Rugged sensor window materials for harsh environments

Bayya, Shyam; Villalobos, Guillermo; Kim, Woohong; Sanghera, J. S.; Hunt, Michael; Aggarwal, Ishwar D.

doi:10.1117/12.2062160

Cited by 3 publications

(3 citation statements)

References 3 publications

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“…The constraint factor L i denotes the orientation of the indented crystal plane. According to equation (2) and the summarized RCSS, 37 the probability T of activating the basal and rhombohedral twinning systems was calculated based on the model of scratching on C-and M-planes with a Vickers pyramidal indenter, the results are illustrated in Figure 6. From the perspective of symmetry, the calculated probability T agrees well with the obtained surface roughness shown in Figure 3 twinning is dominant as scratching along the ½ 1100, ½0 110, and ½10 10 directions, while both basal and rhombohedral twinning play important roles for scratching along the ½1 100, ½01 10, and ½ 1010 directions.…”

Section: Discussion Based On Scratching Testsmentioning

confidence: 99%

“…Sapphire is an increasingly popular material that has been widely used for precision optics, forward looking infra-red (FLIR) windows, and substrates for blue light-emitting diodes (LEDs) for its excellent thermal and mechanical performance, as well as the superior optical clarity over a broad spectral range. [1][2][3] All of the above applications require sapphire to possess high machining quality and defect-free surfaces. However, in addition to the extremely high hardness and brittleness, the inherent anisotropy of sapphire adds further difficulty to machining of uniform surface with high quality.…”

Section: Introductionmentioning

confidence: 99%

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Investigation into the anisotropy of cross-grinding surface quality in C- and M-planes of sapphire

Wang

Guo

Zhao

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part B:

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Sapphire is an important material for optical applications, but the anisotropy of key properties makes it difficult to obtain uniform ground surface. In this work, cross-grinding experiments were first conducted on C- and M-planes of sapphire to investigate the dependence of the ground surface quality on crystal orientation. Then, scratching tests were performed along the specific crystal orientations to explain the formation mechanism of the anisotropic grinding patterns. The results showed that the surface roughness distribution on C-plane is of a threefold symmetry, while one axis of symmetry for M-plane. The damage pits on C-plane possess lower aspect ratio than that on M-plane. By combining the scratching-induced fracture features with the contact-induced deformation theory of sapphire, it was found that the propagation of the primary cracks in sapphire is accompanied by activating different deformation systems. The material removal on C-plane is dominated by the shallow lateral cracks, which propagate parallel to the ground surface and result in shallow and wide pits. However, the deep lateral cracks play an important role on M-plane, which intersect with the ground surface and cause deep and dense defects. The non-uniformity of the ground surface is attributed to the appearance of radial cracks for C-plane, while it is associated with the number of the available deformation systems for M-plane.

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Section: Discussion Based On Scratching Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation into the anisotropy of cross-grinding surface quality in C- and M-planes of sapphire

Wang

Guo

Zhao

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part B:

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show abstract

“…5,6 Sapphire is a promising candidate for hard X-ray optical applications, 7 high pressure cells for neutron scattering experiments, 8,9 and optical windows in corrosive atmospheres. 10,11 Sapphire single crystals with low-to medium-optical quality can satisfy many demands whereas routine production in the highest quality is still an unreached milestone. An emerging application of sapphire is relevant to X-ray monochromatization.…”

Section: Introductionmentioning

confidence: 99%

Rocking curve imaging of high quality sapphire crystals in backscattering geometry

Jafari

Sergueev

Bessas

et al. 2017

Journal of Applied Physics

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We report on the characterization of high quality sapphire single crystals suitable for high-resolution X-ray optics at high energy. Investigations using rocking curve imaging reveal the crystals to be of uniformly good quality at the level of ∼10−4 in lattice parameter variations, δd/d. However, investigations using backscattering rocking curve imaging with a lattice spacing resolution of δd/d∼5×10−8 show very diverse quality maps for all crystals. Our results highlight nearly ideal areas with an edge length of 0.2–0.5 mm in most crystals, but a comparison of the back reflection peak positions shows that even neighboring ideal areas exhibit a relative difference in the lattice parameters on the order of δd/d=10–20×10−8; this is several times larger than the rocking curve width. Stress-strain analysis suggests that an extremely stringent limit on the strain at a level of ∼100 kPa in the growth process is required in order to produce crystals with large areas of the quality required for X-ray optics at high energy.

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Overview of transparent optical ceramics for high-energy lasers at NRL

et al. 2015

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In this review, we present our recent research progress at the Naval Research Laboratory in the development of highly transparent and rugged ceramic window materials such as MgAl2O4 spinel and β-SiC; high-power solid-state laser gain materials based on sesquioxide such as Yb(3+):Y2O3, Yb(3+):Lu2O3, and Ho(3+):Lu2O3; and composite ceramics in the application for high-energy lasers. Various powder synthesis/purification methods and powder post-process techniques necessary to create high-purity powders are described. Ceramic fabrication processes and chemical, morphological, and optical properties of the ceramics developed at the Naval Research Laboratory (NRL) are highlighted. We also report high-efficiency lasing from a hot-pressed rare-earth sesquioxide single layer and composite ceramics made from coprecipitated powder.

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Rugged sensor window materials for harsh environments

Cited by 3 publications

References 3 publications

Investigation into the anisotropy of cross-grinding surface quality in C- and M-planes of sapphire

Investigation into the anisotropy of cross-grinding surface quality in C- and M-planes of sapphire

Rocking curve imaging of high quality sapphire crystals in backscattering geometry

Overview of transparent optical ceramics for high-energy lasers at NRL

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