APPARATUS AND METHOD FOR DETERMINING REFRACTIVE INDEX, CENTRAL TENSION, OR STRESS PROFILE

• Main Authors: Furnas, William John, Sundaram, Balamurugan Meenakshi, Kim, Jin Su
• Format: Patent
• Language: English
• Published: 27.05.2021
• Subjects: MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER,MECHANICAL EFFICIENCY, OR FLUID PRESSURE; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; TESTING

Apparatus can comprise a cavity at least partially defined by a first major surface of a reference block and configured to receive a sample. The apparatus can comprise a first polarization-switching light source configured to emit a first polarization-switched light beam toward the cavity and a first detector configured to detect a corresponding signal. The apparatus can comprise a second polarization-switching light source configured to emit a second polarization-switched light beam toward the cavity and a second detector configured to detect a corresponding signal. The first reference block can be positioned between the second detector and the second reference block. Methods of determining an estimated stress profile can comprise determining a central tension from a measured retardation profile of the sample. Methods can comprise determining an initial stress profile from a refractive index profile of the sample. Methods can comprise scaling and adjusting stress profiles.