Optical article having directional micro- or nanostructured thin film coating, and its process
An optical article includes a substrate with front and rear main faces, one main face coated with a columnar micro- or nano-structured coating. The substrate and optical article are transparent in at least a part of the visible region ranging from 380 to 780 nm, along at least one incidence angle. The columnar micro- or nano-structured coating includes an array of columns including each a core and an upper layer covering the core, the core and the upper layer being structurally and/or chemically different and have light absorbing properties with an extinction coefficient “k” ≥10-2 in the spectrum 250-2500 nm and are able to cause a change in transmission or in reflection of incident light through the optical article as a function of the angle of incidence of light. Also disclosed is a method for manufacturing an optical article including a columnar micro- or nano-structured coating.
1. An optical article comprising a substrate with a front main face and with a rear main face, at least one of the main faces being coated with a columnar micro- or nano-structured coating, wherein
the substrate and the optical article are transparent or can be put in a state where they are transparent in at least a part of the visible region ranging from 380 to 780 nm, along at least one incidence angle;
said columnar micro- or nano-structured coating comprises at least an array of columns comprising each a core and an upper layer covering said core, the core and the upper layer being structurally and/or chemically different and wherein said core and/or upper layer have light absorbing properties or can be put in a state where they have light absorbing properties with an extinction coefficient “k” equal to or higher than 10 −2 in at least a part of the light spectrum ranging from 250 to 2500 nm and are able to cause a change in transmission or in reflection of incident light through the optical article as a function of the angle of incidence of light, and
wherein the core of the columns has a porosity that is equal to or higher than 30%.
2. The optical article according to claim 1 , wherein the columns have a height ranging from 50 to 1000 nm.
3. The optical article according to claim 1 , wherein a tilt angle beta β ranging from 0 to 50° is defined between the columns and the at least one main face of the substrate.
4. The optical article according to claim 1 , wherein the at least one main face of the substrate contains predetermined patterns covered with a columnar micro- or nano-structured coating.
5. The optical article according to claim 1 , wherein the core and/or the upper layer have permanent light absorbing properties with an extension coefficient “k” equal to or higher than 10 −2 at least in a part of the visible range from 380 to 780 nm.
6. The optical article according to claim 5 , wherein the core and/or the upper layer comprise(s) one or more substoichiometric oxides, and/or substoichiometric nitrides, or substoichiometric fluorides.
7. The optical article according to claim 5 , wherein the core and/or the upper layer further has (have) conducting properties and comprise(s) one or more materials selected from: diamond like carbon DLC, graphene/graphite; metals conductive nitrides; semiconductors, doped or not; or transparent conductive oxides.
8. The optical article according to claim 1 , wherein the core and/or the upper layer can be put in a state where they have light absorbing properties with an extension coefficient “k” equal to or higher than 10 −2 at least in a part of the visible range ranging from 380 to 780 nm and are configured to reversibly switch from a deactivated state to an activated state upon the application of activation or deactivation means, respectively.
9. The optical article according to claim 8 , wherein the core and/or the upper layer comprise(s) one or more chromogenic materials.
10. The optical article according to claim 1 , wherein the core is transparent and the upper layer has light absorbing properties or can be put in a state where the upper layer has light absorbing properties with an extension coefficient “k” equal to or higher than 10 −2 in at least a part of the light spectrum ranging from 250 to 2500 nm.
11. The optical article according to claim 1 , wherein the core comprises one or more stoichiometric oxides or nitrides, or fluorides, or a mixture of organic-inorganic materials.
12. The optical article according to claim 1 , wherein the core and/or the upper layer has (have) a high refractive index that is higher than or equal to 1.8, or has (have) a medium refractive index that is lower than 1.8.
13. The optical article according to claim 1 , wherein the upper layer is absent from the columns head.
14. An optical lens comprising a substrate with a front main face and with a rear main face, at least one of the main faces being coated with a columnar micro- or nano-structured coating, wherein
the substrate and the optical article are transparent or can be put in a state where they are transparent in at least a part of the visible region ranging from 380 to 780 nm, along at least one incidence angle;
said columnar micro- or nano-structured coating comprises at least an array of columns comprising each a core and an upper layer covering said core, the core and the upper layer being structurally and/or chemically different and wherein said core and/or upper layer have light absorbing properties or can be put in a state where they have light absorbing properties with an extinction coefficient “k” equal to or higher than 10 −2 in at least a part of the light spectrum ranging from 250 to 2500 nm and are able to cause a change in transmission or in reflection of incident light through the optical article as a function of the angle of incidence of light, and wherein the core of the columns has a porosity that is equal to or higher than 30%.
15. Method of manufacture of an optical article comprising a substrate with a front main face and with a rear main face, at least one of the main faces being coated with a columnar micro- or nano-structured coating, wherein
the substrate and the optical article are transparent or can be put in a state where they are transparent in at least a part of the visible region ranging from 380 to 780 nm, along at least one incidence angle;
said columnar micro- or nano-structured coating comprises at least an array of contiguous columns comprising each a core and an upper layer covering said core, the core and the upper layer being structurally and/or chemically different and wherein said core and/or upper layer have light absorbing properties or can be put in a state where they have light absorbing properties with an extinction coefficient “k” equal to or higher than 10 −2 in at least a part of the light spectrum ranging from 250 to 2500 nm;
the method comprising the following steps:
(a) depositing on the at least one main surface of the substrate, the core by physical directional deposition to create the array of contiguous columns;
(b) depositing, on the core of the columns, at least one—upper layer by atomic layer deposition; the parameters of the deposition of the core and of the upper layer being controlled so as to provide a change in transmission or reflection of incident light through the optical article as a function of the angle of incidence of light, wherein the core of the columns has a porosity that is equal to or higher than 30%.
16. The optical article according to claim 1 , wherein the core of the columns has a porosity that is equal to or higher than 45.
17. The optical article according to claim 1 , wherein the core of the columns has a porosity ranging from 75 to 85%.
18. The optical article according to claim 1 , wherein the columns have a height ranging from 200 to 300 nm.
19. The optical article according to claim 1 , wherein the core and/or the upper layer has (have) a high refractive index that is higher than or equal to 1.9, or has (have) a medium refractive index that is lower than 1.7.
20. The optical article according to claim 1 , wherein the core and/or the upper layer has (have) a high refractive index that is higher than or equal to 2 or has (have) a medium refractive index that is lower than or equal to 1.6.