| 摘要 |
PURPOSE:To prevent malfunction occurring by preventing reflected return light from a recording plane by providing an optical isolator unit at an irradiation optical beam path between two lens systems at an irradiating light source side and an optical signalizing recording medium side. CONSTITUTION:An optical isolator 20 in which a polarizer 21, a 45 deg. Faraday rotary element 22, and an analyzer 23 are arranged sequentially fitting in the optical path of an irradiation optical beam between a collimator lens 3 and a beam shaping prism 19and magnets 24 are arranged in the periphery of the rotary element 22 so as to apply a magnetic field on the rotary element 22 almost along the optical path is provided. And the reflected return light including recording information from the magnetic recording plane 2a of a magnetooptical disk 2 is branched to ordinary light and extraordinary light by the optical isolator 20, and photodiodes 11 and 15 are provided at the positions of two points where respective light is focused with the collimator lens 3, and the photodiodes 11 and 15 are connected to the input of an arithmetic circuit 17, respectively, then, a recording signal can be obtained from the output of the circuit 17. A noise due to the reflected return light can be eliminated by providing the optical isolator unit 20. |
