# US 10,871,400 B2 · Retardation profile for stress characterization of tubing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,400 B2 - Document ID: US10871400B2 - Status: Granted - Kind: B2 - Application number: 16/534,083 - Filed: 2019-08-07 - Published: 2020-02-27 - Granted: 2020-12-22 - Earliest claimed: 2018-08-27 - Assignees: Corning Incorporated - Applicants: Corning Incorporated - Inventors: William John Furnas - Web page: https://patentgrep.com/patent/US10871400B2 ## CPC - G01J 4/00: Measuring polarisation of light - G01B 1/00: Measuring instruments characterised by the selection of material therefor - G01B 11/06: for measuring thickness {; e.g. of sheet material (thickness measurement by thermal means G01B21/085)} - G01B 11/08: for measuring diameters - G01B 11/12: internal diameters - G01B 11/168: {by means of polarisation} - G01L 1/24: by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet} - G01N 21/21: Polarisation-affecting properties (G01N21/19 takes precedence) - G01N 21/8806: {Specially adapted optical and illumination features} - G01N 21/958: Inspecting transparent materials {or objects, e.g. windscreens (for conveyed flat sheet or rod G01N21/896)} - G01J 4/04: Polarimeters using electric detection means (G01J4/02 takes precedence) - G01N 2021/216: {using circular polarised light} - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract Provided herein are systems and methods for monitoring radial stresses in glass tubing. In some embodiments, a measurement system includes a light source delivering a light to a tube, and a polarizer receiving the light after the light is refracted through a wall of the tube. The measurement system may further include a detector receiving the light from the polarizer, the detector operable to capture a first image of the light at a first polarization state and a second image of the light at a second polarization state. The system may further include a controller operable to determine a retardation profile related to the stress profile of the wall of the tube by determining a retardation magnitude of the light refracted through the wall of the tube based on a difference between the first image of the light and the second image of the light. ## Claims ### Claim 1 A measurement system, comprising: a light source delivering a light to a tube; a polarizer receiving the light after the light is refracted through a wall of the tube; a detector receiving the light from the polarizer, the detector operable to capture a first image of the light at a first polarization state and a second image of the light at a second polarization state; and a controller operable to determine a retardation profile of the wall of the tube by determining a retardation magnitude of the light refracted through the wall of the tube based on a difference between the first image of the light and the second image of the light. ### Claim 2 (depends on 1) The measurement system of claim 1, wherein the polarizer includes a driver operable to switch between the first polarization state and the second polarization state. ### Claim 3 (depends on 2) The measurement system of claim 2, wherein the polarizer includes a ferroelectric liquid crystal. ### Claim 4 (depends on 1) The measurement system of claim 1, wherein the controller is further operable to sum the first image and the second image to determine each of: a direct beam location, an edge of the tube, and a beam intersecting the tube tangentially at different radial distances. ### Claim 5 (depends on 1) The measurement system of claim 1, the controller further operable to determine a diameter of the tube and a thickness of the wall of the tube. ### Claim 6 (depends on 1) The measurement system of claim 1, wherein the light source is a circular polarized line light projector, wherein the detector is an array detector, and wherein the light is a collimated line-shaped beam. ### Claim 7 (depends on 6) The measurement system of claim 6, wherein the tube has a lengthwise tube axis extending through a center of the tube, and wherein the collimated line-shaped beam is delivered to the tube at an angle relative to the lengthwise tube axis of less than ninety degrees and greater than zero degrees. ### Claim 8 (depends on 6) The measurement system of claim 6, wherein the collimated line-shaped beam is delivered to the tube at an angle relative to the lengthwise tube axis of approximately forty-five degrees. ### Claim 9 (depends on 1) The measurement system of claim 1, wherein the tube is a transparent tube. ### Claim 10 A non-contact tubing measurement system, comprising: a light source delivering a light to a transparent tube, the light being a collimated line-shaped beam; a polarizer receiving the light after the light is refracted through a wall of the transparent tube; a detector receiving the light from the polarizer, the detector operable to capture a first image of the light at a first polarization state and a second image of the light at a second polarization state; and a controller operable to determine a retardation profile by determining a retardation magnitude of the light refracted through the wall of the transparent tube based on a difference between the first image of the light and the second image of the light. ### Claim 11 (depends on 10) The non-contact tubing measurement system of claim 10, wherein the polarizer includes a ferroelectric liquid crystal having a driver operable to switch between the first polarization state and the second polarization state. ### Claim 12 (depends on 10) The non-contact tubing measurement system of claim 10, the controller further operable to determine a diameter of the transparent tube and a thickness of the wall of the transparent tube. ### Claim 13 (depends on 10) The non-contact measurement system of claim 10, wherein the light source is a circular polarized line light projector, and wherein the detector is an array detector. ### Claim 14 (depends on 10) The measurement system of claim 10, wherein the transparent tube has a lengthwise tube axis extending through a center of the tube, and wherein the light is delivered to the transparent tube at an angle relative to the lengthwise tube axis of less than ninety degrees and greater than zero degrees. ### Claim 15 A method for determining a retardation profile of a tubing wall, the method comprising: delivering a light from a light source to a transparent tube; receiving the light at a polarizer after the light is refracted through a wall of the transparent tube; receiving the light from the polarizer at a detector; capturing, by the detector, a first image of the light at a first polarization state and a second image of the light at a second polarization state; and determining a retardation profile of the transparent tube from a retardation magnitude of the light refracted through the wall, wherein the retardation magnitude is determined based on a difference between the first image of the light and the second image of the light. ### Claim 16 (depends on 15) The method according to claim 15, further comprising switching, using a driver of the polarizer, between the first polarization state and the second polarization state. ### Claim 17 (depends on 15) The method according to claim 15, further comprising determining a diameter of the transparent tube and a thickness of the wall of the transparent tube. ### Claim 18 (depends on 15) The method according to claim 15, further comprising delivering a collimated line-shaped beam to the transparent tube at an angle relative to the lengthwise tube axis of less than ninety degrees and greater than zero degrees. ### Claim 19 (depends on 18) The method of claim 18, further comprising delivering the collimated line-shaped beam at an angle relative to the lengthwise tube axis of approximately forty-five degrees. ### Claim 20 (depends on 18) The method of claim 18, further comprising: positioning the tube between the light source and the polarizer; and delivering the collimated line-shaped beam from the light source to the transparent tube.