Objective lens unit, optical pickup device equipped with the same and optical information recording and reproducing apparatus

摘要

An objective lens unit (1) for use in an optical pickup apparatus, includes a first optical element (B) arranged opposite to the optical information recording medium (M1,M2,M3); a second optical element (A) arranged at a light source side of the first optical element (B) opposite to the first optical element (B) and including a ring-shaped structure in which plural ring-shaped zones are formed on at least one optical surface of the second optical element such that neighboring ring-shaped zones cause a predetermined optical path difference for incident rays; and each of the first and second optical elements having an optical functional section and a flange section formed around the optical functional section (A1,B1), wherein the flange section (B2) of the first optical element and the flange section (A2) of the second optical element are formed so as to fix the first and second optical elements at predetermined respective relative positions. <IMAGE>