Abstract: A pickup lens with a phase compensator is composed of a condenser lens and a phase compensator. At least one surface of the condenser lens has a step-like annular zone structure to compensate wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t1 with a laser beam having a wavelength ?1 and wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t2 with a laser beam having a wavelength ?2. The phase compensator compensates wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t3 with a laser beam having a wavelength ?3.

Abstract: An optical pickup lens focuses laser beams having different wavelengths ?1, ?2 and ?3 on at least three kinds of optical discs. At least one side of the optical pickup lens has a concentric loop zonal structure for compensating wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t1 by the laser beam having the wavelength ?1 and wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t2 by the laser beam having the wavelength ?2. When recording or reproducing an optical disc having a substrate thickness t3 by the laser beam having the wavelength ?3, a phase difference given to the laser beam having the wavelength ?3 due to the concentric loop zonal structure is about 0.15? or smaller.

Abstract: An optical pickup system for reading information of three kinds of optical recording media. The optical pickup system has a wavelength selective filter that includes an outer area for shielding one light beam of light beams having three kinds of wavelengths and an inner area for allowing all the light beams to pass through. The optical pickup system also has an objective lens that focuses each light beam having passed through the wavelength selective filter on each light recording medium. An optical head and an optical disk apparatus have the optical pickup system.

Abstract: A pickup lens with a phase compensator is composed of a condenser lens and a phase compensator. At least one surface of the condenser lens has a step-like annular zone structure to compensate wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t1 with a laser beam having a wavelength ?1 and wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t2 with a laser beam having a wavelength ?2. The phase compensator compensates wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t3 with a laser beam having a wavelength ?3.

Abstract: A pickup lens with a phase compensator is composed of a condenser lens and a phase compensator. At least one surface of the condenser lens has a step-like annular zone structure to compensate wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t1 with a laser beam having a wavelength ?1 and wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t2 with a laser beam having a wavelength ?2. The phase compensator compensates wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t3 with a laser beam having a wavelength ?3.

Abstract: An objective lens optical system includes a light beam splitting element and an objective lens and is configured to focus a light beam with a wavelength ? on an information recording surface of a first optical recording medium as a dual/double layer disc having a transparent substrate with a thickness t1 and to focus a light beam with a wavelength ? on an information recording surface of a second optical recording medium as a dual/double layer disc having a transparent substrate with a thickness t2 (t1<t2). The light beam splitting element is sectioned into regions that are designed to focus a light beams on an information recording surface of either one of the first optical recording medium and the second optical recording medium. Either one region has a negative or positive power so that a light focus position of a light beam having passed through the first region by the objective lens and a light focus position of a light beam having passed through the second region by the objective lens are different.

Abstract: An objective lens optical system focuses a light beam with a wavelength ?1 on an information recording surface of a first optical recording medium including a transparent substrate with a thickness t1, a light beam with the wavelength ?1 on an information recording surface of a second optical recording medium including a transparent substrate with a thickness t2, and a light beam with a wavelength ?3 on an information recording surface of a third optical recording medium including a transparent substrate with a thickness t3, by using a refraction action. Sectioning the area of the objective lens optical system is applied to a compatible technique for the same wavelengths, and generating an aberration for canceling a chromatic aberration caused by a difference in wavelength ? of the light beam is applied to a compatible technique for different wavelengths.

Abstract: There is provided an optical pickup system which includes a first light source emitting first light having a wavelength ?1, a second light source emitting second light having a wavelength ?2 longer than the wavelength ?1, a third light source emitting third light having a wavelength ?3 longer than the wavelength ?2, and an objective lens focusing the first light on an information recording surface of a first optical recording medium, focusing the second light on an information recording surface of a second optical recording medium, and focusing the third light on an information recording surface of a third optical recording medium. In the optical pickup system, at least one lens surface of the objective lens is divided into a plurality of concentric sections with an optical axis, having a step at each boundary between the sections, each of the sections has a different aspherical shape and m1>m2>0 and ?0.060?m3??0.

Abstract: A lens surface of an objective lens is divided into a plurality of zones concentric about an optical axis. The lens surface includes an inner area and an outer area located outside the inner area. The inner area focuses the first light beam on the information recording surface of the first optical recording medium and focuses the second light beam on the information recording surface of the second optical recording medium. The outer area causes the first light beam to become flare and focuses the second light beam on the information recording surface of the second optical recording medium.

