processing. We demonstrated the applicability of synthetic data for the development of multimodal medical image registration algorithms.


Assuntos
Algoritmos , Simulação por Computador , Tomografia Computadorizada de Feixe Cônico/métodos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Imagens de Fantasmas , Humanos
7.
Opt Lett ; 46(5): 965-968, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33649632

RESUMO

We report on a thin-disk laser system with more than 10 kW of output power and a beam quality of M2=1.76 at an overall optical-to-optical efficiency of 51%. The system consists of two thin-disk laser oscillators and a thin-disk multi-pass amplifier system. To reach high output powers while maintaining good beam quality, the output beams of two identical laser oscillators are polarization-combined. Subsequently, the beam is amplified in a multi-pass system. To the best of our knowledge, this is the highest output power achieved for a thin-disk laser system with a beam quality close to fundamental mode.

8.
J Clin Pharm Ther ; 46(3): 838-845, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33609054

RESUMO

WHAT IS KNOWN AND OBJECTIVE: Renal impairment (RI) and renal drug-related problems (rDRP) often remain unrecognized in the community setting. A "renal pharmacist consultant service" (RPCS) at hospital admission can support patient safety by detecting rDRP. However, the efficient information sharing from pharmacists to physicians is still discussed. The aim of the study was to test the implementation of a RPCS and its effectiveness on prescription changes and to evaluate two ways of written information sharing with physicians. METHODS: Urological patients with eGFRnon-indexed of 15-59 ml/min and ≥1 drug were reviewed for manifest and potential rDRP at admission by a pharmacist. Written recommendations for dose or drug adaptation were forwarded to physicians comparing two routes: July-September 2017 paper form in handwritten chart; November 2017-January 2018 digital PDF document in the electronic patient information system and e-mail alert. Prescription changes regarding manifest rDRP were evaluated and compared with a previous retrospective study without RPCS. RESULTS AND DISCUSSION: The RPCS detected rDRP in 63 of 234 (26.9%) patients and prepared written recommendations (median 1 rDRP (1-5) per patient) concerning 110 of 538 (20.5%) drugs at admission. For manifest rDRP, acceptance rates of recommendations were 62.5% (paper) vs 42.9% (digital) (P = 0.16). Compared with the retrospective study without RPCS (prescription changes in 21/76 rDRP; 27.6%), correct prescribing concerning manifest rDRP significantly increased by 27.1%. WHAT IS NEW AND CONCLUSION: A RPCS identifies patients at risk for rDRP and significantly increases appropriate prescribing by physicians. In our hospital (no electronic order entry, electronic chart or ward pharmacists), consultations in paper form seem to be superior to a digital PDF document.

9.
NMR Biomed ; 34(4): e4474, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33480128

RESUMO

Quantitative 23 Na magnetic resonance imaging (MRI) provides tissue sodium concentration (TSC), which is connected to cell viability and vitality. Long acquisition times are one of the most challenging aspects for its clinical establishment. K-space undersampling is an approach for acquisition time reduction, but generates noise and artifacts. The use of convolutional neural networks (CNNs) is increasing in medical imaging and they are a useful tool for MRI postprocessing. The aim of this study is 23 Na MRI acquisition time reduction by k-space undersampling. CNNs were applied to reduce the resulting noise and artifacts. A retrospective analysis from a prospective study was conducted including image datasets from 46 patients (aged 72 ± 13 years; 25 women, 21 men) with ischemic stroke; the 23 Na MRI acquisition time was 10 min. The reconstructions were performed with full dataset (FI) and with a simulated dataset an image that was acquired in 2.5 min (RI). Eight different CNNs with either U-Net-based or ResNet-based architectures were implemented with RI as input and FI as label, using batch normalization and the number of filters as varying parameters. Training was performed with 9500 samples and testing included 400 samples. CNN outputs were evaluated based on signal-to-noise ratio (SNR) and structural similarity (SSIM). After quantification, TSC error was calculated. The image quality was subjectively rated by three neuroradiologists. Statistical significance was evaluated by Student's t-test. The average SNR was 21.72 ± 2.75 (FI) and 10.16 ± 0.96 (RI). U-Nets increased the SNR of RI to 43.99 and therefore performed better than ResNet. SSIM of RI to FI was improved by three CNNs to 0.91 ± 0.03. CNNs reduced TSC error by up to 15%. The subjective rating of CNN-generated images showed significantly better results than the subjective image rating of RI. The acquisition time of 23 Na MRI can be reduced by 75% due to postprocessing with a CNN on highly undersampled data.

