# US 10,480,925 B2 · Inspecting a slab of material > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,480,925 B2 - Document ID: US10480925B2 - Status: Granted - Kind: B2 - Application number: 16/192,626 - Filed: 2018-11-15 - Published: 2019-03-21 - Granted: 2019-11-19 - Earliest claimed: 2017-01-19 - Assignees: Applejack 199 L.P. - Applicants: Applejack 199 L.P. - Inventors: Wojciech Jan Walecki - Web page: https://patentgrep.com/patent/US10480925B2 ## CPC - G01B 9/02011: {using temporal polarization variation} - G01B 9/02007: {Two or more frequencies or sources used for interferometric measurement (using only beat G01B9/02003)} - G01B 9/02025: {Interference between three or more discrete surfaces} - G01B 9/02044: {Imaging in the frequency domain, e.g. by using a spectrometer} - G01B 11/06: for measuring thickness {; e.g. of sheet material (thickness measurement by thermal means G01B21/085)} - G01B 11/24: for measuring contours or curvatures - G01B 11/2441: {using interferometry} - G01N 21/8806: {Specially adapted optical and illumination features} - G01B 2290/70: Using polarization in the interferometer - G01N 2021/8841: {Illumination and detection on two sides of object} - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - 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 A system for inspecting a slab of material may include an optical fiber, a broadband light source configured to emit light having wavelengths of 780-1800 nanometers over the optical fiber, a beam-forming assembly configured to receive the light over the optical fiber and direct the light toward a slab of material, the beam-forming assembly may be configured to maintain the position of one or more elements within the beam-forming assembly despite changes in environmental temperature; a computer-controlled etalon filter configured to receive the light over the optical fiber, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light. ## Claims ### Claim 1 A system for inspecting a slab of material, the system comprising: single mode optical fiber; a broadband light source configured to emit light with wavelengths in a range from 780 nanometers (nm) to 1800 nm over the optical fiber; a beam-forming assembly configured to receive the light over the optical fiber and direct the light toward a slab of material; a computer-controlled etalon filter configured to receive the light over the optical fiber either before the light is directed toward the slab of material or after the light has been reflected from or transmitted through the slab of material, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light. ### Claim 2 (depends on 1) The system of claim 1, wherein the broadband light source is configured to emit light with wavelengths in a range of 780 nm to 1000 nm. ### Claim 3 (depends on 1) The system of claim 1, wherein the broadband light source is configured to emit light with wavelengths in a range of 800 nm to 1000 nm. ### Claim 4 (depends on 3) The system of claim 3, wherein the computer-controlled spectrometer comprises a silicon-based detector. ### Claim 5 (depends on 1) The system of claim 1, wherein the broadband light source is configured to emit light with wavelengths in a range of 1100 nm to 1800 nm. ### Claim 6 (depends on 1) The system of claim 1, wherein the broadband light source is configured to emit light with wavelengths in a range of 1200 nm to 1500 nm. ### Claim 7 (depends on 6) The system of claim 6, wherein the computer-controlled spectrometer comprises an Indium Gallium Arsenide detector. ### Claim 8 (depends on 1) The system of claim 1, wherein the broadband light source comprises a Superluminescent Light Emitter Device. ### Claim 9 (depends on 1) The system of claim 1, wherein each of the single mode fiber, the beam-forming assembly, the computer-controlled etalon filter, and the computer-controlled spectrometer are configured to operate in the same wavelength range as the light emitted by the broadband light source. ### Claim 10 A system for inspecting a slab of material, the system comprising: single mode optical fiber; a broadband light source configured to emit light over the optical fiber; a beam-forming assembly configured to: receive the light over the optical fiber; split the light, at a beam splitter, into first and second portions after receiving the light over the optical fiber; direct the first portion of the light toward the slab of material; direct the second portion of the light onto a reflector that is maintained at a substantially constant distance from the beam splitter; combine the first portion of the light after being reflected from the slab of material and the second portion of the light after being reflected from the reflector; and direct the combined light over the optical fiber; a computer-controlled etalon filter configured to receive the light over the optical fiber either before the light is directed toward the slab of material or after the light has been reflected from or transmitted through the slab of material, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light. ### Claim 11 (depends on 9) The system of claim 9, wherein the beam-forming assembly is comprised of materials having a low coefficient of thermal expansion such that in response to an increase or decrease in a temperature of the system, the reflector is maintained at a substantially constant distance from the beam splitter. ### Claim 12 (depends on 10) The system of claim 10, wherein the beam-forming assembly is comprised of Invar. ### Claim 13 (depends on 9) The system of claim 9, further comprising a temperature controller that is configured to maintain the beam-forming assembly at a substantially constant temperature. ### Claim 14 (depends on 12) The system of claim 12, wherein the temperature controller comprises a temperature sensor, a heater, and feedback electronics. ### Claim 15 (depends on 12) The system of claim 12, wherein the temperature controller comprises a thermoelectric cooler.