| 摘要 |
PURPOSE:To simplify the constitution of an optical memory device and to secure an access to a target position at a high speed, by unifying a recording layer which performs the record or reproduction by means of a light beam with a position detecting layer which can detect the spot position of the light beam. CONSTITUTION:The light beam given from a laser light source of an optical memory device 1 is turned into parallel luminous fluxes 2. These fluxes are condensed and irradiated in a spot form by an objective lens 3. This condensed beam forms a focal point to an optical recording layer 4 and a part of this layer 4 is used as a position detecting layer 5 for beam spot formed on the rear side of a detector. Then photodiode faces 6A and 6B are formed on both sides of a square silicon substrate of high resistance of the layer 5. The pairs of electrodes 7X and 7X' and 7Y and 7Y' for detection of two-dimensional positions are provided at the sides opposite to the faces 6A and 6B respectively. Then the detection currents are extracted out of photocurrent extracting lead wires 8X and 8X' and 8Y and 8Y' to speed up an access to the target position. |
