Diffraction grating element and optical pickup device incorporating the same

An optical pickup device for recording/reproducing information recorded on a recording surface of an optical recording medium based on reflected light from the recording surface, comprising:

• a diffraction grating element for producing a plurality of laser light spots by diffracting laser light emitted from a laser light source in order to perform a tracking control in which the laser light is focused onto a desired track on the recording surface to derive the reflected light, the diffraction grating element comprising:
• a main body provided with a diffraction grating face;
• a holder for holding an outer periphery of the main body, the holder having a first cylindrical outer face an axis of which is coincident with an optical axis of the diffraction grating face;
• and
• an arm portion protruded outward from the first cylindrical outer face of the holder, wherein the main body, the holder and the arm portion are integrally formed as a monolithic structure;
• and
• a frame body comprising:
• a cylindrical mounting hole having a first diameter for rotatably supporting the holder of the diffraction grating element therein;
• and
• an arm receiver for receiving the arm portion of the diffraction grating element such that the arm portion is movable in the circumferential direction of the diffraction grating element about the optical axis in order to perform an angular position adjustment of the main body of the diffraction grating element.

A diffraction grating element comprising:

• a main body provided with a diffraction grating face,
• a holder integrally formed with the main body for holding an outer periphery of the main body, the holder having a cylindrical outer face an axis of which is coincident with an optical axis of the diffraction grating face;
• and
• an arm portion integrally formed with the holder so as to protrudes outward from the outer face of the holder, wherein the arm portion includes a base end portion extending in a radial direction from an outer circumferential face of the holder and a top end portion stepwise extending in the radial direction from the base end portion, wherein a central axis of the base end portion and the top end portion pass through the optical axis of the diffraction grating face.

An optical pickup device for recording/reproducing information recorded on a recording surface of an optical recording medium based on reflected light from the recording surface, comprising:

• a diffraction grating element for producing a plurality of laser light spots by diffracting laser light emitted from a laser light source in order to perform a tracking control in which the laser light is focused onto a desired track on the recording surface to derive the reflected light, the diffraction grating element comprising:
• a main body provided with a diffraction grating face;
• a holder for holding an outer periphery of the main body, the holder having a first cylindrical outer face an axis of which is coincident with an optical axis of the diffraction grating face;
• and
• an arm portion protruded outward from the first cylindrical outer face of the holder, wherein the main body;
• and
• a frame body comprising:
• a cylindrical mounting hole having a first diameter for rotatable supporting the holder of the diffraction grating element therein;
• and
• an arm receiver for receiving the arm portion of the diffraction grating element such that the arm portion is movable in the circumferential direction of the diffraction grating element about the optical axis in order to perform an angular position adjustment of the main body of the diffraction grating element, wherein the arm portion includes a base end portion extending in a radial direction from an outer circumferential face of the holder and a top end portion stepwise extending in the radial direction from the base end portion, wherein a central axis of the base end portion and the top end portion pass through the optical axis of the diffraction grating face.