Abstract: Systems and methods of performing a stress measurement of a chemically strengthened glass using a light-scattering polarimetry system include adjusting the intensity of a light beam from a light source in an illumination system using a rotatable half-wave plate and a first polarizer operably disposed between the light source and a rotating light diffuser that has a rotation time tR. The first polarizer is aligned with a second polarizer in a downstream optical compensator to have matching polarization directions by rotating the rotatable half-wave plate to a position where the exposure time tE falls within an exposure range tR?tE. The method also includes performing an exposure using the exposure time tE to obtain the stress measurement. One or both of the half-wave plate and first polarizer can be tilted to avoid deleterious back-reflected light from entering the light source.

Abstract: The hybrid measurement system includes an evanescent prism coupling spectroscopy (EPCS) sub-system and a light-scattering polarimetry (LSP) sub-system. The EPCS sub-system includes an EPCS light source system optically coupled to an EPCS detector system through an EPCS coupling prism. The LSP sub-system includes an LSP light source optically coupled to an optical compensator, which in turn is optically coupled to a LSP detector system via a LSP coupling prism. A support structure supports the EPCS and LSP coupling prisms to define a coupling prism assembly, which supports the two prisms at a measurement location. Stress measurements made using the EPCS and LSP sub-systems are combined to fully characterize the stress properties of a transparent chemically strengthened substrate. Methods of processing the EPCS and LSP measurements and enhanced configurations of the EPCS and LPS sub-systems to improve measurement accuracy are also disclosed.

Abstract: A lithium containing glass article is provided. In aspects, the lithium containing glass article includes an intensity coupling profile including a plurality of coupling resonances. A first of the coupling resonances has a half-width half-maximum value that is at least 1.8 times greater than the half-width half-maximum value of a second of the coupling resonances. In aspects, the lithium containing glass article includes a smoothed intensity coupling profile including a plurality of coupling resonances. A second derivative of the smoothed intensity coupling profile at a first of the coupling resonances is at least 1.8 times greater than a second derivative of the smoothed coupling profile at a second of the coupling resonances.

Abstract: Ion-exchanged glass ceramic articles described herein have a stress that decreases with increasing distance according to a substantially linear function from a depth of about 0.07 t to a depth of about 0.26 t from the outer surface of the ion-exchanged glass ceramic article from a compressive stress to a tensile stress. The stress transitions from the compressive stress to the tensile stress at a depth of from about 0.18 t to about 0.25 t from the outer surface of the ion-exchanged glass ceramic article. An absolute value of a maximum compressive stress at the outer surface of the ion-exchanged glass article is from 1.8 to 2.2 times an absolute value of a maximum central tension (CT) of the ion-exchanged glass article, and the glass ceramic article has a fracture toughness of 1 MPa?m or more as measured according to the double cantilever beam method.

Abstract: Ion-exchanged glass ceramic articles described herein have a stress that decreases with increasing distance according to a substantially linear function from a depth of about 0.07t to a depth of about 0.26t from the outer surface of the ion-exchanged glass ceramic article from a compressive stress to a tensile stress. The stress transitions from the compressive stress to the tensile stress at a depth of from about 0.18t to about 0.25t from the outer surface of the ion-exchanged glass ceramic article. An absolute value of a maximum compressive stress at the outer surface of the ion-exchanged glass article is from 1.8 to 2.2 times an absolute value of a maximum central tension (CT) of the ion-exchanged glass article, and the glass ceramic article has a fracture toughness of 1 MPa?m or more as measured according to the double cantilever beam method.

Abstract: Methods of characterizing ion-exchanged chemically strengthened glass containing lithium are disclosed. The methods allow for performing quality control of the stress profile in chemically strengthened Li-containing glasses having a surface stress spike produced in a potassium-containing salt, especially in a salt having both potassium and sodium. The method allows the measurement of the surface compression and the depth of the spike, and its contribution to the center tension, as well as the compression at the bottom of the spike, and the total center tension and calculation of the stress at the knee where the spike and the deep region of the stress profile intersect. The measurements are for a commercially important profile that is near-parabolic in shape in most of the interior of the substrate apart from the spike.

