| 摘要 |
PURPOSE:To simplify the whole constitution of an optical system and to perform stable signal reproduction by using an optical circulator which has at least three ports, and separating incident light to an information recording carrier from reflected light from the information recording carrier. CONSTITUTION:Laser light from a semiconductor laser SL3 is polarized by an acoustooptical polarizer 11 in three directions, and those components illuminate the 1st port PA of an optical circulator 12, emitted from the 2nd port PB, and focused on a magnetic disk surface 4 through an objective L12 to form three spots. Then while the reflected light from the magnetic disk surface 4 is emitted from the 2nd port PB of the optical circulator 12 through the 3rd port PC, the current plane of polarization is preserved, so a rotary component of the plane of polarization by magnetic Kerr effect is also transmitted with fidelity, and the reflected light from the magnetic disk surface 4 never returns to the semiconductor laser SL3 through the 1st port PA, thus preventing the operation from being unstable. |
