Dr. Colin M. Harthcock Profile

Dr. Colin M. Harthcock

Staff Scientist at Lawrence Livermore National Lab.

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Publications (6)

Proceedings Article | 12 March 2024 Presentation + Paper

Development of high peak and average power Tm:YLF lasers

Zbynek Hubka, Issa Tamer, Leily Kiani, Jason Owens, Andrew Church, František Batysta, Thomas Galvin, Drew Willard, Andrew Yandow, Alex Chemali, Justin Galbraith, David Alessi, Colin Harthcock, Brad Hickman, Candis Jackson, James Nissen, Sean Tardif, Hoang Nguyen, Hansel Neurath, Emily Sistrunk, Robert Plummer, Brendan Reagan, Thomas Spinka

Proceedings Volume 12864, 1286402 (2024) https://doi.org/10.1117/12.3003283

KEYWORDS: Laser development, Pulsed laser operation, Multiplexing, High power lasers, Laser energy, Thulium, Diode pumped solid state lasers

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Proceedings Article | 3 December 2022 Presentation

Identifying, understanding, and suppressing of ns laser damage precursors in dielectric thin films

S. Roger Qiu, Colin Harthcock, Raluca Negres, Chris Stolz, Gabe Guss, Vanessa Peters, Paul Mirkarimi, Eyal Feigenbaum, Thomas Voisin, Josh Hammons, Chris Colla, Harris Mason, Mengbing Huang

Proceedings Volume PC12300, PC123000P (2022) https://doi.org/10.1117/12.2642498

KEYWORDS: Laser induced damage, Dielectrics, Thin films, Optical coatings, Ultraviolet radiation, Thin film coatings, Systems modeling, Sputter deposition, Pulsed laser operation, Monte Carlo methods

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Proceedings Article | 12 October 2021 Presentation

Impact of film densification on UV-ns laser damage performance for MLD coatings

Colin Harthcock, S. Roger Qiu, Paul Mirkarimi, Thomas Voisin, Christopher Colla, Harris Mason, Raluca Negres, Gabe Guss, Devika Vipin, Mengbing Huang

Proceedings Volume 11910, 119100X (2021) https://doi.org/10.1117/12.2600525

KEYWORDS: Xenon, Sputter deposition, Ion beams, Argon, Laser induced damage, Hafnium, Resistance, Reflection, Optical coatings, Metals

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Proceedings Article | 11 September 2020 Presentation

Towards understanding the difference in ultraviolet, ns-laser damage resistance between hafnia films produced by electron beam evaporation and ion beam sputtering methods

Vanessa Peters, S. Roger Qiu, Colin Harthcock, Raluca Negres, Thomas Voisin, Eyal Feigenbaum, Gabe Guss, Christopher Stolz, M. Huang

Proceedings Volume 11514, 1151416 (2020) https://doi.org/10.1117/12.2572814

KEYWORDS: Laser induced damage, Ultraviolet radiation, Resistance, Electron beams, Ion beams, Sputter deposition, Deposition processes, Dielectrics, Refractive index, Laser development

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It is well known that dielectric coatings used in high energy laser systems for beam steering are susceptible to laser damage. The laser damage ensued in high refractive index materials, such as hafnia, is responsible for limiting the laser operation fluence and lifetime. Although hafnia is an ideal high refractive index material used in dielectric coatings for a broad range of laser wavelengths, defects developed during the deposition process leads to laser-induced damage. In order to increase the resistance to laser damage and improve laser performance, it is imperative to understand the underlying physics of laser damage in high index coating materials. Earlier work observed a substantial difference in laser damage thresholds for hafnia coatings produced by different deposition methods, yet the underlying mechanisms for the observed difference remains elusive. In this work we investigated the responses of single layer hafnia films produced by two deposition processes, electron beam (e-beam) evaporation and ion beam sputtering (IBS) methods upon UV ns-laser exposure. The films underwent laser damage testing using a 1-on-1 laser damage testing protocol with a beam size of 650 µm (1/e2) at 355 nm and 8 ns pulse duration. Both S and P polarizations were tested at a 45° angle of incidence. Chemical, structural and morphological characterizations of the films both pre- and post-laser damage were performed using Rutherford backscattering spectroscopy, glancing incidence X-Ray diffraction, and optical and scanning/transmission electron microscopy. We found that films deposited from the e-beam process had a higher damage onset threshold (4.4 +/- 0.1 J/cm2) than those deposited by IBS method (2.1 +/- 0.2 J/cm2). Furthermore, a polarization-dependent damage threshold onset was observed for the e-beam evaporated coatings but was not observed in IBS films. Although the typical size of the damage in general is larger for the e-beam produced films, the morphology shows similar foamy appearance in both films. The density of the damage sites, on the other hand, was much greater in the IBS produced films than that by the e-beam method. The observed difference can be attributed to their resulting structural/textural differences inherited in each method: porous in the e-beam films and dense with isolated nanobubbles in the IBS films, which can lead to a large difference in laser-defect coupling. The underlying physical mechanism will be discussed in detail. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM Release# LLNL-ABS-809117

Proceedings Article | 11 September 2020 Presentation

The effect of low temperature annealing on the UV, ns laser damage performance of hafnia single layers

Colin Harthcock, Roger Qiu, Raluca Negres, Gabe Guss, Gourav Bhowmik, Mengbing Huang

Proceedings Volume 11514, 1151410 (2020) https://doi.org/10.1117/12.2572175

KEYWORDS: Laser induced damage, Annealing, Ultraviolet radiation, Laser systems engineering, Optical coatings, Oxygen, Chemical analysis, Multilayers, Dielectrics, Laser applications

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Proceedings Article | 26 November 2019 Presentation

The impact and origins of non-stoichiometry on the laser performance of ion beam sputtering deposited hafnia films (Conference Presentation)

Colin Harthcock, Roger Qiu, Paul Mirkarimi, Raluca Negres, Gabe Guss, Marlon Menor, Gourav Bhowmik, Mengbing Huang

Proceedings Volume 11173, 111730Q (2019) https://doi.org/10.1117/12.2537142

KEYWORDS: Planets, Chemistry, Sun, Argon, Ion beams, Optical damage, Multilayers, Dielectrics, Optical coatings, High power lasers

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