Patent ID: 8014061

Claim:
A variable-focal length lens, comprising: an electrooptic material made up of a single crystal having inversion symmetry, the electrooptic material having an incident surface of light and an opposing exit surface of light; and electrodes formed on the incident surface of light and on the exit surface of light of the electrooptic material, wherein an optical axis is set so that the light inputted into a portion of the incident surface where the electrodes of the incident surface are not formed, is transmitted through the electrooptic material, and is outputted from a portion of the exit surface where the electrodes of the exit surface are not formed, wherein a part of an electrical field line connecting the electrodes of the incident surface and the electrodes of the exit surface bends in a portion of the electrooptic material sandwiched between the portion of the incident surface and the portion of the exit surface so that an electric field of a portion of the electrooptic material through which the light is transmitted centering on the optical axis is made to vary, and wherein a focus of the light transmitted through the electrooptic material is variable by varying an applied voltage between the electrodes of the incident surface and the electrodes of the exit surface.