10.
IEEE Trans Biomed Eng ; 68(5): 1518-1526, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33275574

RESUMO

OBJECTIVE: Three-dimensional (3D) blood vessel structure information is important for diagnosis and treatment in various clinical scenarios. We present a fully automatic method for the extraction and differentiation of the arterial and venous vessel trees from abdominal contrast enhanced computed tomography (CE-CT) volumes using convolutional neural networks (CNNs). METHODS: We used a novel ratio-based sampling method to train 2D and 3D versions of the U-Net, the V-Net and the DeepVesselNet. Networks were trained with a combination of the Dice and cross entropy loss. Performance was evaluated on 20 IRCAD subjects. Best performing networks were combined into an ensemble. We investigated seven different weighting schemes. Trained networks were additionally applied to 26 BTCV cases to validate the generalizability. RESULTS: Based on our experiments, the optimal configuration is an equally weighted ensemble of 2D and 3D U- and V-Nets. Our method achieved Dice similarity coefficients of 0.758 ± 0.050 (veins) and 0.838 ± 0.074 (arteries) on the IRCAD data set. Application to the BTCV data set showed a high transfer ability. CONCLUSION: Abdominal vascular structures can be segmented more accurately using ensembles than individual CNNs. 2D and 3D networks have complementary strengths and weaknesses. Our ensemble of 2D and 3D U-Nets and V-Nets in combination with ratio-based sampling achieves a high agreement with manual annotations for both artery and vein segmentation. Our results surpass other state-of-the-art methods. SIGNIFICANCE: Our segmentation pipeline can provide valuable information for the planning of living donor organ transplantations.


Assuntos
Redes Neurais de Computação , Tomografia Computadorizada por Raios X , Abdome/diagnóstico por imagem , Artérias , Humanos , Processamento de Imagem Assistida por Computador
11.
Opt Express ; 28(20): 30164-30173, 2020 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-33114900

RESUMO

We present an ultrafast thin-disk based multipass amplifier operating at a wavelength of 1030 nm, designed for atmospheric research in the framework of the Laser Lightning Rod project. The CPA system delivers a pulse energy of 720 mJ and a pulse duration of 920 fs at a repetition rate of 1 kHz. The 240 mJ seed pulses generated by a regenerative amplifier are amplified to the final energy in a multipass amplifier via four industrial thin-disk laser heads. The beam quality factor remains ∼ 2.1 at the output. First results on horizontal long-range filament generation are presented.

12.
Opt Lett ; 45(19): 5522-5525, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33001936

RESUMO

We present an ultrafast laser with a near-diffraction-limited beam quality delivering more than 1.4 kW of average power in the visible spectral range. The laser is based on second harmonic generation in a lithium triborate crystal of a Yb:YAG thin-disk multipass amplifier emitting more than 2 kW of average power in the infrared.

13.
Eur J Clin Pharmacol ; 76(12): 1683-1693, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32651616

RESUMO

PURPOSE: Two to seven percent of the German adult population has a renal impairment (RI) with an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m2. This often remains unrecognized and adjustment of drug therapy is lacking. To determine renal function in clinical routine, the CKD-EPI equation is used to calculate an indexed eGFR (ml/min/1.73m2). For drug dosing, it has to be individualized to a non-indexed eGFR (ml/min) by the patient's body surface area. Here, we investigated the number of patients admitted to urological wards of a teaching hospital with RI between July and December 2016. Additionally, we correctly used the eGFRnon-indexed for drug and dosage adjustments and to analyse the use of renal risk drugs (RRD) and renal drug-related problems (rDRP). METHODS: In a retrospective observational study, urological patients with pharmacist-led medication reconciliation at hospital admission and eGFRindexed (CKD-EPI) of 15-59 ml/min/1.73m2 were identified. Indexed eGFR (ml/min/1.73m2) was recalculated with body surface area to non-indexed eGFR (ml/min) for correct drug dosing. Medication at admission was reviewed for RRD and based on the eGFRnon-indexed for rDRP, e.g. inappropriate dose or contraindication. RESULTS: Of 1320 screened patients, 270 (20.5%) presented with an eGFRindexed of 15-59 ml/min/1.73m2. After readjustment, 203 (15.4%) patients had an eGFRnon-indexed of 15-59 ml/min. Of these, 190 (93.6%) used ≥ 1 drugs at admission with 660 of 1209 (54.7%) drugs classified as RRD. At least one rDRP was identified in 115 (60.5%) patients concerning 264 (21.8%) drugs. CONCLUSION: Renal impairment is a common risk factor for medication safety in urologic patients admitted to a hospital. Considerable shifts were seen in eGFR-categories when correctly calculating eGFRnon-indexed for drug dosing purposes. The fact that more than half of the study patients showed rDRP at hospital admission underlines the need to consider this risk factor appropriately.


