Abstract: Annealing treatments for modified titania-silica glasses and the glasses produced by the annealing treatments. The annealing treatments include an isothermal hold that facilitates equalization of non-uniformities in fictive temperature caused by non-uniformities in modifier concentration in the glasses. The annealing treatments may also include heating the glass to a higher temperature following the isothermal hold and holding the glass at that temperature for several hours. Glasses produced by the annealing treatments exhibit high spatial uniformity of CTE, CTE slope, and fictive temperature, including in the presence of a spatially non-uniform concentration of modifier.

Abstract: Annealing treatments for modified titania-silica glasses and the glasses produced by the annealing treatments. The annealing treatments include an isothermal hold that facilitates equalization of non-uniformities in fictive temperature caused by non-uniformities in modifier concentration in the glasses. The annealing treatments may also include heating the glass to a higher temperature following the isothermal hold and holding the glass at that temperature for several hours. Glasses produced by the annealing treatments exhibit high spatial uniformity of CTE, CTE slope, and fictive temperature, including in the presence of a spatially non-uniform concentration of modifier.

Abstract: Annealing treatments for modified titania-silica glasses and the glasses produced by the annealing treatments. The annealing treatments include an isothermal hold that facilitates equalization of non-uniformities in fictive temperature caused by non-uniformities in modifier concentration in the glasses. The annealing treatments may also include heating the glass to a higher temperature following the isothermal hold and holding the glass at that temperature for several hours. Glasses produced by the annealing treatments exhibit high spatial uniformity of CTE, CTE slope, and fictive temperature, including in the presence of a spatially non-uniform concentration of modifier.

Abstract: A doped silica-titania (“DST”) glass article that includes a glass article having a glass composition comprising a silica-titania base glass containing titania at 7 to 14 wt. % and a balance of silica, and a dopant selected from the group consisting of (a) F at 0.7 to 1.5 wt. %, (b) B2O3 at 1.5 to 5 wt. %, (c) OH at 1000 to 3000 ppm, and (d) B2O3 at 0.5 to 2.5 wt. % and OH at 100 to 1400 ppm. The glass article has an expansivity slope of less than about 1.3 ppb/K2 at 20° C. For DST glass articles doped with F or B2O3, the OH level can be held to less than 10 ppm, or less than 100 ppm, respectively. In many aspects, the DST glass articles are substantially free of titania in crystalline form.

Abstract: Annealing treatments for modified titania-silica glasses and the glasses produced by the annealing treatments. The annealing treatments include an isothermal hold that facilitates equalization of non-uniformities in fictive temperature caused by non-uniformities in modifier concentration in the glasses. The annealing treatments may also include heating the glass to a higher temperature following the isothermal hold and holding the glass at that temperature for several hours. Glasses produced by the annealing treatments exhibit high spatial uniformity of CTE, CTE slope, and fictive temperature, including in the presence of a spatially non-uniform concentration of modifier.

Abstract: Annealing treatments for modified titania-silica glasses and the glasses produced by the annealing treatments. The annealing treatments include an isothermal hold that facilitates equalization of non-uniformities in fictive temperature caused by non-uniformities in modifier concentration in the glasses. The annealing treatments may also include heating the glass to a higher temperature following the isothermal hold and holding the glass at that temperature for several hours. Glasses produced by the annealing treatments exhibit high spatial uniformity of CTE, CTE slope, and fictive temperature, including in the presence of a spatially non-uniform concentration of modifier.

Abstract: A doped silica-titania (“DST”) glass article that includes a glass article having a glass composition comprising a silica-titania base glass containing titania at 7 to 14 wt. % and a balance of silica, and a dopant selected from the group consisting of (a) F at 0.7 to 1.5 wt. %, (b) B2O3 at 1.5 to 5 wt. %, (c) OH at 1000 to 3000 ppm, and (d) B2O3 at 0.5 to 2.5 wt. % and OH at 100 to 1400 ppm. The glass article has an expansivity slope of less than about 1.3 ppb/K2 at 20° C. For DST glass articles doped with F or B2O3, the OH level can be held to less than 10 ppm, or less than 100 ppm, respectively. In many aspects, the DST glass articles are substantially free of titania in crystalline form.

