Patent ID: 8619522

Claim:
An optical pickup comprising: a light source; an optical system which forms multiple light beams based on the light that has been emitted from the light source and which converges a write beam and a read beam, included in the multiple light beams, thereby forming a main spot and a sub-spot, respectively, on an optical storage medium, the optical system converging the write and read beams onto the optical storage medium so that the main spot moves through the same region on the optical storage medium ahead of the sub-spot; and a detector which senses the write and read beams that have been reflected from the optical storage medium and which generates electrical signals, wherein the detector includes a first photodiode that receives reflected light that has left the main spot on the optical storage medium and a second photodiode that receives only a portion of the reflected light that has left the sub-spot on the optical storage medium, a signal component representing marks, which have been recorded on the storage medium by the write beam, included in the reflected light received by the first photodiode is larger than that included in the portion of reflected light received by the second photodiode.