Abstract: An optical disc device that irradiates an optical beam to an optical disc including a recording layer for recording information and a positioning layer provided with a track for identifying a recording position of the information on the recording layer, includes: objective lens that converges a predetermined positioning optical beam to adjust the optical beam to a desired track on the positioning layer and converges an information optical beam that shares an optical axis with the positioning optical beam on the recording layer; moving section that moves the objective lens in a tracking direction which is substantially orthogonal to the track to make a focal point of the positioning optical beam to follow the desired track; a detection section that detects a moving amount of the objective lens to the tracking direction; and correction section that corrects a converging position of the information optical beam in accordance with the moving amount.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: A laminated wave plate having a wider bandwidth at a desired retardation is provided. A laminated wave plate 1 includes a first wave plate 2 and a second wave plate 3 that are laminated each other so that respective optical axes of the first wave plate and the second wave plate are intersected each other at an angle of 51.5 degrees when the first wave plate has a retardation ?1 of 360 degrees and an in-plane azimuth of ?8 degrees, while the second wave plate has a retardation ?2 and an in-plane azimuth of 43.5 degrees. Thus the laminated wave plate 1 functions as a desired retardation ?2 in a wavelength from 600 nm to 800 nm as a whole.

Abstract: A device reads and/or records marks in a track on a record carrier via near field optical recording. The device has a head including a lens to be positioned at a near field distance from a surface of the record carrier. An air gap controller is for controlling an air gap (81) between the lens and the surface, and has an approach mode for bringing the lens from a remote distance in the far field to the near field distance. Thereto the controller provides an increasing periodical excitation signal (83) for generating a sequence of approach instants at which the lens approaches the surface. At the approach instants the lens has substantially zero velocity (84). The sequence of approach instants brings the lens subsequently closer to the surface. When the lens enters in the near field range at one of the approach instants, the air gap controller is switched to closed loop mode.

Abstract: In an optical head operable to record to and read from an optical recording medium, a beam emitted by a light-emitting element is reflected toward the light-emitting element by a first reflective mirror, and this reflected beam is reflected toward the optical recording medium by a second reflective mirror and focused on a recording surface of the optical recording medium. In this case, the first reflective mirror blocks a principal ray of the beam traveling toward the optical recording medium from the second reflective mirror, and the second reflective mirror consists of a plurality of concentric annular mirrors centered on the principal ray of the beam and separated from each other by a predetermined interval.