Abstract: Annealing treatments for modified titania-silica glasses and the glasses produced by the annealing treatments. The annealing treatments include an isothermal hold that facilitates equalization of non-uniformities in fictive temperature caused by non-uniformities in modifier concentration in the glasses. The annealing treatments may also include heating the glass to a higher temperature following the isothermal hold and holding the glass at that temperature for several hours. Glasses produced by the annealing treatments exhibit high spatial uniformity of CTE, CTE slope, and fictive temperature, including in the presence of a spatially non-uniform concentration of modifier.

Abstract: The invention is directed to calcium fluoride crystal optics with improved laser durability that can be used for the transmission of below 250 nanometer (nm) electromagnetic radiation. The optics consists of CaF2 as the major component and Mg in an amount in the range of 13 ppm to 20 ppm while Ce and Mn are <0.5 ppm. The doped crystal and optics made therefrom have a ratio of 515/380 nm transmission loss of less than 0.3 after exposure to greater than 2.8 MRads of ?-radiation. Further, the doped crystal and optics made therefrom exhibit a greatly improved lifetime as shown by ALDT testing to at least 1 billion pulses.

Abstract: A fused silica glass article having greater resistance to damage induced by exposure to laser radiation such as laser induced wavefront distortion at deep ultraviolet (DUV) wavelengths, and behaviors such as fluence dependent transmission, which are related to intrinsic defects in the glass. The improved resistance to laser damage may be achieved in some embodiments by loading the glass article with molecular hydrogen (H2) at temperatures of about 400° C. or less, or 350° C. or less. The combined OH and deuteroxyl (OD) concentration may be less than 10 ppm by weight. In other embodiments, the improved resistance may be achieved by providing the glass with 10 to 60 ppm deuteroxyl (OD) species by weight. In still other embodiments, improved resistance to such laser damage may be achieved by both loading the glass article with molecular hydrogen at temperatures of about 350° C. or less and providing the glass with less than 10 ppm combined OH and OD, or 10 to 60 ppm OD by weight.

Abstract: A method of loading at least one fused silica article with hydrogen. At least one fused silica article is first loaded with an amount of hydrogen so that the hydrogen concentration at the center of the article exceeds a minimum concentration upon completion of loading. An amount of hydrogen is the removed from the fused silica article so that the fused silica article has an average hydrogen concentration that is less than the maximum average concentration limit. The surface region of the fused silica article is then reloaded to ensure that the hydrogen concentration throughout the article is within a predetermined pressure range. A fused silica article comprising hydrogen is also described.

Abstract: The invention is directed to calcium fluoride crystal optics with improved laser durability that can be used for the transmission of below 250 nanometer (nm) electromagnetic radiation. The optics consists of CaF2 as the major component and Mg in an amount in the range of 13 ppm to 20 ppm while Ce and Mn are <0.5 ppm. The doped crystal and optics made therefrom have a ratio of 515/380 nm transmission loss of less than 0.3 after exposure to greater than 2.8 MRads of ?-radiation. Further, the doped crystal and optics made therefrom exhibit a greatly improved lifetime as shown by ALDT testing to at least 1 billion pulses.

Abstract: The present disclosure is directed to a method for producing constancy of the ion-exchanged product stress profile through adjustment of ion-exchange conditions by taking account of the influence of salt bath poisoning on the bath's useful lifetime. The present disclosure is directed to a method of ion-exchange in which the salt bath temperature and salt bath time are adjusted as a function of the amount of alkali metal ions that exchange in the bath. That is, temperature and time are adjusted as a function of salt bath poisoning. Temperature is set to its highest value and time to its shortest value in the starting un-poisoned salt bath, those values chosen to hit target values of surface compressive stress and exchange depth of layer. Temperature is then reduced and time lengthened as salt bath poisoning proceeds, those changes chosen to maintain the same surface compressive stress and exchange depth of layer.

