| 摘要 |
PURPOSE:To eliminate the effects of variation of the atmospheric humidity against an optical head device by providing the optical elements before and after a plastic lens in order to shield the plastic lens from the open air by those optical elements. CONSTITUTION:A plastic condenser lens 4 is sealed up into a lens barrel 9 so that the lens 4 is shielded from the open air by two glass plates 8 set at the front end back positions in the direction of an optical axis. Here the glass plates 8 are set vertical to the optical axis. Thus an optical head device is never affected by the atmospheric moisture change and can maintain the satisfactory recording/reproducing characteristics. |
