Patent ID: 7586819

Claim:
An optical pickup device, comprising: three light sources having different wavelengths; a condenser lens for condensing light emitted from the light sources onto a recording surface of the optical recording medium; a hologram element for diffracting light reflected by the recording surface after condensed by the condenser lens; and a photo detector having two light receiving portions for receiving separately +1st order light and −1st order light of the light diffracted by the hologram element, wherein the three light sources include a first light source, a second light source and a third light source in descending order of wavelength thereof, light emitted from the first through the third light sources are referred to as first light, second light and third light, respectively, and light spots formed on the photo detector by 0 order light of the diffracted light of the first through the third light are referred to as a first spot, a second spot and a third spot, respectively, then the three light sources is disposed so that a position of either one of the first spot and the third spot matches substantially a position of the second spot, and a position of the other is shifted from the position of the second spot in either one of two diffraction directions including a diffraction direction of the +1st order light and a diffraction direction of the −1st order light, if the positions of the second spot and the third spot match substantially each other, one of the light receiving portions that exists on the side where the first spot is shifted from the second spot is divided into a light receiving area for receiving 1st order diffracted light of the first light and a light receiving area for receiving 1st order diffracted light of the second light and the third light, and if the positions of the second spot and the first spot match substantially each other, one of the light receiving portions that exists on the side opposite to the side where the third spot is shifted from the second spot is divided into a light receiving area for receiving 1st order diffracted light of the third light and a light receiving area for receiving 1st order diffracted light of the first light of the second light.