Morphological asymmetry in laser damage of transparent dielectric surfaces

Boling, N. L.; Dubé, G.; Crisp, Michael D.

doi:10.1063/1.1654229

Cited by 17 publications

(8 citation statements)

References 7 publications

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“…retically 44% higher on the output surface, as predicted by Boling and Dubé. 40 Each contamination particle was positioned at the center of the beam and was irradiated with a single 3-ns pulse by a 355-nm Nd:YAG laser. The laser was focused to provide a far-field circular Gaussian beam with a diameter of 1.1 mm at 1͞e 2 ͑14%͒ of the maximum intensity ͑see Fig.…”

Section: Sample Preparation and Laser Testing Proceduresmentioning

confidence: 99%

Rear-surface laser damage on 355-nm silica optics owing to Fresnel diffraction on front-surface contamination particles

et al. 2000

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Light intensity modulations caused by opaque obstacles (e.g., dust) on silica lenses in high-power lasers often enhance the potential for laser-induced damage. To study this effect, particles (10-250 mum) with various shapes were sputter deposited on the input surface and irradiated with a 3-ns laser beam at 355 nm. Although a clean silica surface damages at fluences above 15 J/cm(2), a surface contaminated with particles can damage below 11.5 J/cm(2). A pattern that conforms to the shape of the input surface particle is printed on the output surface. Repetitive illumination resulted in catastrophic drilling of the optic. The damage pattern correlated with an interference image of the particle before irradiation. The image shows that the incident beam undergoes phase (and amplitude) modulations after it passes around the particle. We modeled the experiments by calculating the light intensity distribution behind an obscuration by use of Fresnel diffraction theory. The comparison between calculated light intensity distribution and the output surface damage pattern showed good agreement. The model was then used to predict the increased damage vulnerability that results from intensity modulations as a function of particle size, shape, and lens thickness. The predictions provide the basis for optics cleanliness specifications on the National Ignition Facility to reduce the likelihood of optical damage.

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Section: Sample Preparation and Laser Testing Proceduresmentioning

confidence: 99%

Rear-surface laser damage on 355-nm silica optics owing to Fresnel diffraction on front-surface contamination particles

et al. 2000

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“…According to the previous report on laser damage of optical components, the thermally induced plasma appears below the front surface during the front surface damage and gradually grows in the opposite direction of laser propagation during laser irradiation. 24 − 26 Therefore, we can believe that the high-temperature center corresponds to the plasma observed during the damage transient processes, which will gradually move to the front surface with the laser action, and has a greater effect on heating the surrounding material. The energy of the laser pulse reduces rapidly at t = 3000 ps.…”

Section: Resultsmentioning

confidence: 99%

Model Development for Nanosecond Laser-Induced Damage Caused by Manufacturing-Induced Defects on Potassium Dihydrogen Phosphate Crystals

et al. 2020

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Nanosecond laser-induced damage on (potassium dihydrogen phosphate) KDP crystals is a complex process, which involves coupled actions of multi-physics fields. However, the mechanisms governing the laser damage behaviors have not been fully understood and there have been no available models to accurately describe this complex process. In this work, based on the theories of electromagnetic, thermodynamic, and hydrodynamic fields, a coupled multi-physics model is developed to describe the transient behavior of laser-supported energy deposition and diffusion accompanied by the surface defect (e.g., surface cracks)-initiated laser damage process. It is found that the light intensification caused by the defects near the crystal surface plays a significant role in triggering the laser-induced damage, and a large amount of energy is quickly deposited via the light intensity-activated nonlinear excitation. Using the developed model, the maximum temperature of the crystal material irradiated by a 3 ns pulse laser is calculated, which agrees well with previously reported experimental results. Furthermore, the modeling results suggest that physical processes such as material melting, boiling, and flowing have effects on the evolution of the laser damage process. In addition, the experimentally measured morphology of laser damage sites exhibits damage features of boiling cores, molten regions, and fracture zones, which are direct evidence of bowl-shaped high-temperature expansion predicted by the model. These results well validate that the proposed coupled multi-physics model is competent to describe the dynamic behaviors of laser damage, which can serve as a powerful tool to understand the general mechanisms of laser interactions with KDP optical crystals in the presence of different defects.

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“…The earlier study indicated that the surface entrance damage characteristics are due to thermal shock from the hot plasma contiguous to the surface. 18 Explosive boiling occurs much more easily on the coating surface than bulk material due to the porous structure which facilitates the bubble nucleation. However, the formation mechanism of the hot plasma that is in a large area within the pulse duration is still unclear.…”

mentioning

confidence: 99%

“…The formed laser-supported solid-state absorption fronts in solids strongly absorb and reflect the laser beam. 22 At the strongly absorptive state, the reflectivity of absorption fronts tends to 1 and the maximal laser intensity in air shows about a fourfold rise, 18 which is independent on the detailed coating material. Therefore, we infer that the required incident fluence to start the electron avalanche in air would decrease to a quarter of 27.34 J/cm 2 (i.e., 6.84 J/cm 2 , the scalding threshold fluence).…”

mentioning

confidence: 99%

Origin of the plasma scalds in dielectric coatings induced by 1ω laser

Wang

Zhao

et al. 2016

Applied Physics Letters

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The plasma scalds initiated by a 1053 nm (1ω) nanosecond laser are separated from the defect-induced damage pits, which is verified as a result of the ionization wavefront with the subnanosecond laser. Considering the beam reflection from solid-state absorption fronts during the damage process, a theoretical scalding threshold about 6.84 J/cm2 (12 ns) based on the energy required to start an air avalanche is evaluated and agrees well with the experimental scalding threshold. The occurrence order of the initial explosion and subsequent ionization wavefront is verified to explain most of the damage morphologies caused by the 1ω laser. In addition to the significance in laser conditioning or cleaning for a high-power laser system, the results also indicate that through the occurrence of plasma scalds it is possible to mark the onset time of air plasma during laser-coating interaction.

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Morphological asymmetry in laser damage of transparent dielectric surfaces

Cited by 17 publications

References 7 publications

Rear-surface laser damage on 355-nm silica optics owing to Fresnel diffraction on front-surface contamination particles

Rear-surface laser damage on 355-nm silica optics owing to Fresnel diffraction on front-surface contamination particles

Model Development for Nanosecond Laser-Induced Damage Caused by Manufacturing-Induced Defects on Potassium Dihydrogen Phosphate Crystals

Origin of the plasma scalds in dielectric coatings induced by 1ω laser

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