Variable-focal length lens

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.