Variable-focus lens and method of manufacturing the same
The invention relates to a variable-focus lens ( 60 ) for focusing light rays in light paths passing through the lens along an optical axis (Δ). The lens comprises an arrangement of first and second immiscible liquids ( 67, 68 ) that have different refractive indices and are in contact over a moveable refractive optical interface ( 69 ), a volume of gas ( 72 ) in contact with one of said liquids, and a retention measure ( 70, 74 ) for keeping the volume of gas away from the light paths of the light rays passing through the lens for focusing.
1. A variable-focus lens for focusing light rays in light paths passing through the lens along an optical axis (Δ), the lens comprising an arrangement of first and second immiscible liquids that have different refractive indices and are in contact over a moveable refractive optical interface, a volume of gas in contact with one of said liquids, and a retention measure for keeping the volume of gas away from the light paths of the light rays passing through the lens for focusing.
2. Lens according to claim 1 , wherein the arrangement comprises:
a first chamber containing the first and second liquids;
a second chamber containing the first liquid and the volume of gas;
a passage for the first liquid to pass between the first and second chambers.
3. Lens according to claim 2 , wherein the first liquid is an aqueous liquid and wherein the passage comprises walls comprising or covered by a hydrophilic material.
4. Lens according to claim 2 , wherein the second chamber is bounded by first, second and third walls, the first wall being inclined at a first angle (α) to the second wall, the second wall being inclined at a second angle (β) to the third wall, and the first wall being inclined at a third angle (γ) to the third wall, the first angle being smaller than the second angle and smaller than the third angle.
5. Lens according to claim 2 , wherein the passage comprises pores of a porous material.
6. Lens according to claim 2 , wherein the second chamber comprise pores of a porous material, and the volume of gas is dispersed in the pores.
7. Lens according to claim 2 , wherein the second chamber has the form of a tube, one end of which opens into the first chamber and the opposite end of which is closed.
8. Lens according to claim 1 , wherein the volume of gas comprises one or more gas bubbles.
9. Lens according to claim 1 , wherein the gas comprises air, an inert gas or a mixture of inert gases, or the vapour of one of the liquids contained in the lens.
10. Lens according to claim 1 , wherein the volume of gas is equal to between 5% to 50% of the internal volume of the lens.
11. Lens according to claim 10 , wherein the volume of gas is equal to between 10% to 20% of the internal volume of the lens.
12. Lens according to claim 1 , further comprising a system for moving the refractive interface by electrowetting effects.
13. Lens according to claim 1 , wherein said arrangement comprises:
First and second transparent windows; and
an intermediate piece having said windows sealed thereto and comprising a central opening, with symmetry of rotation about the axis (Δ), that defines a first chamber containing the first and second liquids.
14. Lens according to claim 13 , wherein said intermediate piece further comprises a second opening that defines an expansion chamber that connects with the first chamber and contains said volume of gas.
15. Lens according to claim 14 , wherein said second opening comprises a groove made in said intermediate piece, with symmetry of rotation about the axis (Δ).
16. Camera module comprising a lens according to claim 1 .
17. Mobile phone comprising a camera module according to claim 16 .
18. Lens according to claim 2 , wherein the first liquid is an insulating liquid.