Evidence of a green luminescence band related to surface flaws in high purity silica glass

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. AbstractThe mechanical behavior of materials is usually simulated by a continuous mechanics approach. However, noncontinuous phenomena such as multi-fracturing cannot be accurately simulated using a continuous description. The discrete element method (DEM) naturally accounts for discontinuities and is therefore a good alternative to the continuum approach.This study continues previous work in which a DEM model was developed to quantitatively simulate an elastic material with the cohesive beam bond model. The simulation of brittle cracks is now tackled. This goal is attained by computing a failure criterion based on an equivalent hydrostatic stress. This microscopic criterion is then calibrated to fit experimental values of the macroscopic failure stress. The simulation results are compared to experimental results of indentation tests in which a spherical indenter is used to load a silica glass, which is considered to be a perfectly brittle elastic material.

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“…The experimental procedure were similar to those described in (35,36). Tables 2 and 3 list the properties of the indenter and the silica sample.…”

Section: Overview Of Experimental Observations Used As Referencementioning

confidence: 99%

Using the discrete element method to simulate brittle fracture in the indentation of a silica glass with a blunt indenter

Debenath

Jebahi

Iordanoff

et al. 2013

Computer Methods in Applied Mechanics and Engineering

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“…Structural defects in damage initiation, such as NBOHC (Non Bridging Oxygen Hole center), ODC (Oxygen Deficient Center) or others 16 , were observed around surface defects (indentation, scratches). An unexplained green photoluminescence was also evidenced 17 , 18 and potentially involved in the damage initiation process. However, these photo luminescent defects were removed by an HF-based etch of 1 to 2 µm 11 , 19 .…”

Section: Introductionmentioning

confidence: 94%

Understanding the effect of wet etching on damage resistance of surface scratches

Fernandes

Pfiffer

Cormont

et al. 2018

Sci Rep

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Fused silica optics often exhibit surface scratches after polishing that radically reduce their damage resistance at the wavelength of 351 nm in the nanosecond regime. Consequently, chemical treatments after polishing are often used to increase the damage threshold and ensure a safe operation of these optics in large fusion-scale laser facilities. Here, we investigate the reasons for such an improvement. We study the effect of an HF-based wet etching on scratch morphology and propose a simple analytic model to reflect scratch widening during etching. We also use a finite element model to evaluate the effect of the morphological modification induced by etching on the electric field distribution in the vicinity of the scratch. We evidence that this improvement of the scratch damage resistance is due to a reduction of the electric field enhancement. This conclusion is supported by secondary electron microscopy (SEM) imaging of damage sites initiated on scratches after chemical treatment.

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“…Three-dimensional defect detection methods can be divided into bright-field detection methods and dark-field detection methods. Bright-field detection methods mainly include optical coherence tomography [4] , confocal microscopy [5] , structured illumination microscopy [6] , etc., which can obtain rich surface information. However, due to the illumination background light, the defect detection sensitivity is rather low.…”

Section: Introductionmentioning

confidence: 99%

Defect detection of precision optics by bright-dark-field structured illumination microscopy

Zhang

Liu

2023

Conference on Infrared, Millimeter, Terahertz Waves and Applications (IMT2022)

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Defect has become the bottleneck that limits the further increase of energy output in high-power laser devices, accurate defect detection is important for defect evaluation and optical component quality control. The bright-field methods have the problem that the illumination background light affects the measurement sensitivity. The dark-field measurement methods can remove the illumination background light, and the defect detection sensitivity is higher. However, the surface shape information is also removed out, thus the defect depth information is missing. In addition, the axial resolution of defect detection under regular illumination is rather low due to the influence of out-of-focus light. In this paper, a defect detection method based on bright-dark-field structured illumination microscopy (BDSIM) is proposed. This method takes the advantage of the high axial resolution of structured illumination, reconstructs the surface shape by bright-field configuration, and detects the surface and subsurface defect by dark-field configuration. Experiments prove that our method can effectively measure the surface and subsurface defects with accurate depth information.

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Evidence of a green luminescence band related to surface flaws in high purity silica glass

Cited by 29 publications

References 20 publications

Using the discrete element method to simulate brittle fracture in the indentation of a silica glass with a blunt indenter

Using the discrete element method to simulate brittle fracture in the indentation of a silica glass with a blunt indenter

Understanding the effect of wet etching on damage resistance of surface scratches

Defect detection of precision optics by bright-dark-field structured illumination microscopy

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