Assuntos
Cálculos da Dosagem de Medicamento , Taxa de Filtração Glomerular/fisiologia , Admissão do Paciente , Insuficiência Renal Crônica/fisiopatologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Superfície Corporal , Feminino , Alemanha , Humanos , Testes de Função Renal , Masculino , Reconciliação de Medicamentos , Pessoa de Meia-Idade , Eliminação Renal/fisiologia , Insuficiência Renal Crônica/diagnóstico , Estudos Retrospectivos , Adulto Jovem
14.
Opt Express ; 28(8): 11415-11423, 2020 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-32403653

RESUMO

An ultrafast Yb-doped thin-disk multi-pass laser amplifier system with flexible parameters for material processing is reported. We can generate bursts consisting of four pulses at a distance of 20 ns and a total energy of 46.7 mJ at a repetition rate of 25 kHz. In single-pulse operation, 1.5 kW of average output is achieved at 400 kHz when optimizing for a beam quality of M2 = 1.5. Alignment for maximum output power provides 1.9 kW at the same repetition rate. All results are obtained without chirped-pulse amplification in the multi-pass set-up. The application potential of the system is demonstrated exploring its performance in materials processing of dielectrics. Cleaving of 3.8-mm-thick SCHOTT borofloat glass with a velocity of 1200 mm/s is demonstrated with 300 W of input power. Single-pass modification of 30 mm borosilicate glass is enabled with a Bessel beam at 1 kW of average power delivered by four-pulse bursts of an energy of 30 mJ.

15.
Int J Comput Assist Radiol Surg ; 14(10): 1741-1750, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31378841

RESUMO

PURPOSE: The potential of medical image analysis with neural networks is limited by the restricted availability of extensive data sets. The incorporation of synthetic training data is one approach to bypass this shortcoming, as synthetic data offer accurate annotations and unlimited data size. METHODS: We evaluated eleven CycleGAN for the synthesis of computed tomography (CT) images based on XCAT body phantoms. The image quality was assessed in terms of anatomical accuracy and realistic noise properties. We performed two studies exploring various network and training configurations as well as a task-based adaption of the corresponding loss function. RESULTS: The CycleGAN using the Res-Net architecture and three XCAT input slices achieved the best overall performance in the configuration study. In the task-based study, the anatomical accuracy of the generated synthetic CTs remained high ([Formula: see text] and [Formula: see text]). At the same time, the generated noise texture was close to real data with a noise power spectrum correlation coefficient of [Formula: see text]. Simultaneously, we observed an improvement in annotation accuracy of 65% when using the dedicated loss function. The feasibility of a combined training on both real and synthetic data was demonstrated in a blood vessel segmentation task (dice similarity coefficient [Formula: see text]). CONCLUSION: CT synthesis using CycleGAN is a feasible approach to generate realistic images from simulated XCAT phantoms. Synthetic CTs generated with a task-based loss function can be used in addition to real data to improve the performance of segmentation networks.


