Variable focal lens

1. A variable focus lens having an optical axis, comprising: a housing that defines a chamber for containing a conductive liquid and an insulating liquid, the two fluids having different refractive indices and contacting one another to form a surface of contact that comprises a deformable refractive surface having a periphery that is caused to move along the wall of the housing as a function of an applied electric voltage (V), wherein the housing comprises:

an upper wall portion inclined at first angle relative to a plane perpendicular to the optical axis (Δ) of the lens;

a lower wall portion inclined at a second angle relative to said plane, wherein the second angle is greater than the first angle;

a junction zone (B′) between the upper and lower wall portions, wherein the surface of the housing at the junction zone presents a variation in wall inclination relative to the plane perpendicular to the optical axis of the lens sufficient to substantially block movement of the deformable refractive surface at said junction zone upon an incremental increase in applied voltage.

2. A lens according to claim 1 , wherein the upper portion is inclined with respect an axis parallel to the optical axis (Δ).

3. A lens according to claim 1 , wherein the lower portion has a generally cylindrical shape with an axis at least approximately parallel to the optical axis (Δ).

4. A lens according to claim 1 , wherein the lower portion has a generally inclined shape with respect to an axis parallel to the optical axis (Δ), and wherein the angle of inclination of the lower portion relative to the plane perpendicular to the optical axis (Δ) is greater than the angle of inclination of the upper portion relative to the plane perpendicular to the optical axis, at the junction between the upper portion and the lower portion.

5. A lens according to claim 1 , wherein the junction zone (B′) has a continuously variable curvature.

6. A lens according to claim 1 , wherein the junction zone has a curved surface.

7. A lens according to claim 6 , wherein the radius of said curved surface is less than about 0.1 mm.

8. A lens according to claim 7 , wherein said radius is less than about 0.05 mm.

9. A lens according to claim 6 , wherein the housing comprises a bottom at least approximately perpendicular to the optical axis (Δ) and extending from said lower portion, the bottom of the housing comprising, at its periphery, a surface portion of the insulating layer covering the metallic layer.

10. A lens according to claim 1 , wherein the upper portion and the lower portion correspond to surface portions of an insulating layer covering a metallic layer forming an electrode, itself deposited on an insulating substrate.

11. An optical device including a variable focal length lens according to claim 1 .

12. A mobile phone including an optical device according to claim 11 .

13. A variable focus lens having an optical axis, comprising: a housing that defines a chamber for containing a conductive liquid and an insulating liquid, the two fluids having different refractive indices and contacting one another to form a surface of contact that comprises a deformable refractive surface having a periphery that is caused to move along the wall of the housing as a function of an applied electric voltage (V), wherein the housing comprises:

a light-exit wall oriented at least essentially perpendicular to the optical axis;

a first side wall portion having a first orientation relative to a plane perpendicular to the optical axis (Δ) of the lens;

a second side wall portion, adjacent to said light-exit wall, having a second orientation relative to said plane;

a junction zone (B′) between the first and second side wall portions, wherein the surface of the housing at the junction zone presents a variation in a wall characteristic sufficient to substantially block movement of the deformable refractive surface at said junction zone upon an incremental increase in applied voltage.