| 摘要 |
PURPOSE:To increase the utilization efficiency of the light from a semiconductor laser, to efficiently focus a light on a recording face and to improve the recording/reproducing characteristics by converting the light from a semiconductor laser into the optical distribution that the optical strength on an optical axis is small and on the peripheral edge strong. CONSTITUTION:The light emitted from a semiconductor laser 1 is converted into the annular light whose optical strength on the optical axis is small and on the peripheral edge strong by an optical distribution convertor 3 (made by superposing conical or truncated conical transparent members having two same apex angles) via a condensing lens 2. The light thereof is condensed on the optical disk recording face 7 forming a pregroove via a polarized beam splitter (PBS) 4, 1/4 wavelength plate 5 and diaphragm lens 6. The reflection light thereof is split by a half mirror 9 via a convex lens 8 through the PBS 4 with its retrograde. The light reflected by the half mirror 9 is made incident on the optical detector 10 installed at the front of a focus and a transmitted light is made incident on the optical detector 11 installed at the rear part of the focus. |
