HOLOGRAM ELEMENT FOR DETECTING SPHERICAL ABERRATION OF OPTICAL PICKUP SYSTEM, CONCERNED WITH COMPENSATING FOR THE ABERRATION WHILE ENABLING AUTOMATIC FOCUSING CONTROL

摘要

PURPOSE: A hologram element for detecting a spherical aberration of an optical pickup system is provided to configure at least more than one mixed pattern area where different hologram patterns are overlapped to detect an amount of a spherical aberration with optical information from an optical detector, thereby compensating for the aberration while enabling an AF(Automatic Focusing) control. CONSTITUTION: A collimating lens(21) converts an optical beam generated from a light source(20) into a parallel light. An objective lens(22) condenses the parallel light into an optical disk(10). A beam splitter(23) separates an incident light from a reflected light. Coupling lenses(24) condense the separated reflected light. A hologram element(25) is formed with hologram patterns. An optical detector(26) detects optical information and spherical aberration information stored in the optical disk(10) through an interference waveform mapped by the hologram element(25).