Abstract: Methods of improving the measurement of knee stress in an ion-exchanged chemically strengthened Li-containing glass sample that includes a knee are disclosed. One of the methods includes compensating for a shift in the location of the TIR-PR transition location associated with the critical angle location, wherein the shift is due to the presence of a leaky mode. Another method includes applying select criteria to the captured mode spectra image to ensure a high-quality image is used for the knee stress calculation. Another method combines direct and indirect measurements of the knee stress using the mode spectra from multiple samples to obtain greater accuracy and precision as compared to using either the direct measurement method or the indirect measurement method alone. Quality control methods of forming the glass samples using measured mode spectra and related techniques for ensuring an accurate measurement of the knee stress are also disclosed.

Abstract: A lithium containing glass article is provided. In aspects, the lithium containing glass article includes an intensity coupling profile including a plurality of coupling resonances. A first of the coupling resonances has a half-width half-maximum value that is at least 1.8 times greater than the half-width half-maximum value of a second of the coupling resonances. In aspects, the lithium containing glass article includes a smoothed intensity coupling profile including a plurality of coupling resonances. A second derivative of the smoothed intensity coupling profile at a first of the coupling resonances is at least 1.8 times greater than a second derivative of the smoothed coupling profile at a second of the coupling resonances.

Abstract: Systems and methods of performing a stress measurement of a chemically strengthened glass using a light-scattering polarimetry system include adjusting the intensity of a light beam from a light source in an illumination system using a rotatable half-wave plate and a first polarizer operably disposed between the light source and a rotating light diffuser that has a rotation time tR. The first polarizer is aligned with a second polarizer in a downstream optical compensator to have matching polarization directions by rotating the rotatable half-wave plate to a position where the exposure time tE falls within an exposure range tR?tE. The method also includes performing an exposure using the exposure time tE to obtain the stress measurement. One or both of the half-wave plate and first polarizer can be tilted to avoid deleterious back-reflected light from entering the light source.

Abstract: A method of reworking lithium containing ion exchanged glass articles is provided. The method includes a reverse ion exchange process that returns the glass article to approximately the composition of the glass from which the glass article was produced, before being subjected to ion exchange. The reworked glass articles exhibit a K2O concentration profile comprising a portion wherein a K2O concentration increases to a local K2O concentration maximum.

Abstract: The prism-coupling systems and methods include using a prism-coupling system to collect a 2D digital mode spectrum of an IOX article. The mode line and critical angle positions and orientations are found by performing a weighted fit to mode line and critical angle images and are used to define a compensated mode spectrum. If mode line tilt is found, it is removed from the 2D digital mode spectrum to define the compensated mode spectrum. The compensated mode spectrum is then processed using techniques known in the art to provide a more accurate estimate of stress-related characteristics of the IOX sample versus using the uncompensated mode spectrum. Derivative-based methods of accurately establishing positions of intensity transitions in a mode spectrum of an IOX sample using a derivative spectrum and curve fitting are also disclosed.

Abstract: The hybrid measurement system includes an evanescent prism coupling spectroscopy (EPCS) sub-system and a light-scattering polarimetry (LSP) sub-system. The EPCS sub-system includes an EPCS light source system optically coupled to an EPCS detector system through an EPCS coupling prism. The LSP sub-system includes an LSP light source optically coupled to an optical compensator, which in turn is optically coupled to a LSP detector system via a LSP coupling prism. A support structure supports the EPCS and LSP coupling prisms to define a coupling prism assembly, which supports the two prisms at a measurement location. Stress measurements made using the EPCS and LSP sub-systems are combined to fully characterize the stress properties of a transparent chemically strengthened substrate. Methods of processing the EPCS and LSP measurements and enhanced configurations of the EPCS and LPS sub-systems to improve measurement accuracy are also disclosed.

Abstract: A method for determining crystal phases of a glass ceramic sample, including the steps of applying energy to the sample using an excitation source, detecting raw Raman spectral energy that is given off by the sample using a detector, wherein the raw Raman spectral energy includes peak values, determining a plurality of predetermined energy peaks based off a composition of the sample, superimposing the plurality of predetermined energy peaks over the raw Raman spectral energy, applying a baseline value between each predetermined energy peak, subtracting the baseline value from the raw Raman spectral energy, calculating corrected peak values based on the raw Raman spectral energy and baseline value, and determining the crystal phases of the glass ceramic sample based on the corrected peak values.

