Optical article comprising an antireflective coating with a low reflection both in the ultraviolet region and in the visible region
View Patent ↗This invention relates to an ophthalmic lens with a low reflection both in the ultraviolet region and in the visible region, comprising a substrate provided on its rear main face with a multilayered antireflective coating (3-7 layers) comprising a stack of at least one layer with a high refractive index and at least one layer with a low refractive index, having a mean reflection factor on the rear face in the visible region R m lower than or equal to 1.15%, a mean light reflection factor on the rear face in the visible region R v lower than or equal to 1%, a mean reflection factor R UV on the rear face between 280 nm and 380 nm, weighted by the function W(λ) defined in the ISO 13666:1998 standard, lower than 5%, for angles of incidence of 30° and 45°, the antireflective coating outer layer being a silica-based layer. The lens according to the invention does especially prevent the reflection of the UV radiation produced by light sources located behind the wearer.
1. An ophthalmic lens comprising a substrate with a front main face and a rear main face, the rear main face being coated with a multilayered antireflective coating comprising a stack of at least one layer having a refractive index higher than 1.6 and of at least one layer having a refractive index lower than 1.5, wherein:
the refractive index is expressed at a wavelength of 550 nm,
the mean reflection factor on the rear face in the visible region R m is lower than or equal to 1.15%;
the mean light reflection factor on the rear face in the visible region R v is lower than or equal to 1%;
the mean reflection factor R UV on the rear face between 280 nm and 380 nm, weighted by the function W(λ) defined in the ISO 13666:1998 standard, is lower than 5%, for both an angle of incidence of 30° and for an angle of incidence of 45°;
the multilayered antireflective coating comprises from 3 to 7 layers;
the multilayered antireflective coating does not comprise any layer with a thickness higher than 15 nm based on indium oxide;
the multilayered antireflective coating:
does not comprise any MgF 2 layer,
comprises at least one layer having a refractive index lower than 1.5 and a thickness ranging from 10 to 100 nm,
comprises at least one layer having a refractive index higher than 1.6 and a thickness ranging from 8 to 120 nm,
has a total thickness lower than 1 micrometer
and
the multilayered antireflective coating outer layer is a silica-based layer,
wherein
(a) the mean spectral reflection factor on the rear face for at least one wavelength in the 280-295 nm range for both an angle of incidence of 30° and an angle of incidence of 45° is higher than 5%, or
(b) the mean spectral reflection factor on the rear face over at least 70% of the 280-290 nm wavelength range, for an angle of incidence of 15° is higher than 10%.
2. The lens of claim 1 , wherein the mean spectral reflection factor on the rear face for at least one wavelength in the 280-295 nm range for both an angle of incidence of 30° and an angle of incidence of 45° is higher than 6%.
3. The lens of claim 1 , wherein the multilayered antireflective coating comprises at least 4 layers.
4. The lens of claim 1 , wherein the mean spectral reflection factor on the rear face over at least 20% of the 280-295 nm wavelength range is higher than 5%, for both an angle of incidence of 30° and an angle of incidence of 45°.
5. The lens of claim 1 , wherein the multilayered antireflective coating outer layer is a 10-100 nm thick silica-based layer.
6. The lens of claim 1 , wherein the antireflective coating does not comprise any layer comprising titanium oxide with a thickness higher than 90 nm.
7. The lens of claim 1 , wherein the mean spectral reflection factor on the rear face over at least 70% of the 280-295 nm wavelength range for an angle of incidence 15° is higher than 10%.
8. The lens of claim 1 , wherein the mean spectral reflection factor on the rear face over at least 70% of the 280-290 nm wavelength range for an angle of incidence 15° is higher than 15%.
9. The lens of claim 1 , wherein the multilayered antireflective coating comprises at least one electrically conductive layer.
10. The lens of claim 1 , wherein the rear face has a mean reflection factor R m-UV1 between 290 nm and 330 nm lower than 15% for an angle of incidence of 15°.
11. The lens of claim 1 , wherein the rear face has a mean reflection factor R m-UV2 between 300 nm and 320 nm lower than 4% for an angle of incidence of 15° and/or 30° and/or 45°.
12. The lens of claim 1 , wherein the rear face has a mean reflection factor R m-UV3 between 300 nm and 380 nm lower than 5%, for an angle of incidence of 15°.
13. The lens of claim 1 , wherein the mean reflection factor on the rear face in the visible region R m is lower than or equal to 1%.
14. The lens of claim 1 , wherein the mean light reflection factor on the rear face in the visible region R v is lower than or equal to 0.90%.
15. The lens of claim 1 , wherein the mean reflection factor R UV on the rear face between 280 nm and 380 nm, weighted by the function W(λ) defined in the ISO 13666:1998 standard, is lower than or equal to 4%, for both an angle of incidence of 30° and an angle of incidence of 45°.
16. The lens of claim 1 , wherein the multilayered antireflective coating is deposited on a sub-layer comprising a SiO 2 -based layer, said SiO 2 -based layer comprising at least 80% by weight of silica.
17. The lens of claim 16 , wherein the silica-based layer has a thickness of from 100 to 300 nm.
18. The lens of claim 16 , wherein the sub-layer is deposited on an anti-abrasion coating, having a thickness ranging from 2 to 10 μm.
19. The lens of claim 16 , wherein the sub-layer is deposited on an anti-abrasion coating.
20. The lens of claim 19 , wherein the anti-abrasion coating is prepared from a composition comprising at least one alkoxysilane and/or a hydrolyzate thereof.