Patent ID: 6778474
Filing Date: 2004-08-17
Classification: G11B

Abstract:
An optical pickup device comprising:a light source having at least a spot for emitting a flux of light; an objective lens for converging the flux of light on the signal recording surface of an optical recording medium having a series of helical or coaxial alternating lands and grooves defining a track pitch and irradiating the signal recording surface with the flux of light; and a photo-detection means for receiving the flux of light reflected from the signal recording surface of the optical recording medium; the flux of light emitted from the light source producing a main flux of light for forming a main spot on the signal recording surface of the optical recording medium for the purpose of recording and/or reproducing an information signal and an auxiliary flux of light for forming an auxiliary spot on the signal recording surface of the optical recording medium at a position separated from the main spot by an amount equal to a multiple of one-half of the track pitch; and the auxiliary flux of light travelling a distance between the objective lens and the focussed point thereof different from that of the main flux of light.