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Subsurface Polishing Damage Of Fused Silica
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Book Synopsis Subsurface Polishing Damage of Fused Silica by : NJ. Brown
Download or read book Subsurface Polishing Damage of Fused Silica written by NJ. Brown and published by . This book was released on 1991 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nature of subsurface damage incurred during polishing of fused silica varies greatly with the polishing process. Although subsurface damage is known to lower laser damage thresholds for fused silica surfaces1,2, the effect on thresholds of coated dielectric surfaces has not been previously documented. This study describes features of subsurface damage due to polishing by ten commercial fabricators and compares laser damage thresholds of a high reflection coating on these surfaces.
Book Synopsis Subsurface Defect Characterization and Laser-induced Damage Performance of Fused Silica Optics Polished with Colloidal Silica and Ceria by :
Download or read book Subsurface Defect Characterization and Laser-induced Damage Performance of Fused Silica Optics Polished with Colloidal Silica and Ceria written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared (RMS) average surface roughness values are 0.7 nm and 1.0 nm, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive contaminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics.
Book Synopsis The Distribution of Subsurface Damage in Fused Silica by : P. E. Miller
Download or read book The Distribution of Subsurface Damage in Fused Silica written by P. E. Miller and published by . This book was released on 2005 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Managing subsurface damage during the shaping process and removing subsurface damage during the polishing process is essential in the production of low damage density optical components, such as those required for use on high peak power lasers. Removal of subsurface damage, during the polishing process, requires polishing to a depth which is greater than the depth of the residual cracks present following the shaping process. To successfully manage, and ultimately remove subsurface damage, understanding the distribution and character of fractures in the subsurface region introduced during fabrication process is important. We have characterized the depth and morphology of subsurface fractures present following fixed abrasive and loose abrasive grinding processes. At shallow depths lateral cracks and an overlapping series of trailing indentation fractures were found to be present. At greater depths, subsurface damage consists of a series of trailing indentation fractures. The area density of trailing fractures changes as a function of depth, however the length and shape of individual cracks remain nearly constant for a given grinding process. We have developed and applied a model to interpret the depth and crack length distributions of subsurface surface damage in terms of key variables including abrasive size and load.
Book Synopsis Correlation of Polishing-induced Shallow Subsurface Damages with Laser-induced Gray Haze Damages in Fused Silica Optics by :
Download or read book Correlation of Polishing-induced Shallow Subsurface Damages with Laser-induced Gray Haze Damages in Fused Silica Optics written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Laser-induced damage in fused silica optics greatly restricts the performances of laser facilities. Gray haze damage, which is always initiated on ceria polished optics, is one of the most important damage morphologies in fused silica optics. In this paper, the laser-induced gray haze damages of four fused silica samples polished with CeO2, Al2 O3, ZrO2, and colloidal silica slurries are investigated. Four samples all present gray haze damages with much different damage densities. Then, the polishing-induced contaminant and subsurface damages in four samples are analyzed. The results reveal that the gray haze damages could be initiated on the samples without Ce contaminant and are inclined to show a tight correlation with the shallow subsurface damages.
