Pickup for magneto-optical recording medium

#1. Field of the Invention

#The present invention relates to a pickup for a magneto-optical recording medium, for recording information into magneto-optical recording media and/or for reproducing information from the magneto-optical recording medium.

#2. Description of the Related Art

#Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:

#FIG. 1 is a side view of an arrangement illustrating, in a simplified manner, the constitution of a pickup for a magneto-optical recording medium according to a first embodiment of the invention;

#FIG. 2 is a sectional view illustrating the constitution of a light-branching diffraction element;

#Now referring to the drawings, preferred embodiments of the invention are described below.

#FIG. 1 is a side view of an arrangement illustrating, in a simplified manner, the constitution of a pickup 51 for a magneto-optical recording medium according to a first embodiment of the invention. The pickup 51 for a magneto-optical recording medium (hereinafter simply referred to as a pickup) includes a light source 52, an objective lens 54, a light-branching diffraction element 55, first and second polarization/separation elements 56 and 57, first and second light detectors 58 and 59, a first phase compensation element 60, a second phase compensation element 61, and a collimator lens 62 the light source 52 emits light. The objective lens 54 collects the light emitted from the light source 52 onto an information recording surface of a magneto-optical recording medium 53 (often called magneto-optical disk). The light-branching diffraction element 55 is disposed between the light source 52 and the objective lens 54 and diffracts the light (often called return light) reflected by the magneto-optical recording medium 53 and has passed through the objective lens. The first and second polarization/separation elements 56 and 57 polarize and separate + first-order diffracted light 64 and − first-order diffracted light 65 diffracted through the light-branching diffraction element 55, respectively. The first and second light detectors 58 and 59 receive and detect the light separated by the first and second polarization/separation elements 56 and 57, respectively. The first phase compensation element 60 is provided on an optical path of the + first-order diffracted light 64 between the light-branching diffraction element 55 and the first polarization/separation element 56. The second phase compensation element 61 is provided on an optical path of the − first-order diffracted light 65 between the light-branching diffraction element 55 and the second polarization/separation element 57. The collimator lens 62 is provided between the light-branching diffraction element 55 and the objective lens 54 The pickup 51 is used for recording information into the magneto-optical recording medium 53 and/or for reproducing information from the magneto-optical recording medium 53.

#As for the three-dimensional azimuth axes drawn in FIG. 1 in a state where the magneto-optical recording medium 53 is mounted on the pickup 51, the x-axis represents a direction of radius of the magneto-optical recording medium 53, the y-axis represents a direction of a tangential line of a track formed in the information recording surface of the magneto-optical recording medium 53, and the z-axis represents a direction that meets at right angles with the x-axis and the y-axis. In the pickup 51 of this embodiment, the z-axis is in agreement with the axial direction of light emitted from the light source 52. The notation of x-, y- and z-axes is commonly used throughout the specification.