Optical article with reduced visual fatigue
An optical article includes a front face adapted to receive incident optical beams and a back face through which transmitted optical beams exit to reach an eye, wherein the front face includes an interferential multilayer coating including a stack of dielectric layers. The interferential multilayer coating provides the optical article with a mean visible light reflection factor Rv that is lower than or equal to 2.0% over a range of angle of incidence included between 0 and 20 degrees, and that is higher than or equal to 2.0% over a range of angle of incidence included between 40 degrees and 60 degrees, the optical article having a higher mean visible light transmittance for low incidence angles and a lower mean visible light transmittance for high incidence angles.
1 . Optical article comprising a front face adapted to receive incident optical beams and a back face through which transmitted optical beams exit to reach an eye of an individual, wherein the front face comprises an interferential multilayer coating comprising a stack of dielectric layers, the interferential multilayer coating providing the optical article with a mean visible light reflection factor R v that is a function of an angle of incidence of each optical beam on the front face, said optical article being designed such that said optical article has a higher mean visible light transmittance for low incidence angles and a lower mean visible light transmittance for high incidence angles:
the mean visible light reflection factor R y being lower than or equal to 2.0% for incident optical beams on the front face over a first range of angle of incidence with respect to a perpendicular to said front face higher than or equal to 0 degrees and lower than or equal to 20 degrees, and
the mean visible light reflection factor being higher than or equal to 2.0% for incident optical beams on the front face over a second range of angle of incidence with respect to the perpendicular to said front face higher than or equal to 40 degrees and lower than or equal to 60 degrees.
2 . Optical article according to claim 1 wherein the mean visible light reflection factor is lower than or equal to 8.0% for incident optical beams on the front face over said second range of angle of incidence with respect to the perpendicular to said front face higher than or equal to 40 degrees and lower than or equal to 60 degrees.
3 . Optical article according to claim 1 wherein the mean visible light reflection factor is higher than or equal to 2.5% and lower than or equal to 11.5% for incident optical beams on the front face over said second range of angle of incidence with respect to the perpendicular to said front face higher than or equal to 40 degrees and lower than or equal to 60 degrees.
4 . Optical article according to claim 1 wherein the mean visible light reflection factor is higher than or equal to 3.5% and lower than or equal to 14.0% for incident optical beams on the front face over said second range of angle of incidence with respect to the perpendicular to said front face higher than or equal to 40 degrees and lower than or equal to 60 degrees.
5 . Optical article according to claim 1 wherein the mean visible light reflection factor is higher than or equal to 4.5% and lower than or equal to 16.0% for incident optical beams on the front face over said second range of angle of incidence with respect to the perpendicular to said front face higher than or equal to 40 degrees and lower than or equal to 60 degrees.
6 . Optical article according to claim 1 , wherein a ratio between R v min(40°) and R v (0°) is higher than 3, wherein R v min(40°) is the minimum R 2 value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
7 . Optical article according to claim 1 , wherein the interferential multilayer coating comprises at least one layer of high refractive index material having a refractive index higher than 1.55 and at least one layer of low refractive index material having a refractive index of 1.55 or less.
8 . Optical article according to claim 7 , wherein said high refractive index material is selected among ZrO 2 , SnO 2 , SiN, TiO 2 , PrTiO 3 , LaTiO 3 , Ta 2 O 5 , Y 2 O 3 , Ce 2 O 3 , La 2 O 3 , Dy 2 O 5 , Nb 2 O 5 , HfO 2 , Sc 2 O 3 , Pr 2 O 3 , Al 2 O 3 , or Si 3 N 4 and said low refractive index material is selected among SiO 2 , MgF 2 , ZrF 4 , Al 2 O 3 , AlF 3 , chiolite Na 3 [Al 3 F 14 ], cryolite Na 3 [AlF 6 ], or any mixture thereof.
9 . An optical article according to claim 8 , wherein said interferential multilayer coating comprises layers of different materials from an innermost layer to an outermost layer:
a layer of zirconium dioxide having a thickness of 15-130 nm;
a layer of silicon dioxide having a thickness of 130-300 nm;
a layer of zirconium dioxide having a thickness of 30-130 nm;
a layer of tin oxide having a thickness of 5-30 nm;
an outermost layer comprising a layer of silicon dioxide having a thickness of 5-130 nm.
10 . Optical article according to claim 1 , further comprising a hard coating, the interferential multilayer coating being arranged on said hard coating.
11 . Ophthalmic lens comprising an optical article according to claim 1 .
12 . Ophthalmic equipment comprising a frame and at least one ophthalmic lens according to claim 11 , mounted on the frame.
13 . Ophthalmic equipment comprising a frame and two ophthalmic lenses according to claim 11 , mounted on the frame.
14 . Optical article according to claim 2 , wherein a ratio between R v min(40°) and R v (0°) is higher than 3, wherein R v min(40°) is the minimum R 2 value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
15 . Optical article according to claim 3 , wherein a ratio between R v min(40°) and R y (0°) is higher than 3, wherein R v min(40°) is the minimum R 2 value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
16 . Optical article according to claim 4 , wherein a ratio between R v min(40°) and R y (0°) is higher than 3, wherein R v min(40°) is the minimum R v value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
17 . Optical article according to claim 5 , wherein a ratio between R v min(40°) and R y (0°) is higher than 3, wherein R v min(40°) is the minimum R 2 value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
18 . Optical article according to claim 1 , wherein a ratio between R v min(40°) and R y (0°) is higher than 4, wherein R v min(40°) is the minimum R 2 value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
19 . Optical article according to claim 1 , wherein a ratio between R v min(40°) and R v (0°) is higher than 5, wherein R v min(40°) is the minimum R 2 value at an angle of incidence with respect to the perpendicular to said front face that is equal to 40 degrees and R v (0°) is the R v value at an angle of incidence perpendicular to said front face.
20 . Optical article according to claim 7 , wherein said high refractive index material is selected among ZrO 2 , SnO 2 , SiN, TiO 2 , PrTiO 3 , LaTiO 3 , Ta 2 O 5 , Y 2 O 3 , Ce 2 O 3 , La 2 O 3 , Dy 2 O 5 , Nb 2 O 5 , HfO 2 , Sc 2 O 3 , Pr 2 O 3 , Al 2 O 3 , or Si 3 N 4 and said low refractive index material is SiO 2 or SiO 2 doped with Al 2 O 3 with from 1 to 10% by weight of Al 2 O 3 relative to a total weight of SiO 2 and Al 2 O 3 in said low refractive index material layer.