HOLOGRAM OPTICAL DEVICE, COMPATIBLE OPTICAL PICKUP INCLUDING THE HOLOGRAM OPTICAL DEVICE, AND OPTICAL INFORMATION STORAGE MEDIUM SYSTEM INCLUDING THE COMPATIBLE OPTICAL PICKUP

摘要

A hologram optical device, a compatible optical pickup including the hologram optical device, and an optical information storage medium system including the compatible optical pickup are provided. The hologram optical device includes: a first hologram area having a hologram that is asymmetric with respect to an optical axis to diffract an incident light in a 0<SUP>th</SUP> order diffractive light and a 1<SUP>st</SUP> order diffractive light, wherein light spots are formed by focusing the 0<SUP>th</SUP> order and 1<SUP>st</SUP> order diffractive lights using a lens. Accordingly, a light spot of the 1<SUP>st</SUP> order diffractive light is formed at a position separated from an optical axis of the lens when a light spot formed by the 0<SUP>th</SUP> order diffractive light is formed on the optical axis of the lens.