Abstract: The present disclosure is directed to a method for producing constancy of the ion-exchanged product stress profile through adjustment of ion-exchange conditions by taking account of the influence of salt bath poisoning on the bath's useful lifetime. The present disclosure is directed to a method of ion-exchange in which the salt bath temperature and salt bath time are adjusted as a function of the amount of alkali metal ions that exchange in the bath. That is, temperature and time are adjusted as a function of salt bath poisoning. Temperature is set to its highest value and time to its shortest value in the starting unpoisoned salt bath, those values chosen to hit target values of surface compressive stress and exchange depth of layer. Temperature is then reduced and time lengthened as salt bath poisoning proceeds, those changes chosen to maintain the same surface compressive stress and exchange depth of layer.

Abstract: The invention is directed to calcium fluoride crystal optics with improved laser durability that can be used for the transmission of below 250 nanometer (nm) electromagnetic radiation. The optics consist of CaF2 as the major component and, in one embodiment, at least one dopant/amount selected >0.3-1200 ppm Mg, >0.3-200 ppm Sr, >0.3-200 ppm Ba, while Ce and Mn are <0.5 ppm. The doped crystal and optics made therefrom have a ratio of 515/380 nm transmission loss of less than 0.3 after exposure to greater than 2.8 MRads of ?-radiation.

Abstract: A laser beam is generated and transmitted within an enclosed pathway through at least one crystal optic at a power density that progressively degrades transmissivity of the crystal optic with accumulating fluence. The crystal optics are cooled below normal operating temperatures to slow the progressive degradation in the transmissivity of the crystal optics with the accumulating fluence or to accommodate a higher power density without correspondingly increasing the progressive degradation in transmissivity.

Abstract: The invention is directed to a method for reducing striae in ultra-low expansion glass, for example, silica-titania glass, by heat-treating the glass at temperatures above 1600° C. for a time in the range of 72-288 hours. The silica-titania glass is formed by substantially simultaneously forming, collecting and consolidating a silica-titania soot formed in one or a plurality of burners using silicon-containing feedstock and a titanium-containing feedstock. In one embodiment of the invention the glass is heat treated without forcing the glass to flow or “move”. The invention was found to reduce the magnitude of striae in an ultra-low expansion glass by at least 50%, and particularly reduces most of the “higher frequency” striae.

Abstract: The invention is directed to calcium fluoride crystal optics with improved laser durability that can be used for the transmission of below 250 nanometer (nm) electromagnetic radiation. The optics consist of CaF2 as the major component and, in one embodiment, at least one dopant/amount selected >0.3-1200 ppm Mg, >0.3-200 ppm Sr, >0.3-200 ppm Ba, while Ce and Mn are <0.5 ppm. The doped crystal and optics made therefrom have a ratio of 515/380 nm transmission loss of less than 0.3 after exposure to greater than 2.8 MRads of ?-radiation.

Abstract: A crystal optical material is illuminated at a wavelength of light that does not ionize the crystal optical material. Birefringence is measured between a plurality of voxels within the crystal optical material having spatial dimensions small enough to distinguish optical propagations of the light encountering boundary regions between subgrains of the crystal mosaic from optical propagations of the light through the subgrains themselves. The measured birefringence is evaluated for quantifying a characteristic of the crystal matrix. Metrics describing the crystal matrix are associated with performance of the crystal optical material.

Abstract: A method of loading at least one fused silica article with hydrogen. At least one fused silica article is first loaded with an amount of hydrogen so that the hydrogen concentration at the center of the article exceeds a minimum concentration upon completion of loading. An amount of hydrogen is the removed from the fused silica article so that the fused silica article has an average hydrogen concentration that is less than the maximum average concentration limit. The surface region of the fused silica article is then reloaded to ensure that the hydrogen concentration throughout the article is within a predetermined pressure range. A fused silica article comprising hydrogen is also described.