Abstract: An optical pickup lens focuses laser beams having different wavelengths ?1, ?2 and ?3 on at least three kinds of optical discs. At least one side of the optical pickup lens has a concentric loop zonal structure for compensating wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t1 by the laser beam having the wavelength ?1 and wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t2 by the laser beam having the wavelength ?2. When recording or reproducing an optical disc having a substrate thickness t3 by the laser beam having the wavelength ?3, a phase difference given to the laser beam having the wavelength ?3 due to the concentric loop zonal structure is about 0.15 ? or smaller.

Abstract: A pickup lens with a phase compensator is composed of a condenser lens and a phase compensator. At least one surface of the condenser lens has a step-like annular zone structure to compensate wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t1 with a laser beam having a wavelength ?1 and wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t2 with a laser beam having a wavelength ?2. The phase compensator compensates wavefront aberration generated when recording and reproducing data on an information recording medium having a substrate thickness of t3 with a laser beam having a wavelength ?3.

Abstract: An optical pickup system for reading information of three kinds of optical recording media. The optical pickup system has a wavelength selective filter that includes an outer area for shielding one light beam of light beams having three kinds of wavelengths and an inner area for allowing all the light beams to pass through. The optical pickup system also has an objective lens that focuses each light beam having passed through the wavelength selective filter on each light recording medium. An optical head and an optical disk apparatus have the optical pickup system.

Abstract: An optical pickup system for reading information of three kinds of optical recording media. The optical pickup system has a wavelength selective filter that includes an outer area for shielding one light beam of light beams having three kinds of wavelengths and an inner area for allowing all the light beams to pass through. The optical pickup system also has an objective lens that focuses each light beam having passed through the wavelength selective filter on each light recording medium. An optical head and an optical disk apparatus have the optical pickup system.

Abstract: An information recording medium, an information recording/reproduction head, and an information storage device are provided for performing a track servo operation at a smaller track pitch than that conventionally used without reducing the widths of servo burst patterns. The widths of servo burst patterns (107, 108, 109, 110) are increased over a track pitch (TP) and the end of the servo burst pattern is disposed so as not to coincide with a center line (111) of an information track. In addition, a servo magnetic head (112) and a reproduction magnetic head (113) are implemented in one magnetoresistance element (159).

Abstract: An optical information reproducing method for reproducing information recorded at at least one mark on an optical information medium. The method includes irradiating a laser to the optical information medium, detecting a reflected beam reflected from the optical information medium, and reproducing information recorded on the optical information medium from an output signal of a detector which detects the reflected beam. The step of reproducing information is changed in dependence upon a length of the mark of the optical information medium.

Abstract: An optical information reproducing method for reproducing information recorded at at least one mark on an optical information medium. The method includes irradiating a laser to the optical information medium, detecting a reflected beam reflected from the optical information medium, and reproducing information recorded on the optical information medium from an output signal of a detector which detects the reflected beam. The step of reproducing information is changed in dependence upon a length of the mark of the optical information medium.

Abstract: An optical information reproducing method for reproducing information recorded at at least one mark on an optical information medium. The method includes irradiating a laser to the optical information medium, detecting a reflected beam reflected from the optical information medium, and reproducing information recorded on the optical information medium from an output signal of a detector which detects the reflected beam. The step of reproducing information is changed in dependence upon a length of the mark of the optical information medium.

Abstract: An optical information reproducing method for reproducing information recorded at at least one mark on an optical information medium. The method includes irradiating a laser to the optical information medium, detecting a reflected beam reflected from the optical information medium, and reproducing information recorded on the optical information medium from an output signal of a detector which detects the reflected beam. The step of reproducing information is changed in dependence upon a length of the mark of the optical information medium.

Abstract: Information recorded on an optical disk in accordance with a mark edge recording scheme is detected by a center detection circuit which includes a bisected beam detector to obtain a mark center position signal. In succession, the mark center position signal is converted to a mark edge position signal by an edge signal generating circuit. An information reproducing device is implemented which is capable of performing reproducing operation on an information medium conforming to a high-density mark edge recording scheme and which is stable against changes of recording paper, recording sensitivity and reflectivity.