Optical lens with variable focal length
The invention concerns an optical lens comprising a cavity formed by two transparent windows and a peripheral frame positioned in between, said cavity containing first and second liquids, non miscible, forming an interface, said interface being movable by electrowetting on a wall of said peripheral frame by application of a voltage between first and second electrodes, wherein said wall has a non symmetrical revolution surface, the geometrical shape of which is calculated such that said interface is of a predetermined shape, for example substantially spherical, for at least one value of said voltage.
1. An optical lens comprising:
a cavity formed by two transparent windows and a peripheral frame positioned in between the two transparent windows, said cavity containing first and second liquids, non-miscible, forming an interface, said interface being movable by electrowetting on a wall of said peripheral frame by application of a voltage between first and second electrodes,
wherein said wall has a non-symmetrical revolution surface, the geometrical shape of which is calculated such that said interface is of a substantially spherical or elliptical shape for at least one value of said voltage.
2. The optical lens according to claim 1 , wherein the geometrical shape of the wall is calculated using finite elements method calculation.
3. The optical lens according to claim 1 , wherein at least one of the windows is a fixed lens.
4. The optical lens according to claim 1 , wherein the cavity and the electrodes are made of transparent material.
5. A spectacles comprising at least one optical lens according to claim 1 , and adjustment means to control the focal length of said optical lens.
6. The spectacles according to claim 5 , wherein the adjustment means are manual.
7. The spectacles according to claim 5 , wherein the adjustment means are automatic and comprise a distance measurement device to estimate the distance of an object to be viewed by an user of the spectacles.
8. The spectacles according to claim 5 , wherein the adjustment means are automatic and comprise a device for measuring the convergence of an user's eyes.
9. The spectacles according to claim 5 , further comprising a power control for electrical alimentation of the adjustment means.
10. The spectacles according to claim 9 , wherein the power control is an autonomous power supply arranged on the spectacles.
11. A method for forming an optical lens, comprising:
providing a cavity formed by two transparent windows and a peripheral frame positioned in between, said cavity containing first and second liquids being non-miscible and forming an interface, said interface being movable by electrowetting on a wall of said peripheral frame by application of a voltage between first and second electrodes, said wall having a non-symmetrical revolution surface; and
calculating the geometrical shape of said wall such that a substantially spherical or elliptical shape of the interface is generated for at least one value of said voltage.
12. The method for forming an optical lens according to claim 11 , wherein the geometrical shape of said wall is calculated using finite elements method calculation.
13. The method for forming an optical lens according to claim 11 , wherein the optical lens has a variable optical power.
14. The method for forming an optical lens according to claim 13 , wherein the geometrical shape of said wall is calculated such that the interface is substantially spherical for n positions of the interface on said wall, n being greater than or equal to two.