Abstract: An optical pick up apparatus includes: a first, a second and a third light emitting points for emitting light beams; an optical system for introducing the light beams emitted from the first, second and third emitting points to an objective lens; an objective lens for converging the light beams introduced by the optical system onto an information recording medium; and a light detector for detecting reflected light from the information recording medium, wherein a relationship of ?1<?2<?3 is satisfied, where ?1, ?2 and ?3 denote the respective wavelengths of the light beams emitted from the first, second and third light emitting points, and a relationship of either L1=L2<L3 or L1<L2=L3 or L1<L2<L3 is satisfied, where L1, L2 and L3 denote the respective distances between a reference axis which optically matches a center axis of the objective lens and the first, second and third light emitting points.

Abstract: To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with a fewer parts. Of the light beam output from a semiconductor laser light source 101, a peripheral beam component is entered by a light reflection element 107 into an anterior light monitoring photodetector 103 formed in the vicinity of a semiconductor laser light source 101. Furthermore, the surface of the reflection sphere of the light reflection element is formed anamorphic, and thus condensed to an appropriate size on the photodetector without being focused, providing high frequency responsivity. Furthermore, the light reflection element 107 is placed inclined at a predetermined angle so as to cancel out astigmatic difference of the optical semiconductor laser light source 101.

Abstract: An optical pickup for recording and reproducing information on record media is provided. The pickup includes light sources corresponding to the record media, a drive circuit for driving one of the light sources, a switch for switching a connection between the drive circuit and one of the light sources, and a control circuit for controlling the drive circuit and the switch. With respect to transmission line lengths between the switch and the light sources, the shorter a wavelength of a light source, the shorter the corresponding transmission line length.

Abstract: To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with a fewer parts.

Abstract: To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with fewer parts. Of the output from a semiconductor laser light source, a peripheral component is entered by a light reflection element into an anterior light monitoring photodetector formed in the vicinity of a semiconductor laser light source. Furthermore, the surface of the reflection sphere of the light reflection element is anamorphic, and thus condensed to an appropriate size on the photodetector without being focused, providing high frequency responsivity. Furthermore, the light reflection element is inclined at a predetermined angle to cancel out astigmatic differences of the optical semiconductor laser light source. In addition, the photodetector is placed so that reflected light is bent by an inclination of the light reflection element, reducing the amount of parallel displacement during adjustment of the light reflection element.

Abstract: An optical pickup for recording and reproducing information on a plurality of record media respectively, the pickup has