Abstract: Ion-exchanged glass ceramic articles described herein have a stress that decreases with increasing distance according to a substantially linear function from a depth of about 0.07t to a depth of about 0.26t from the outer surface of the ion-exchanged glass ceramic article from a compressive stress to a tensile stress. The stress transitions from the compressive stress to the tensile stress at a depth of from about 0.18t to about 0.25t from the outer surface of the ion-exchanged glass ceramic article. An absolute value of a maximum compressive stress at the outer surface of the ion-exchanged glass article is from 1.8 to 2.2 times an absolute value of a maximum central tension (CT) of the ion-exchanged glass article, and the glass ceramic article has a fracture toughness of 1 MPa?m or more as measured according to the double cantilever beam method.

Abstract: The prism-coupling systems and methods include using a prism-coupling system to collect initial TM and TE mode spectra of a chemically strengthened article having a refractive index profile with a near-surface spike region and a deep region. The initial TM and TE mode spectra are examined to see if they fall within a preferred measurement window that can produce an accurate estimate of the knee stress to within a select tolerance. If not, then measurement configuration of the prism-coupling system is changed and new TM and TE mode spectra are collected. This process is repeated until the new TM and TE mode spectra fall within the preferred measurement window. The new TM and TE mode spectra are then used to determine the knee stress. Changing the measurement configuration can include changing at least one of the measurement wavelength, interfacing fluid thickness and interfacing fluid refractive index.

Abstract: A method of reworking lithium containing ion exchanged glass articles is provided. The method includes a reverse ion exchange process that returns the glass article to approximately the composition of the glass from which the glass article was produced, before being subjected to ion exchange. The reworked glass articles exhibit a K2O concentration profile comprising a portion wherein a K2O concentration increases to a local K2O concentration maximum.

Abstract: The hybrid measurement system includes an evanescent prism coupling spectroscopy (EPCS) sub-system and a light-scattering polarimetry (LSP) sub-system. The EPCS sub-system includes an EPCS light source optically coupled to an EPCS detector system through an EPCS coupling prism. The LSP sub-system includes an LSP light source optically coupled to an optical compensator, which in turn is optically coupled to a LSP detector system via a LSP coupling prism. A support structure supports the EPCS and LSP coupling prisms to define a coupling prism assembly, which supports the two prisms at a measurement location. Stress measurements made using the EPCS and LSP sub-systems are combined to fully characterize the stress properties of a transparent chemically strengthened substrate. Methods of processing the EPCS and LSP measurements to improve measurement accuracy are also disclosed.

Abstract: Ion-exchanged glass ceramic articles described herein have a stress that decreases with increasing distance according to a substantially linear function from a depth of about 0.07 t to a depth of about 0.26 t from the outer surface of the ion-exchanged glass ceramic article from a compressive stress to a tensile stress. The stress transitions from the compressive stress to the tensile stress at a depth of from about 0.18 t to about 0.25 t from the outer surface of the ion-exchanged glass ceramic article. An absolute value of a maximum compressive stress at the outer surface of the ion-exchanged glass article is from 1.8 to 2.2 times an absolute value of a maximum central tension (CT) of the ion-exchanged glass article, and the glass ceramic article has a fracture toughness of 1 MPa?m or more as measured according to the double cantilever beam method.

Abstract: A method of reworking lithium containing ion exchanged glass articles is provided. The method includes a reverse ion exchange process that returns the glass article to approximately the composition of the glass from which the glass article was produced, before being subjected to ion exchange. The reworked glass articles exhibit a K2O concentration profile comprising a portion wherein a K2O concentration increases to a local K2O concentration maximum.

Abstract: The prism-coupling systems and methods include using a prism-coupling system to collect initial TM and TE mode spectra of a chemically strengthened article having a refractive index profile with a near-surface spike region and a deep region. The prism-coupling system has a light source configured to generate sequential measurement light beams or reflected light beams having different measurement wavelengths. The different measurement wavelengths generate different TM and TE mode spectra. The light source can include multiple light-emitting elements and optical filters or a broadband light source and optical filters. The optical filters can be sequentially inserted into either the input optical path or the output optical path of the prism-coupling system.