Patent ID: 6418109
Filing Date: 2002-07-09
Classification: G11B

Abstract:
An optical recording/reproduction apparatus comprising:an irradiation optical system for irradiating a light beam from a light source onto a predetermined track of an optical recording medium having a plurality of neighboring tracks as a fine light spot so as to perform recording/reproduction of information or reproduction of information by time-serially scanning a plurality of marks located on the predetermined track; a detection optical system for detecting a returned light beam from the optical recording medium; and mask means, arranged in a far field region sufficiently separated from a focal plane of said detection optical system in an optical path of said detection optical system, for masking marginal rays, in the track direction, of the returned light beam, wherein said mask means satisfies the following relation: 0.77âˆ’0.1Â·(d2/m)2/A2<1.07âˆ’0.1Â·(d2/m) â€ƒfor 02/A2<1 where A2: the beam diameter of the returned light beam in the track direction B2: the aperture width of said mask means for masking the returned light beam in the track direction d2: the 1/e2 diameter of the light spot on the optical recording medium in the track direction m: the shortest mark length on the optical recording medium whereby information reproduced by the light spot from a mark adjacent to a predetermined mark on the predetermined track upon reproduction of the predetermined mark located on the predetermined track by the light spot is reduced.