Asahi Glass Company, Limited

Ryuichiro Shimizu

Yoshiharu Ooi

Hiromasa Sato

Takuji Nomura

Yuzuru Tanabe

Mitsuo Oosawa

The present application relates to a liquid crystal lens element and an optical head device, in particular order, to a liquid crystal lens capable of switching the focal length among a plurality of different focal lengths according to switching of applied voltage among a plurality of applied voltages, and an optical head device employing the liquid crystal lens, for writing and/or reading an information to/from an optical recording medium.

Liquid crystal lens element and optical head device

A liquid crystal lens element having a lens function is provided, which is small sized without having moving part, and which can stably carry out correction of spherical aberration containing a power component corresponding to focal point change of incident light. A liquid crystal lens element which changes a focal length of light transmitted through a liquid crystalaccording to the magnitude of the voltage applied to the liquid crystalsandwiched between a pair of transparent substratesand, which comprises transparent electrodesandprovided on the respective transparent substratesandfor applying a voltage for the liquid crystal, and a concave-convex portionhaving a saw-tooth-shaped cross-sectional shape having a rotational symmetry about an optical axis and formed on one surface of the transparent electrodewith a transparent material, wherein at least concave portions of the concave-convex portionare filled with the liquid crystalso as to change the substantial refractive index of the liquid crystalaccording to the magnitude of applied voltage.

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Koriyama, Japan

Ryuichiro Shimizu