| 摘要 |
PURPOSE:To attain the recording, reproduction and erasion of information by means of a compact and light-weight optical head, by irradiating the beam light in an erasion mode for a long period of time with the luminous intensity reduced less than a record mode and at the same time reducing the scan speed of the beam light less than the record and reproduction modes. CONSTITUTION:When the erasion data is supplied, a motor 2 is revolved at a low speed. Then a control part 33 supplies the erasion data to a modulation circuit 36. The circuit 36 modulates the erasion data and supplies it to a laser driver 37. The driver 37 delivers the beam signals for emission of beam light of strong, weak and medium levels in response to the signals supplied. In this case, the mobile contact of a switch circuit 38 is sitched to the side C and therefore the beam signal of medium luminous intensity is supplied to a semiconductor laser oscillator 21 from the driver 37. Then the beam light of a medium level is produced from the oscillator 21 and led to a polarized beam splitter 23. This led luminous flux is reflected and then made incident on an objective lens 25 via a lambda/4 plate 24 to be focused on an optical disk 1. |
