Hologram optical device, compatible optical pickup including the hologram optical device, and optical information storage medium system including the compatible optical pickup

A compatible optical pickup usable with a first information storage medium in accordance with a first standard and a second information storage medium in accordance with a second standard, the first information storage medium and the second information storage medium having different thicknesses, the compatible optical pickup comprising:

• a light source configured to emit an incident light along an optical axis, the incident light comprising a predetermined wavelength;
• an objective lens configured to focus the incident light on an information storage medium that is one of the first information storage medium and the second information storage medium;
• and
• a hologram optical device comprising:
• a first hologram area comprising a hologram that is asymmetric with respect to the optical axis and is configured to:
• diffract the incident light to produce a first 0th order diffractive light and a first 1st order diffractive light;
• and
• diverge the first 1st order diffractive light;
• and
• a second hologram area provided outside of the first hologram area and comprising a hologram configured to:
• diffract the incident light to produce a second 0th order diffractive light and a second 1st order diffractive light;
• and
• converge the second 1st order diffractive light;
• wherein the objective lens is further configured to:
• focus the first 0th order diffractive light to form a first light spot on the optical axis on the information storage medium;
• and
• focus the first 1st order diffractive light to form a second light spot at a predetermined distance from the optical axis in a direction perpendicular to the optical axis.

An optical information storage medium system comprising:

• a compatible optical pickup usable with a first information storage medium in accordance with a first standard and a second information storage medium in accordance with a second standard, the first information storage medium and the second information storage medium having different thicknesses;
• and
• a control portion to control the compatible optical pickup;
• wherein the compatible optical pickup comprises:
• a light source configured to emit an incident light along an optical axis, the incident light comprising a predetermined wavelength;
• an objective lens configured to focus the incident light on an information storage medium that is one of the first information storage medium and the second information storage medium;
• and
• a hologram optical device comprising:
• a first hologram area comprising a hologram that is asymmetric with respect to the optical axis and is configured to:
• diffract the incident light to produce a first 0th order diffractive light and a first 1st order diffractive light;
• and
• diverge the first 1st order diffractive light;
• and
• a second hologram area provided outside of the first hologram area and comprising a hologram configured to:
• diffract the incident light to produce a second 0th order diffractive light and a second 1st order diffractive light;
• and
• converge the second 1st order diffractive light;
• wherein the objective lens is further configured to:
• focus the first 0th order diffractive light to form a first light spot on the optical axis on the information storage medium;
• and
• focus the first 1st order diffractive light to form a second light spot at a predetermined distance from the optical axis in a direction perpendicular to the optical axis.

A method of recording data on/reproducing data from a first information storage medium in accordance with a first standard and a second information storage medium in accordance with a second standard using one compatible optical pickup, the first information storage medium and the second information storage medium having different thicknesses, the method comprising:

• emitting an incident light along an optical axis, the incident light comprising a predetermined wavelength;
• diffracting the incident light with a first hologram that is asymmetric with respect to the optical axis to produce a first 0th order diffractive light and a first 1st order diffractive light;
• focusing the first 0th order diffractive light to form a first light spot on the optical axis on the first information storage medium;
• and
• focusing the first 1st order diffractive light to form a second light spot on the second information storage medium at a predetermined distance from the optical axis in a direction perpendicular to the optical axis.