Anti-reflective optical element

Abstract

Anti-reflective optical element Optical element (30) comprising: - a transparent substrate (32), - at least one porous layer (36) extending over at least one optical surface (34) of the substrate (32), the porous layer (36) comprising a plurality of elongated elements (40) extending from the optical surface (34), characterized in that the elongated elements (40) have helical shapes, each elongated element (40) extending along a central axis (H) substantially perpendicular to the optical surface (34) and having an overall diameter (D), measured perpendicular to the central axis (H), said overall diameter (D) being less than or equal to 100 nm. Figure to be published with the abstract: 3

Claims

Claims

1. Optical element (30) comprising: - a transparent substrate (32), - at least one porous layer (36) extending over at least one optical surface (34) of the substrate (32), the porous layer (36) comprising a plurality of elongated elements (40) extending from the optical surface (34), characterized in that the elongated elements (40) have helical shapes, each elongated element (40) extending along a central axis (H) substantially perpendicular to the optical surface (34) and having an overall diameter (D), measured perpendicular to the central axis (H), said overall diameter (D) being less than or equal to 50 nm.

2. Optical element (30) according to the preceding claim, in which each elongated element (40) comprises a plurality of successive turns in the direction of the main axis (H), two neighboring turns being separated by a constant pitch (P), said pitch (P) being greater than or equal to 50 nm.

3. Optical element (30) according to the preceding claim, in which the pitch (P) is greater than or equal to 100 nm, preferably greater than or equal to 200 nm, more preferably greater than or equal to 400 nm and better still greater than or equal to 600 nm.

4. An optical element (30) according to claim 2 or 3, wherein the pitch (P) is less than or equal to 1000 nm.

5. Optical element (30) according to one of the preceding claims, in which each elongated element (40) is formed of an elongated branch (42), wound around the main axis (H) and having a branch diameter (d), measured perpendicular to a local direction of elongation of the branch (42), said branch diameter (d) being less than or equal to 60 nm, in particular less than or equal to 40 nm, and preferably less than or equal to 20 nm.

6. Optical element (30) according to one of the preceding claims, in which the elongated elements (40) are formed by a low index material, such as for example SiO2, Al2O3, or even MgF2.

7. Optronic device comprising at least one optical element (30) according to one of the preceding claims, arranged along the same optical axis.

8. Optronic device according to the preceding claim, in which a luminous flux intended to pass through the optical element (30) comprises radiation having at least one wavelength between 400 nm and 550 nm.

9. A method of manufacturing an optical element (30) according to one of claims 1 to 6, comprising steps of: - providing a substrate (32) and placing the substrate (32) in a deposition device, and - depositing the porous layer (36) on an optical surface (34) of the substrate (32), according to an oblique incidence deposition method, in which an angle of incidence of a deposition beam, measured relative to a local normal to the optical surface (34), is greater than or equal to 45°, and preferably substantially equal to 80°, and in which, during the step of depositing the porous layer (36), the substrate (32) is maintained in azimuthal rotation at a rotation speed of between 0.05 revolutions per minute and 0.5 revolutions per minute, preferably substantially equal to 0.125 revolutions per minute.

Images