Catadioptric objective system and objective system

A catadioptric objective system used for storage/reproduction of information by use of an optical near field, the catadioptric objective system comprising:

• a catadioptric objective lens comprising a first surface and a second surface, the first surface having a positive optical power and transmitting incident rays, the second surface having a positive optical power, reflecting incident rays and having a plane portion in a center;
• and
• a light transmitting plate comprising a third surface and a fourth surface which are substantially parallel to each other, the third surface being bonded to the second surface of the catadioptric objective lens by an adhesive agent;
• wherein incident rays pass through the first surface of the catadioptric objective lens, are reflected by the second surface, are reflected by the first surface, pass through the plane portion of the second surface and are converged in vicinity of the fourth surface of the plate, and
• wherein the following condition is fulfilled:
• d/D<0.5
• wherein D is a diameter of an entrance pupil, and d is a diameter of a bundle of rays passing through the second surface.

An objective system for storing/reproducing information in/from a storage medium, said objective system comprising:

• a catadioptric optical element comprising:
• a first surface having a positive optical power and transmitting incident rays;
• and
• a second surface having a positive optical power, reflecting incident rays and having a plane portion in a center;
• and
• a light transmitting plate comprising:
• a third surface bonded to the second surface of the catadioptric objective lens by an adhesive agent;
• and
• a fourth surface substantially in parallel to the third surface, wherein:
• incident rays extending approximately to the periphery of the catadioptric objective lens pass through the first surface of the catadioptric optical element, are reflected by the second surface, are reflected by the first surface, pass through the plane portion of the second surface and are converged in vicinity of the fourth surface;
• and
• by use of the converged rays, information is stored/reproduced in/from a storage medium.