&lt;title&gt;Modeling of laser damage initiated by surface contamination&lt;/title&gt;

Feit, Michael D.; Rubenchik, Alexander M.; Faux, Douglas R.; Riddle, R.A.J.; Shapiro, A.B.; Eder, David C.; Penetrante, B.M.; Milam, D.; Génin, François Y.; Kozlowski, Mark R.

doi:10.1117/12.274234

Cited by 42 publications

(27 citation statements)

References 2 publications

(2 reference statements)

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“…It has generally been concluded [9,10,11] that the initial absorbers are small, submicron in size, that generate plasma that heats and transforms the surrounding material to create additional absorption [12,13,14]. The precise mechanism by which modification of the surrounding material can occur has been the subject of a number of studies.…”

Section: Introductionmentioning

confidence: 99%

Strong nonlinear growth of energy coupling during laser irradiation of transparent dielectrics and its significance for laser induced damage

Duchateau

Feit

Demos

2012

Journal of Applied Physics

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The interaction of high power nanosecond laser pulses with absorbing defects, located in the bulk of transparent dielectric materials and having a multilevel electronic structure, is addressed. The model assumes a moderate localized initial absorption that is strongly enhanced during the laser pulse via excited state absorption and thermally-driven generation of new point defects in surrounding material. This model is applied to laser induced damage in the bulk of potassium dihydrogen phosphate crystals (KH 2 PO 4 or KDP) and plausibly explains how during a fraction of the pulse duration the host material around the defect is transformed into a strong absorber that leads to the sufficiently large energy coupling resulting in a damage event. This scenario is supported by time resolved imaging of material modification during the initial phases of laser induced damage.

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Section: Introductionmentioning

confidence: 99%

Strong nonlinear growth of energy coupling during laser irradiation of transparent dielectrics and its significance for laser induced damage

Duchateau

Feit

Demos

2012

Journal of Applied Physics

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“…Cu, TiO 2 and ZrO 2 ) and the modeling of damage initiation have been reported elsewhere. [19][20] Damage on the input surface Damage on the output surface 100 µm 100 µm showing that the shape of the 20 µm contamination particle located on the input surface is often "printed" on the output surface.…”

Section: Results At 355 Nmmentioning

confidence: 99%

“…In order to obtain sufficient statistical information at 1064 nm, 5 dots of a given size were tested. Six particle sizes were investigated (10,20,30,50,150, and 250 µm). The damage morphology was characterized after the 1-on-1, 20-on-1 and S-on-1 tests by Nomarski and back light optical microscopy in order to measure the size of the damage.…”

Section: Laser Testing Conditionsmentioning

confidence: 99%

<title>Laser-induced damage of fused silica at 355 and 1064 nm initiated at aluminum contamination particles on the surface</title>

et al. 1997

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Contamination particles of controlled size and shape were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. The particles were 1 µm thick circular dots, 10 to 250 µm in diameter. Al shavings were also deposited on the windows to investigate the effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on the input and output surfaces of the window.During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphological features of the damage initiated at the metal dots were very reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm.The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). The onset of catastrophic damage on the output surface occurred only when particles exceeded a critical size. The damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions.

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“…crater) resembles that created by particle impact on a glass surface. Recent results from Feit et al 13 show that the over-pressure generated by the shock wave produced during laser damage is sufficient to create such a fracture crater. Multiple laser shots cause this fracture site to grow in depth at the rate of about 30 um/shot; this agrees with predictions by Feit et al The flaw depth is generally less than the flaw radius and is typically one-half to two-thirds the radius.…”

Section: Experimental Systemmentioning

confidence: 99%

<title>Laser-induced damage and fracture in fused silica vacuum windows</title>

et al. 1997

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Laser induced damage, that initiates catastrophic fracture, has been observed in large (up to 61-cm diameter), fused silica lenses that also serve as vacuum barriers in high-fluence positions on the Nova and Beamlet lasers. In nearly all cases damage occurs on the vacuum (tensile) side of the lens. The damage can lead to catastrophic crack growth if the flaw (damage) size exceeds the critical flaw size for SiO 2 . If the elastic stored energy in the lens is high enough, the lens will fracture into many pieces resulting in an implosion. The consequences of such an implosion can be severe, particularly for large vacuum systems. Three parameters control the degree of fracture in the vacuum barrier window: 1) the elastic stored energy (i.e. tensile stress) 2) the ratio of the window thickness to flaw depth and 3) secondary crack propagation. Fracture experiments have been carried out on 15-cm diameter fused silica windows that contain surface flaws caused by laser damage. The results of these experiments, combined with data from window failures on Beamlet and Nova have been used to develop design criteria for a "fail-safe" lens (that is, a lens that may catastrophically fracture but will not implode). Specifically the window must be made thick enough such that the peak tensile stress is less than 500 psi (3.4 MPa) and the corresponding ratio of the thickness to critical flaw size is less that 6. Under these conditions a properly mounted window, upon failure, will break into only two pieces and will not implode. One caveat to these design criteria is that the air leak through the window fracture and into the vacuum must be rapid enough too reduce the load on the window before secondary crack growth occurs. Finite element stress calculations of a window before and immediately following fracture into two pieces show that the elastic stored energy is redistributed if the fragments "lock" in place and thereby bridge the opening. In such cases, the peak stresses at the flaw site can increase leading to further (i.e. secondary) crack growth.

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<title>Modeling of laser damage initiated by surface contamination</title>

Cited by 42 publications

References 2 publications

Strong nonlinear growth of energy coupling during laser irradiation of transparent dielectrics and its significance for laser induced damage

Strong nonlinear growth of energy coupling during laser irradiation of transparent dielectrics and its significance for laser induced damage

<title>Laser-induced damage of fused silica at 355 and 1064 nm initiated at aluminum contamination particles on the surface</title>

<title>Laser-induced damage and fracture in fused silica vacuum windows</title>

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