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Morphology Of Ejected Particles And Impact Sites On Intercepting Substrates Following Exit Surface Laser Damage With Nanosecond Pulses In Silica
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Book Synopsis Morphology of Ejected Particles and Impact Sites on Intercepting Substrates Following Exit-surface Laser Damage with Nanosecond Pulses in Silica by :
Download or read book Morphology of Ejected Particles and Impact Sites on Intercepting Substrates Following Exit-surface Laser Damage with Nanosecond Pulses in Silica written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A volume of superheated material reaching localized temperatures of the order of 1 eV and pressures of the order of 10 GPa is generated following laser-induced damage (breakdown) on the surface of transparent dielectric materials using nanosecond pulses. This leads to material ejection and the formation of a crater. To elucidate the material behaviors involved, we examined the morphologies of the ejected particles and found distinctive features that support their classification into different types. The different morphologies arise from the difference in the structure and physical properties (such as the dynamic viscosity and presence of instabilities) of the superheated and surrounding affected material at the time of ejection of each individual particle. In addition, the temperature and kinetic energy of a subset of the ejected particles were found to be sufficient to initiate irreversible modification on the intercepting silica substrates. Finally, the modifications observed are associated with mechanical damage and fusion of melted particles on the collector substrate.
Book Synopsis Morphology of Ejected Debris from Laser Super-heated Fused Silica Following Exit Surface Laser-induced Damage by :
Download or read book Morphology of Ejected Debris from Laser Super-heated Fused Silica Following Exit Surface Laser-induced Damage written by and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser-induced Damage of Fused Silica at 355 and 1065 Nm Initiated at Aluminum Contamination Particles on the Surface by :
Download or read book Laser-induced Damage of Fused Silica at 355 and 1065 Nm Initiated at Aluminum Contamination Particles on the Surface written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 1-[mu]m thick circular dots, 10-250[mu]m dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate 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 input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were 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). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. 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.
Book Synopsis Laser Induced Damage in Optical Materials by :
Download or read book Laser Induced Damage in Optical Materials written by and published by . This book was released on 1976 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser-induced Damage Initiated on the Surface of Particle Contamination Fused Silica at 1064nm by :
Download or read book Laser-induced Damage Initiated on the Surface of Particle Contamination Fused Silica at 1064nm written by and published by . This book was released on 1998 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was undertaken to quantify the effects of contamination particles on the damage threshold of laser-illuminated fused silica optics and set cleanliness requirements for optics on the beam line of the National Ignition Facility at Lawrence Livermore National Laboratory. Circular contamination particles were sputter-deposited onto fused silica windows which were then illuminated repetitively using a 1064nm laser. A variety of contaminants were tested including metals, oxides, and organics. Tests were conducted with particles on the input and output surfaces of the window, and the morphological features of the damage were very reproducible. A plasma often ignited at the contamination particle; its intensity was dependent upon the mass of the contaminant. Input surface damage was characteristically more severe than output surface damage. The size of the damaged area scaled with the size of the particle. On a few occasions, catastrophic damage (cracking or ablation of the substrate) initiated on the output surface due to contamination particles on either the input or output surface. From damage growth plots, predictions can be made about the severity of damage expected from contamination particles of known size and material.