Assuntos
Redes Neurais de Computação , Tomografia Computadorizada por Raios X/métodos , Aprendizado Profundo , Humanos , Imagens de Fantasmas
16.
Opt Lett ; 44(17): 4227-4230, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31465368

RESUMO

Several approaches to power scaling of mode-locked thin-disk oscillators exist. One of these approaches is based on the increased gain provided by multiple passes through the thin-disk laser medium. For the first time, to the best of our knowledge, we applied this approach to a Kerr-lens mode-locked thin-disk oscillator. The so obtained additional gain allowed mode-locked operation with up to 50% output coupling rate. This first demonstration is of particular importance for gain media with inherently low-emission cross sections and paves the way to even more powerful Kerr-lens mode-locked thin-disk oscillators. Moreover, the experimental results indicate an increased self-amplitude modulation related to an overall increase in the soft-aperture Kerr-lens effect.

17.
PLoS One ; 13(7): e0196213, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29975694

RESUMO

Conservation of large carnivores, such as the African lion, requires preservation of extensive core habitat areas, linkages between them, and mitigation of human-wildlife conflict. However, there are few rigorous examples of efforts that prioritized conservation actions for all three of these critical components. We used an empirically optimized resistance surface to calculate resistant kernel and factorial least cost path predictions of population connectivity and conflict risk for lions across the Kavango-Zambezi Transfrontier Conservation Area (KAZA) and surrounding landscape. We mapped and ranked the relative importance of (1) lion dispersal areas outside National Parks, (2) corridors between the key areas, and (3) areas of highest human-lion conflict risk. Spatial prioritization of conservation actions is critical given extensive land use redesignations that are reducing the extent and increasing the fragmentation of lion populations. While our example focuses on lions in southern Africa, it provides a general approach for rigorous, empirically based comprehensive conservation planning based on spatial prioritization.


Assuntos
Conservação dos Recursos Naturais , Leões/fisiologia , Dinâmica Populacional , África Austral , Animais , Animais Selvagens , Ecossistema , Humanos
18.
Light Sci Appl ; 7: 17180, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30839530

RESUMO

The demand for and usage of broadband coherent mid-infrared sources, such as those provided by synchrotron facilities, are growing. Since most organic molecules exhibit characteristic vibrational modes in the wavelength range between 500 and 4000 cm-1, such broadband coherent sources enable micro- or even nano-spectroscopic applications at or below the diffraction limit with a high signal-to-noise ratio1, 2, 3. These techniques have been applied in diverse fields ranging from life sciences, material analysis, and time-resolved spectroscopy. Here we demonstrate a broadband, coherent and intrinsically carrier-envelope-phase-stable source with a spectrum spanning from 500 to 2250 cm-1 (-30 dB) at an average power of 24 mW and a repetition rate of 77 MHz. This performance is enabled by the first mode-locked thin-disk oscillator operating at 2 µm wavelength, providing a tenfold increase in average power over femtosecond oscillators previously demonstrated in this wavelength range4. Multi-octave spectral coverage from this compact and power-scalable system opens up a range of time- and frequency-domain spectroscopic applications.

19.
Opt Lett ; 41(15): 3567-70, 2016 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-27472620

RESUMO

We have recently demonstrated a simple power scaling procedure for Kerr-lens mode-locked thin-disk oscillators. Here we report on the extension of this scheme to a broadband high-peak-power thin-disk oscillator, delivering 140-fs pulses with a peak and average power of 62 MW and 155 W, respectively. This result shows that reaching the emission bandwidth of the gain material in Kerr-lens mode-locked thin-disk oscillators is feasible without sacrificing output power, efficiency, or stability by relying on high intracavity nonlinearities.

20.
Opt Express ; 23(16): 21064-77, 2015 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-26367957

RESUMO

We report on an Yb:YAG thin-disk multipass laser amplifier delivering sub-8 ps pulses at a wavelength of 1030 nm with 1420 W of average output power and 4.7 mJ of pulse energy. The amplifier is seeded by a regenerative amplifier delivering 6.5 ps pulses with 300 kHz of repetition rate and an average power of 115 W. The optical efficiency of the multipass amplifier was measured to be 48% and the beam quality factor was better than M2 = 1.4. Furthermore we report on the external second harmonic generation from 1030 nm to 515 nm using an LBO crystal leading to an output power of 820 W with 2.7 mJ of energy per pulse. This corresponds to a conversion efficiency of 70%. Additionally, 234 W of average power were obtained at the third harmonic with a wavelength of 343 nm.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...