# US 8,570,527 B2 · Polarization-sensitive spectral interferometry > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,527 B2 - Document ID: US8570527B2 - Status: Granted - Kind: B2 - Application number: 13/327,492 - Filed: 2011-12-15 - Published: 2012-05-31 - Granted: 2013-10-29 - Earliest claimed: 2006-06-05 - Assignees: Board of Regents, The University of Texas System - Applicants: Thomas E. Milner; Nathaniel J. Kemp; Eunha Kim - Inventors: Thomas E. Milner; Nathaniel J. Kemp; Eunha Kim - Web page: https://patentgrep.com/patent/US8570527B2 ## CPC - G01B 9/02091: Tomographic interferometers, e.g. based on optical coherence - A61B 1/00096: {Optical elements} - A61B 1/00167: {Details of optical fibre bundles, e.g. shape or fibre distribution} - A61B 1/00172: {with means for scanning} - A61B 5/0066: {Optical coherence imaging} - A61B 5/0075: {by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy (A61B5/0071 takes precedence)} - A61B 5/0084: {for introduction into the body, e.g. by catheters (A61B5/1459 takes precedence)} - A61B 5/6852: {Catheters} - G01B 9/02004: using frequency scans - G01B 9/02069: {Synchronization of light source or manipulator and detector} - G01B 9/02097: Self-interferometers - A61B 5/0086: {using infrared radiation} - A61B 5/4523: {Tendons} - A61B 5/7257: {using Fourier transforms} - G01B 2290/70: Using polarization in the interferometer - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A polarization sensitive spectral interferometer apparatus and method for analyzing a sample by optical energy reflected from the sample. The polarization sensitive spectral interferometer apparatus and method determines polarization properties of the sample by optical energy reflected from the sample. ## Claims ### Claim 1 A polarization-sensitive spectral interferometer for analyzing a sample comprising: a light source that produces light over a multiplicity of optical frequencies; at least one optical fiber through which the light is transmitted to the sample; a fiber-optic spectral polarimetry instrument disposed in and optically coupled to a detection path of the spectral interferometer; a receiver which receives the light reflected from the sample; and a computer coupled to the receiver that determines polarization properties of the sample without prior knowledge of the polarization state of light incident on the sample. ### Claim 2 (depends on 1) The interferometer as described in claim 1, further comprising an optical spectrum analyzer coupled to the receiver, wherein the optical spectrum analyzer records the intensity of light at the output of the interferometer. ### Claim 3 (depends on 2) The interferometer as described in claim 2, wherein the computer determines simultaneously the depth and polarimetric properties of the light reflected from the sample. ### Claim 4 (depends on 2) The interferometer as described in claim 2, wherein the computer identifies the tissue type of the sample by the polarization properties as a function of depth from the biattenuance of the sample Δχ, which is given by: Δχ=χs−χf, where χs and χf are attenuation coefficients of the slow and fast eigenpolarizations. ### Claim 5 (depends on 2) The interferometer as described in claim 2, wherein the computer identifies the tissue type of the sample by the polarization properties as a function of depth from the birefringence of the sample by a nonlinear fitting of normalized Stokes vectors from multiple incident polarization states. ### Claim 6 (depends on 3) The interferometer as described in claim 3, wherein the computer identifies tissue type of the sample as a function of depth from the depth-resolved birefringence, depth resolved biattenuance, depth resolved retardation, or depth resolved optical axis of the sample. ### Claim 7 (depends on 3) The interferometer as described in claim 3, wherein the optical fiber is coupled to a catheter. ### Claim 8 (depends on 3) The interferometer as described in claim 3, wherein the computer identifies the tissue type of the sample by the polarization properties as a function of depth from the depth-resolved birefringence of the sample by employing a multi-state nonlinear algorithm that uses M incident polarization states uniformly distributed on a great circle of the Poincaré sphere and utilizing multiple incident polarization states to give M distinct separation-angles (γm) distributed within the interval. ### Claim 9 A polarization-sensitive optical coherence tomography apparatus comprising: a broadband frequency-swept light source optically coupled to an interferometer; an auxiliary wavemeter optically coupled to the interferometer; a detection path optically coupled to a computer to determine the depth-resolved polarization properties of a sample without prior knowledge of the polarization state of light incident on the sample; and a fiber-optic spectral polarimetry instrument disposed in and optically coupled to the detection path. ### Claim 10 (depends on 9) The apparatus as described in claim 9, wherein the computer simultaneously determines the depth and polarimetric properties of the light reflected from the sample. ### Claim 11 (depends on 10) The apparatus as described in claim 10, wherein the computer determines variations of the polarization of the reflected light as a function of depth of the sample. ### Claim 12 (depends on 9) The apparatus as described in claim 9, wherein the computer determines birefringence of the sample, biattenuance of the sample, retardation of the sample, or optical axis of the sample. ### Claim 13 (depends on 9) The apparatus as described in claim 9, wherein the computer identifies the tissue type of the sample as a function of depth from the depth-resolved birefringence, depth-resolved biattenuance, depth-resolved retardation, or depth-resolved optical axis of the sample. ### Claim 14 (depends on 13) The apparatus as described in claim 13, wherein the interferometer is coupled to a catheter. ### Claim 15 (depends on 9) The apparatus as described in claim 9, wherein the computer identifies the tissue type of the sample by the polarization properties as function of depth from the depth-resolved birefringence of the sample by employing a multi-state nonlinear algorithm that uses M incident polarization states uniformly distributed on a great circle of the Poincaré sphere and utilizing multiple incident polarization states to gives M distinct separation-angles (γm) distributed within the interval. ### Claim 16 A polarization-sensitive spectral interferometer for analyzing a sample comprising: a light source that produces light over a multiplicity of optical frequencies; at least one optical fiber through which the light is transmitted to the sample; an optical spectrum analyzer; a fiber-based common-path spectral interferometer; a fiber-optic spectral polarimetry instrument disposed in and optically coupled to a detection path of the common-path spectral interferometer; a receiver which receives the light reflected from the sample; and a computer coupled to the receiver that determines polarization properties of the sample without prior knowledge of the polarization state of light incident on the sample. ### Claim 17 (depends on 16) The interferometer as described in claim 16, wherein the computer simultaneously determines the depth and polarimetric properties of the light reflected from the sample and determines variations of the polarization of the reflected light as a function of depth of the sample. ### Claim 18 (depends on 16) The interferometer as described in claim 16, wherein the computer determines birefringence of the sample, biattenuance of the sample, retardation of the sample, or optical axis of the sample. ### Claim 19 (depends on 16) The interferometer as described in claim 16, wherein the computer identifies the tissue type of the sample as a function of depth from the depth-resolved birefringence, depth-resolved biattenuance, depth-resolved retardation, or depth-resolved optical axis of the sample. ### Claim 20 (depends on 16) The interferometer as described in claim 16, wherein the computer identifies the tissue type of the sample by the polarization properties as function of depth from the depth-resolved birefringence of the sample by employing a multi-state nonlinear algorithm that uses M incident polarization states uniformly distributed on a great circle of the Poincaré sphere and utilizing multiple incident polarization states to gives M distinct separation-angles (γm) distributed within the interval.