# US 11,906,771 B2 · Long length uniform illumination light diffusing fiber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,906,771 B2 - Document ID: US11906771B2 - Status: Granted - Kind: B2 - Application number: 17/312,180 - Filed: 2019-12-09 - Published: 2022-01-13 - Granted: 2024-02-20 - Earliest claimed: 2018-12-19 - Assignees: Corning Incorporated - Applicants: Corning Incorporated - Inventors: Kevin Wallace Bennett; Stephan Lvovich Logunov - Web page: https://patentgrep.com/patent/US11906771B2 ## CPC - C03C 25/14: Spraying - G02B 6/001: {the light being emitted along at least a portion of the lateral surface of the fibre} - C03B 19/1453: {Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering} - C03B 37/025: from reheated softened tubes, rods, fibres or filaments {, e.g. drawing fibres from preforms (draw-down of tubes, rods or preforms to reduced diameter preforms C03B37/0124)} - C03C 25/105: Organic claddings - C03C 25/106: Single coatings - C03C 25/285: Acrylic resins - C03C 25/47: containing particles, fibres or flakes, e.g. in a continuous phase - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES ## Abstract Embodiments of the disclosure relates to a light-diffusing element. The light diffusing element includes a glass core having a first refractive index. The light diffusing element also includes a cladding surrounding the glass core. The cladding includes an inner cladding surface and an outer cladding surface. The inner cladding surface and the outer cladding surface define a cladding thickness of from 5 μm to 30 μm. The cladding has a second refractive index that is less than the first refractive index of the glass core. The light diffusing element also includes a coating surrounding the cladding. The coating has an inner coating surface and an outer coating surface. The inner coating surface contacts the outer cladding surface. The outer coating surface defines an outermost surface of the light-diffusing element, and the coating includes first scattering centers. ## Claims ### Claim 1 A light-diffusing element comprising: a glass core comprising a first refractive index and an outer surface; a cladding surrounding the glass core, the cladding comprising an inner cladding surface and an outer cladding surface, wherein the inner cladding surface contacts the outer surface of the glass core, wherein the inner cladding surface and the outer cladding surface define a cladding thickness of from 5 μm to 30 μm, and wherein the cladding has a second refractive index that is less than the first refractive index of the glass core; and a coating surrounding the cladding, the coating comprising an inner coating surface and an outer coating surface, wherein the inner coating surface contacts the outer cladding surface and the outer coating surface defines an outermost surface of the light-diffusing element and wherein the coating includes first scattering centers; wherein light having wavelength of 2000 nm has a first scattering intensity, wherein light having a wavelength of 440 nm has a second scattering intensity, and wherein the first scattering intensity is within 5% of the second scattering intensity over a length of at least 50 m of the light-diffusing element. ### Claim 2 (depends on 1) The light-diffusing element of claim 1, wherein the glass core comprises silica glass. ### Claim 3 (depends on 1) The light-diffusing element of claim 1, wherein a numerical aperture as calculated based on the first refractive index and the second refractive index is from 0.2 to 0.45. ### Claim 4 (depends on 1) The light-diffusing element of claim 1, wherein the glass core has a diameter of from 65 μm to 500 μm. ### Claim 5 (depends on 1) The light-diffusing element of claim 1, wherein the inner coating surface and the outer coating surface define a thickness of from 20 μm to 50 μm. ### Claim 6 (depends on 1) The light-diffusing element of claim 1, wherein the coating has a third refractive index and wherein the third refractive index is greater than the second refractive index. ### Claim 7 (depends on 1) The light-diffusing element of claim 1, wherein the first scattering centers comprise at least one of TiO2, Al2O3, or ZrO2. ### Claim 8 (depends on 1) The light-diffusing element of claim 1, wherein the concentration of the first scattering centers in the coating is at least 1% by volume. ### Claim 9 (depends on 1) The light-diffusing element of claim 1, wherein the cladding comprises no voids or airlines. ### Claim 10 (depends on 1) The light-diffusing element of claim 1, wherein the light-diffusing element has a diffusion length of at least 30 m. ### Claim 11 (depends on 1) The light-diffusing element of claim 1, wherein the coating is comprised of acrylic polymer. ### Claim 12 (depends on 1) The light-diffusing element of claim 1, wherein the cladding comprises a polymer. ### Claim 13 (depends on 1) The light-diffusing element of claim 1, wherein the cladding includes second scattering centers. ### Claim 14 (depends on 1) The light-diffusing element of claim 1, wherein the outer coating surface defines a maximum outer diameter of the light-diffusing element of 230 μm. ### Claim 15 (depends on 1) The light-diffusing element of claim 1, wherein the light-diffusing element has a length of at least 50 m over which light scattering is at least 0.2 dB/m. ### Claim 16 (depends on 1) The light-diffusing element of claim 1, wherein the light-diffusing element has absorption losses of less than 10% in the cladding. ### Claim 17 (depends on 1) An illumination system comprising a light source optically coupled to a light-diffusing element according to claim 1. ### Claim 18 (depends on 6) The light-diffusing element