Optical element, optical unit, and image-taking apparatus

1. An optical element comprising:

a fluid container which contains an insulative fluid and a conductive fluid that are different in refractive index from each other, mutually immiscible, and optically transparent, the fluid container being transparent to light at least in a predetermined direction;

a first electrode placed in contact with the conductive fluid in the fluid container;

a plurality of transparent second electrodes placed on a transparent surface of the fluid container and insulated from the conductive fluid the fluid container, with a voltage being applied between the first electrode and each of the plurality of transparent second electrodes; and

a plurality of transparent transistors placed on the transparent surface of the fluid container together with the plurality of second electrodes to adjust the voltages applied to the plurality of second electrodes.

2. The optical element according to claim 1 , wherein an inner surface of the fluid container is covered at least partially with a coating whose wettability by the conductive fluid is lower than by the insulative fluid.

3. The optical element according to claim 1 , wherein the plurality of second electrodes are arranged in a matrix.

4. An optical unit comprising:

a fluid container which contains an insulative fluid and a conductive fluid that are different in refractive index from each other, mutually immiscible, and optically transparent, the fluid container being transparent to light at least in a predetermined direction;

a first electrode placed in contact with the conductive fluid in the fluid container;

a plurality of transparent second electrodes placed on a transparent surface of the fluid container and insulated from the conductive fluid in the fluid container, with a voltage being applied between the first electrode and each of the plurality of transparent second electrodes;

a plurality of transparent transistors placed on the transparent surface of the fluid container together with the plurality of second electrodes to adjust the voltages applied to the plurality of second electrodes; and

a control section which controls refraction of light passing through the fluid container by applying individually drive signals to the plurality of transistors separately, thereby applying a voltage between the first electrode and each of the plurality of second electrodes, and thereby changing shape of a boundary surface between the insulative fluid and the conductive fluid.

5. An image-taking apparatus, comprising:

a fluid container which is transparent to light at least in a predetermined direction and contains a fluid;

an optically transparent dispersion medium contained in the fluid container;

an optically transparent dispersoid which, being dispersed in the dispersion medium and different in refractive index from the dispersion medium, achieves an electrophoretic movement in the dispersion medium by application of an electric field

a first electrode;

a plurality of transparent second electrodes placed on a transparent surface of the fluid container, with a voltage being applied between the first electrode and each of the plurality of transparent second electrodes;

a plurality of transparent transistors placed on the transparent surface of the fluid container together with the plurality of second electrodes to adjust the voltages applied to the plurality of second electrodes;

a control section which controls refraction of light passing through the fluid container by applying individually drive signals to the plurality of transistors separately, thereby applying a voltage between the first electrode and each of the plurality of second electrodes, and thereby changing shape of a boundary surface between the insulative fluid and the conductive fluid; and

an image pickup device which generates an image signal of subject light that forms an image on a surface of the image pickup device after passing through the fluid container.