Reflection type compound prism and optical pickup apparatus employing the same

An optical pickup apparatus comprising:

• a light source which emits a light beam;
• an objective lens which condenses light to form a light spot on a recording surface of a recording medium;
• an actuator which drives the objective lens in focus and/or track directions;
• a reflection type compound prism which:
• reduces a size of the emitted light beam with respect to a first direction which is perpendicular to a reference plane by using a difference in angles between surfaces of the prism,
• propagates the reduced size light beam adjacent the actuator, and
• reflects the light beam in the first direction toward the objective lens using a surface forming an angle less than 45° with respect to the reference plane;
• and
• a photodetector which photoelectrically converts the light beam reflected by the recording medium and passed through the objective lens and the reflection type compound prism.

An optical pickup for recording/reproducing a signal to/from a recording medium, the optical pickup comprising:

• a light source which emits a light beam;
• and
• a reflection type compound prism, which communicates the light beam toward the optical recording medium, the reflection type compound prism comprising:
• a first surface which transmits the light beam,
• a second surface which reflects the transmitted light beam to be inclined with respect to a reference plane and reduces a size of the transmitted light beam in a direction perpendicular to the reference plane,
• third and fourth surfaces disposed parallel to the reference plane and which propagate the reduced size light beam by total internal reflection, and
• a fifth surface which reflects the propagated reduced size light beam toward the optical recording medium and adjusts a size of the propagated reduced size light beam.

An optical pickup for recording/reproducing a signal to/from a recording medium, the optical pickup comprising:

• a light source which emits a light beam;
• and
• a compound prism, comprising:
• a first surface,
• a second surface, oriented at a first angle with respect to a first surface, which transmits the light beam,
• a third surface oriented at a second angle with respect to the second surface and which reflects the light beam toward the first surface by total internal reflection,
• a fourth surface, spaced apart from the first surface, which together with the first surface propagates the light beam by total internal reflection, and
• a fifth surface, oriented at an angle in a range including 20 degrees and 40 degrees with respect to the first surface, which reflects the propagated light beam toward the optical recording medium.