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 1989 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser Induced Damage in Optical Materials, 1975 by : Alexander J. Glass
Download or read book Laser Induced Damage in Optical Materials, 1975 written by Alexander J. Glass and published by . This book was released on 1976 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis FY07 LDRD Final Report A Fracture Mechanics and Tribology Approach to Understanding Subsurface Damage on Fused Silica During Grinding and Polishing by :
Download or read book FY07 LDRD Final Report A Fracture Mechanics and Tribology Approach to Understanding Subsurface Damage on Fused Silica During Grinding and Polishing written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this work is to develop a solid scientific understanding of the creation and characteristics of surface fractures formed during the grinding and polishing of brittle materials, specifically glass. In this study, we have experimentally characterized the morphology, number density, and depth distribution of various surface cracks as a function of various grinding and polishing processes (blanchard, fixed abrasive grinding, loose abrasive, pitch polishing and pad polishing). Also, the effects of load, abrasive particle (size, distribution, foreign particles, geometry, velocity), and lap material (pitch, pad) were examined. The resulting data were evaluated in terms of indentation fracture mechanics and tribological interactions (science of interacting surfaces) leading to several models to explain crack distribution behavior of ground surfaces and to explain the characteristics of scratches formed during polishing. This project has greatly advanced the scientific knowledge of microscopic mechanical damage occurring during grinding and polishing and has been of general interest. This knowledge-base has also enabled the design and optimization of surface finishing processes to create optical surfaces with far superior laser damage resistance. There are five major areas of scientific progress as a result of this LDRD. They are listed in Figure 1 and described briefly in this summary below. The details of this work are summarized through a number of published manuscripts which are included this LDRD Final Report. In the first area of grinding, we developed a technique to quantitatively and statistically measure the depth distribution of surface fractures (i.e., subsurface damage) in fused silica as function of various grinding processes using mixtures of various abrasive particles size distributions. The observed crack distributions were explained using a model that extended known, single brittle indentation models to an ensemble of loaded, sliding particles. The model illustrates the importance of the particle size distribution of the abrasive and its influence on the resulting crack distribution. The results of these studies are summarized in references 1-7. In the second area of polishing, we conducted a series of experiments showing the influence of rogue particles (i.e., particles in the polishing slurry that are larger than base particles) on the creation of scratches on polished surfaces. Scratches can be thought of a as a specific type of sub-surface damage. The characteristics (width, length, type of fractures, concentration) were explained in terms of the rogue particle size, the rogue particle material, and the viscoelastic properties of the lap. The results of these studies are summarized in references 6-7. In the third area of etching, we conducted experiments aimed at understanding the effect of HF:NH4F acid etching on surface fractures on fused silica. Etching can be used as a method: (a) to expose sub-surface mechanical damage, (b) to study the morphology of specific mechanical damage occurring by indentation, and (c) to convert a ground surface containing a high concentration of sub-surface mechanical damage into surface roughness. Supporting models have been developed to describe in detail the effect of etching on the morphology and evolution of surface cracks. The results of these studies are summarized in references 8-9. In the fourth area of scratch forensics or scratch fractography, a set of new scratch forensic rule-of-thumbs were developed in order to aid the optical fabricator and process engineer to interpret the cause of scratches and digs on surfaces. The details of how these rules were developed are described in each of the references included in this summary (1-9). Figure 2 provides as a summary of some of the more commonly used rules-of-thumbs that have been developed in this study. In the fifth and final area of laser damage, we demonstrated that the removal of such surface fractures from the surface during optical fabrication can dramatically improve the laser damage.
Book Synopsis Laser Induced Damage in Optical Materials: by : Arthur H. Guenther
Download or read book Laser Induced Damage in Optical Materials: written by Arthur H. Guenther and published by ASTM International. This book was released on 1977 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 CO2-laser Polishing of Fused Silica Surfaces for Increased Laser Damage Resistance at 1. 06. Mu. M by :
Download or read book CO2-laser Polishing of Fused Silica Surfaces for Increased Laser Damage Resistance at 1. 06. Mu. M written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Bare fused silica surfaces were prepared by subjecting the mechanically polished surface to a rastered cw CO2 laser beam. Analysis shows that this processing causes: (a) removal of a uniform layer of fused silica; and (b) a probable re-fusing or healing of existing subsurface fractures. The fused silica removal rate is found to be a function of the laser intensity and scan rate. These surfaces are seen to have very low scatter and to be very smooth. In addition, they have exhibited entrance surface damage thresholds at 1.06 .mu.m, and 1 nsec, which are substantially above those seen on the mechanically polished surface. When damage does occur, it tends to be at a few isolated points rather than the general uniform damage seen on the mechanicaly polished part. In addition to the damage results, we will discuss an observational technique used for viewing these surfaces which employs dark-field illumination.