Book Synopsis Laser Induced Damage in Optical Materials by : Brian E. Newnam
Download or read book Laser Induced Damage in Optical Materials written by Brian E. Newnam and published by ASTM International. This book was released on 1986 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Imaging System to Measure Kinetics of Material Cluster Ejection During Exit-Surface Damage Initiation and Growth in Fused Silica by :
Download or read book Imaging System to Measure Kinetics of Material Cluster Ejection During Exit-Surface Damage Initiation and Growth in Fused Silica written by and published by . This book was released on 2009 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-induced damage on the surface of optical components typically is manifested by the formation of microscopic craters that can ultimately degrade the optics performance characteristics. It is believed that the damage process is the result of the material exposure to high temperatures and pressures within a volume on the order of several cubic microns located just below the surface. The response of the material following initial localized energy deposition by the laser pulse, including the timeline of events and the individual processes involved during this timeline, is still largely unknown. In this work we introduce a time-resolved microscope system designed to enable a detailed investigation of the sequence of dynamic events involved during surface damage. To best capture individual aspects of the damage timeline, this system is employed in multiple imaging configurations (such as multi-view image acquisition at a single time point and multi-image acquisition at different time points of the same event) and offers sensitivity to phenomena at very early delay times. The capabilities of this system are demonstrated with preliminary results from the study of exit-surface damage in fused silica. The time-resolved images provide information on the material response immediately following laser energy deposition, the processes later involved during crater formation or growth, the material ejecta kinetics, and overall material motion and transformation. Such results offer insight into the mechanisms governing damage initiation and growth in the optical components of ICF class laser systems.
Book Synopsis Laser-induced Damage in Optical Materials, 1990 by : Harold Earl Bennett
Download or read book Laser-induced Damage in Optical Materials, 1990 written by Harold Earl Bennett and published by ASTM International. This book was released on 1991 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of meeting -- Materials and measurements -- Surfaces and mirrors -- Thin films -- Fundamental mechanisms -- Presented by title only (papers not presented at conference).
Book Synopsis Surface Contamination Initiated Laser Damage by :
Download or read book Surface Contamination Initiated Laser Damage written by and published by . This book was released on 1997 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, ''splashing'' of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations. On the entrance optical surface, small particles can ablate nearly completely. In this case, only relatively weak shockwaves are launched into the substrate, but some particulate material may be left on the surface to act as a diffraction mask and cause further absorption. Diffraction by wavelength scale scattering centers can lead to significant intensity modulation. Larger particles will not be completely vaporized. The shockwave generated in this case 1642is larger and can lead to spallation of contaminant material which then may be deposited in the substrate. A gaseous atmosphere can lead to radiation trapping with concomitant increases in temperature and pressure near the surface. In addition, supersonic ionization waves in air may be generated which greatly extend the plasma plume spatially and temporally. Contaminants on the exit optical surface behave differently. They tend to heat and pop off completely in which case significant damage may not occur. Since plasma formed at the interface of the optic and absorbing particle is confined, much stronger pressures are generated in this case. Imaging of contaminants resulting in ''writing'' a diffraction pattern on the exit surface due to contamination on the entrance surface has been observed experimentally and predicted theoretically. Such imprinted damage regions can seed damage from subsequent pulses.
Book Synopsis High-power Laser Damage in Fused Silica by : Alberto Salleo
Download or read book High-power Laser Damage in Fused Silica written by Alberto Salleo and published by . This book was released on 2001 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Imaging the Early Material Response Associated with Exit Surface Damage in Fused Silica by :
Download or read book Imaging the Early Material Response Associated with Exit Surface Damage in Fused Silica written by and published by . This book was released on 2010 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The processes involved at the onset of damage initiation on the surface of fused silica have been a topic of extensive discussion and thought for more than four decades. Limited experimental results have helped develop models covering specific aspects of the process. In this work we present the results of an experimental study aiming at imaging the material response from the onset of the observation of material modification during exposure to the laser pulse through the time point at which material ejection begins. The system involves damage initiation using a 355 nm pulse, 7.8 ns FWHM in duration and imaging of the affected material volume with spatial resolution on the order of 1 [mu]m using as strobe light a 150 ps laser pulse that is appropriately timed with respect to the pump pulse. The observations reveal that the onset of material modification is associated with regions of increased absorption, i.e., formation of an electronic excitation, leading to a reduction in the probe transmission to only a few percent within a time interval of about 1 ns. This area is subsequently rapidly expanding with a speed of about 1.2 [mu]m/ns and is accompanied by the formation and propagation of radial cracks. These cracks appear to initiate about 2 ns after the start of the expansion of the modified region. The damage sites continue to grow for about 25 ns but the mechanism of expansion after the termination of the laser pulse is via formation and propagation of lateral cracks. During this time, the affected area of the surface appears to expand forming a bulge of about 40 [mu]m in height. The first clear observation of material cluster ejection is noted at about 50 ns delay.
