Owen J.D.,University of North Carolina at Charlotte |
Davies M.A.,University of North Carolina at Charlotte |
Schmidt D.,Rochester Precision Optics, LLC |
Urruti E.H.,SCHOTT North America Inc
CIRP Annals - Manufacturing Technology | Year: 2015
Chalcogenide glasses are important materials for components in thermal imaging systems (IR-optics). While suitable for molding, the machining characteristics of these brittle materials are largely unknown. In this paper, ultra-precision machining data for a common chalcogenide glass (As40Se60) is presented. Data acquired from orthogonal cutting experiments show a transition in cutting mechanics at an uncut chip thickness of approximately one micrometer. This data is used to identify parameters for high-speed milling, and results are used to produce a thermal imaging lens. This paper demonstrates that the milling process is suitable for prototyping and low-batch production of IR-optics in this glass. © 2015 CIRP.
Massera J.,Clemson University |
Remond J.,INSA Lyon |
Musgraves J.,Clemson University |
Davis M.J.,SCHOTT North America Inc |
And 3 more authors.
Journal of Non-Crystalline Solids | Year: 2010
The kinetics of crystallization of glasses in the (90 - x)TeO 2-10Bi2O3-xZnO system with x = 15, 17.5, 20 and 25 have been studied using differential thermal analysis (DTA), hot stage XRD and optical microscopy. Thermal properties, activation energy for crystallization, Johnson-Mehl-Avrami exponent, nucleation and growth regimes and rates were determined and shown to depend on glass composition. These variations were related to the domain of glass formation in the TeO 2-Bi2O3-ZnO ternary glass system: the glasses with x = 15 and 25 are at the limit of the glass formation domain while the glasses with x = 17.5 and 20 are in the middle of the glass-forming region. From the Johnson-Mehl-Avrami parameter, which increases slightly from 1.7 to 2.2 when x increases from 15 to 25, and from optical micrographs, the predominant crystallization in the investigated glasses is expected to be 2 dimensional bulk crystallization governed by diffusion. Using XRD, we found that Bi 2O3 crystals are the first crystals to form in the glasses when heat treated at their respective temperatures of maximum nucleation. When heat treated at a higher temperature the Bi2O3 crystals were found to transform into Bi2Te4O11. We observed an increase in the crystal size when the glasses were heat treated at their respective temperatures of maximum nucleation revealing a probable overlap between the nucleation and growth regimes in all the glasses, the largest overlap being for the glass with x = 15. Thus, this glass is not an appropriate material candidate for applications which require controlled nucleation and growth as a large distribution of crystal sizes can be obtained in the glass when heat treated at its temperature of maximum nucleation rate. The glass with x = 25 is suspected to be also an inappropriate candidate for this kind of applications as it has a higher tendency to fully crystallize in a small temperature range than the other glasses as evidenced by its high Nq and In. © 2010 Elsevier B.V. All rights reserved.
Hayden J.S.,SCHOTT North America Inc
International Journal of Applied Glass Science | Year: 2015
The long-term commercial potential for solid-state laser gain materials based on glass has only been possible by constant technological developments that have overcome otherwise "market lethal" performance and cost issues. We will discuss a few examples that resulted in the development of completely new manufacturing processes that expanded the laser glass operation window and made possible the construction of large laser systems such as the National Ignition Facility in the United States and the French Laser Mégajoule. In parallel, through compositional modifications and identification of special postprocessing treatments, new active glasses with tailored properties have been continuously developed for specific laser architectures. We will also discuss current research activity directed at finding customized laser glass compositions for the next generation of high-peak-power (e.g., Exawatt class) laser systems. © 2015 American Ceramic Society and Wiley Periodicals, Inc.
Campbell J.H.,Lawrence Livermore National Laboratory |
Hayden J.S.,SCHOTT North America Inc |
Marker A.,SCHOTT North America Inc
International Journal of Applied Glass Science | Year: 2011
Advances in laser glass compositions and manufacturing have enabled a new class of high-energy/high-power (HEHP), petawatt (PW), and high average power (HAP) laser systems that are being used for fusion energy ignition demonstration, fundamental physics research, and materials processing, respectively. The requirements for these three laser systems are different, necessitating different glasses or groups of glasses. The manufacturing technology is now mature for melting, annealing, fabricating, and finishing of laser glasses for all three applications. The laser glass properties of major importance for HEHP, PW, and HAP applications are briefly reviewed and the compositions and properties of the most widely used commercial laser glasses are summarized. Proposed advances in these three laser systems will require new glasses and new melting methods, which are briefly discussed. The challenges presented by these laser systems will likely dominate the field of laser glass development over the next several decades. © 2011 The American Ceramic Society and Wiley Periodicals, Inc.
George S.,SCHOTT North America Inc |
Vullo P.,SCHOTT North America Inc
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015
Phosphate glasses are known to produce high gain for the Er3+ emission into 1540nm, especially when sensitized with Yb. Unfortunately, the phosphate glass matrix tends to be weaker than other available amorphous materials. Being that glasses are engineerable, a study was initiated in order to strengthen the glass structure of a commercially available phosphate laser glass without impacting its laser output efficiencies. Secondly, we seek to understand the impact of the various glass modifiers that drive thermal shock resistance of phosphate glasses on the Er emission manifolds. This report details a number of compositions that were designed, melted and analyzed for properties. Laser output performance results for the glasses that met the targeted parameters are presented. © 2015 SPIE.