Book Synopsis Laser Induced Damage in Optical Materials, 1989 by : Harold Earl Bennett
Download or read book Laser Induced Damage in Optical Materials, 1989 written by Harold Earl Bennett and published by . This book was released on 1990 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Schetsen, bevattende ziel-, mensch-, opvoed- en onderwijskundige grondtrekken by :
Download or read book Schetsen, bevattende ziel-, mensch-, opvoed- en onderwijskundige grondtrekken written by and published by . This book was released on 1820 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser Induced Damage in Optical Materials: 1983 by : Harold Earl Bennett
Download or read book Laser Induced Damage in Optical Materials: 1983 written by Harold Earl Bennett and published by ASTM International. This book was released on 1985 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Subsurface Structure in Polished Fused Silica and Diamond Turned Single Crystal Silicon by :
Download or read book Subsurface Structure in Polished Fused Silica and Diamond Turned Single Crystal Silicon written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface and near surface structure of glass and other optical materials is greatly influenced by the nature of the processes used to generate that surface. In high quality optics, the effects of process changes are often subtle and cannot be seen with conventional metrology. The presence of process induced damage in the near surface region is felt in a number of ways. Damage thresholds for optics subjected to high fluences are a particular problem in UV or high-powered laser systems. In high quality glass, the chemical and material composition of the outermost layer is influenced principally by the grinding, lapping and polishing processes used in fabrication. Performance in high fluence applications is often dominated by these process-induced inhomogeneities in the first few hundred nanometers of material. Each succeeding step in a process is designed to remove the damage from the previous operation. However, any force against the surface, no matter how slight will leave evidence of damage. Fabrication processes invariably create dislocations, cracks and plastic deformation between 100 nm and 500 nm below the surface. In glass polishing, the first 100 nm is comprised of material redeposited from the polishing solution. This redeposition layer is responsible for the extremely smooth surfaces that can be generated on glass. Unfortunately, this layer also conceals many flaws present in the deeper surface regions.
Book Synopsis The Effect of Subsurface Defects on "Incipient" (Below Threshold) Laser Damage Nucleation in Fused Silica Optical Flats by : JD. Boyer
Download or read book The Effect of Subsurface Defects on "Incipient" (Below Threshold) Laser Damage Nucleation in Fused Silica Optical Flats written by JD. Boyer and published by . This book was released on 1990 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of subsurface defects in optical components has been extensively investigated by the authors and others over the past few years. Investigation of optical components using nondestructive photon backscattering (PBSTM), delineation etch/optical microscopy and charge decoration/delineation techniques has shown laterally variable spatial distributions of subsurface defects in the form of lineated remnant polishing traces, voids, and microscopic impurity clusters introduced during the surface finishing process. In this paper, we report on the correlation between nondestructive PBSTM mapping and delineation etch/optical microscopy techniques for detection of subsurface defects, as well as the effect of subsurface defects on the initiation of microscopic or "incipient" laser damage (?= 248 nm) at levels below the point of macroscopic or catastrophic failure observed at the surface. The detection of laser induced microscopic cracking on nucleation sites within nondestructively identified areas provides additional insight into the progressive development of failure sites in distributed subsurface regions of low RMS, optically finished surfaces.
Book Synopsis Laser Induced Damage in Optical Materials: 1989 by : Alexander J. Glass
Download or read book Laser Induced Damage in Optical Materials: 1989 written by Alexander J. Glass and published by ASTM International. This book was released on 1978 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Subsurface Damage in Glass and Metal Optics by : CJ. Evans
Download or read book Characterization of Subsurface Damage in Glass and Metal Optics written by CJ. Evans and published by . This book was released on 1991 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: Even unusual care in polishing, leads to optics with somewhat damaged working faces. The question is, to what degree? the physical nature of this damage depends on the ductility or plasticity of the construction material. Glassy materials (glass, brittle metals and semiconductors) fracture, while ductile materials work harden. Beryllium suffers from both modes. To physically model damage, we oversimplify and picture a surface layer with two features, a depth and an intensity of the bulk property changes. A statistical alternative to intensity is the visible flaw density. We use a variety of analytical methods, but mainly x-ray diffraction, metallography and instrumented microindentation, and frequently use them in combination. Our problem is to develop a general basis and means of characterizing subsurface damage. To illustrate the diversity, difficulty and our progress with the problem, we will report experiences with a variety of examples. The talk will consider damage in "ductile regime" ground, classically polished fused silica BK-7, pyrex optics, "super" polished BK-7, precision ground silicon nitride and alumina ceramics, and precision CBN turned beryllium.7.