Book Synopsis Laser-induced Damage Initiated on the Surface of Particle Contaminated Fused Silica Optics at 1064nm by : Kenneth Jerome Francis Michlitsch
Download or read book Laser-induced Damage Initiated on the Surface of Particle Contaminated Fused Silica Optics at 1064nm written by Kenneth Jerome Francis Michlitsch and published by . This book was released on 1997 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effect of Pulse Duration on the Growth Rate of Laser-induced Damage Sites at 351 Nm on Fused Silica Surfaces by :
Download or read book The Effect of Pulse Duration on the Growth Rate of Laser-induced Damage Sites at 351 Nm on Fused Silica Surfaces written by and published by . This book was released on 2009 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as [tau]{sup 0.3} for sites in the 50-100 [mu]m size range.
Book Synopsis Ultra-violet Laser Damage in Fused Silica by : Alberto Salleo
Download or read book Ultra-violet Laser Damage in Fused Silica written by Alberto Salleo and published by . This book was released on 1998 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Morphologies of Laser-induced Damage in Hafnia-silica Multilayer Mirror and Polarizer Coatings by :
Download or read book Morphologies of Laser-induced Damage in Hafnia-silica Multilayer Mirror and Polarizer Coatings written by and published by . This book was released on 1996 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hafnium-silica multilayer mirrors and polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The mirrors and polarizers were coated for operation at 1053 nm at 45° and at Brewster's angle (56°), respectively. They were tested with a single 3-ns laser pulse. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies were found: pits, flatbottom pits, scalds, and delaminates. The pits and flat bottom pits (
Book Synopsis Experimental Study of 351-nm and 527-nm Laser-initiated Surface Damage on Fused Silica Surfaces Due to Typical Contaminants by : M. A. Johnson
Download or read book Experimental Study of 351-nm and 527-nm Laser-initiated Surface Damage on Fused Silica Surfaces Due to Typical Contaminants written by M. A. Johnson and published by . This book was released on 2004 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optics damage under high-intensity illumination may be the direct result of laser light interaction with a contaminant on the surface. Contaminants of interest are small particles of the materials of construction of large laser systems and include aluminum, various absorbing glasses, and fused silica. In addition, once a damage site occurs and begins to grow, the ejecta from the growing damage site create contamination on nearby optic surfaces and may initiate damage on these surfaces via a process we call ''fratricide.'' We report on a number of experiments that we have performed on fused silica optics that were deliberately contaminated with materials of interest. The experiments were done using 527-nm light as well as 351-nm light. We have found that many of the contaminant particles are removed by the interaction with the laser and the likelihood of removal and/or damage is a function of both fluence and contaminant size. We have developed an empirical model for damage initiation in the presence of contaminants.
Book Synopsis Growth of Laser Initiated Damage in Fused Silica at 527 Nm by : J. N. McElroy
Download or read book Growth of Laser Initiated Damage in Fused Silica at 527 Nm written by J. N. McElroy and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The effective lifetime of optics is limited by both laser-induced damage and the subsequent growth of laser initiated damage sites. We have measured the growth rate of laser-induced damage in fused silica in both air and vacuum at 527 nm. For damage on the exit surface, the data shows exponential growth in the lateral size of the damage site with shot number. The exponential growth coefficient depends linearly on the laser fluence. The behavior at the fluence threshold for growth is contrasted to that observed at 351 nm. The growth rate was not significantly affected by either the wavelength of the initiating fluence or the presence of 10 torr of air as compared to vacuum. When the damage is located on the input surface, it has both a higher threshold for growth and does not grow exponentially.
