| 摘要 |
PURPOSE:To simply detect information included in amplitude distribution of laser beam returned from an optical disk based on a new theory by detecting an edge of an information bit of the optical disk utilizing an interference between an even and odd numbered mode through a waveguide for a double mode channel. CONSTITUTION:The beam emitted by a laser beam source 1, and passed through a half mirror 2, a collimator lens 3 and an objective lens 4, forms a spot on the optical disk 5. A reflected beam, retrograding and transmitting through the half mirror 2, forms a spot at a light incident edge 8 of the waveguide for the double mode channel 7 formed on a base 6. The even numbered mode and the odd numbered mode excited by the waveguide 7 propagate while interfering with each other branched at a branch 9, and propagate on waveguides 10, 11, then, are detected independently by a photodetector 12, 13 fixed on the base 6. The edge of the information bit on the optical disk can be detected by detecting a differential signal 15 of outputted signal of detectors 12 and 13 by a differential detector 14. |
