Dynamic behavior modeling of laser-induced damage initiated by surface defects on KDP crystals under nanosecond laser irradiation

Hollow and porous gold nanoshells with high surface-enhanced Raman scattering efficiency have been fabricated through utilizing nanosecond laser irradiation.

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Performance of rapid-grown KDP crystals with continuous filtration

High Power Laser Science and Engineering ◽

10.1017/hpl.2015.7 ◽

2015 ◽

Vol 3 ◽

Cited By ~ 11

Author(s):

Guohang Hu ◽

Yueliang Wang ◽

Junxiu Chang ◽

Xiaoyi Xie ◽

Yuanan Zhao ◽

...

Keyword(s):

Near Infrared ◽

Laser Damage ◽

Damage Resistance ◽

Damage Initiation ◽

Micron Size ◽

Continuous Filtration ◽

Laser Induced Damage ◽

Almost All ◽

Lower Correlation ◽

Kdp Crystals

Rapid growth processing of KDP crystals was improved by employing continuous filtration to eliminate bulk defects. The performances of the KDP crystals, including scattering defects, laser damage resistance and transmittance, were measured and analyzed. Compared with rapid-grown KDP without continuous filtration, the transmittance in the near-infrared was increased by at least 2%, almost all of ‘micron size’ defects were eliminated and ‘sub-micron size’ defects were decreased by approximately 90%. Laser damage testing revealed that the laser-induced damage thresholds (LIDTs), as well as the consistency of the LIDTs from sample to sample, were improved greatly. Moreover, it identified that ‘micron size’ defects were the precursors which initiated laser damage at relative lower laser fluence (4–6 J cm−2), and there was a lower correlation between smaller size scattering defects and laser damage initiation. The improved consistency in the LIDTs, attributed to elimination of ‘micron size’ defects, and LIDT enhancement originated from the decreased absorption of the KDP crystals.

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Er:YAG laser-induced damage to a dental composite in simulated clinical scenarios for inadvertent irradiation: an in vitro study

Lasers in Medical Science ◽

10.1007/s10103-021-03348-4 ◽

2021 ◽

Author(s):

Katharina Kuhn ◽

Carmen U. Schmid ◽

Ralph G. Luthardt ◽

Heike Rudolph ◽

Rolf Diebolder

Keyword(s):

Laser Irradiation ◽

Laser Fluence ◽

Ablation Threshold ◽

Er:Yag Laser ◽

In Vitro Study ◽

Vitro Study ◽

Crater Diameter ◽

Clinical Scenarios ◽

Laser Induced Damage

AbstractInadvertent Er:YAG laser irradiation occurs in dentistry and may harm restorative materials in teeth. The aim of this in vitro study was to quantify Er:YAG laser-induced damage to a nanohybrid composite in simulated clinical scenarios for inadvertent direct and indirect (reflection) laser irradiation. The simulation was performed by varying the output energy (OE;direct˃indirect) reaching the specimen and the operating distance (OD;direct˂indirect). Composite specimens were irradiated by an Er:YAG laser. The ablation threshold was determined and clinically relevant parameters were applied (n = 6 for each OE/OD combination) for direct (OE: 570 mJ/OD: 10 mm, OE: 190 mJ/OD: 10 mm) and indirect irradiation (OE: 466 mJ/OD: 15 mm, OE: 57 mJ/OD: 15 mm, OE: 155 mJ/OD: 15 mm, OE: 19 mJ/OD: 15 mm). The extent of damage in the form of craters was evaluated using a laser scanning microscope (LSM) and a conventional light microscope (LM). The ablation threshold was determined to be 2.6 J/cm2. The crater diameter showed the highest value (LM: 1075 ± 18 µm/LSM: 1082 ± 17 µm) for indirect irradiation (reflectant:dental mirror) (OE: 466 mJ/OD: 15 mm). The crater depth showed the highest and comparable value for direct (OE: 570 mJ/OD: 10 mm; LSM: 89 ± 2 µm) and indirect irradiation (OE: 466 mJ/OD: 15 mm; LSM: 90 ± 4 µm). For each OD, the crater diameter, depth, and volume increased with higher laser fluence. However, the OD—and thus the laser spot diameter—also had an enlarging effect. Thus, indirect irradiation (reflectant:dental mirror) with only 47% of the laser fluence of direct irradiation led to a larger diameter and a comparable depth. The three-dimensional extent of the crater was large enough to cause roughening, which may lead to plaque accumulation and encourage caries, gingivitis, and periodontitis under clinical conditions. Clinicians should be aware that reflected irradiation can still create such craters.

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