| 摘要 |
PURPOSE:To easily detect disk information with a miniaturized device by detecting the disk information included in the amplitude distribution of a laser beam returned from an optical disk by a new principle. CONSTITUTION:The laser beam emitted from a laser beam source 1 is reflected on a half mirror 2, and is changed to parallel beams by a collimator lens 3. which generates a laser spot of diffraction margin size on the optical disk 5 by an objective lens 4. The light reflected on the optical disk 5 passes again the objective lens 4 and the collimator lens 3, and is converged on the incident terminal 8 of a double mode channel waveguide 7 formed on a substrate 6 via the half mirror 2, and a laser spot can be image-formed at the terminal. The light of both even and odd modes excited in the double mode channel waveguide 7 by the spot are propagated being interfered with each other, and arrive at a branching point 9, and branched light are propagated through waveguides 10, 11, and are detected independently by optical detectors 13, 13 fixed on the substrate 6. The differential signal 15 of the output of detectors 12, 13 is taken by a differential detector 4, and the edge part of an information pit on the disk 5 can be detected. |
