US 2004/0071072 A1 · Optical head apparatus

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 an amorphic, 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. In addition, the photodetector 103 is placed in the direction so that a reflected light 108 is bent by an inclination of the light reflection element 107, reducing the amount of parallel displacement during adjustment of the light reflection element 107.

Claims30

Dependent claims

An optical head apparatus, comprising:

a semiconductor laser light source;
a photodetector that receives at least one part of light from said semiconductor laser light source;
a light reflection element 107 provided with a peripheral section 203 that reflects peripheral light of the light from said semiconductor, laser light source and condenses it into said photodetector and a central section 202 that transmits central light of the light from said semiconductor laser light source;
and
a condenser lens that condenses the light that passes through said light reflection element onto an optical disc,
wherein:
each surface of the central section of said light reflection element has a flat shape;
and
at least one surface of the peripheral section of said light reflection element has a spherical or non-spherical shape.

6 more elements

An optical head apparatus, comprising:

a semiconductor laser light source;
a plurality of photodetectors placed adjacent to said semiconductor laser light source;
a reflection type hologram element provided with a peripheral section that reflects and diffracts peripheral light of the light from said semiconductor laser light source and condenses it into one of said plurality of photodetectors and a central section that transmits central light of the light from said semiconductor laser light source;
and
a condenser lens that condenses the light that passes through the central section of said reflection type hologram element onto an optical disc,
wherein:
said photodetector that receives said reflected and diffracted light is placed closer, with respect to said semiconductor laser light source, in the direction of the major axis of an ellipse than in the direction of the minor axis of the ellipse of an elliptic far field patter nof outgoing light from said semiconductor laser light source;
and
the photodetector that receives signal light from said optical disc is placed closer, with respect to said semiconductor laser light source, in the direction of the minor axis of the ellipse than in the direction of the major axis of the ellipse of an elliptic far field pattern of outgoing light from said semiconductor laser light source.

6 more elements

Dependencies are inferred from the claim text.

Optical head apparatus

Life of this patent

Optical head apparatus

Life of this patent

Abstract

Claims30