System and method for glass processing and stress measurement

• Main Authors: KHALEEL MOHAMMAD A, SHEPARD CHESTER L, CANNON BRET D
• Format: Patent
• Language: English
• Published: 24.04.2003
• Edition: 7
• Subjects: CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GLASS; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES; MEASURING; METALLURGY; MINERAL OR SLAG WOOL; PHYSICS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TESTING; TESTING STATIC OR DYNAMIC BALANCE OF MACHINES ORSTRUCTURES; TESTING STRUCTURES OR APPARATUS NOT OTHERWISE PROVIDED FOR

A non-destructive and non-contact method for measuring stress at the mid-plane of tempered glass plates that uses Bragg scattering from a pair of thermal gratings. The gratings are formed by parallel writing beams of laser light retroreflected through the glass. The polarization state of light from a delayed laser beam that scatters from both these thermal gratings is measured, and the change in polarization of the doubly scattered light with separation between the two gratings is correlated to the in-plane stress. Systems and techniques to take these measurements and control a glass manufacturing process are also disclosed.