US 12,345,905 B2
Optical article having a reflective coating with high abrasion-resistance
William Trottier-Lapointe, Charenton-le-Pont (FR); Alexis Theoden, Charenton-le-Pont (FR); Philippe Romand, Charenton-le-Pont (FR); and Surin Maidam, Bangkok (TH)
Assigned to Essilor International, Charenton-le-Pont (FR)
Appl. No. 17/414,799
Filed by ESSILOR INTERNATIONAL, Charenton-le-Pont (FR)
PCT Filed Dec. 18, 2019, PCT No. PCT/EP2019/086066
§ 371(c)(1), (2) Date Jun. 16, 2021,
PCT Pub. No. WO2020/127564, PCT Pub. Date Jun. 25, 2020.
Claims priority of application No. 18306727 (EP), filed on Dec. 18, 2018.
Prior Publication US 2022/0066079 A1, Mar. 3, 2022
Int. Cl. G02B 5/28 (2006.01); G02C 7/02 (2006.01)
CPC G02B 5/286 (2013.01) [G02C 7/022 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An optical article comprising:
a substrate having at least one main face coated with a reflective coating in the visible range comprising a stack of at least one high refractive index layer having a refractive index greater than 1.55 and at least one low refractive index layer having a refractive index of 1.55 or less, the refractive indexes being expressed for a wavelength of 550 nm,
wherein the reflective coating comprises at least four layers, and
the outermost low refractive index layer of the reflective coating has a physical thickness Tho of at least 10 nm,
the outermost high refractive index layer of the reflective coating has a physical thickness of 75 nm or less,
the penultimate low refractive index layer of the reflective coating, in a direction moving away from the substrate, has a physical thickness Thp of at least 150 nm,
the penultimate high refractive index layer of the reflective coating, in the direction moving away from the substrate, has a physical thickness ranging from 5 nm to 90 nm, and
Tho/4+Thp≥200 nm, or
wherein the reflective coating has exactly three layers, and
the outermost layer of the reflective coating is a low refractive index layer having a physical thickness of 70 nm or less,
the penultimate layer of the reflective coating, in the direction moving away from the substrate, is a high refractive index layer having a physical thickness of 50 nm or less, and
the first layer of the reflective coating is a low refractive index layer having a physical thickness of at least 200 nm, and
wherein the penultimate low refractive index layer of the reflective coating is the penultimate low refractive index layer within the low refractive index layers of the reflective coating,
wherein the penultimate high refractive index layer of the reflective coating is the penultimate high refractive index layer within the high refractive index layers of the reflective coating,
wherein high refractive index layers and low refractive index layers alternate with each other in the reflective coating, and
wherein, when determining the number of layers of the reflective coating, two or more adjacent high refractive index layers form a single high refractive index layer having a thickness equal to the sum of the thicknesses of individual layers of the two or more adjacent high refractive index layers, and two or more adjacent low refractive index layers are a single low refractive index layer having a physical thickness equal to the sum of the thicknesses of individual layers of the two or more adjacent low refractive index layers.