Variable-focus lens
The invention relates to a variable-focus lens comprising two opposing walls ( 21, 22 ) which are orthogonal to the axis of the lens and which define a space containing an isolating liquid ( 31 ) on the first wall ( 22 ) and a conductive liquid ( 32 ) which covers the isolating liquid and which comes into contact with the second wall ( 21 ). The surface ( 24 ) of the first wall ( 22 ) has high wettability for the isolating liquid and low wettability for the conductive liquid, while the surface ( 23 ) of the second wall ( 21 ) has high wettability for the conductive liquid and low wettability for the isolating liquid.
1. A variable-focus lens comprising:
first and second transparent insulating plates ( 21 , 22 ) placed facing each other orthogonally to the axis of the lens;
in a space defined between said plates, an insulating liquid ( 31 ) on the first plate ( 22 ), and a conducting liquid ( 32 ) covering the insulating liquid and coming into contact with the second plate ( 21 ), the surface ( 24 ) of the first plate ( 22 ) having high wettability for the insulating liquid and low wettability for the conducting liquid, and the surface ( 23 ) of the second plate ( 21 ) having high wettability for the conducting liquid and low wettability for the insulating liquid; and
a conducting plate ( 26 ) deposited on the first plate and provided with a central opening in which the insulating liquid is placed, the conducting plate being, on the inside of the cell, coated with an insulating coating ( 27 ), the wettability characteristics of which are optimized for obtaining the desired miniscus shape at rest between the insulating liquid and the conducting liquid.
2. The lens as claimed in claim 1 , in which the surface of at least one of the walls is coated with a layer ( 23 , 27 ) giving it the desired wettability characteristics.
3. The lens as claimed in claim 1 , in which the wettability of the surface ( 24 ) of the first wall ( 22 ) is such that the contact angle of a drop of the insulating liquid in the conducting liquid for this surface is less than 75°.
4. The lens as claimed in claim 1 , in which the wettability of the surface ( 23 ) of the second wall ( 1 , 11 , 21 ) is such that the contact angle of a drop of the conducting liquid in the insulating liquid for this surface is less than 75°.