of claim 6, wherein the first scattering centers have an average particle size of 30 nm to 2000 nm and wherein the first scattering centers have a fourth refractive index that is different from a third refractive index of the coating by at least 0.05. ### Claim 19 (depends on 12) The light-diffusing of claim 12, wherein the polymer comprises fluorine. ### Claim 20 (depends on 13) The light-diffusing element of claim 13, wherein the second scattering centers comprise at least one of TiO2, Al2O3, or ZrO2. ### Claim 21 (depends on 13) The light-diffusing element of claim 13, wherein the second scattering centers have a particle size in the range of from 30 nm to 2000 nm. ### Claim 22 (depends on 13) The light-diffusing element of claim 13, wherein the concentration of the second scattering centers in the cladding is from 0.05% to 1% by volume. ### Claim 23 (depends on 17) The illumination system of claim 17, wherein the light source comprises at least one of a lamp, a diode, a laser, a laser diode, or an LED. ### Claim 24 A method for forming a light-diffusing element comprising: forming a glass core; forming a cladding having a thickness of 5 μm to 30 μm on the glass core, the cladding having a lower refractive index than the glass core; and forming a coating on the cladding, the coating including first scattering centers; wherein light having wavelength of 2000 nm has a first scattering intensity, wherein light having a wavelength of 440 nm has a second scattering intensity, and wherein the first scattering intensity is within 5% of the second scattering intensity over a length of at least 50 m of the light-diffusing element. ### Claim 25 (depends on 24) The method of claim 24, wherein the step of forming the glass core includes drawing a glass preform. ### Claim 26 (depends on 24) The method of claim 24, wherein the step of forming the cladding includes applying a curable composition to said core and curing said curable composition. ### Claim 27 (depends on 24) The method of claim 24, wherein the first scattering centers comprise TiO2 dispersed in acrylic polymer. ### Claim 28 (depends on 24) The method of claim 24, wherein the step of forming the cladding further comprises dispersing second scattering centers comprising at least one of TiO2, Al2O3, or ZrO2 in the cladding. ### Claim 29 (depends on 24) The method of claim 24, wherein the step of forming the coating further comprises forming the coating such that a thickness of the coating is from 20 μm to 50 μm. ### Claim 30 (depends on 24) The method of claim 24, wherein the step of forming the coating further comprises including the first scattering centers at a concentration of at least 1% by volume. ### Claim 31 (depends on 26) The method of claim 26, wherein the step of forming the cladding includes curing the curable composition in a manner that avoids the formation of voids. ### Claim 32 An illumination system comprising: a light source configured to produce light in which a portion of the light from the light source has a wavelength from 440 nm to 2000 nm; and a light-diffusing element comprising: a glass core having a first refractive index and a longitudinal axis defining a length of at least 30 m; a cladding surrounding the glass core along the longitudinal axis, the cladding having a second refractive index that is less than the first refractive index of the glass core; and a coating surrounding the cladding, the coating including first scattering centers; wherein the light source is optically coupled to a light-diffusing element; wherein light from the light source having wavelength of 2000 nm has a first scattering intensity, wherein light from the light source having a wavelength of 440 nm has a second scattering intensity; and wherein the first scattering intensity is within 5% of the second scattering intensity over a length of at least 30 m of the light-diffusing element. ### Claim 33 (depends on 32) The illumination system of claim 32, wherein the cladding comprises an inner cladding surface and an outer cladding surface, the inner cladding surface and the outer cladding surface defining a cladding thickness therebetween, wherein the cladding thickness is from 5 μm to 30 μm. ### Claim 34 (depends on 32) The illumination system of claim 32, wherein the light source comprises at least one of a lamp, a diode, a laser, a laser diode, or an LED. ### Claim 35 (depends on 32) The illumination system of claim 32, wherein the first scattering centers comprise at least one of TiO2, Al2O3, or ZrO2. ### Claim 36 (depends on 32) The illumination system of claim 32, wherein a numerical aperture as calculated based on the first refractive index and the second refractive index is from 0.2 to 0.45. ### Claim 37 (depends on 32) The illumination system of claim 32, wherein the concentration of the first scattering centers in the coating is at least 1% by volume. ### Claim 38 (depends on 32) The illumination system of claim 32, wherein the cladding comprises a polymer. ### Claim 39 (depends on 32) The illumination system of claim 32, wherein the cladding includes second scattering centers. ### Claim 40 (depends on 32) The illumination system of claim 32, wherein the light-diffusing element has absorption losses of less than 10% in the cladding. ### Claim 41 (depends on 38) The illumination system of claim 38, wherein the polymer comprises fluorine. ### Claim 42 (depends on 39) The illumination system of claim 39, wherein the second scattering centers comprise at least one of TiO2, Al2O3, or ZrO2. ### Claim 43 (depends on 39) The illumination system of claim 39, wherein the concentration of the second scattering centers in the cladding is from 0.05% to 1% by volume.